STRUCTURE magazine | August 2014

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE

®

August 2014 Steel/Cold-Formed Steel NCSEA 2014

Annual Conference New Orleans, LA September 17–20

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CONTENTS

FEATURES Fault Line Pipelines

35

August 2014

By Stephanie A. Wong, P.E. S.E. The 78-inch and 96-inch-diameter Bay Division Pipelines 3 and 4 are two of the major regional transmission pipelines in the San Francisco Public Utilities Commission’s Hetch Hetchy Regional Water System. These two pipelines cross the Hayward Fault at the intersection of a major interstate freeway and a state highway. To address this area of vulnerability in the system, a seismic retrofit program was initiated for the two pipelines to ensure that water delivery continues after a major earthquake.

Atrium Roof Structural Artistry

38

By John P. Miller, P.E., S.E. and Marc A. Friedman, P.E., S.E. Most structural engineers are creative, but they are not often thought of as artistic. Once in a great while, a design team and an owner come together, and the whole is truly more than the sum of its parts. This was the case with the new Knight Hall and Bauer Hall on the Danforth Campus of Washington University in St. Louis.

Full Metal Jacket – Part 2

42

By D. Matthew Stuart, P.E., S.E., SECB and Richard H. Antoine III, P.E., S.E.

By Larry Kahaner Structural engineers are starting to see wisps of the cloud. What has become common in many industries – working from the cloud – is beginning to see daylight among those engaged in construction. Read how software vendors are approaching changes in technology for 2014 and beyond.

DEPARTMENTS Awakening Young Minds to Structural Engineering

By Craig E. Barnes, P.E., SECB and Jennifer dos Santos

62 Professional Issues Deferred Submittals – Part 2

Exclusively published for the practicing structural engineer

STRUCTURE

®

By Dean D. Brown, S.E.

August 2014 Steel

SPECIAL

SOFTWARE

SECTION

9 Structural Licensure 10 Obstacles to Meaningful Licensing of Structural Engineers

By Marc S. Barter, P.E., S.E., SECB

12 Structural Economics Engineering Costs Out of the Steel Project

By Joseph Penepent, P.E. and Phillip Knodel, E.I.

16 Building Blocks Modern Timber Connections

20 Structural Performance Modern Construction: Standing Solid on Shaky Ground

By Jerry Hatch, P.E.

24 Code Updates

By John “Buddy” Showalter, P.E., Bradford K. Douglas, P.E., Philip Line, P.E., Peter J. Mazikins, P.Eng and Loren Ross, E.I.T.

28 Historic Structures B&O Railroad Bridge at Harpers Ferry – 1836

32 InSights Post-Installed Anchors

Recognizing Outstanding Structural Engineers

74 Structural Forum Certification as a Bridge to Structural Licensure

By Timothy M. Gilbert, P.E., S.E., SECB

A work of structural art… the atrium roof for the Olin Business School at Washington University in St. Louis.

Courtesy of Alan Karchmer. See feature article on page 38.

By Carrie Johnson, P.E., SECB

By Frank Griggs, Jr., D.Eng, P.E.

67 Spotlight

ON THE COVER

Topics That Structural Engineers Can Really Use

2012 WFCM Changes

Working from the Cloud

60 Education Issues

7 Editorial

By Eric Karsh, M.Eng, P.Eng

Part 1 of this series discussed the investigation of an existing timber-framed, multi-story building, that is over one hundred years old, and the resulting evacuation of the occupants due to an unsafe condition. This installment discusses the nature of the deterioration observed and the solutions considered for repair.

45 Special Section

COLUMNS

Publication of any article, image, or advertisement in STRUCTURE® magazine does not constitute endorsement by NCSEA, CASE, SEI, C 3 Ink, or the Editorial Board.

Authors, contributors, and advertisers retain sole responsibility for the content of their submissions.

STRUCTURE magazine

5

August 2014

By Neal S. Anderson, P.E., S.E. and Donald F. Meinheit, Ph.D., P.E., S.E.

57 Structural Forensics Engineering Evaluation of Fire Damage to Concrete Foundations

By Peter Marxhausen, M.S., P.E.

IN EVERY ISSUE 8 Advertiser Index 52 Resource Guide (Software) 64 InBox 68 NCSEA News 70 SEI Structural Columns 72 CASE in Point

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Editorial

Topics That Structural Engineers new trends, new techniques and current industry issues Can Really Use

By Carrie Johnson, P.E., SECB, NCSEA President

I

Laissez les bon temps rouler!

’m very excited about the upcoming 2014 NCSEA Conference in New Orleans. This year, we once again focused on putting together a schedule of well-known speakers with topics that the practicing structural engineer can really use, and we continued last year’s practice of offering concurrent sessions that allow attendees a choice between topics. We also have several receptions, giving attendees the opportunity to meet and mingle with other practicing engineers and leaders of our industry. Plus, New Orleans is a great location – one of the most fascinating places you can visit!

The formal program begins on September 18 with our keynote speaker, Kelly Riggs with Vmax Performance Group. Mr. Riggs is a powerful speaker and dynamic trainer in the field of leadership, development, and strategic planning and will present Prepare Your Practice: Why Your Strategic Plan is Doomed to Fail featuring tips on how to create an effective strategic plan for your business or organization.

This will be followed by a presentation given by a panel of speakers from NCSEA’s Code Advisory Committee entitled Prepare for the Future: Where Codes and Standards are Heading and promises to include lively discussion. Then Bill Coulbourne with the Applied Technology Council will present Prepare for the Unthinkable – Designing Buildings for Tornadoes. The presentation will use information recently developed from research and disaster assessments to illustrate how to perform calculations for buildings that are expected to survive a tornado.

After lunch, we begin our concurrent sessions. The first two sessions will be titled ACI 562 Building Code for Repair of Existing Concrete Structures and Wind Engineering Beyond the Code. Keith Kesner, a Senior Associate with WDP & Associates in New York and Chair of the 562 Code Committee, will speak about the development of the ACI 562-13 Code for evaluation, repair and rehabilitation of concrete buildings. Roy Denoon, with CPP Wind Engineering Consultants in Fort Collins, will speak about unique wind cases not covered by the code and provide insight on how to analyze these structures.

Our next two sessions are titled 2012 National Design Specification for Wood Construction Overview and Three Diverse Adaptive Reuse/ Renovations. Michelle Kam-Biron, who is director of Education for the American Wood Council, will provide an overview of recent changes to the NDS code. Bill Bast, a Principal with Thornton Tomasetti in Chicago, will speak about the unique challenges faced on adaptive reuse projects. Our last two concurrent sessions on Thursday will be AISI Standard & Tech Notes and High Roller Observation Wheel.

Vince Sagan, Chairman of the Cold-Formed Steel Engineers Institute (CFSEI), will focus on CFSEI’s recent Tech Note developments, intended to aid design engineers in the application of the AISI code.

Brandon Sullivan with ARUP in San Francisco will discuss the unique design constraints and challenges faced designing the new Las Vegas High Roller – the world’s largest observation wheel at 550 feet with a maximum capacity of 1,120 passengers.

Friday morning, attendees can choose to either sit in on a presentation where each of the 44 NCSEA Member Organizations will provide updates on recent activities, or several presentations given by the vendors exhibiting at our trade show. The remainder of the morning will feature a panel discussion led by the NCSEA Young Member Group Support Committee, entitled Student to Teacher – Gaining STRUCTURE magazine

Competency after the University. The session will focus on technical training programs and will include young engineer panelists as well as established structural engineers.

After lunch, we will have a presentation titled The Most Common Errors in Wind Design & How to Avoid Them given by Emily Guglielmo, an Associate with Martin/Martin in San Francisco and a member of the ASCE 7 Committee. Her presentation will include information on the future of the wind load provisions and how the practicing structural engineer can help focus the direction of the code. Following this presentation, we have The Most Common Errors in Seismic Design & How to Avoid Them. It will be given by Tom Heausler with Heausler Structural Engineers in Kansas City and a member of the ASCE 7 Seismic Provisions Committee. He will cover both low and high seismic design areas and how to avoid misapplication of the code.

Our next session, Practical HSS Design with the Latest Codes and Standards, will be presented by Kim Olson with FORSE Consulting in Eau Claire and a technical advisor to the Steel Tube Institute. The presentation will include a look at novel uses for HSS members, available software, and a look at potential upcoming changes to HSS design and capabilities. Our final presentation will be Practical Steel Connection Software Design Using 2010 AISC Standard. Our speaker, Steve Ashton with Ashton Engineering & Detailing in Kansas City and a former senior engineer with AISC, will focus on designing connections, including tips on how to quickly evaluate software results.

Friday evening, attendees will want to go to the NCSEA Banquet and Awards Presentation. The NCSEA Excellence in Structural Engineering Awards program celebrates our profession by annually highlighting some of the best examples of structural ingenuity throughout the world. The program also includes awards given out to engineers who have made outstanding contributions to the structural engineering profession.

We finish up on Saturday morning with the Annual Meeting of NCSEA’s 44 Member Organizations. This is an open meeting and includes reports on the activities of NCSEA’s committees. It is always interesting to hear updates highlighting the hard work everyone is doing to enhance our profession.

What started out as a meeting between the member organizations of NCSEA has grown to be so much more. To reflect this, it is our intent, starting next year, to call this the Structural Engineering Summit. I hope all of you will consider joining us. Registration discounts are available for young members (under 36) and first time attendees. Young members can also apply for scholarships.

For more information, visit www.ncsea.com. I hope to see you in New Orleans! Laissez les bon temps rouler!▪

7

August 2014

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Albina Co., Inc...................................... 37 American Galvanizers Association ......... 65 Atlas Tube ............................................. 34 Baldridge & Assoc. Structural Engin. .... 13 Bentley Systems, Inc. ............................. 75 CADRE Analytic .................................. 33 Canadian Wood Council ....................... 53 Clark Dietrich Building Systems ........... 11 Design Data .......................................... 44 Enercalc, Inc. .......................................... 3 Engineering International, Inc............... 17 Gerdau .................................................. 23 Integrated Engineering Software, Inc..... 66 Integrity Software, Inc. .......................... 33 ITW Red Head ....................................... 6

KPFF Consulting Engineers .................. 41 Lindapter .............................................. 19 LNA Solutions ...................................... 43 MMFX Steel Corporation of America ... 29 National Concrete Masonry Assoc......... 31 Nemetschek Scia ................................... 47 New Millennium Building Systems ....... 15 Powers Fasteners, Inc. .............................. 2 PPI (Professional Publications, Inc.) ...... 25 PT-Structures ........................................ 33 Ram Jack Systems Distribution ............. 50 RISA Technologies ................................ 76 S-Frame Software, Inc. ............................ 4 Simpson Strong-Tie............................... 49 Soc. of Naval Arch. & Marine Eng. ....... 61

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tructural engineers in certain parts of the country have practiced under a separate licensing law for many years, most under a title act, not by choice, but by compromise. Two states have full practice acts limiting the practice of structural engineering to structural engineers and architects, also a compromise. The number of U.S. jurisdictions that place some form of limitation on the practice of structural engineering beyond the typical “practice within one’s area of expertise” is less than 25% overall.

Why do so few choose the level of protection for the public that licensing structural engineers can provide?

The following are ten potential obstacles to obtaining meaningful regulation of the practice of structural engineering. Every group seeking a change in the licensing laws will encounter at least some of these obstacles. The concept that engineers should only practice within their areas of expertise is a dubious means of regulating a profession with such a direct relationship to public safety and is tantamount to changing interstate speed limit signs to read, “Be safe.”

1) Apathy. The vast majority of engineers practicing structural engineering are disinterested in the issue of structural licensing, as evidenced by just how few structural engineers associations have active committees working to secure it in some form. Without a groundswell from the profession, any licensing movement takes on the persona of a mission of zealots and gatekeepers. To succeed, the profession must become fully engaged in the effort – intellectually, politically, and with a commitment of time and treasure.

2) Management. Large engineering concerns are usually multi-disciplined, with structural engineers comprising a small department or division within the organization. Very large firms, the ones most likely to have political connections, are often publicly traded companies whose management may not be engineers. They answer to a board of directors elected by stockholders, and focus on profit and growth. Additional regulation brings additional expense, which in turn reduces earnings. Unfortunately, with the consolidation of the industry, the support of these entities is close to mandatory. The significance of opposition from industry to professional engineering licensure has already been demonstrated in the form of industrial exemptions in state licensing laws.

3) Public Indifference. Without images in the news of death and destruction, and their correlation to the actions of unqualified engineers, the public is not likely to have much interest in the regulation of the practice of structural engineering. The public takes notice when there are events such as earthquakes,

associating structural engineers with better designed buildings, translating into increased public safety and reduced property damage.

Structural engineers in places directly affected by this natural phenomenon have been able to leverage such public awareness and get licensing laws passed. Many U.S. jurisdictions with equally devastating natural disasters have yet to correlate bad design with increased damage and utilize public awareness to pass licensing laws. Public education is the answer, but by whom and at what expense?

4) Organizational Dysfunction. Within the last 18 months, SEI, NCSEA, SECB, and CASE have joined together to promote structural licensure under the auspices of the Structural Engineering Licensure Coalition (SELC). Up until now, each organization has supported the concept to a different degree and extent.

SEI and CASE are subsidiaries of larger groups – ASCE and ACEC, respectively – and their endorsement of the concept reflects their political realities. In the past, civil engineers have generally opposed any practice restrictions, and ACEC is a business-based organization that looks at regulation with a critical eye. By contrast, NCSEA is autonomous and has supported structural licensure unequivocally, while SECB is a credentialing organization that was established with the stated goal of securing structural engineering licensure in all U.S. jurisdictions. The four groups have now come together with a unified voice to endorse structural licensure as a post-P.E. credential for “certain structures.” While this development is promising, and the compromise position of a post-P.E. license is surely more palatable to the general engineering population, the litmus test for success will be the number of jurisdictions that adopt structural licensure in the future and the role that SELC takes in making that happen. A national coalition could provide significant assistance to state associations if funded properly and focused accordingly.

5) Licensing Boards. Licensing boards are varied in their makeup, from those that regulate only the practice of engineering to ones that regulate engineers, surveyors, architects, geologists, etc. It stands to reason that the more generic the board, the more difficult the sell for special treatment for structural engineers, who are a very small segment of the engineering profession. Illinois has about 11,000 licensed professional engineers and 1,300 licensed structural engineers residing in the

STRUCTURE magazine

Structural licenSure issues related to the regulation of structural engineering practice

10 Obstacles to Meaningful Licensing of Structural Engineers

9

By Marc S. Barter, P.E., S.E., SECB

Marc S. Barter, P.E., S.E., SECB (mbarter@barterse.com), is the president of Barter & Associates, Inc., a structural engineering consulting firm in Mobile, Alabama. He is a past president of NCSEA and current member of the Alabama Board of Licensure for Professional Engineers and Land Surveyors.

state, suggesting that just 12% of licensed engineers practice structural engineering.

There are about 420,000 licensed engineers in the U.S., and applying the Illinois ratio leads to the conclusion that there are about 50,000 who practice structural engineering. Licensing boards are wary of the potential for increased costs and difficulties associated with discipline-specific licensing, as well as the signal that “special treatment” of structural engineers could send to the other disciplines. Without an overwhelming mandate from structural engineers, board support is unlikely to be forthcoming; and without board support, changing the laws will be much more difficult, if not impossible.

6) Regulation. The United States has become a hostile environment for new regulations. While structural engineering licensure is insignificant when compared to Sarbanes-Oxley, the Affordable Care Act, and Dodd-Frank, it still constitutes new regulation and thus will be opposed on principle by many people, especially the more conservative members of a legislative body, regardless of their overall understanding of the proposition. The more conservative the legislative body, the less likely new regulations affecting business will be embraced without overwhelming evidence that public safety is at stake, and even then it can be a hard sell. It is essential that politicians be educated on the amount of public protection afforded by structural engineering licensure, and that other stakeholders, such as the insurance industry and building officials, be supportive of the process.

7) Politics. Structural engineers tend to be apolitical. As a rule, those firms that have an interest in state politics express it through membership in the state ACEC organization. State ACEC organizations expend their political capital on business issues such as infrastructure funding, tort reform, and quality-based selection.

Licensing of structural engineers is not a popular issue for business because it costs money and is, therefore, somewhat counter to ACEC’s mission. Additionally, these organizations count as members of large civil and multi-disciplined firms who may view structural licensure as a restrictive impediment. Given the current trends in engineering organization membership, ACEC’s state organizations may well become the de facto representative of engineers in general and, due to their broad composition and familiarity with the political system, the voice to which

the politicians listen. Therefore, soliciting and receiving the active support of a state’s ACEC organization is imperative.

Active opposition can spell the end for any structural licensure effort.

8) Money. One undeniable fact is that the passing of laws generally requires money. It can take attorneys to write the legislation, especially if it is a completely new law, and it can take a lobbyist to promote the passage of the law. Some structural engineers associations have had success with their own grassroots efforts, but these have typically been in areas of high seismicity where the routine shaking of buildings serves as a reminder to the public and its representatives that just saying “be safe” is not the answer. An impediment to raising money is that many engineers are cheap. We do not like to spend money, and it can take lots of money to get a law passed. No doubt it will take a national effort to raise the funds for a single state initiative; improbable, but not impossible. If each structural engineer contributed $10/year to a political action committee, with the stated goal of securing structural licensure where it does not currently exist, many of the obstacles listed in this article could be overcome.

9) Aversion to Change. Engineers generally do not like change. We like symmetry, consistency, uniformity, and predictability. We generally want today to be the same as yesterday and tomorrow to be the same as today. Structural engineers who currently make a living with a P.E. license often see very little need to distinguish themselves with a structural license or SECB credential, especially if it costs money. Colleagues who practice in other disciplines are even more averse to changing laws to suit one discipline. The motivation to change is not there and, in fact, the natural tendency to oppose this change is strong. This is very difficult behavior to modify, but it is necessary if structural engineering licensure is to receive broad support. We need to view regulation of the profession in the same vein that we are forced to view the practice of the profession. We no longer use slide rules, T-squares, vellum, Kroy machines, or moment distribution. They are not appropriate solutions, and generic licensing is no longer an appropriate solution for the protection of the public. We, as the engineering profession, have to realize that and embrace the change.

10) Other Associations. It would be simple if a single organization’s opposition to structural licensure were the only impediment

STRUCTURE magazine

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August 2014

to states passing such laws. Currently, NSPE, with the recent compromise that would make the structural license a postP.E. credential, is more an opponent of the past than of the future; but associations of the other disciplines and subsets of those disciplines can be just as vocal in their opposition. For structural engineers, the P.E. is not the Holy Grail; prestige comes with a structural license or the SECB credential. That is not the case for other disciplines. Many licensed engineers never design a thing, never seal a drawing or a document, or actually practice engineering at all. Their Holy Grail is the P.E. license.

They hang the certificate on the wall, put P.E. after their names, and are very proud of it. They are defensive when it comes to any change that lessens its significance. The challenge for structural engineers wanting to pass licensure laws is to identify these associations – especially at the state level – then educate them and attempt to eliminate them as an opponent.

On a more positive note, one major obstacle of the past is gone, and an opportunity has replaced it. The elimination of the NCEES Structural I and Structural II exams leaves structural engineers with only one test to take, and that is the new 16-hour exam. In the past, state licensing boards could assume that they were properly testing structural engineers when they allowed them to pass the Structural I for licensure as a P.E. Now licensing boards are left with only one correct choice, requiring structural engineering candidates to sit for the 16-hour exam. The Alabama and Georgia boards of licensure have gone on record stating that structural engineers who seek licensure as PEs should take the 16-hour structural exam.

It would be very good for the structural licensure movement if all jurisdictions adopted this approach. In the interim, structural engineering employers who routinely pay for their employees to take P.E. exams can make it office policy for their structural engineers to take and pass the 16-hour exam.

If getting structural engineering licensure laws passed was easy, there would not be 48 states without a full practice restriction and 40 states without a restriction at all (roster designations aside). Recognizing obstacles and addressing them is prudent strategy in any endeavor. The ten obstacles presented here are probably the most significant, and all of them can be overcome. It has been over 100 years since Illinois passed the first structural engineering licensing law. If we recognize the obstacles and methodically address them, it will not take another 100 years to finish the process.▪

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teel joist and deck systems are already an efficient means of construction, but there are ways an engineer can design these systems more efficiently and cost effectively. Techniques include designing support framing to maximize deck strength utilization, selecting seat sizes to accommodate long joist top chord extensions, detailing of moment and axial connections in rigid frames, improving detailing coordination, and deciding between ASD and LRFD design methodologies.

Optimizing Joist Framing to Maximize Deck Utilization There are two ways to specify the loading for joists. Either choose a standard Steel Joist Institute (SJI) designation with its accompanying total load (TL) and live load (LL) capacities, or specify all applicable design loadings with a base TL/ LL designation. The latter specifying method allows for the most economical joist design. The joist will be designed specifically for the needs of the project. Deck design, however, only allows for standard designations to be chosen. The properties and capacities listed in manufacturer provided load tables cannot be changed, disregarding base material changes. The best way to maximize the utilization of a chosen deck size and section is to utilize the allowable loads and maximum construction spans indicated in the deck tables. In doing so, the specifying professional is taking full advantage of the deck strength, resulting in fewer joists, less steel to buy, lower transportation costs, and shorter erection time. For example, consider a given design load of 25/30 psf, dead/live load respectively, a joist span of 50 feet, a girder span of 40 feet, and a common joist spacing of 5 feet. Using the economic joist tables (Figure 1) we get 30K10 as an economical joist. Now if we re-orient the joist while staying within the maximum construction span for the deck, and try a 6-foot 8-inch joist spacing, an economical joist is 32LH07. The entire bay weight for the 5-foot joist spacing is 11,980 pounds and the entire bay weight for 6-foot 8-inch joist spacing is 9,960 pounds. This yields a 16.8% weight savings and an estimated erection savings of 22%.

Another consideration is to evaluate the capacities of the roof deck for higher yield strengths for given spans. For example, standard B deck has a minimum yield strength of 33 ksi, though materials with higher yields are available. American Iron and Steel Institute (AISI) material standards limit the maximum design yield stress to 60 ksi.

On larger projects, instead of increasing deck gage, engineers should consider contacting the

Engineering Costs Out of the Steel Project 5 Steps to Improved Steel Joist and Deck Design

By Joseph Penepent, P.E. and Phillip Knodel, E.I.

Joe Penepent, P.E. (joe.penepent@newmill.com), specializes in joist and deck customer application engineering for New Millennium Building Systems.

Phillip Knodel, E.I. (phillip.knodel@newmill.com), is a joist and deck design engineer at New Millennium Building Systems.

12 August 2014

Figure 1. Excerpt of economical joist design table.

deck manufacturer for the option of specifying a higher yield strength. In most cases, a stronger steel deck will be more economical than a thicker steel deck gage of lesser yield strength. For example, consider a roof design load of 100 psf, a triple span condition, and a 6-foot joist spacing. Typically a B20 deck section would be specified with the standard 33 ksi yield strength, but when considering increasing the yield strength to 40 ksi, a B22 deck would be sufficient. If this option is chosen, the material requirements must be noted clearly on the contract documents so the deck coil can be properly sourced for the minimum required yield and carried out through the entire project. The use of non-standard material strengths is most effective in situations where the deck section with standard material strength is almost sufficient in capacity, but still falls short. Non-standard yield strength selections may result in additional cost and/or additional required scheduling time.

The impact on both cost and schedule is greater on smaller projects than it is on larger projects.

Another deck sourcing option for larger projects is the use of alternate special deck gauge. For example, a 500,000 square-foot building using 20 gage B deck has an approximate weight of 490 tons. By using 21 gage B-deck instead, the approximate weight of the deck is lowered by 40 tons (now to 450 tons total). As with non-standard material strength requirements, non-standard gages may result in additional cost and/or additional required scheduling time, but result in an overall lower construction cost. Coordinating with a deck manufacturer early in the design process will minimize these issues.

Selecting Appropriate Joist Seat Sizing

Detailing of Moment and Axial Connections in Rigid Frames

Figure 2. SJI standard load table for top chord extensions.

Benefits of Improved Detailing Coordination

chords have a relatively low moment capacity. When these eccentric loads become large, chord designs will generate larger sections and/ or expensive chord reinforcement. The most economical way to design for these induced axial loads is to provide a direct load path from the chords to the support or to another abutting member. The alternate load path will reduce or eliminate the eccentric moment in the joist or joist girder chord. It is preferred that the specifying engineer design the tying mechanism between the chords and/or support. In doing so, the specifying engineer will have more control over his or her design, require less coordination with the joist manufacturer and obtain the most economical joist or joist girder. Some example connections are indicated in Figure 4 (page 14).

Also, visit www.steeljoist.org/design_tools to access free moment connection design tools, provided by the Steel Joist Institute.

At present, there is a need for more communication between suppliers, engineers, architects, and fabricators. Often, structural contract drawings are incomplete. Drawings are missing dimensions and loads, have “canned” notes which do not apply to the project, or have contradicting requirements in the notes and project specifications. These and other issues can lead to project delays, contingency fees, and occupancy income loss.

The RFI process, which must handle the drawing issues, is intended as a valuable way of opening communication, expediting fabrication and delivery, and preventing additional project costs. When the joist manufacturer is brought into the design process early in a project, the specifying engineer can make use of the

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Using joists and joist girders as part of a rigid moment frame is common. It can often provide an economic advantage to the project as compared to wide flange beams in moment frames, or using steel braced frames or concrete shear walls. The axial loads induced by the rigid moment frame develop secondary moments (M=+/- P x Ecc.) in the joist chords, especially when the load path is through the joists seats and column connection. Joist and joist girder

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Top chord extensions (TCXs) are a common feature in most structures. They are excellent elements for spanning small bays adjacent to the main spans, and for providing a cantilevered ledge over the edge of a building. TCX’s tend to be fairly unfavorable at shallow and longer lengths. The SJI K-Series standard seat depth is 2½ inches and, therefore, joist top chords are limited to angles with 2½-inch legs or less.

The specifying professional can simply verify acceptable load and length limits by referring to the SJI standard load table for joist top chord extensions (Figure 2). In Figure 2, notice that as the length of the extension increases, the load per foot capacity decreases. If the specifying professional’s design criterion falls outside of the limits listed in the SJI table, a change to the seat design will need to be coordinated with the joist manufacturer. Design loads may be achieved by simply increasing the seat depth. K-Series joists are designed for a maximum allowable uniform load of 550 plf. Per the SJI table, for a 4-foot 6-inch span, the TCX can support a 550 plf load, though this is possibly not the most efficient design. For example, consider a 30K10 joist with a 50-foot span and a TCX to be designed for 550 plf. If the 30K10 joist has a standard 2.5inch seat depth, the total joist weight will equal 810 pounds. This same joist with an increased seat depth of 3.5-inch will have a total weight of 710 pounds. With a 5-inch seat depth, the weight is reduced further to 695 pounds. Using the deeper seat depth of 5 inches results in an approximate 14% weight savings. With a shallow seat depth, the size of the top chord (TC) angles are controlled by the loading on the TCX, not by the loading of the main span.

The deeper seats allow for the main span of the joist to control material sizing of the TC. See Figure 3 (page 14 ) for general seat schematics and section properties.

Figure 3. Joist seat size examples.

engineering experience of the manufacturer to create the most efficient joist and deck system.

This increased collaboration fosters increased communication between the different parties on the project and allows for the manufacturer to think creatively about engineering from the standpoint of cost-reduction.

A major subject of communication between the project designer and the joist manufacturer is the issue of non-uniform loading.

Some common non-uniform loadings include snowdrifts, roof top mechanical units, screenwalls, cranes, folding partition walls, fall arrest systems, fire sprinklers, parapet bracing, and wind uplift. The best way to communicate special loadings is to include them in load diagrams with appropriate “Tag End” or gridline labels. Using well-labeled and dimensioned loading diagrams clearly communicates to the joist manufacturer what loads to design for, and where to exactly locate them.

Commonly, the final positions of nonuniform loads are not known until late in the production schedule. In these situations, there are several techniques that can be used to allow the joist manufacturer to properly design for the final loading. A concentrated load can be applied in a zone across the joist.

The load would be specified with a location dimension and an accompanying +/- length dimension. The joist chord would need to be reinforced in the field at the final load location with a field vertical if the load did not land at an existing panel point. If the location is not known at all, the concentrated load can be specified to land at any panel point or at any point along the chord. A load located at any point would not require field panel point reinforcement; however, if it is located along the chord, it would increase the section size of the loaded chord to resist local bending.

For non-uniform loading, the more location information that is provided, the more efficient the joist design can be.

Roofs will typically require design for snowdrift and uplift forces. Supplying the joist manufacturer with net uplift drawings instead of “component and cladding” loads will save detailing time and shorten the approval process. Clearly indicating snowdrift loads on the

drawing, and whether the drift loading has already been included in the design, will also save time.

If moving loads from cranes or folding partition walls need to be specified, multiple load cases and load locations must be provided to the joist manufacturer to allow for the proper design of the joists. For crane loads, it is very important to include the Crane Manufacturers Association of America classification (A, B, or C) or the estimated lifetime loading cycles, the impact loading, and the operating method of the crane in question, as this information is required for the fatigue design of the joists.

When considering joists supporting dynamic loads such as these, it is also important to specify whether any special camber or deflection requirements are required, as they can change joist size requirements significantly.

Coordinating information about loading early and completely to the joist manufacturer will speed up the design process and limit the extent of RFIs on a project.

ASD or LRFD Design For some time now, the Steel Joist Institute has provided ASD (Allowable Strength Design) or LRFD (Load Resistance Factor Design) load tables. The specifying professional should indicate on the contract drawings which design method was chosen for the design. When specifying the LRFD method, it is necessary to provide factored loads on the drawings, as well as to state that the loads are factored. When specifying a girder, remember to provide the total factored load and designate the girders with “F” instead of the “K” designation, which will help distinguish that the load has already been factored. For example, a girder designation in ASD would be 50G8N10K and the same designation in LRFD would be 50G8N15F. Joists built to the same SJI joist designation will have the same weight, regardless of which design methodology was used to select them.

The required SJI joist designation, however, may differ for the same required TL/LL loading depending upon which design methodology is used. If a TL/LL designation is specified, any joists could see savings. The simplest way to

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Figure 4. Axial load tie examples.

determine which design method will provide the most value is to examine the ratio of dead loads to live loads. For exceptionally light dead loads, an ASD design is more than likely to produce a lighter joist. When the live loading is less than three times the dead loading, the LRFD design method would produce the lighter joist. For example, consider a joist with a 50-foot span, 6-foot spacing (roof application), a DL of 20 psf (120 plf), and a LL of 30 psf (180 plf). Using the LRFD design method, the required factored load capacity for the joist is (1.2*DL+1.6*LL) = 432 plf. For this span and loading, a 30K10 would be the most economical joist (Figure 1).

The self-weight of a 30K10 is 11.5 plf. Using the ASD design method, the required service load capacity for the joist is (DL+LL) = 300 plf.

For this span and loading, a 30K11 would be required (Figure 1). The self-weight of a 30K11 is 13.1 plf, which is 1.6 plf heavier than the LRFD chosen 30K10. An important note to remember when deciding on a design method is that the methodology must remain consistent across all joists on a project. The cost savings across the entire project must be considered, not the individual savings on a small area.

Summary These techniques, when used individually, can have small impacts on the economy of the steel joist and deck system. However, when used together and used often, the cascading savings will lead to shorter project schedules, less re-work, fewer joists to erect, and lower material pricing. Partnering with a joist and deck manufacturer early in a project will bring in more expertise and experienced engineers who can help you design the most efficient joist and deck system possible.▪

Specify New Millennium. We are your unparalleled resource for competitive structural steel solutions. Nationwide engineering, manufacturing and supply of standard and special profile steel joists, plus steel decking for roof and floor applications.

Building Blocks updates and information on structural materials

U

ntil the middle of the 19th Century, wood was commonly used as a primary structural building material in many types of non-residential buildings around the world. Many of these timber-built structures remain standing and are still in use today, including factories, warehouses, schools, temples, and churches – some dating as far back as the seventh century. Famous examples include the 106.6-foot (32.5 meter) high Horyu-ji Temple in Nara, Japan, which demonstrates the durability and strength of building with wood.

With the industrial revolution came significant evolution in steel and concrete technology, and these materials, popularized by construction of revolutionary projects such as the Eiffel Tower and new “skyscrapers” in America, took over as materials of choice for large and important projects.

As a result, timber has more or less been relegated for use as a material for smaller structures. And with the development of efficient and versatile light wood-frame construction monopolizing the low-rise residential market in North America, wood initially all but lost large portions of the non-residential construction market to steel and concrete.

Over the past two or three decades, however, timber engineering and construction has experienced significant and transformative advances,

Modern Timber Connections

By Eric Karsh, M.Eng, P.Eng, StructEng, MIStructE, Ing

Eric Karsh, M.Eng, P.Eng, StructEng, MIStructE, Ing, is a founding principal of Equilibrium Consulting Inc., a structural engineering consulting firm located in Vancouver, BC. Eric has designed a number of innovative, award winning timber structures, and is co-author of the Tall Wood report. Eric can be reached at ekarsh@eqcanada.com.

HSK connector at the fully cantilevered atrium stair at UBC Earth Sciences Building. Courtesy of Equilibrium Consulting.

setting wood products up for a comeback. These include new engineered wood products, including solid panel products such as cross-laminated timber (CLT), computer numerically controlled (CNC) fabrication, versatile high-efficiency timber connectors, and progress in fire protection engineering. With technical progress and increased demand for wood products comes greater economic opportunities.

Today the most ancient construction material, and the only one that is naturally grown by the sun, is becoming more high-tech and still has considerable development potential in store.

This technical progress seems to have combined with other positive influences to reposition wood on the world stage. A renewed interest in timber as an architectural medium, combined with strong trends in sustainability, is promoting the expanded use of wood in several countries including Canada, the U.S., Japan, Australia and several countries in Europe. Emboldened by these trends, timber is slowly but surely reclaiming its place as a viable option for commercial construction in a wide variety of building types including airports, museums, university facilities and even skyscrapers.

Timber Connection Options

Cantilevered atrium stair at UBC Earth Sciences Building. Courtesy of Martin Tessler.

16 August 2014

Key to the successful execution of large timber structures is the availability of economical, versatile and reliable connectors. The different timber connection systems available are comparable to individual tools in a toolbox.

As an engineer looking for innovative, elegant solutions, one needs a toolbox with a variety of reliable and high-quality tools. Some of these were covered previously in STRUCTURE’s January 2007 article, New Concealed Connectors Bring More Options for Timber Structures; however, several new options have been added in the time since then. The North American toolbox for wood connections is the first of four main compartments: standard through bolts, screws and nails, timber rivets, truss plates and

pre-engineered light gauge metal connectors. These are all longstanding inductees of local codes and are well known to most.

This does not include North American style split rings and shear plates, which are specified less frequently today.

In compartment number two, we find connection systems that are not explicitly covered by building codes but can be designed within the scope of the codes using first principles.

These include castings, shear keys, wood-towood notches and steel-to-wood notches.

The third compartment includes generic connection systems, which are not covered in North American codes but are officially recognized in reputable foreign codes such as the Swiss, German or Eurocode. These include tight-fit bolts and pins and ring nails.

The final compartment houses state-of-theart proprietary systems that are supported by empirical data and usually by foreign (European) codes and approvals. These require careful review and, occasionally, local testing.

The National Design Specification® (NDS®) for Wood Construction 10.1.1.3 states, “Connection design provisions…shall not preclude the use of connections where it is demonstrated by analysis based on generally recognized theory, full-scale or prototype loading tests, studies of model analogues or extensive experience in use that the connections will perform satisfactorily in their intended end uses.” The Canadian standard includes similar provisions.

The proprietary systems the author’s firm engineers have used the BVD or Bertsche

system developed by German engineer Peter Bertsche, the SFS WS system by SFS Intech, the HBV and HSK adhesive-based system by TiComTec and developed by Dr. Leander Bathon, the Sherpa or Pitzl aluminum dovetail systems and finally, but not least, the very versatile self-tapping screws.

The following are a number of modern connector types, all of which the author’s firm has used and continue to use. North American connectors are well known to most and will not be discussed in detail here.

Wood-to-Wood Bearing Connections The entire family of wood-to-wood bearing connections are an ancient way to transfer shear and compression loads in timber.

They used to be done by hand and required skill and time to fabricate. They fell out of favor over the last century, but are making a comeback with the use of CNC equipment.

Direct bearing is often the most efficient way to transfer heavy shear and compression loads in wood, and appropriately designed notches, used in combination with selftapping screws, can be a very cost effective connection solution.

Where notches are required, they should be designed from first principles using the bearing and shear formulas of the code. As a matter of standard practice, ensure that the longitudinal shear portion of a connection, particularly at the end of a member, is proportioned so as not to be the primary failure mode, as it is brittle.

STRUCTURE magazine

Castings Castings, usually made of Ductaline steel, are also designed from first principles. They offer an elegant, very versatile way to achieve architecturally important connections, and can be relatively economical in large numbers.

Their drawback is that they are susceptible to fire and cannot be used in exposed conditions in a rated assembly.

Tight-Fit Bolts and Pins Tight-fit bolts are essentially regular bolts installed in bolt holes, both in timber and connecting steel plates, which are drilled to much tighter tolerances. The Eurocode requirement for tight-fit bolts is to have a bolt hole which matches the bolt diameter or is up to 0.5 mm smaller. The bolt hole in the steel must be less than 1.0 mm larger than the bolt diameter. Tight-fit pins, often used for high-end exposed connections, must meet

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Stainless tight-fit dowels and steel castings at the Prince-George Airport. Courtesy of MacFarlane Green Architecture.

Terminal 2 at the Raleigh Durham Airport with BVD moment connections. Courtesy of Brady Lambert.

3D model of a BVD moment connection at the Raleigh Durham Airport. Courtesy of Equilibrium Consulting.

HSK connector being test-fitted for the fully cantilevered atrium stair at UBC Earth Sciences Building.

Courtesy of Structurlam Products.

the same requirements, and usually consist of a headless stainless steel shaft with slightly chamfered edges.

The advantage of tight-fit dowels is that the connectors can be relied upon to take the load at essentially the same time, mostly eliminating group effects. A very high degree of accuracy is required, and CNC fabrication is almost always required to achieve a multiple fastener tight-fit connection, particularly with multiple knife plates.

Tight-fit pins are the basis of many proprietary connections, some of which are discussed below.

system’s strength and reliability is enhanced by the intersecting dowels, which help contain the wood fiber and resist splitting force.

Ultimate loads of 2.5 to 3 times the specified loads are consistently achieved. The system is very efficient for high-tension connections, to carry direct axial loads.

The system is completely tight-fit and therefore can be used in groups without concerns for group effects. It is also concealed by the wood and therefore resistant to fire.

Ring Nails Ring nails are Europe’s version of timber rivets.

Shiny and having a round head, they look somewhat tidier than timber rivets. The Swiss code provides specific guidelines based on empirical data for achieving ductile connections. One proprietary ring nail connection system is called the Gunnebo nail from Sweden.

The WS System by SFS Intec The proprietary WS System by the billiondollar Swiss fastener company SFS Intec, consists of self-drilling, small diameter dowels equipped with a drill tip designed to core through wood and 3 to 5 mm mild

The BVD System by Bertsche The BVD system is a proprietary connector developed and sold by engineer Peter Bertsche of Germany. The system consists of a grooved, drop-forged insert, locked into place by intersecting 16 mm diameter (0.63-inch) tight-fit pins. The cavity is grouted solid with a high-performance cementitious grout to ensure a completely tight-fit load transfer between the dowels and the cast insert. The insert is threaded on the end and can receive a bolt supplied with the insert. Alignment tolerances are dealt with using a spherical washer.

BVDs come in six sizes, normally installed in the shop with 4 (BVD 1) to 24 pins (BVD 6), and can carry a specified pull-out load of 13 to 80 kips (60 to 360 kN) per anchor. The

Pre-engineered dovetail connection and HSK wood concrete composite connection at the UBC Earth Sciences Building. Courtesy of Equilibrium Consulting.

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steel internal plates. The pin is driven using a hydraulic press sold by the company.

The advantages of the system are that it requires no pre-drilling, avoids fabrication tolerances and is completely tight-fit. It is ductile, yet very compact due to the small diameter of the pins (5 to 8 mm), and is concealed – making the system fire resistant. The system is quite efficient and versatile, and can be used in shear, axial or moment connections.

Self-Tapping Screws Self-tapping screws are the space-age version of the North American lag screw. They are now sold in North America by four major suppliers: SFS, GRK, Wurth and Heco. They are the main connector type now used in solid wood panel construction.

Self-tapping screws are proprietary, selfdrilling screws made from high strength (around 115ksi or 800 MPa) steel, and come in a wide variety of sizes from 3/16 to ½-inch (5 mm to 12 mm) in diameter and 3 to 23 inches (8 cm to 60cm) in length. The diameter refers to the diameter of the thread, not the shaft.

There are three major types of self-tapping screws. Fully threaded screws are used to transfer large tension loads in wood-to-wood connections without the need for a washer plate. Partially threaded screws are used to anchor steel bearing plates and can transfer shear as well. They have great clamping capacity. Variable pitch screws are used to pull two pieces of wood together and are often used in solid wood panel edge-to-edge connections to align the panels and transfer longitudinal shear.

Self-tapping screws are extremely versatile, efficient, and reliable, as they require no pre-drilling. They eliminate the risk that an inexperienced carpenter may not drill and counter bore a lag screw hole correctly.

Pre-Engineered Aluminum Dovetail Connections Aluminum dovetail connectors are preengineered aluminum dovetail inserts, normally installed in the shop using selftapping screws, allowing for timber elements to be very rapidly and accurately erected on site. There are two main suppliers for this type of insert, both represented in North America: Pitzl and Sherpa.

The inserts come in a variety of sizes and capacities. They are recessed and completely concealed by the timber material, making the connection completely invisible and also fire resistant.

The HBV and HSK Connector The HBV and HSK connectors were both developed by German engineer Leander Bathon. HBV is a connector used to achieve wood-concrete composite floor systems. It consists of an expanded steel mesh glued into a saw cut on the top of the timber beam or solid wood panel using a proprietary adhesive, and cast into the concrete above, rigidly connecting the two together.

The HSK system is similar, but is used to connect steel elements to wood or, occasionally, to connect two wood elements together.

It consists of a 2.8 mm (approximately 3/32inch) perforated steel plate, welded to a steel part in the case of a steel-to-wood connection and glued into a kerf in the timber element, rigidly connecting the two members.

The HSK system is ductile, as the steel parts are usually designed to yield before the adhesive or the wood fails. It can also be completely concealed and therefore resistant to fire.

Growing Market for Timber Applications The North American timber construction industry has transformed signifi cantly throughout history – and even more rapidly in the past decade alone. At the turn of the 20 th century, steel and concrete widely replaced wood in the construction of commercial buildings. A century later, technical advances in fabrication techniques and connection engineering, coupled with a renewed interest in timber as an environmentally friendly building material, have driven renewed interest in the building material. Wood products are being re-examined for new opportunities, in a wider range of building types and reaching greater heights than ever before.▪

Cantilevered atrium stair at UBC Earth Sciences Building. Courtesy of Martin Tessler.

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The Hollo-Bolt 5 Part Fasteners are similar, except that they include a nitrile rubber washer and separate collar. ® Figure 1 provides a picture of the Hollo-Bolt 3 Part and ® Hollo-Bolt 5 Part. Table 1 provides part codes, design strengths, and installation information.

EVALUATION SUBJECT: ®

HOLLO-BOLT FASTENERS

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Structural 2.0 USES ®

Fasteners are designed for connecting Hollo-Bolt structural steel to hollow structural section (HSS) steel members and other structural steel elements where ® access is difficult or restricted to one side only. Hollo-Bolt fasteners are intended for use with rectangular or square HSS members and are recognized for resisting static tension and shear loads in bearing-type connections. The fasteners are alternatives to bolts described in Section J3 of AISC 360, which is referenced in Section 2205.1 of the IBC, for bearing-type connections.

The Hollo-Bolt® Fasteners may be used to resist wind loads, and seismic loads in Seismic Design Categories A, B and C. 3.0 DESCRIPTION

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A Subsidiary of the International Code Council ® slits 90 degrees from each other. The collar is a circular element having two flat surfaces (to accommodate an open-ended wrench) with a circular hole integral with the sleeve. The cone is a steel circular internally threaded nut with grooves on the outer surface.

Nominal Hollo-Bolt® sizes include 5/16 inch (M8), 3/8 inch (M10), 1/2 inch (M12), 5/8 inch (M16), and 3/4 inch (M20), with each size of bolt available in three lengths.

Hollo-Bolt 3 Part Fasteners are assembled from three components, consisting of the core bolt, the body (sleeve) including the shoulder (collar), and the cone. The steel core bolt features a threaded shank and hexagonal head.

The body is a steel segmented hollow cylinder, with four

3.2 Materials: 3.2.1 Set Screw: The core bolt is manufactured from steel complying with EN ISO 898-1, Class 8.8, having a specified Fu of 116,030 psi (800 MPa).

3.2.2 Body (sleeve) with Integral Collar, Body (sleeve without collar), Collar and Cone: The parts are manufactured from free cutting carbon steel Grade 11SMn30 or 11SMnPb30, conforming to BS EN 10087, having a minimum tensile strength of 62,400 psi 2 (430N/mm ) (sizes up to LHB16) or 56,500 psi (390N/mm2) (size LHB20); or cold drawn steel AISI C10B21, having a minimum tensile strength of 2 68,000 psi (470N/mm ).

3.2.3 Rubber Washer: The measured on the A scale 80-90.

shore

hardness

is

3.2.4 Finish Coating: All components, except the rubber washer, are hot dipped galvanized/high temperature galvanized to BS EN ISO 1461, as described in the quality documentation.

4.0 DESIGN AND INSTALLATION 4.1 Design: The fasteners are alternatives to bolts described in Section J3 of AISC 360, which is referenced in Section 2205.1 of the IBC, for bearing-type connections. The design of the Hollo-Bolt® Fasteners must comply with this report, Section J3 of AISC 360 and the strength design information for the Hollo-Bolt® provided in Table 1 of this report. The load-carrying capacity of the assembly depends on the fasteners, the type of elements connected, such as a HSS and its their cross

ICC-ES Evaluation Reports are not to be construed as representing aesthetics or any other attributes not specifically addressed, nor are they to be construed as an endorsement of the subject of the report or a recommendation for its use. There is no warranty by ICC Evaluation Service, LLC, express or implied, as to any finding or other matter in this report, or as to any product covered by the report.

1000

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Visit www.LindapterUSA.com to download the full Evaluation Report today.

STRUCTURE magazine

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August 2014

Structural Performance performance issues relative to extreme events

L

ife safety has always been a fundamental goal of U.S. building codes. With the introduction of the International Building Codes (IBC) in 2000, new demands have been placed on engineers, manufacturers and builders who produce structures in earthquake-prone regions. Prior to the IBC, engineers were accustomed to designing buildings to prevent damage such as buckling and yielding. Today, the challenge is to better understand what happens after buckling and yielding, up to and including collapse. Life safety through the avoidance of earthquake-induced collapse is the approach today’s engineers must take to accomplish the intent of the code for structures in areas with high seismic activity. This change in design objective spurred much needed research and testing in the industry.

There are numerous ways to determine when a building will reach collapse. The most advanced of these are complex, lengthy and ill-suited for use in a production design setting.

Fortunately, the IBC code writers had the foresight to include a simplified method for production settings that approximates building behavior when considering collapse for common systems made of concrete, masonry, steel and wood structures. Since 2000, Metal Building Manufacturers Association (MBMA) has been working to extend the knowledge base contained in the code by researching the particular phenomenological, or characteristic, behaviors (such as buckling and yielding) of moment frames with tapered members subject to earthquake-induced

Modern Construction: Standing Solid on Shaky Ground New Advances in Design and Testing for Seismic Demands

By Jerry Hatch, P.E.

shaking. The objective has been to quantify how tapered member frames behave after buckling and yielding, and then to confirm or develop new factors and limits for design.

Framing the Situation Moment frames make up a key force-resisting system in any building. For decades, MBMA and its member companies have been designing buildings with moment frames containing tapered members with the objective of precluding yielding and buckling within a margin of safety. Today, most companies design for seismic demands using the simplified method contained in the IBC. Seismic performance factors (SPFs) in building design are simplified and approximate methods of accounting for post-peak behavior exhibited when buildings are subject to strong earthquake shaking. Post-peak behavior occurs after buckling and yielding, but before collapse. More advanced methods of analysis include inelastic pushover and inelastic dynamic analysis methods that consider post-peak behavior, and then set an adequate margin of safety against collapse. The FEMA P695 document illustrates a detailed analysis method used to generate seismic performance factors for simplified design.

Steel ordinary moment frames (OMF) are used by the industry where allowed by the code. Steel OMF SPFs have been used to address a wide range of building configurations. Steel OMFs, in general, are expected to exhibit limited ductile behavior and, therefore, have limits placed on design. For example, steel OMFs in Seismic Design Category D are limited to building heights up to 65 feet with a roof dead load that does not exceed 20 psf and a wall dead load does not exceed 20 psf above 35 feet.

Jerry Hatch, P.E., is manager of engineering development for NCI Building Systems and past chairman of the Metal Building Manufacturers Association Technical Committee.

Jerry may be reached at Jerry.Hatch@ncigroup.com.

A 60-foot wide steel building tested during the MBMA and AISI sponsored Moment Frame Seismic Study at the University of California San Diego in Spring 2011. The study included three frames placed on the largest shake table in the U.S. to better understand how metal buildings behave when subject to earthquake loading.

20 August 2014

Ductility is important in building materials because it allows dissipation of the energy introduced by an earthquake through damage to the structure. It changes the physical behavior of the structure, thereby reducing the damaging effects of the shaking.

Said another way, ductility is the ability of an element to sustain large amounts of damage prior to developing degrading behavior.

Ductile behavior is not only important in preserving life safety but also in producing economical buildings.

Researchers and engineers in the metal building industry have long felt that better differentiation was needed in the simplified method to characterize building types produced by MBMA. The MBMA has been working to fully understand the post-peak behavior exhibited by the frames produced.

Therefore, the industry is using detailed testing and analysis to develop appropriate SPFs and limits for tapered member moment frames for a range of applications.

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Understanding Behavior MBMA, under the guidance of Lee Shoemaker, Ph.D., P.E., F.SEI, MBMA’s director of research and engineering, has been working to better understand the phenomenological behaviors of metal building components which have contributed to metal buildings’ faring well in recent major California earthquakes, like those in Loma Prieta in 1989 and Northridge in 1994. The low level of damage experienced by metal buildings in those seismic events can be attributed – in large part – to their low rise and lightweight. MBMA does produce structures with heavier loads such as buildings with tiltwalls and mezzanines. For these structures, seismic loads have a large influence on design.

A multi-year research program is now underway to help researchers and engineers understand why metal buildings perform so well, and to take full advantage of the benefits of these structures. To better understand ductility in metal buildings, MBMA initially sponsored full-scale push over and shake table tests at The University of California at San Diego (UCSD). Chia-Ming Uang, Ph.D., and graduate student Matt Smith, performed initial research on tapered member frames.

These tests determined that low-rise buildings with metal roofs and wall panels exhibit a large degree of over-strength for seismic loads.

In addition to metal buildings with roof and wall metal panels, shake table tests were also performed on a frame with tilt-wall panels and a frame with a mezzanine. During the test, lateral-torsional buckling (LTB) followed

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results, it may also be appropriate to use a patterned vertical load to reflect wide span rafter behavior subject to lateral loads.

Smith also developed a fundamental period equation that approximates low-rise building behavior more closely than the approximate options currently contained in the codes for all building heights.

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A close-up of the panel zone, showing buckling sustained during the shake table testing at the University of California San Diego in Spring 2011. The building actually survived 300 percent of its design load.

by flange rupture was observed in the rafters of these frames, along with damage found in the panel zone and at the column base plates.

The most ductility in the frames tested was attributed to the dissipation of energy in the panel zone. The LTB of frame rafters allowed redistribution of lateral load to a more stable configuration. These initial frame tests will provide data for future studies and ideas.

Redistribution of load was another interesting observation resulting from the shake table tests. Once LTB occurred in a rafter of single span frames, the load on the frame was redistributed. Smith noticed the single span frame behaved like a three-pinned arch after LTB, which is a stable configuration. With load applied to the right side, the right rafter developed LTB. When the load was reversed, the LTB in the right rafter straightened out and LTB occurred in the left rafter. Again, the result was a stable three-pinned arch. The different unbraced lengths at the top and bottom flanges of the rafter made this possible. The extent of this behavior has yet to be determined, but doing so will help to predict behavior all the way to collapse.

Based on observations during the shake table tests, it was concluded that rafter LTB would be useful in evaluation of when a building will collapse. The decision was made for UCSD to perform 10 rafter component tests in order to gather the data to calibrate rafter LTB postpeak behavior models, which will be useful in the more advanced analyses.

Through the shake table tests, unanticipated rafter vertical behavior was observed. The code currently requires a uniform vertical load be applied to frame design, which approximates the vertical motions of an earthquake. Based on the observations of the shake table test

A major goal of the metal building industry is to numerically define the behavior and ductility available in the frame components. MBMA, through their research efforts, has gathered data to model LTB in rafters. These data provide some of the building blocks for the detailing, design and construction of tapered members intended to preclude collapse under code prescribed seismic loading. Focuses of current studies were determined from observations of the shake table testing of three full-scale single span buildings.

Modeling for the panel zone, beam-tocolumn connections and column bases still needs to be addressed. Data collected from the shake table testing was used to create models that characterize panel-zone behavior in the test frames, but it needs to be extended to accommodate all the panel-zone geometries produced by MBMA member companies. Connection modeling is well under way. The metal building industry has been studying bolted beam-to-column connections for the past 40 years. Tom Murray, Ph.D., P.E., professor emeritus at Virginia Tech, and others have provided multiple research papers describing bolted connections subject to static and dynamic loading.

This connection research contributed to the development of the AISC Steel Design Guides No. 4 and No. 16. Work is underway at Virginia Tech by Matt Eatherton, Ph.D., and Murray to expand the applicable configurations addressed in Design Guide No. 16.

Tapered rafters attached to columns tend to move the location of first damage (LTB) away from the column. Due to this behavior, the industry feels that AISC Design Guide No. 16 connections are adequate for tapered member rafters since the first damage is not adjacent to the connection. The connections used in the shake table testing were designed using the AISC Design Guide No. 16 and performed well when load was applied.

Many distinguished researchers have studied column base modeling, including Bora Gencturk, Ph.D., at the University of Houston. He is working to understand the level of stiffness available in column bases

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accessible to the engineer in production design of metal buildings and to observe post-peak behavior of these elements. He is also researching the pinned assumption, or when the connection is free to rotate but not free to translate, and at what point it no longer adequately models actual frame behavior in the column base configuration.

For metal building frames, it is a conservative assumption that the column base is pinned, especially when estimating building drift.

The implications on the foundation are of more concern.

Putting the Pieces Together Once post-peak models of appropriate elements are generated, FEMA P695 modeling can begin. The benefit of this analysis comes from quantifying the post-peak behavior of appropriate elements. Shoemaker assembled a peer committee to oversee efforts to perform a P695 analysis. The peer committee, composed of Greg Deierlein of Stanford University, Tom Sabol of Englekirk and Sabol, Mark Saunders of Rutherford & Chekene and Mike Engelhardt of The University of Texas, attended the UCSD shake table testing to provide insights and recommendations.

The task of P695 modeling is not isolated to one building or one type of building.

The range of products offered by MBMA member companies is large and several different groups of SPFs will need to be better understood, including the following types of buildings: single span, multi span with light metal panel wall, walls clad with tiltpanels, brick, and masonry. Heavy roof loads or crane loading, along with buildings with mezzanines, are also on the agenda to be investigated. Once MBMA has obtained numerical modeling of appropriate components, the effort of inelastic pushover and dynamic analysis begins. Only then will researchers truly understand the ways different buildings behave up to and including collapse.

It is important for engineers to understand that the limits placed on systems in the building code as part of the simplified procedure were placed there for a reason. It was the judgment of the experienced engineers who wrote the limits, and designing beyond them should only be done through the P695 methods of analysis. MBMA is closer than ever before to understanding how tapered member frames behave up to and including collapse.

Accomplishing this goal will give the industry more flexibility in design with appropriate limits set on these systems.▪

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Code Updates code developments and announcements

T

he Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings was updated and is designated ANSI/AWC WFCM-2012 (Figure 1). The 2012 WFCM was developed by the American Wood Council’s (AWC) Wood Design Standards Committee and is referenced in the 2012 International Residential Code (IRC) and 2012 International Building Code (IBC).

The WFCM includes design and construction provisions for high wind, seismic, and snow loads for connections, wall systems, floor systems, and roof systems. A range of structural elements are covered, including sawn lumber, structural glued laminated timber, wood structural sheathing, I-joists, and trusses.

Primary changes to the 2012 WFCM are listed here, and are subsequently covered in more detail: • Design load provisions are updated per ASCE/SEI 7-10 Minimum Design Loads for Buildings and Other Structures • Wood structural panels are permitted to resist wind uplift • Shear wall story offset provisions are clarified • Design values for lumber, structural glued laminated timber, and fasteners are in accordance with the 2012 National Design Specification® (NDS®) for Wood Construction and 2012 NDS Supplement: Design Values for Wood Construction • Engineering design of horizontal diaphragm assemblies and vertical wall assemblies are in accordance with Special Design Provisions for Wind and Seismic, ANSI/AWC SDPWS-2008 • Wind exposure categories B and C are incorporated together in Chapter 3 prescriptive provisions • Header tables include both “dropped” and “raised” header conditions

2012 WFCM Changes

By John “Buddy” Showalter, P.E., Bradford K. Douglas, P.E., Philip Line, P.E., Peter J. Mazikins, P.Eng and Loren Ross, E.I.T.

John “Buddy” Showalter, P.E., is Vice President of Technology Transfer, Bradford K. Douglas, P.E., is Vice President of Engineering, Philip Line, P.E., is Director of Structural Engineering, Peter J. Mazikins, P.Eng, is Senior Manager of Engineering Standards, and Loren Ross, E.I.T., is Manager of Engineering Research with the American Wood Council. Contact Mr. Showalter (bshowalter@awc.org) with questions.

ASCE 7-10 Load Provisions Tabulated engineered and prescriptive design provisions in WFCM Chapters 2 and 3, respectively, are based on the following loads from ASCE 7-10: • 0 to70 psf ground snow loads • 110 to 195 mph 700-year return period, 3-second gust basic wind speeds • Seismic Design Categories A-D

Figure 1. Wood Frame Construction Manual (WFCM) for One- and TwoFamily Dwellings, 2012 Edition.

Ground snow loads in the WFCM take into account both balanced and unbalanced snow load conditions. Unbalanced snow load provisions were revised in ASCE 7-05 which resulted in reduced loads (O’Rourke 2006). Those provisions are relatively unchanged in ASCE 7-10, resulting in net reductions to snow loads where unbalanced cases govern.

All seismic-related tables in the 2012 WFCM are updated to new ASCE 7-10 seismic provisions.

New risk-based maps generally reduce areas of highest seismic risk along the New Madrid fault and in the Charleston, SC area. Revised map contours will influence Seismic Design Categories of some geographic areas.

Revised wind speed maps are on a “strength design” basis. Wind speeds are higher, but load factors for design are also adjusted so that the net effect will be a reduction of wind pressures in some regions (Line 2011). There are separate wind speed maps for each Risk Category in the code, and Exposure D will become applicable again in hurricane prone regions.

When basic wind speeds from ASCE 7-05 are used, the value shall be converted to the ASCE 7-10 basis using the Table.

While the 90 mph wind speed zone from ASCE 7-05 and the 2012 IRC covers approximately the same geographical area as the 115 mph wind speed zone in ASCE 7-10, the Table shows a slight difference of 116 mph versus 115 mph due to rounding in the direct conversion from the ASCE 7-05 basis to the ASCE 7-10 basis.

The local authority having jurisdiction should be consulted to determine whether conversion to a 115 mph basis is permissible.

Wind speed conversion.

ASCE 7-05 Basic Wind Speeds based on 50 yr. return period 3 second gust (mph) The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

85

90

100

110

120

130

140

150

Equivalent ASCE 7-10 Basic Wind Speeds based on 700 yr. return period 3 second gust (mph) 110

116

129

142

24 August 2014

155

168

181

194

Wood Structural Panels Resisting Wind Uplift Walls sheathed with wood structural panels can be used to resist uplift alone, or simultaneously resist uplift and shear from wind forces.

These provisions were adapted from the 2008 SDPWS (Coats 2010). Section 3.2.3 of the 2012 WFCM now contains provisions for the use of certain wood structural panel shear walls, with a list of requirements for installation and illustrations for nailing. Capacities are based on provisions in the 2005 NDS and have been verified by full scale testing.

The primary characteristic of this method is increased nailing of panels to framing to provide a continuous load path and enable uplift loads to be transferred to existing wall anchorage at the foundation. A desire to investigate the inherent uplift capacity of nailed wood structural panel shear walls was the impetus for development of this design method.

In the last two decades, as design standards have evolved to address losses associated with high-wind events, designers and home builders have been challenged by the substantially “beefed up” methods and equipment required to resist wind forces. Among the concerns is the number of tie-downs required for shear

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Setback Offset

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Shear Wall

Triple Joists, 2x8 or Larger, at Shear Wall Ends

Shear Wall Tension Strap to Resist Overturning

Twist Tension Straps d

Blocking Required Shear Wall Cantilever Offset

Figure 2. Shear wall story offset limits.

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Offset ≤ d (℄ of Stud to ℄ of Stud)

walls, which can present both cost increases and practical construction challenges.

Traditional methods of providing for uplift resistance with additional tie-downs at shear walls can be cumbersome and expensive.

An integral Appendix of the 2012 WFCM still contains uplift strap and ridge strap capacity tables for those wishing to maintain that option.

Shear Wall Story Offsets Shear wall story offset provisions were clarified in the 2012 WFCM. Shear wall segments are

permitted to be offset out-of-plane from the story below by a maximum distance equal to the depth, d, of the floor joists (Figure 2, page 25), where all of the following conditions are met: • Upper and lower story shear wall segments are attached to the floor diaphragm through wall plate to blocking connection and wall plate to band joist connections • Floor diaphragm wood structural panel sheathing is nailed to blocking and band joist at 6 inches on-center.

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• Allowable unit shear capacity for the shear wall above does not exceed 436 plf for wind or 239 plf for seismic • Floor joists supporting the shear wall are nominal 2x8 or larger, tripled at ends of shear walls, and provide support for loads from roof and ceiling only • Continuous load path is provided for uplift and overturning.

Design Values Design values for structural lumber, structural glued laminated (glulam) timber, and fasteners were incorporated in the integral Supplement of the 2001 WFCM. The 2012 WFCM now references the 2012 NDS Supplement for lumber and glulam design values. For fastener design values, the 2012 NDS is the reference standard.

Shear Wall and Diaphragm Design Design properties for horizontal diaphragms and shear walls were incorporated in the integral Supplement of the 2001 WFCM. The 2012 WFCM now references the 2008 SDPWS for engineered design of shear walls and diaphragms.

Prescriptive tables in WFCM Chapter 3 still contain shear wall and diaphragm tables similar to the 2001 WFCM.

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Wind Exposure B & C Tables Wind Exposure C tables were incorporated in a separate Appendix in the 2001 WFCM. The 2012 WFCM now integrates Exposure B and C tables together in the prescriptive provisions of Chapter 3.

More Details A comprehensive table listing section by section changes to the WFCM, including modifications to Supplement and Appendix material, is available at www.awc.org.

Conclusion The 2012 WFCM represents the state-ofthe-art for design of one- and two-family dwellings for high wind, high seismic, and high snow loads. Its reference in the 2012 IBC and 2012 IRC will allow for its use in those jurisdictions adopting the latest building code.▪ Download at uspconnectors.com/specifier

This article originally appeared in the Winter 2012 issue of Wood Design Focus published by the Forest Products Society and is reprinted with permission.

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STRUCTURE magazine

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August 2014

Historic structures significant structures of the past

T

he Baltimore & Ohio Railroad broke ground in Baltimore, Maryland on July 4, 1827 and planned on running from Baltimore to the Ohio River along the Potomac River to Cumberland, Maryland. After delays at Point of Rocks due to a right of way conflict with the Chesapeake and Ohio (C&O) Canal, it arrived at Sandy Point, across the river from Harpers Ferry, on December 1, 1834. The Virginia Free Press reported, Monday last, will be remembered by the citizens of Harpers Ferry as an important one in its history. On that day, at half past 2 o’clock, P. M. a locomotive came thundering up to the bridge, drawing after it a train of cars carrying nearly a hundred passengers…the hand of man has cut a pathway through the cliffs that had been considered impregnable; and he has constructed causeways to bear him in safety, where he and his steel had trembled at the dashing billows.

A four span wooden bridge built in 1829 by Lewis Wernwag as a toll bridge for James and Catherine Wager crossed the river at the time. Wernwag also built a wooden three arch deck bridge across the Monocacy (Monoguay) River in 1831 for the B&O. It was the first wooden bridge to carry railroad traffic in the United States. The Frederick Herald reported of this bridge, We here present our readers with a description of the splendid bridge or viaduct, over the Monocacy, constructed by Lewis Wernwag, Esq. whose reputation as a scientific bridge-builder no one will question. The bridges constructed by him in various parts of the country have long been celebrated for their beauty, strength and scientific adaptation to the difficulties encountered – but we regard that which we are now about to describe as his ‘chef d’ouevre’ which will long remain a monument of his genius, and the discrimination of the directors in assigning its erection to his judgment and experience.

In addition to many bridges across the Susquehanna River, etc., he built the Colossus Bridge across the Schuylkill River (STRUCTURE, June 2014). The C&O Canal arrived at Harpers Ferry in 1833 and the Frederick-Harpers Ferry Turnpike arrived in 1832. As a part of the right of way settlement between the B&O and C&O, the canal was given the right to extend its line along the easterly bank of the river, forcing the B&O to cross the river and reach Cumberland along or westerly of the west bank of the river.

Construction was underway on the Winchester and Potomac (W&P) Railroad with Moncure Robinson as Chief Engineer. It connected Winchester, Virginia with Harpers Ferry to the north. Construction on the C&O was proceeding

B&O Railroad Bridge at Harpers Ferry – 1836

By Frank Griggs, Jr., Dist. M. ASCE, D. Eng., P.E., P.L.S.

Dr. Griggs specializes in the restoration of historic bridges, having restored many 19 th Century cast and wrought iron bridges. He was formerly Director of Historic Bridge Programs for Clough, Harbour & Associates LLP in Albany, NY, and is now an independent Consulting Engineer.

Dr. Griggs can be reached at fgriggs@nycap.rr.com.

28 August 2014

up the left bank of the Potomac past Harpers Ferry towards Cumberland. A bridge, strong enough to carry a railroad, was badly needed by the B&O to pick up traffic from the W&P and continue its route westerly to Cumberland and thence to the Ohio River.

In the summer of 1834, Benjamin Latrobe (the son of Benjamin Latrobe, an early architect/engineer in the United States) of the B&O, along with Robinson, began looking into using Wager’s bridge. Since the entrance to the bridge from the east required a 90-degree left hand turn, which a railroad could not navigate, they decided it wasn’t feasible. The B&O decided, …to construct a substantial viaduct across the Potomac, on the prolonged trace of the Winchester road and capable of permitting the passage of locomotive engines, with their usual trains, to which the present bridge is wholly incompetent. Contracts for this purpose have already been entered into, and it is expected that the viaduct will be completed nearly in the ensuing summer. The piers, six in number, with their abutments will be of undressed masonry, and the superstructure of wood. Its entire length including the portion crossing the Chesapeake and Ohio Canal will be 830 feet.

Philip Thomas, the President of the B&O, along with John Bruce, President of the W&P, determined the cost of a new bridge on this alignment “would be $85,000, not all that much more than the cost of paying Wager to use his bridge; $15,000 for the privilege of laying a track over it (on which he planned to levy tolls) and building a depot on his land, and $25-30,000 for reconditioning the structure…” Even with their own bridge, it had to be on Wager’s land and they had to recognize Wager’s right to carry toll passengers, carriages, etc. across the river on it. It wasn’t until July 15, 1835 that a contract was prepared which met all of the Wager’s demands.

At the time, they did not know how they would be leaving Harper’s Ferry to the west, so they went straight across the river and tied into the projected line of the W&P tracks with W&P to build the westerly abutment and the B&O to build the rest of the bridge. Jonathan Knight, Chief Engineer of the B&O, reported to the Board, The plan of a viaduct to be erected across the Chesapeake and the Ohio Canal and the Potomac river at Harper’s Ferry, has been designed chiefly by my late assistant, B. H. Latrobe. The mason work of this structure which is (besides other uses) to form a connection between the Baltimore and Ohio and the Winchester and Potomac Railroads, has already been contracted for and it is intended likewise to contract for the superstructure of, which is to be of wood, as soon as practicable; in order the entire viaduct may be finished in the shortest time possible.

In Latrobe’s diary, he recorded his first meeting with Wernwag at Harpers Ferry, who was then 66 years old. They had been out looking at the bridge site when “a fierce southeast wind, bearing rain, blew through the Potomac passes like a hurricane and chased the surveyors from the river the next day.” Latrobe spent most of the day with Wernwag in his shop, “Examining his models and amusing and edifying myself with his conversation…

Wernwag is certainly a most uncommon man.

His conceptions of complicated machinery are exceedingly clear and ingenious. He is a thorough-bred German in his dialect and manners and knew my father 35 years ago.”

Wernwag and Latrobe arrived at a bridge style, something like the famous Schaffhausen Bridge across the Rhine River in Switzerland built by Grubenmann in 1757, that Latrobe would design and Wernwag would build.

The B&O, based upon the agreement with the Wagers, designed the bridge to serve the railroad, carriages, pedestrians, livestock, and a towpath for the Shenandoah Canal. The towpath was to be added on the downstream side to accommodate canal boats transferring from the Shenandoah River into the C&O Canal. The C&O canal would build an inlet lock to lift this traffic from the Potomac to the canal just east of lock #33. After Latrobe

Bridge with Wye Span and Bollman Truss on W&P line, lower right.

finished his design in mid to late 1835, he left the B&O for a short time to work on the Baltimore and Port Deposit Railroad.

Work began on the bridge in the fall of 1835.

The Virginia Free Press wrote, “A grand piece of workmanship is about to commence at Harpers Ferry. Proposals are to be received in a few days for the mason work of the bridge, which is to be constructed across the Potomac.

It is to rest on seven substantial piers and two abutments – the whole to be erected by the Baltimore and Ohio Railroad Company, except the abutment on this side, which is to be raised by the Virginia Company. This structure, when completed will be regarded with peculiar interest. It will make the two great works of Internal Improvement, and

connect with bands of iron, two independent sister states. The Baltimore Railroad Company may address those States in the language of Virgil, “Conubio iungam stablili” (I will join together in steady union).”

Caspar Wever, Knight’s assistant in charge of all masonry, after receiving bids, awarded the masonry contract to Charles Wilson and Wernwag was given the superstructure work, probably without any competitive bidding as no announcement was published in the Virginia Free Press. On March 31, 1836, the opening of W&P was celebrated along its entire length. With the completion of railroads on both sides of the river, the pressure was on to finish the connecting bridge. Wernwag did not start his work

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Wye Span and original Wernwag/Latrobe truss, top left.

until late summer 1836. After he had his first span up, Latrobe, now back with the B&O, visited the site and wrote in his journal, “it is a beautiful combination of timbers, but the lumber of which it is built is rough stuff.” Latrobe next visited the site in January 1837 after the bridge was completed, but not covered. Upon inspecting the bridge, he determined that the foundations were inferior and suggested wrapping the heads of the masonry piers with iron bands, as well as other remedial work.

The Virginia Free Press reported in early 1837, “We learn that the bridge of the Potomac at Harpers Ferry, for the purpose of uniting the Baltimore and Ohio Railroad with the branch to Winchester, Va. is so far completed that locomotives and their trains have passed over it.” Much work, however, was still required to make the bridge safe and stable. During the repair, no heavy locomotives were allowed on the bridge. There were no problems with the foundations on the span over the C&O Canal, so it was roofed and covered in 1837 while repairs to the river piers were made. Latrobe’s report to the Board in 1838 noted, The wooden superstructure of the bridge has justified the confidence entertained, in the excellence of its principle of construction, the only weakness which it has exhibited, being shown by three of the timbers supporting a part of the flooring, which cracked

during the passage of one of the trains. The recurrence of such a fracture, caused by an accidental imperfection in one to the timbers which failed, will be effectually prevented by the proposed immediate introduction of an additional timber between each of those upon which the floor and tracks depend for their support.

The total cost of the bridge is not known, but it was surely in excess of the $85,000 estimated earlier by Thomas. It is known that the company spent $23,450.60 on the repairs in 1837 and another $5,596.34 later in the year.

In 1839, after the passage of an Act by the Virginia Legislature permitting the line to cross over the Potomac and run through the state to Cumberland, the B&O had to determine its route through the state.

The options were to run about six miles southwesterly on the W&P lines and then northwesterly across Virginia to Cumberland or, after crossing the bridge, run through the Arsenal (Armory) grounds along the westerly side of the Potomac for some distance and then run inland through Martinsburg to Cumberland. The latter route was chosen, but this required a branch to be built into the existing bridge to provide the change in direction of the main line to the north and west. Latrobe solved this problem by designing a two span addition to the bridge that branched off at the second pier from Harpers Ferry. What was called Pier A was

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August 2014

extended 38 feet upstream to accommodate the necessary curvature for the track. The two new spans were called the “WYE span” and the “curved span” and they had a variable width to permit the track to be curved as required. It was at the WYE spans that the rail traffic had to cross over the carriage traffic lanes that followed the W&P line, since they were on the northerly side of the bridge. Gatekeepers were placed to stop all carriage and wagon traffic when a train was passing over the bridge. The remainder of the bridge was not covered until the WYE and curved spans were completed. Latrobe spent a large sum of money in the covering and portal on the Harpers Ferry approach to give the bridge what he thought was a necessary amenity for the community.

There is no evidence that Wernwag was involved in building the WYE or curved spans, even though he did not die until August 1843. Maybe it is just as well that he was not involved, as the bridge failed twice, once in September 1844 and again in March 1845. The failures were due to decay combined with the fact that the very long floor beams overloaded the trusses.

On June 15, 1861, General Joseph Johnson, CSA, upon evacuating Harpers Ferry early in the Civil War, burned the bridge. After the war, all spans were rebuilt with Bollman iron truss spans which survived until the 1890s.▪

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F

ormal concrete anchorage design provisions first appeared in ACI 318-02 as Appendix D, with applications limited to cast-in-place anchors and postinstalled mechanical expansion anchors. The codified design provisions represented a generic approach to anchorage design, which diverged from past design practice of using manufacturers design tables; these tables may or may not have represented all characteristics associated with an anchor’s design capacity.

In 12 years, we have codified anchorage design procedures and developed anchor qualification standards that have greatly raised the reliability bar for anchors used in practical design conditions. So, what is the state of the anchoring industry and where do the codes go from here?

ACI 318-14 The new structural building code (ACI 2014) will be re-organized based on member type. Appendix D will now formally be placed in the body of the Code as Chapter 17. But unlike other chapters in the re-organized Code, Chapter 17 essentially remained an untouched clone of Appendix D. This was a conscientious decision by the 318 Code Committee at the beginning of the reorganization work, because: (1) the Appendix D anchor design provisions are still “relatively new” and (2) there was a desire to keep things the same, as the design profession and university classrooms are just getting familiar with the provisions. The next code cycle will contemplate further additions and layout reorganization.

Post-Installed Anchors The Present State of the Industry

By Neal S. Anderson, P.E., S.E. and Donald F. Meinheit, Ph.D., P.E., S.E.

Neal S. Anderson, P.E., S.E., is a Staff Consultant at Simpson Gumpertz & Heger Inc. in their new Chicago office. He is involved with anchorage issues through his participation on ACI 355 – Anchorage to Concrete, ACI 318-B – Reinforcement, and ACI 318 – Structural Concrete Building Code. Neal may be reached at nsanderson@sgh.com.

Donald F. Meinheit, Ph.D., P.E., S.E., retired from Wiss, Janney, Elstner Associates – Chicago, is the past chair of ACI 355 – Anchorage to Concrete and member of ACI 318-B – Reinforcement. He has been involved with concrete anchorage issues throughout his career and is a frequent lecturer on the subject. Donald may be reached at dmeinheit@wje.com.

Adhesive Anchors This anchor type was accepted by ACI 318-11 in a three-part acceptance format: Design Provisions Adhesive anchors were incorporated into ACI 318 under the premise that the existing design models would be minimally affected. Adhesive anchor design provisions for tension were the only provisions supplemented, necessitating new checks for concrete bond stress. Adhesive anchors loaded in shear behave similar to other post-installed and cast-in-place anchors, and, hence, existing design models and procedures could be used.

Qualification For post-installed mechanical anchors, anchors must be qualified to the criterion in the ACI 355.2 standard (ACI 355 2007). Similarly, adhesives used in ACI 318-11 (2011) anchor designs

32 August 2014

Figure 1. Undercutting of screw threads in concrete (from Olsen, et. al., 2012).

must be qualified in accordance with the ACI 355.4-11 standard (ACI 355 2011). ACI 355.4 is a comprehensive product standard for structural adhesives used for anchoring, modelled after the ICC/ES Acceptance Criteria (AC) 308 (2013). Due to improvements in the ACI qualification document, AC308 was recently revised to conform to ACI 355.4-11, to avoid having the anchoring industry work to two different standards for acceptance.

Certification Based partially on the Boston Big Dig tunnel accident, the adhesive anchor installer must be certified to install anchors in certain orientations and under certain load conditions. This requirement is recognition by the ACI 318 Code committee that adhesive anchor installation needed some oversight qualifications to achieve satisfactory installations, consistent with the written design requirements and anchor manufacturer installation instructions.

The success, or failures, of adhesive anchors are highly dependent on the installer and the procedures employed to install the anchor.

Certification was deemed an important component of adhesive anchor usage, on par with certified welders for welding key structural steel connections. In addition to installer certification, inspection is an important requirement required in ACI 318-11.

The ACI Code provisions are not mandatory unless adopted by the local building code for the given jurisdiction. For states and municipalities using the 2012 International Building Code (IBC 2012), IBC 2012 has adopted ACI 318-11 and ACI 355.4-11. However, the U.S. is under a stepped phase-in period for adoption of the design and qualification of adhesive anchors.

As of 15 January 2014, the following actions were taken: • All adhesive anchor Evaluation Service Reports (ESR) will reference ACI 318-11, Appendix D. This includes the design provisions for bond strength and concrete breakout.

• ESR’s also carry forth several of the code provisions for qualified installation personnel and inspection.

As of 15 January 2015, the following will be required: • Testing referenced in the ESR’s by the manufacturers will conform to the revised AC308, which is essentially ACI 355.4-11.

There are many more nuances to the IBC 2012 and ACI codes referenced and the phase-in situation. Reference should be made to a paper by Hoermann-Gast (2013) for additional information.

Screw Anchors There are a wide variety of post-installed concrete anchors, and the newest postinstalled anchor is the screw anchor. In reality, screw anchors have been around since the early 1990s. They are intended to carry direct tension, direct shear, or combinations of tension and shear loadings. Although the design procedure for screw anchors has not been codified, they are gaining acceptance in building practice

as a reliable fastening element (Olsen, et. al., 2012).

To provide the mechanical interlock to the concrete, the screw anchor cuts a thread into the concrete during the installation process.

This makes the use of screw anchors a singleuse item; removing and reusing the screw anchor in the drilled hole is not advised because the cutting threads on the screw are worn and getting the screw threads into the original cut threads in the concrete is difficult.

In Figure 1, the undercutting of the threads in the concrete is illustrated. The creation of the threads in the concrete gives the screw anchor some advantage in cracked concrete where a small-narrow crack intersecting the threads has only a minor reduction on tension capacity.

Currently, screw anchors fall outside the scope of ACI 318-11 Appendix D and Chapter 17 of ACI 318-14, Anchoring to Concrete. In the next Code cycle, screw anchors will be studied for inclusion.

Research testing of screw anchors has shown that failure can occur in tension via three modes: steel failure, concrete breakout failure, and pullout failure. Pullout failures look

very much like bond failures for adhesively bonded anchors. Pullout failures also occur for screw anchors only when they are deeply embedded. Deep embedments are often difficult to achieve because the friction of cutting a thread can exceed the torsional capacity of the screw shank and fail the steel in torsion.

Consequently, it is recommended that screw anchors be used within a limited embedment depth, that is, 15/8 inches < hef < 11 da.

A design procedure for screw anchors does exist; they can be safely designed using a procedure found in ICC/ES AC193 (2012). The AC193 design procedure follows closely the European design procedures in ETAG 001 (2013). AC193 also outlines the qualification tests required for screw anchors. The ACI qualification standard, ACI 355.2, is being updated to include screw anchor qualification testing.▪ The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

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Fault line PiPelines

Delivering Water unDer Pressure

By Stephanie A. Wong, P.E. S.E.

Figure 1. The slip joint was lowered into the vault by crane. Courtesy of San Francisco Public Utilities Commission, Robin Scheswohl.

I

nstalled between 1952 and 1973, the 78-inch and 96-inchdiameter Bay Division Pipelines (BDPLs) 3 and 4 are two of the major regional transmission pipelines in the San Francisco Public Utilities Commission’s (SFPUC’s) Hetch Hetchy Regional Water System. The system delivers water a distance of 167 miles from the Hetch Hetchy Reservoir in Yosemite National Park across California to the Bay Area, and supplies approximately 260 million gallons per day of drinking water to 2.6 million people in the San Francisco Bay Area. Water is critical to the economic viability of the Bay Area, and the public health and safety of those who live and work there.

BDPLs 3 and 4 cross the Hayward Fault at the intersection of a major interstate freeway and a state highway in the city of Fremont on the east side of San Francisco Bay. The 2007 Working Group on California Earthquake Probabilities, made up of the U.S. Geological Survey and partners, estimated a 31% probability that an earthquake of magnitude 6.7 or greater would occur on the Hayward Fault by the year 2036. Studies by Geomatrix Consultants, Inc. (2004) and William Lettis & Associates (2008) concluded that a major earthquake could cause a significant fault displacement at the project site, which would result in certain rupture of both pipelines and extensive localized flooding and loss of water supply to the Bay Area. To address this area of vulnerability in the system, the SFPUC initiated a seismic retrofit program for the two pipelines to ensure that water delivery continues after a major earthquake.

The Program The first phase of the seismic retrofit program included installing two isolation valve vaults on BDPLs 3 and 4 on either side of the Hayward Fault. This work, which was completed in 2007, provided the SFPUC with the capability of shutting down the pipelines quickly if they rupture at the fault, reducing the extent of flooding and property damage.

The objective of the second phase of the retrofit program, the $78 million Seismic Upgrade of BDPLs 3 and 4 Project designed by URS Corporation (2011), is to ensure continuous delivery of water after a major earthquake. This project spans approximately half a mile between the two previously-constructed isolation valve vaults.

STRUCTURE magazine

Figure 2. Hayward Fault Traces A, B, and C. Courtesy of URS Corporation.

The limited 80-foot-wide right-of-way through a congested freeway interchange and residential neighborhood does not allow for both pipelines to be replaced with parallel pipelines while remaining in service. Also, hydraulic studies showed that post-earthquake service could be maintained with only one of the two pipes remaining in service. Thus it was decided that BDPL 3, the older pipeline, will be replaced with a new welded steel pipeline and BDPL 4 will be retrofitted to limit damage and leakage.

Criteria The seismic design criteria for the project consist of both ground shaking and fault displacement criteria corresponding to a 975-yearreturn-period earthquake, which is the SFPUC standard for critical facilities that need to be operational within 24 hours after an earthquake. The ground-shaking criteria were developed via site-specific probabilistic hazard analysis considering the Hayward, Calaveras and San Andreas Faults, and numerous other subsidiary faults within 31 miles (50 km) of the project site. The resulting design response spectrum has a zero-period acceleration of 1.05g.

A site-specific study including extensive fault trenching and study of historical records was carried out to determine the fault displacement design criteria. At the project site, the Hayward Fault consists of three distinct traces, Traces A, B and C, with defined primary and

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Figure 3. Plan of Trace B fault-crossing. Courtesy of URS Corporation.

Figure 4. Trace B fault-crossing concept. Courtesy of URS Corporation.

secondary rupture hazard zones (Figure 2, page 39 ). To be conservative, it was assumed that all of the expected displacement for a particular trace will occur as a knife-edge displacement anywhere within the primary rupture zone.

Trace A intersects the pipelines under a major interstate freeway and has an expected horizontal displacement of 1 foot and vertical displacement of 0.7 feet. Trace B, the main and central trace, crosses the pipe under a state highway (Mission Blvd.) and has an expected horizontal displacement of 6.5 feet. Trace C intersects the pipe in a residential neighborhood and has expected horizontal and vertical displacements of 0.5 feet. In addition to the large expected displacements, the approximately 45-degree angle at which the pipe crosses the fault traces would cause both compression and rotation forces in the pipe which are much more challenging to accommodate than tension.

zones of Trace B (Figure 3). The design intent is to allow the pipe to rotate at the ball joints and compress at the slip joint to accommodate the fault displacement, while the concrete vault protects the pipe within (Figure 4).

The 20-foot-wide, 18-foot-high, and 305-foot-long articulated vault has 2-foot-thick reinforced concrete walls and slabs and consists of eleven vault segments separated by 6-inch-wide gaps which will allow it to “articulate” to absorb the compression and rotation from the fault displacement. Each vault segment is expected to shift transversely with respect to each other, and to also shift longitudinally to close the gaps. In plan, each of the nine 20-foot-long middle segments is shaped as a 45-degree-angle parallelogram. Both computer analyses by URS Corporation and scale-model laboratory testing at Cornell University showed that vault segments with gaps parallel to the fault perform better than segments with gaps perpendicular to the pipeline.

Inside the vault, the 72-inch-inner-diameter ball joints are installed approximately 200 feet apart and are capable of accommodating 12 degrees of rotation. To the author’s knowledge, these ball joints that were specially fabricated for the project by EBAA Iron, Inc. are the largest ever built. Also specially designed and fabricated for the project, the slip joint is capable of accommodating 9 feet of contraction and 1 foot of extension, as well as an external bending moment of 55 kip-feet and shear of 32 kips which result from the design earthquake.

Since no commercially-available slip joints even came close to meeting these specifications, the SFPUC conducted a nationwide search for qualified suppliers and ultimately contracted with Stress Engineering Services, Inc. to design and build the slip joint.

Inside the articulated vault, the pipe is supported on various fixed, sliding, and guided supports. At the sliding supports, the pipe is welded to a steel-plate saddle with a stainless steel bottom sliding surface. This saddle sits on a concrete pedestal topped by a steel plate with a Teflon (PTFE) sliding surface that will allow the pipe to slide in any horizontal direction.

The four guided supports consist of upside-down W-beam U-frames that reduce the bending moment and shear in the pipe, and allow only axial movement of the pipe in the direction of the slip joint to prevent binding. The section of pipe through the guided supports is strengthened with steel stiffener plates and fitted with stainless steel and Hastelloy sliding plates on four sides (Figure 5 ). The use of the highly corrosion-resistant Hastelloy alloy for the southernmost guided support was necessary to achieve a sliding surface that will maintain its low coefficient of friction long-term in the cold and damp underground vault.

Solutions The BDPL 3 replacement consists of installing approximately 2,175 feet of new welded steel pipe (ASTM A1018 Grade 60) with a wall thickness ranging from 1 to 1.25 inches between the two existing isolation valve vaults. The new pipeline has the same inside diameter of 78 inches as the existing pipeline, except for the section that crosses Trace B which is 72 inches in diameter.

Due to the differing magnitudes of expected displacement at the three traces, three different fault-crossing designs were developed. To accommodate the displacements at Trace A, the new BDPL 3 consists of 1.25-inch-thick-wall steel pipe inside of an existing 114-inchdiameter corrugated metal pipe casing under the freeway that provides rattle space for the pipe to flex and bend in response to fault movement. The annulus between the pipe casing and the pipe is filled with low-density cellular concrete. At Trace C, the new BDPL 3 has 1-inch-thick pipe walls and is buried. This new welded steel pipeline was calculated to have sufficient strength capacity for the relatively minor displacements predicted for Trace C. The large displacement of 6.5 feet expected at Trace B, which would produce a large amount of compression and rotation in BDPL 3, requires a unique and innovative design solution. Design concepts used on previous fault-crossing projects, such as the zig-zag pipeline concept used for the Denali Fault crossing of the Alyeska oil pipeline in Alaska, could not be used for this project due to space limitations.

The resulting fault-crossing design consists of new 1-inch-thick wall welded steel pipe with a ball joint on each side of the fault trace and a slip joint to the north, all installed within an underground articulated concrete vault that spans both the primary and secondary rupture STRUCTURE magazine

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August 2014

Analysis and Testing Since the Trace B fault-crossing concept was newly developed for the project, the SFPUC evaluated its reliability through an extensive program of computer analysis and laboratory and factory testing.

Explicit dynamic finite element analyses of the pipeline were performed using ANSYS to capture the effects of sliding friction and large axial pipeline displacements from both fault displacement and ground shaking. Parametric studies were done to test and optimize pipe wall thickness, location and number of ball and slip joints, and location and number of sliding and guided supports. The design objective was a system that would offer a high degree of seismic reliability with relatively low maintenance.

To vet the articulated vault concept, soil-structure interaction analyses were performed using FLAC 3D (Fast Lagrangian Analysis of Continua) which is an advanced geotechnical software program used for continuum analysis of soil, rock and structural support in three dimensions.

Concurrently, a 1/10 scale model of the vault was built and tested at the Large-Scale Lifelines Testing Facility at Cornell University. Both the computer analyses and the laboratory testing modeled the 6.5-foot fault displacement and confirmed the individual vault segments would shift and rotate to accommodate the expected ground displacement, while leaving enough rattle space for the pipe within.

Lastly, vigorous factory testing of the ball joint by EBAA Iron, Inc. and the slip joint by Stress Engineering Services, Inc. were performed to demonstrate their behavior under the expected fault displacement.

A third full-size ball joint was fabricated for the testing which involved rotating the joint between +8 and -8 degrees while under 200 psi of internal hydrostatic pressure. The slip joint was first hydrostatically tested to 200 psi at the three following static positions: fully extended

Figure 5. Cross-section of guided supports. Courtesy of URS Corporation.

at +1 feet, fully compressed at -9 feet, and in the as-installed position of zero. Then to prove dynamic performance, the slip joint was subjected to a simultaneous contraction of 9 feet, hydrostatic pressure of 125 psi, bending moment of 55 kip-feet, and shear of 32 kips. The rate of the contraction of the test was 6.25 feet in 2.0 seconds, which is the predicted speed of the fault displacement. Both the ball and slip joints performed as designed. Construction of this project by contractor Steve P. Rados, Inc. began in September of 2012 and is expected to be completed in early 2015.▪ Stephanie A. Wong, P.E. S.E., is a licensed Structural Engineer who is the lead SFPUC engineer for the Seismic Upgrade of Bay Division Pipelines 3 and 4 Project.

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Atrium Roof Structural Artistry The Olin Business School at Washington University in St. Louis

By John P. Miller, P.E., S.E. and Marc A. Friedman, P.E., S.E., LEED AP Figure 1. Interior view of completed atrium. Courtesy of Alan Karchmer.

M

ost structural engineers are creative in the sense of finding a structural solution to an architectural challenge, but they are not often thought of as artistic.

Once in a great while, a design team and an owner come together and the whole is truly more than the sum of its parts.

This was the case with the new Knight Hall and Bauer Hall, the new building for the Olin Business School on the Danforth Campus of Washington University in St. Louis. Structural engineer KPFF Consulting Engineers took an active artistic role with the architect in developing a unique roof structure. While there are many interesting structural aspects about this beautiful new $70 Million, 177,000 square foot building to accommodate faculty, numerous large classrooms, a 300-seat auditorium, and a magnificent multi-functional atrium space, the atrium roof structure deserves special emphasis as a work of structural art.

The building footprint is generally U-shaped and organized around a roughly 90- by 90-foot atrium space. Tiered seating is carved from the lower floors of the atrium to create a forum. The architectural firm of Moore Ruble Yudell Architects & Planners of Santa Monica, CA working with Mackey Mitchell Associates and the Owner wanted this space to be light-filled and open, able to host large and small functions, and to serve as an informal gathering space. It was obvious that this place needed to be surrounded by a very special structure, and the atrium roof was to be the architectural centerpiece of the Olin Business School expansion project.

Structural art is defined by three guiding principles known as the ‘Three Es’: Efficiency, Economy, and Elegance. Structures that minimize the use of materials while they safely carry loads are efficient;

STRUCTURE magazine

ones that are less costly in terms of construction are economical; and structures that are pleasing to the eye are elegant. All three of the Es must be present in a structure to be characterized as structural art.

Starting with a blank canvas, the design team seized the opportunity to compose a beautiful glass-covered work of structural art.

Design Constraints The atrium space was to be column-free, so the atrium roof structure would be supported on its perimeter. It was preferred not to have any roof structural systems with a bottom horizontal plane, since this would tend to reduce the soaring volume of the space. The west wall and part of the south wall would be all glass, and the spring-line of the atrium roof structure would be a few feet above the surrounding U-shaped main building. Therefore, there would be no rigid perimeter means to resist horizontal thrust from the roof structure, and these forces would need to be resolved internally. It was also desired to have some roof surfaces angled to the south or vertical to regulate the sun, add ventilation, or to use for solar arrays. Because this roof structure would be on the interior of the building footprint, at the farthest reach from both of the tower cranes, it would be important to be able to erect the structure in small, manageable sections.

Evolution and Symbology of the Roof Form Elegant and mysterious. These were the two words Buzz Yudell of Moore Ruble Yudell used to describe what the atrium roof structure should be within the context of the building. The roof form evolved by studying

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August 2014

Figure 2. Buff sketches showing conceptual evolution of the atrium roof structure.

numerous structural concepts, generally categorized as “compression type” and “flexural type.” Compression type forms rely on stiff perimeter members to resist horizontal thrust and vertical deflections, while the members that span over the space are generally in compression. Several different compression type structural concepts were studied, including wood and steel lamellas, various arched notions, and several configurations of steel domes. All of these roof structures were quite elegant, and they could be made relatively thin and soaring, but they all required uneconomical perimeter framing to resist thrust and deflection. None of them were particularly mysterious, meaning one could look up at it and immediately resolve the forces with the eye.

Flexural type forms rely on bending stiffness of the structure to resist vertical loads. A series of flexural type structural concepts were imagined such as arching trusses, various pin-connected trusses, and undulating flexural members. While these designs minimized the thrust problem and were relatively efficient and economical, they encroached into the volume and were fairly common looking.

A breakthrough came one day with a roll of yellow tracing paper, and sparked a very iterative design process between KPFF and Moore Rubel Yudell. What if two arches leaned on each other? Why not move them to the corners, where the compression could be resolved?

Then the arches were pulled apart, vertical surfaces were created by lowering a roof plane surface on both sides, and the leaning arches became curved trusses. The spaces in between were filled with various forms of flexural secondary members that had very little thrust, which set up an interesting visual hierarchy. Now we had a soaring roof with the spatial focus of a dome, but with a dynamic modern expression. The curved trusses also recall the iconic form of St. Louis’s Gateway Arch, just seven miles east, which is a symbol of the westward expansion of the country.

Geometric Basis of the Roof Form In order to accurately model, analyze, render, and ultimately construct the roof structure, geometric parameters needed to be established that resemble the art form. Figure 3 illustrates the intersection of two sloping planes and a cylinder, forming two ellipses. These ellipses define the top chords of the elliptical trusses. To form the bottom chords of the elliptical trusses, two more sloping planes intersect vertical surfaces projecting through the top chords (Figure 4).

Figure 3. Geometric basis of elliptical truss top chords.

Structural Flow of Forces Secondary trusses collect load from the glass panels and deliver it to the elliptical trusses and the perimeter ring beam. The elliptical trusses, primarily through axial compression, carry the load to the corners of the structure where the perimeter ring beam resolves the forces in tension. The top HSS chords of rod trusses at the center of the roof also serve as compression struts between the elliptical trusses.

Structural Loading and Analysis The atrium roof structure was modeled and analyzed using RISA 3D. Load cases and load combinations were defined using ASCE 7-05.

Load cases include dead, live, snow, wind, seismic, and temperature.

In particular, unbalanced snow and wind loads were given careful consideration. In total, 197 load combinations were analyzed. Basic loads were applied as line loads to the secondary members. Steel rods were modeled as Euler buckling members.

The elliptical trusses consist of a round HSS18 top chord, 6-inch standard pipe verticals, rectangular HSS bottom chords, and steel rod web members. The trusses are separated by ten feet at their apexes.

Three pipe X-braces connect the two elliptical trusses at their apexes to resist unbalanced vertical loads.

The secondary infill members between the elliptical trusses are generally of two types: parallel-chord steel trusses and rod trusses, the depths of which vary in proportion to their span length. The steel trusses span one direction and form sloping planar roof surfaces on the north and south sides of the roof, and are comprised of rectangular HSS top chords to receive the glass roof panels, with steel pipe bottom chords and diagonal web members. All truss panel points and top chord bridging elements align with the glazing system they support. The steel trusses are designed to be as small as possible to achieve lightness, and so bottom chord compression under wind uplift is resisted by almost invisible bottom chord wire bracing.

The rod trusses were inspired by many iconic glass buildings around the world, such as the glass pyramid at the Louvre in Paris, France.

Rod trusses were used in the atrium roof where it is a cylindrical form and they form a two-way system. The webs of these trusses in the north-south direction lie in a plane perpendicular to the cylindrical surface of the roof. All bottom chords and diagonals of the rod trusses

Figure 4. Geometric basis of elliptical truss bottom chords.

STRUCTURE magazine

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August 2014

Figure 5. Structural flow of forces in primary roof members.

Figure 7. RISA–3D model.

Documentation

Figure 6. Examples of wind pressure load cases.

are designed for the predicted compression and tension forces under various unbalanced and uplift load cases, and the depth of each truss varies according to its span. The rod trusses have rectangular HSS top chords to receive the glass roof panels and round pipe verticals.

The rods are all reverse threaded to their clevises so no turnbuckles are required. To reduce the compression demand to within allowable limits on the steel rod bottom chords under wind uplift conditions, steel cables anchored to building columns were added in four discreet locations to hold down the field of the curved rod trusses.

A ring beam consisting of an HSS18x18 resolves the thrust from the elliptical trusses in the corners and also resists the minor amount of horizontal thrust from the secondary members. Steel columns support the ring beam vertically at each corner and intermittently around the perimeter. Slotted holes and fixed bearings were carefully arranged around the perimeter of the ring beam to anchor the roof structure for horizontal and uplift loads, and to allow for horizontal movements due to thermal changes and live loads.

KPFF chose to document this roof structure in AutoCad 2D, although study models in Revit, Sketch-Up, and AutoCad 3D were utilized. Conventional plans, sections and details were drawn to fully describe the dimensional parameters of the structure.

Figure 8 shows one building section cut through the center of the cylindrical portion of the roof.

Fabrication and Erection The construction manager, Tarlton Corporation of St. Louis, contracted with The Gateway Company of St. Louis to provide the detailing and fabrication of the atrium roof structure and the associated glass wall steel framing. Gateway had the elliptical pipes rolled out of town and shipped to their fab shop, where they pre-assembled most of the roof structure in their yard to assure good fit up in the field.

The steel erector for the entire building, including the atrium roof structure, was Ben Hur Construction of St. Louis. In order to safely

Figure 8. Construction document section through center cylindrical portion of roof structure.

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Figure 9. Roof pre-assembly at fabricator’s yard.

Figure 10. Temporary work platform during roof erection.

erect the atrium roof steel, along with facilitating roof glazing, sprinkler piping, field painting, and electrical work, Tarlton and Ben Hur chose to build a temporary work platform just below the roof structure. The scaffold for this platform extended some 65 feet down through the atrium floor openings below, and was a significant structure in and of itself. It also proved to be an invaluable benefit to provide access for inspections of the structure.

Gateway and Ben Hur collaborated and separated each of the elliptical trusses into three sections to stay within the tower crane’s load capacity. Due to careful planning, the atrium roof structure was erected quickly in a little over one month.

Conclusion

John P. Miller, P.E., S.E., is one of the founding principals of the St. Louis office of KPFF Consulting Engineers. John can be reached at john.miller@kpff.com.

Marc A. Friedman, P.E., S.E., is an Associate at KPFF Consulting Engineers’ St. Louis office. Marc can be reached at marc.friedman@kpff.com.

Owner: Washington University in St. Louis Structural Engineer: KPFF Consulting Engineers, St. Louis Architect of Record: Moore Ruble Yudell Architects & Planners, Santa Monica, CA Associate Architect: Mackey Mitchell Associates, St. Louis Construction Manager: Tarlton Corporation, St. Louis Steel Erector: Ben Hur Construction, St. Louis Fabricator: The Gateway Co., St. Louis

CHATHAM UNIVERSITY EDEN HALL CAMPUS, RICHLAND TOWNSHIP, PA PHOTO BY: BLAKE INOUYE

SUPPORTING

SUSTAINABILITY IN ARCHITECTURE

Seattle • Tacoma • Lacey • Portland • Eugene • Sacramento • San Francisco • Walnut Creek • Los Angeles • Long Beach • Pasadena • Irvine • San Diego • Boise • Phoenix • St. Louis • Chicago • New York

KPFF is an Equal Opportunity Employer. www.kpff.com

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By listening to and embracing the artistic goals and visions of the architect, a structural engineer can provide valuable feedback and input into an artistic pursuit. The Olin Business School was a project in which the structural engineer was able to take an active artistic role in developing a striking work of structural art in terms of efficiency, economy, and elegance in the atrium roof structure. The soaring and dynamic atrium roof structure has become the architectural centerpiece of Knight Hall and Bauer Hall.▪

Project Team

FULL METAL JACKET Part 2: Solutions

By D. Matthew Stuart, P.E., S.E., F. ASCE, F.SEI, SECB, MgtEng and Richard H. Antoine III, P.E., S.E. Part 1 of this series discussed the investigation of an existing timber-framed, multi-story building, that is over one hundred years old, and the resulting evacuation of the occupants due to an unsafe condition at the main support columns of the building. This installment discusses the nature of the deterioration observed and the solutions considered for repair.

Figure 1.

T

he deterioration and damage of the timber columns could be attributed to two primary causes: moisture and insects.

It was unclear to what extent each column base had deteriorated, but visual observations indicated that at least three of the eight affected primary wood columns had lost almost all of the cross-sectional area at the base below the top of the basement slab on grade. Partial removal of the concrete slab from around the column bases at the remaining five locations, to determine the extent of deterioration, was not possible because the slab in the same immediate area provided the only support for the 3x12 side plates.

This restriction occurred because it had been observed that, as the deterioration progressed in the main building columns, the load had been transferred to the 3x12 side plates via the existing through bolts.

As a result, the 3x12 side plates were beginning to exhibit localized crushing at their bases, which allowed the building to settle vertically.

The resulting deflection subsequently allowed the second floor framing to move and rotate as the columns dropped unevenly into the voids left by the deteriorated timber. Continued vertical movement was also allowed by the deterioration of the column side plates; however, at the worst areas of deterioration of the 3x12’s, masonry piers had been previously installed adjacent to the building columns (Figure 1). Unfortunately, these supplemental supports were only able to engage the first floor framing, rather than assist with the transfer of the main building column loads from any of the other floors above.

Solutions to the observed conditions were limited due to the lack of continuity of the beam-to-column connections throughout the building, and the unstable nature of the basement deterioration. One option that was considered initially involved shoring the columns from the basement slab up to the roof, removing the columns, and then replacing them with structural steel. This conventional solution was quickly ruled out after it was determined that it was not practical to remove or shore around the large first-floor kilns that were located immediately adjacent to the columns. In addition, it was also determined that the third- and fourth-floor residential plans were laid out such that bathrooms, closets, kitchen countertops and other finishes would have to be removed in order to facilitate the temporary shoring and permanent replacement of the building columns.

A second option that was considered involved strengthening the second-floor beams at the joint above the first-floor columns so that the same beams could act as transfer girders to support the upper floors, via new columns that would be installed down to additional STRUCTURE magazine

foundations through the first floor and basement spaces. This option was also ruled out because of the precarious rotated condition of the second-floor beam, corbel and column joint, and the resulting difficulty of installing adequate strengthening of the second-floor beams through this same joint directly above the existing adjacent kilns.

It was eventually decided that temporarily shoring of the timber columns in the basement using miscellaneous steel plates and channels down to the slab on grade should be implemented until a more permanent solution could be established. Ultimately, it was determined that the best solution involved developing this temporary shoring into a permanent fix. Initially this approach involved using through bolts to attach the steel reinforcing to the sides of the column in order to engage the wood, and transfer the entire reaction down to the slab on grade by distributing the load over a large area via steel

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Figure 2.

August 2014

grillage. However, due to the extensive damage to the wood columns for most of the basement height, it was determined that the use of through bolts would require extensive epoxy injection in order to make the timber sound enough to engage the bolts properly. Because there was a concern that the extent of epoxy injection might result in localized failure of the adjacent deteriorated wood, and potentially cause complete failure of the column, this alternative was discarded.

As a result, the final permanent solution evolved into an approach that involved abandoning the deteriorated timber column in place. This was accomplished by designing the steel reinforcing as a metal jacket built completely around each column using various steel plates and chan- Figure 3. nels (Figure 2). The jackets were prefabricated in such a way that they could be brought to the site in two pieces and then erected and bolted together around the column. Bolting the jacket assembly together was preferred in order to avoid field-welding as much as possible, due to the age and condition of the timber in the basement. The steel jackets that encapsulated the timber columns were supported at the base by a series of steel channels that transferred the vertical loads on to additional steel to stabilize the wood, and then drilling through the timber column channel grillage, which were designed to span continuously over the top and installing the steel rods one by one in the specified sequence. of the slab on grade parallel to the column centerline. The slab on grade Pre-drilling also enabled the detection of interior deterioration by was analyzed as an unreinforced section, and the steel channel grillage noting any variations in the drilling resistance encountered. The rods was arranged and extended in such a way that the modulus of rupture of were placed side-by-side such that, once all of the specified number the unreinforced concrete slab was not exceeded under the full column of rods were in place, the load from the column would be entirely design load. There were two critical assumptions that were made as a part supported by the rods and therefore transferred to the steel jacket, of the grillage design and slab on grade analysis: effectively abandoning the timber column below the rods.

1) The slab was a minimum of six inches thick.

Part 3 of this series will discuss the impact of the findings of a soil 2) The soil had an allowable bearing capacity of at least 3,000 investigation that resulted in the need to develop alternate pounds per square foot. foundation solutions for the support of the steel jacket, Both of these assumptions were to be verified prior to the installation as well as repairs that were required in addition to the of the grillage. column jackets.▪ The final successful approach to avoid through-bolting of the jacket to the wood columns involved the following solutions. First, because D. Matthew Stuart, P.E., S.E., F. ASCE, F.SEI, SECB, MgtEng the first floor beams did not attach directly to the building columns, (MStuart@Pennoni.com), is the Structural Division Manager at structural steel channel outriggers were cantilevered from the top of Pennoni Associates Inc. in Philadelphia, Pennsylvania. each jacket to support the beam reactions that were being resisted by Richard H. Antoine III, P.E., S.E. (rantoineiii@gmail.com), was a the 3x12 side plates. Timber blocking was placed between the top of project engineer at Pennoni Associates Inc. and is now with Jacobs in the channel outriggers and the bottom of the existing beams, in order Philadelphia, Pennsylvania. to provide an adequate load path mechanism to the steel jacket for the first floor framing. The critical method for transferring the primary column load to the steel jacket involved the use of a series of 1½-inch-diameter steel rods that were drilled through the top of the column just below the first-floor framing. Locating the through rods at the top of the columns was determined to be a safer approach than the initial through-bolting scheme over the entire height of the columns in • Versatile - allows for varying the basement, because the extent of existcrossover angles ing deterioration of the wood was much • Corrosion resistant less at the top of the columns than that • Saves time and money - observed over the lower portion. no drilling or welding The methodology for installing the rods • Guaranteed Safe Working Loads was similar to that used for underpinning • Will not harm protective coatings an existing foundation, in that the rods • Flush connection between both were installed in a logical sequence that steel sections allowed for the progressive transfer of the column load to the steel jacket (Figure 3).

This was accomplished by first pre-drilling a pilot hole, inspecting for deterioration of the wood, injecting epoxy as required Fast service for info & pricing: Toll-Free: 1-888-724-2323 • www.LNAsolutions.com/Fast-Fit

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SPECIAL SECTION

Engineering Software

Working from the Cloud New Software, Interoperability and Mobile Apps Pushing Construction Technology

By Larry Kahaner

S

tructural engineers are starting to see wisps of the cloud.

What has become common in many industries – working from the cloud – is beginning to see daylight among those engaged in construction.

“There are a lot of questions about the ‘cloud’ and what it means to the structural engineer,” says Raoul Karp, Vice President – Structural & BrIM, Bentley Systems (www.bentley.com/structural) in Exton, Pennsylvania. “On the information consumption side, the advantages are clear; being able to access project data authored anywhere, at any time, from any location. For example, Bentley’s Field Supervisor is the perfect companion for the structural engineer to help access all project data in the field. In addition, Bentley Navigator provides full 3D model navigation, visualization tools, and data interrogation capabilities. Soon we will have the ability to access and manage site administration tasks, markups, RFIs, and much more from the field. The cloud will also offer opportunities to consider more alternatives and more complex and complete solutions than ever before.

Optimization across multiple disciplines is something that has existed in other industries for years, and we expect to see more of that with greater cloud analytical capacity and better optimization tools in the future.” (See ad on page 75.)

At Enercalc, Inc. (www.enercalc.com) in Corona del Mar, California, President Michael Brooks says that cloud-based software is on the way.

“Our products are continually enhanced according to user requests and advances in software development technology. Currently, we’ve upgraded our software to support all new building codes and we will be premiering a cloud-based software system before year’s end.” (See ad on page 3.)

Other new products and services are coming along, too, says Karp.

“Last year, all RAM products were updated to 64 bit, which gave our users the ability to create larger models and conduct faster analyses.

Information mobility was improved with RAM Connection and RAM Concept, which are now managed directly through the RAM Structural System to provide a more unified and seamless workflow.

Other enhancements include modeling, reporting, and analysis, including the addition of the SJI Joist Girder tables to allow consideration of joists in lateral analysis, and the addition of new ASTM A1085 and Jumbo HSS Shapes. The new release of RAM Connection included the latest design standard and seismic requirements from STRUCTURE magazine

AISC 360-10, AISC 341-10, and AISC 358-10 for moment, brace, and HSS connection design.”

He adds that Bentley’s SELECT Open Access is an industry first that provides any subscriber with unrestricted portfolio-wide access to the company’s products. “This allows subscribers to employ the best and most comprehensive mix of Bentley applications for all disciplines for every project. Subscribers also benefit from convenient and cost-effective Quarterly Term Licensing at the end of each calendar quarter, as well as on-demand and live training in the virtual classroom through Bentley LEARN. With SELECT Open Access, the purchasing barriers to the most effective software utilization are eliminated so that all Bentley applications are at your service.”

As for his company’s new offerings, Brooks says that Enercalc releases updates when available and not on a regular timetable. “Instead, we are continually improving the software and releasing it through our web update system. New enhancements come in a continual flow to our Maintenance & Support Plan subscribers.”

He notes: “Software trends in engineering design still follow the basic trends of all software. These are cloud-based solutions for global deployment, incremental pricing structures to provide more cost effectiveness to customers, and software solutions made available on multiple platforms (desktop, laptop, tablet) and multiple operating systems (Windows, Mac, Android, IOS). ENERCALC is one of the three senior structural engineering software companies, now in business for 31 years. This type of staying power reflects the necessity of the market we serve and the dedication of our long-term staff to the products and our loyal customers.”

Amber Freund, Director of Marketing at RISA Technologies (www.risatech.com) in Foothill Ranch, California, says that her company has been developing world-class structural design software for over 25 years. “Our products are used to design towers, skyscrapers, airports, stadiums, petrochemical facilities, bridges, roller coasters and everything in between. The seamless integration of our product suite creates a powerful, versatile and intuitive structural design environment, ready to tackle almost any design challenge.”

Freund says: “We recently released RISAFloor ES which will design one and two-way elevated concrete slabs. This addition to RISAFloor gives engineers the ability to design any commercial building within one familiar, easy to use interface. After releasing RISAFoundation,

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SPECIAL SECTION Engineering Software

which designs mat slabs, engineers started requesting that same interface and design features in an elevated slab design program. The most requested feature, beyond the easy-to-use interface, was to be able to customize design strips. Although RISAFloor ES can automatically generate your design strips, the engineer also has the ability to modify them to fit his/her design needs.”

As for trends, Freund continues to see integration and interoperability being key to design projects. “We are working closely with Autodesk and Tekla to enhance our direct links so that data can be transferred seamlessly between 3D modeling, analysis-design and detailing software. Our developers, technical support group, and even our sales team are all structural engineers. Given our background, we are uniquely able to predict and meet the needs of our clients and continually produce the most user-friendly software on the market.”

(See ad on page 76.)

Another long-time software solutions company is Design Data (www.sds2.com) of Lincoln, Nebraska, which has been in business for over 30 years, says Doug Evans, Vice President of Sales. “SDS/2 software solutions are a suite of products developed for the manufacturing and engineering components of the construction industry.

The flagship product, SDS/2 Detailing, automatically designs codecompliant connections and creates shop drawings and CNC data for machines on the shop floor.”

When it comes to new offerings, Evans says that SDS/2 Approval is a proven product that has been utilized in the new model approval process and is becoming increasing popular on BIM projects. “With the added ability to transfer job status, and new tools to approve and review members, this product has seen significant market penetration.

Engineers and detailers are moving away from drawing-based methods to approve project and design intent, and embracing model-based methods to accomplish the same goal. SDS/2 Approval product provides them the right tools to work in this environment,” he says.

Evans wants SEs to know about two other new products. “SDS/2 Erector combines the ability to build your own intelligent cranes with the crane building functionality and the fabricated BIM model from the manufacturer. This combination gives erectors and general contractors the needed tools to plan and organize the site to make for a smooth project.” He adds: “The SDS/2 Detailing flagship product is bringing dramatic improvement to market this year. The automatic connection design functionality now creates the ability to lock any design element, and design a connection around that variable. This gives engineers full control over every aspect of a connection. In addition, the ability to create components will increase the productivity when modeling miscellaneous elements like outriggers, conveyors and platework.” (See ad on page 44.)

Evans concludes: “All of the new offerings are a direct result of the BIM work process, and utilizing the model and model data in new and innovative ways to reduce cost and improve quality in the construction cycle. A majority of the new products and features have come out of the collaborative effort of development with our current installed base and our experienced development staff.”

There are four key trends that improve user experience: interoperability, ease of use, integration and the ability to easily automate repetitive tasks, according to Marinos Stylianou, CEO of S-FRAME STRUCTURE magazine

Software (www.s-frame.com) in Guilford, Connecticut. “Ideally, clients want a single model for their software and tools. They can’t afford to move back and forth between dissimilar products and technologies. Integration is key not only at the designer or engineering level, but at the entire business level of the company and its partners.

With each new release of our product suite, we continue to offer our clients tangible improvements in all four key areas.”

S-FRAME recently released S-FOUNDATION, a foundation analysis and design product with automation and customization capabilities.

“S-FOUNDATION has been very well received by the structural engineering community since its release in 2013, and is helping to expand our presence in the concrete analysis and design arena,” says Stylianou. “In addition, all our core products saw significant updates and new feature functionality with release R11. Our interoperability with BIM and CAD systems was expanded through new bi-directional links with Tekla and Revit. The DXF translator was also completely rewritten and modified to handle increased customer needs.”

He adds: “Industry trends and demands motivate our team to provide the best state-of-the-art technology, while providing an enjoyable and simple user experience. The ability to communicate among our products, and with 3rd party and in-house products, is another driver requested by our clients. Clients are seeing a refresh in their business that requires faster concepts and better designs at a reasonable cost. Our solutions aim to address all three of these points.” (See ad on page 4.)

Celebrating its 40th anniversary, Scia Engineer is part of a new breed of integrated 3D structural analysis software that makes it easy for engineers to plug analyses and designs into today’s BIM workflows, says Dan Monaghan U.S. managing director of Nemetschek Scia (www.nemetschek-scia.com) . He is based in Columbia, Maryland.

“Flexibility is a big benefit of Scia Engineer. It is used by engineering companies across a numbers of industries including plant/process, buildings and transportation. It’s a great design tool for day-to-day engineering work, but has the advanced analysis capabilities and multi-material code support firms need to tackle larger, more complex projects.”

The company has recently released Scia Engineer v14. “With Scia Engineer v14 we are introducing a new Open Check technology that allows firms to easily script their own custom structural calculations inside Scia Engineer’s 3D FEA environment. Giving engineers the ability to write and run their own custom checks and calculations in their structural design software is a real game changer for some firms,” says Monaghan. “It removes the dependency that firms have on any one software vendor. Engineers can now easily extend their analysis software by adding their own design checks whenever they need them. It also removes the biggest criticism that engineers have with structural engineering software: the software is too black box.

With Open Checks, engineers can see the formulas and methods that are being used to derive a check. And, best of all, they can edit them to suit their own preferences or design criteria.”

Simpson Strong-Tie (www.strong-tie.com) of Pleasanton, California, has worked with structural engineers for nearly 60 years providing engineered structural connectors, lateral-force resisting systems and other building solutions, says Paul McEntee, continued on page 48

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Plugging Analysis and Design into Your 3D Workflow

W

ITH new processes like BIM (Building Information Modeling) and VDC (Virtual Design and Construction) and new project delivery methods like IPD (Integrated Project Delivery), more and more engineering firms are being asked to participate in collaborative, model-based workflows.

Migrating to these new processes can be made easier with software designed to support them— software like Scia Engineer from Nemetschek.

Scia Engineer is a new breed of integrated structural design software that goes beyond analysis and helps firms successfully join in today’s collaborative 3D workflows.

Fast and Efficient Modeling Modeling is an essential requirement for any 3D workflow. As projects become more complex and project timelines compressed, modeling needs to be fast and efficient, but also not restrictive. Engineers need to be able to keep up with the modern designs coming from architects and contractors who push the limits of new materials and methods.

“A unique feature of Scia Engineer is its modeling capabilities,” says Mark Flamer, M.I. Flamer & Associates. “It’s a very fast and efficient FEA (Finite Element Analysis) modeling tool. freeform modeling capabilities make it easy for me to work up designs in 3D and keep pace with my architect’s avant-garde designs. And, its parametric object technology has allowed me to automate routine and repetitive work. I can quickly work up and test design concepts. Then, when the design has gelled, I can develop an accurate structural model in Scia Engineer or link my design to another BIM program for model coordination or construction drawings.”

With support for open standards like IFC 2x3 and direct links to a number of BIM software programs, Scia Engineer makes it easier for engineers to reuse models created by others and leverage them into analysis.

This is a huge advantage when working in a collaborative workflow.

“For the new National Music Centre project in Calgary, Canada, the architect made frequent and sometimes dramatic changes,” says Andrea Hektor, KPFF Portland. “We needed to be able to give them a quick thumbs up or thumbs down on their revised designs. With Scia Engineer it was great. The architects would just send us their updated models. We would import them into

Scia Engineer, update our model, run a quick analysis, and give them enough information to continue moving forward.

I don’t think we would have been able to do this with any of the other analysis software we have in our office.”

Another advantage of Scia Engineer is its extensive functionality. Analysis and design is becoming more rigorous, and owners are looking for highly optimized structures to minimize materials, construction time, and costs. Being able to have one program that is efficient for your day-do-day work, and at the same time offers the ability to handle complex analysis tasks is a big benefit.

“With support for advanced FEA analysis and multi-material design I’ve avoided having to invest in disparate analysis programs,” continues Flamer. “Reducing the number of analysis programs we manage saves on maintenance costs and makes it less expensive to train new employees. Most importantly, it reduces the risks that come with manually coordinating multiple analysis models.

For occasions when I need to go outside Scia Engineer, the program’s Open Design technology, allows me to script my own checks to expand its built-in design capabilities.”

When Modeling Matters, Scia Engineer Delivers

“More in tune with the engineer’s workflow” “Eye-opening” “Extremely impressed”

Growing with Technology In addition, the right software makes a firm more flexible, allowing them to go beyond their usual projects, and take on work wherever they find it. “Scia Engineer allows our firm to confidently compete for bigger building projects as well as go beyond buildings,” says Flamer.

“While our expertise is in commercial, we just completed a bridge project and are ready to take on larger, complex structures. A flexible tool like Scia Engineer makes all the difference.”

He added: “I evaluated the usual list of structural analysis programs, and there isn’t another program in the market like it. Scia Engineer is the only program I found that integrates fast and efficient modeling, lets me script my own calculations, and easily reuse and share 3D models. For us, Scia Engineer was a logical choice.”

Read the AECbytes Article www.nemetschek-scia.com/review

Scia Engineer is a new breed of integrated structural design software that goes beyond analysis to help firms excel in today’s collaborative 3D workflows.

Discover fast, efficient modeling and intelligent FEM analysis. Recycle and leverage models created by others into analysis. And, centralize your design tasks with static and advanced nonlinear and dynamic analysis, plus multi-material design in ONE program.

Request your FREE Trial.

Daniel Monaghan is the U.S. Managing Director of Nemetschek Scia, developers of leading software products for AEC software industry. He can be reached at dmonaghan@scia-online.com

(877) 808-7242

www.nemetschek-scia.com

SPECIAL SECTION Engineering Software

Engineering R&D Manager. “Today, we offer a full line of structural products that help customers design and build safer and strong homes and buildings to resist high winds, hurricanes and seismic forces. We also continue to focus on technology by providing free software, web and mobile apps, online calculators and other resources to help structural engineers design and model projects using our products.”

The company has announced a new software program for coldformed steel design that automates product selection and helps navigate the complicated design provisions of AISI, while offering more robust design tools for users, according to McEntee. “The new program has an upgraded user interface that makes input faster and more intuitive. CFS Designer software is the new version of LGBEAMER, a software program that has been one of the most widely-used CFS member design tools in the industry. The new streamlined software gives structural engineers the ability to design CFS beam-column members according to AISI specifications, and to analyze complex beam loading and span conditions.”

McEntee adds: “With our new Literature Library mobile app, it’s easier than ever for engineers to take Simpson Strong-Tie product information on the go. With the Literature Library app on iPhone, iPad and Android devices, SEs can now access and download all catalogs, fliers and technical bulletins to a mobile device, bookmark the pages they use most, create a customized library on their device, and view downloaded documents without Wi-Fi.” In addition, the Simpson Strong-Tie Strong Frame moment frame selector software is designed to help engineers select an ordinary or special moment frame for their project’s given geometry and loading.

McEntee says that only minimum input geometries are required for the software to select an appropriate frame for the available space. “Based on input geometry, the Strong Frame selector software will narrow down the available stock frames to a handful of possible solutions.

If opening dimensions are outside stock frame sizes, designers can enter the specific opening dimensions and the Strong Frame selector will provide possible customized solutions.

“We also have updated the Holdown Selector web app so it is available in U.S. and Canadian versions. The Holdown Selector web app is a quick and easy tool that selects the most cost-effective holdown connector based on the type of installation, demand load and the wood species of the post,” McEntee says.

Although not a software company, Ram Jack (www.ramjack.com) offers many products and tools for engineers, including software.

Ram Jack is a helical and hydraulically-driven steel manufacturer and distributer, says Darin Willis, Director of Engineering for the Ada, Oklahoma-based company. “Ram Jack has an international network of franchises throughout the U.S., Canada, Puerto Rico and South America. We offer a wide arsenal of brackets and pilings that are available for almost every situation.”

In addition to its free, web-based helical design software, Foundation Solution, Ram Jet also offers: • An engineering department staffed with structural and geotechnical engineers who are available to assist with pile designs, provide calculations, shop drawings or answer any technical questions.

STRUCTURE magazine

• An engineering portal on Ram Jack’s website that provides product shop drawings of their most common brackets and piles, standard specifications and general notes for helical and hydraulically-driven piles. It also has procedures for designing helical piles in accordance with the International Building Code, ICC ESR report. Engineers can contact the engineering department directly for any additional assistance.

• Free Lunch and Learn presentations in most locations. The presentations cover the theory and application of helical piles.

Most state engineering boards accept continuing education credits based on the technical presentations.

• To further guarantee quality control and assurance to its clients, Ram Jack’s manufacturing and distribution arms have both received certification for ISO 9000 compliance.

“Even though helical piles have been used for more than 175 years, most engineers were not educated on how to design them during their college curriculum,” Willis says. “The last 25 years has seen exponential growth in the use of helical piles and tieback anchors. The ICC adopted the acceptance criteria for helical piles in June 2007, and included helical piles in the 2009 and 2012 IBC. The Lunch and Learn’s technical information provided on the engineering portal, the design software and the engineering support, are in place to help engineers understand the design theory, capacities and applications of this valuable tool.” (See ad on page 50.)

StructurePoint, LLC (www.structurepoint.org) in Chicago, Illinois, was formerly the Engineering Software Group of the Portland Cement Association, and is a dedicated team of engineering professionals committed to excellence, continuous improvement, and service, according to Marketing Director Heather Johnson. “We provide civil and structural engineers with the software and technical resources they need for designing concrete buildings and structures. StructurePoint is a convenient single point of access to the vast resources and knowledge base of the entire cement and concrete industry including library services, training, R&D, publications, building codes, specialty engineering services, concrete material and testing, concrete repair, codes and standards consulting.”

StructurePoint’s primary focus is concrete structures. “We are watching closely every code change and amendment relevant to concrete design. We are also behind the scenes looking for important upcoming changes to make concrete design simpler, faster, and more accurate.

We do it once and well, so that every engineer knows that at least his concrete design is optimal, economical, safe and code compliant,” Johnson says. “In spColumn v4.81, StructurePoint has further refined slender column design provisions to meet stringent new requirements of ACI-318.”

Business has been improving, says Johnson. “Companies of all sizes and geographies have been increasingly more upbeat about business opportunities, and cement shipments have been growing steadily indicating more construction spending. Among our users, geotechnical engineers have been exceptionally active responding to exploding opportunities in oil, gas and petrochemical projects. These opportunities continue to drive additional demand of our spMats and spBeam program for foundations in industrial facilities and infrastructure construction.” (See ad on page 51.) continued on page 50

48

August 2014

Get there quicker

with Simpson Strong-Tie CFS Designer™ software ®

When designing cold-formed steel structures, you want a software program that is easy to navigate, versatile, and saves time by automating product selection and complicated design provisions of AISI. The new streamlined CFS Designer™ software by Simpson Strong-Tie does all of that and more. By shifting between design tools, you can model beams up to three spans and automate the design of wall openings, shearwalls, floor joists and roof rafters. All models are saved in a single file and output is saved as a PDF. To test drive CFS Designer, call your local representative at 800-999-5099 or visit www.strongtie.com/CFSDesigner to learn more. ©2014 Simpson

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SPECIAL SECTION Engineering Software

The Canadian Wood Council (CWC) (www.woodworks-software.com) is the national association representing Canadian manufacturers of wood products used in construction. CWC’s main priority is to ensure that building professionals such as engineers, architects, and other design professionals have the needed information to specify and use wood products in a safe, secure, and code-compliant manner, according to Josée Lalonde, Marketing & Sales Coordinator. “One way we do this is through our wood engineering software, WoodWorks.

Separate Canadian and U.S. versions of WoodWorks software are available. For the U.S. version – compatible with the IBC, NDS, SDPWS, and ASCE7 – CWC works closely with the American Wood Council (AWC) to ensure consistency in technical interpretations,” says Lalonde.

In the United States, the latest version of the software is US Design Office 10 (SR2a), released in February, 2014. This version conforms to the 2012 IBC, the 2012 NDS, and the 2010 ASCE-7.

Also, new features added to the February release of the Shearwalls program are: • Worst-case design of shear walls considering wind and seismic loads. Envelopes the worst case distribution (rigid and flexible diaphragm), providing the designer with an immediate assessment of whether the walls meet all the desired design criteria.

• Reduced processing time. The software was capable of doing increasingly complex calculations. For very complex buildings the run time was as long as 10 minutes. It has been reduced to 20 seconds.

In Canada, a new release (Cdn Design Office 9) is scheduled for August. Says Lalonde: “This version will include improvements made in the US DO 10, including allowing pdf and bitmaps to be used as templates for modeling the building in the Shearwalls program, highlighting walls that are over capacity, and grouping user-defined walls together to ensure a consistent design. Additionally, an expanded list of Canadian cities will allow designers to select any of the over 600 cities listed in the NBC 2010 Design Data, which automatically populates most of the wind and seismic data needed, and, at the push of a button, determine the lateral loads on the structure.”

(See ad on page 53.)

According to Stuart Broome, Business Manager, Engineering at Tekla (www.tekla.com), the Kennesaw, Georgia company is focused on building and construction. Its customers are in the architectural, engineering and construction (AEC) markets and include structural engineers, contractors, fabricators and steel detailers. “The company was established in 1966, and today it has customers in 100 countries, offices in 15 countries, and a global partner network. In 2011, Tekla continued on page 52

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became part of Trimble Buildings Group and then, in 2013, Trimble acquired CSC which is now incorporated into Tekla,” he says.

“Launched in 2004, Tekla Structures is the preferred tool of construction professionals around the world to model, detail, fabricate and build many of the world’s buildings, bridges, and sports complexes.

The software is designed to work seamlessly with Tekla BIMsight, a free online tool and portal for construction project collaboration,” Broome says. “The most recent version, released in March, brings even more detailed information and flexibility to modeling while reducing the need for manual data transfer. Information now flows more efficiently from design, purchasing and production to the shop floor.

Tekla also provides more links to architectural and design solutions to remove the technical and compatibility barriers that compromise workflow between project teams and subcontractors using different types of applications.” For more information and to download Tekla Structures 20 go to www.tekla.com/tekla-structures-20.

In June 2014, Tekla released Tedds 2014, a new version of its calculation production suite which automates the design and documentation of structural components. “A major new development to Tedds 2014 is the inclusion of the Tedds Project Manager,” Broome notes. “Project Manager allows users to create a project of related Tedds documents that can easily be managed directly within Tedds. Teams using Tedds are able to work even more

SOFTWARE GUIDE

efficiently by using Project Manager to streamline their workflows and administration, and create dynamic reports directly from the Project Manager.”

Fastrak, another offering, is a steel building design tool. It is a physical object-based modeling solution which automates the requirements of AISC360 and ASCE7, according to Broome. He says that the main reasons why clients use Fastrak are: • The ability to model and automate the design of composite floors and complex roof structures/trusses in one model and in one interface • The ability to model and automatically design gravity and lateral systems in one model and in one interface • The ability to synchronize a design model with a Revit model and pass information in both directions, as many times as required, in a manageable way.

Broome concludes: “Our solutions contribute to the essential processes of today’s information-intensive construction industry. Ultimately, it comes down to collaboration and sharing of information. We continually add new features to help our clients work efficiently. BIM is increasingly becoming common practice and it’s vital that we offer our clients a cutting-edge BIM solution so that they can increase their productivity, win more work and be more profitable.” (See ad on page 56.) ▪

BIM, Bridges, Building Components, Business/Productivity, CAD, Concrete, Found./Retain. Walls, Gen./Packages/Suites, Light Guage Steel, Masonry, Steel, Wood

ADAPT Corporation

Applied Science International, LLC

Phone: 650-306-2400 Email: info@adaptsoft.com Web: www.adaptsoft.com Product: ADAPT-PT RC Strip Design Description: The most popular software for design of post-tensioned slabs and beams now includes a Reinforced Concrete design option.

This new capability lets engineers use the strip design software they are already used to on all their concrete projects, saving time and the hassle of switching between software.

Phone: 919-645-4090 Email: tdigirolamo@appliedscienceint.com Web: www.appliedscienceint.com Product: Extreme Loading for Structures Description: An advanced non-linear structural analysis software tool designed specifically for structural engineers. Easily study static and dynamic loads such as those generated by blast, seismic events, impact, progressive collapse, and wind.

Product: ADAPT-Builder with Column Design Description: An integrated analysis and design software for concrete buildings that now includes code check and design capabilities for columns. Use it to efficiently analyze and design your complete concrete building from foundation to roof slab all in one model – post-tensioned or mild reinforced. Seamlessly integrates with Revit Structure.

Product: ADAPT-ABI 4D Construction Phase Analysis Description: 4D construction phase analysis of concrete bridge or building structures. Models construction phases including temporary structures, closure strips, pre- and post-tensioning. Reports forces, creep, shrinkage and deflections using nonlinear material behavior. Great tool for calculating long-term effects, camber, super-positioning, and investigation of construction methods.

Product: SteelSmart System (SSS) Description: Available as a complete suite, SSS will streamline production through the design and detailing of members, connections, and fasteners. Available design modules include: Curtain Wall, Load Bearing Wall, X-Brace Shear Wall, Floor Framing, Roof Framing, Roof Truss, and Moment-Resisting Short Wall.

Bentley Systems Phone: 610-458-5000 Email: katherine.flesh@bentley.com Web: www.bentley.com Product: ProConcrete Description: Advanced 3D CAD program for modeling, detailing, scheduling of reinforced insitu/ precast and post-tensioned concrete structures. Offers simple and easy-to-use tools for advanced 3D modeling of reinforced concrete structures, producing automated design and detail drawings and rebar schedules. Enables engineers to reduce documentation production time.

STRUCTURE magazine

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August 2014

Product: LEAP Bridge Steel Description: An integrated, 3D Steel bridge design and rating program. It provides comprehensive layout, geometric modeling, design, analysis, and load-rating for small to medium steel bridges. This intuitive software complements Bentley’s LEAP Bridge Enterprise for concrete design with Bridge Information Modeling (BrIM) for steel bridge design.

Product: STAAD Foundation Advanced Description: Comprehensive foundation design program which offers the ability to model complex or simple footings, including those specific to Plant facilities: octagonal footings supporting vertical vessels, strap beam foundations supporting horizontal vessels, ring foundations supporting tank structures, and drilled or driven pier foundations.

CADRE Analytic Phone: 425-392-4309 Email: cadresales@cadreanalytic.com Web: www.cadreanalytic.com Product: CADRE Pro 6 Description: Finite element structural analysis application for Windows. Solves beam and/or plate type structures for loads, stress, displacement, and vibration modes. Advanced features for stability, buckling, dynamic analysis and shock. Complete seismic analyses to comply with current codes. Special provisions for unusual structural types such as geodesic domes.

continued on page 54

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BIM, Bridges, Building Components, Business/Productivity, CAD, Concrete, Found./Retain. Walls, Gen./Packages/Suites, Light Guage Steel, Masonry, Steel, Wood

Computers & Structures, Inc.

Enercalc, Inc.

Phone: 510-649-2200 Email: info@csiamerica.com Web: www.csiamerica.com Product: SAP2000, CSiBridge, ETABS and SAFE Description: Computers & Structures, Inc. develops leading structural and earthquake engineering software used in more than 160 countries worldwide. From simple building structures to complex long-span bridges, CSI products do it all with a balance of practicality and sophistication.

Phone: 800-424-2252 Email: info@enercalc.com Web: www.enercalc.com Product: Structural Engineering Library Description: A proven solution to all the typical, repetitive and daily design tasks performed by structural engineers.

By carefully combining building code provisions, proven analysis techniques, and standard materials into simple and elegant software, you can quickly design, analyze, or optimize all your daily design tasks.

Phone: 303-939-9700 Email: info@masonrysociety.org Web: www.masonrysociety.org Product: Masonry Codes and Guides Description: The 2013 edition of the code and minimum specification is now available. A major update from the 2011 edition both in technical requirements and in layout. This edition will be referenced by the 2015 ICB for the design and construction of structural masonry, veneer, and glass unit masonry.

Concrete Masonry Association (CMACN)

FabTrol Systems, Inc.

National Concrete Masonry Association

Phone: 916-722-1700 Email: info@cmacn.org Web: www.cmacn.org Product: CMD12 Description: Structural design of reinforced concrete and clay hollow unit masonry elements. For design of masonry elements in accordance with provisions of Ch. 21 – 1997 UBC, 2001 – 2013 CBC or 2003 – 2012 IBC and 1999 – 2011 Bldg. Code Requirements for Masonry Structures (TMS 402/ACI 530/ASCE 5).

Phone: 541-485-4719 Email: info@fabtrol.com Web: www.fabtrol.com Product: FabTrol Pro Description: Steel Fabrication Management Software

Phone: 703-713-1900 Email: dgraber@ncma.org Web: www.ncma.org Product: Direct Design Software Description: Using the IBC and IRC-referenced standard Direct Design Handbook for Masonry Structures (TMS 403-13), this software package allows users to generate final structural designs for whole concrete masonry buildings in minutes.

Decon USA Phone: 707-996-5954 Email: frank@deconusa.com Web: www.deconusa.com Product: Jordahl Anchor Channels Description: Software allows a user friendly and safe calculation for anchoring in concrete with JTA anchor channels. Features a technical and economical optimization of the design for each individual connection. 3D graphics are easy to use and allow a fast and clear input of all data.

Product: Studrails® Description: A free design software for Studrails called STDESIGN 3.1. The software can be downloaded from our website and complies to ACI 318, ACI 421.1 and CSA A23.3. PC based and excellent for efficient and verifiable output on punching shear reinforcement.

Design Data Phone: 402-441-4000 Email: marnett@sds2.com Web: www.sds2connect.com Product: SDS/2 Connect Description: Enables users of Revit Structure for BIM to intelligently design steel connections and produce detailed documentation on those connections. SDS/2 Connect is the only product that enables structural engineers to design and communicate connections based on their Revit Structure design model as part of the fabrication process.

Devco Software, Inc. Phone: 541-426-5713 Email: rob@devcosoftware.com Web: www.devcosoftware.com Product: LGBEAMER v8.0 Description: Analyze and design cold-formed cee, channel and zee sections. Uniform, concentrated, partial span and axial loads. Single and multi-member designs.

2007 NASPEC, including the 2010 Supplement (2013 IBC) compliant. Pro-Tools include shearwalls, framed openings, X-braces, joists and rafters.

ENERCALC

Hilti, Inc. Phone: 800-879-8000 Email: us-sales@hilti.com Web: www.us.hilti.com Product: PROFIS Anchor and PROFIS DF Description: PROFIS Anchor performs anchor design for cast-in-place and Hilti post-installed anchors using ACI 318, Appendix D provisions. PROFIS DF Diaphragm optimizes design of steel deck roof and floor diaphragms using the SDI Diaphragm Design Manual, 3rd Edition provisions.

IES, Inc. Phone: 800-707-0816 Email: sales@iesweb.com Web: www.iesweb.com Product: VisualAnalysis Description: Engineers have enjoyed solving problems with our easy-to-use, flexible, general analysis tool.

With 20-years of customer-tuning, you will wonder why you struggled with anything else.

Integrity Software, Inc. Phone: 512-372-8991 Email: sales@softwaremetering.com Web: www.softwaremetering.com Product: SOFTRACK Description: Provides Calendar Hour control for all your Bentley applications and helps you reduce or eliminate quarterly trust licensing overage billings by Bentley.

Losch Software Ltd Phone: 323-592-3299 Email: LoschInfo@gmail.com Web: www.LoschSoft.com Product: LECWall Description: Concrete column and sandwich wall design and analysis. Includes handling design, prestressed and mild reinforcing.

MadSoftware, Inc. Phone: 720-362-2470 Email: info@madsoftware.net Web: www.madsoftware.net Product: AxisVM Description: Advanced Visual Modeling for most engineered structures. Linear, Non-Linear, Buckling, Vibration, Seismic, Dynamic analysis.

STRUCTURE magazine

54

August 2014

The Masonry Society

Product: Structural Masonry Design Software Version 6.1 Description: Now updated to include the 2012 International Building Code and 2011 MSJC. Includes new larger allowable stresses per code.

Designs walls, columns, lintels and much more.

Product: SRW Design Software – SRWall Description: Superior segmental retaining wall (SRW) designs produce superior results. Stay on the cutting edge of SRW design with the latest industry standard design tools. 30-day free trial download.

Nemetschek Scia Phone: 877-808-7242 Email: info@scia-online.com Web: www.nemetschek-scia.com Product: Scia Design Forms Description: Engineers can easily script custom calculations and output professional reports showing the exact formulas used to derive a check. Checks can be run as stand-alone, or linked to Scia Engineer.

Imagine being able to write checks linked your FEA software. Download the FREE trial.

Product: Nemetschek Scia Description: Request a FREE tryout and plug structural analysis and design into today’s 3D workflows. Tackle larger projects with advanced nonlinear and dynamic analysis. Design to multiple codes and script your own custom checks. Plug into BIM with links to Revit, Tekla, and others.

Powers Fasteners Phone: 985-807-6666 Email: jack.zenor@sbdinc.com Web: www.powers.com Product: Powers Design Assist (PDA) Description: Enables users to input technical data into a dynamic model environment; to specify anchors. PDA-360 is a FREE online version of our popular anchor design software. Powerful calculations with fast, detailed results. Works with any popular internet browser or mobile device.

BIM, Bridges, Building Components, Business/Productivity, CAD, Concrete, Found./Retain. Walls, Gen./Packages/Suites, Light Guage Steel, Masonry, Steel, Wood

SOFTWARE GUIDE

RISA Technologies

Standards Design Group, Inc.

Struware, LLC

Phone: 949-951-5815 Email: info@risa.com Web: www.risa.com Product: RISA-3D, RISAFloor and RISAFoundation Description: Developing cutting-edge structural design software for over 25 years, RISA software products are used around the world for buildings, stadiums, bridges and everything in between. RISA-3D, RISAFloor, and RISAFoundation allow you to work with steel, concrete, timber, masonry, aluminum and cold-formed steel in a single, seamlessly integrated model.

Phone: 800-366-5585 Email: info@standardsdesign.com Web: www.standardsdesign.com Product: Wind Loads on Structures 4 Description: Performs computations in ASCE 7-10 and ASCE 7-98, computes wind loads by analytical method rather than the simplified method, provides basic wind speeds from a built-in version of the wind speed, allows the user to enter wind speed. WLS4 has numerous specialty calculators.

Phone: 904-302-6724 Email: email@struware.com Web: www.struware.com Product: Steel Floor Vibration Analysis Description: Analyzes floor systems in accordance with AISC Design Guide 11 and can compare up to 4 systems side by side. Demos at website.

S-FRAME Software Phone: 203-421-4800 Email: info@s-frame.com Web: www.s-frame.com Product: S-FRAME R11 Description: S-FRAME Analysis, an industry standard for over 30 years, is a powerful, efficient 4D structural analysis and design environment with fully integrated steel, concrete and foundation design and optimization tools. Use S-FRAME to perform linear or advanced non-linear analysis on buildings and industrial structures. Includes advanced BIM and CAD links.

Product: S-FOUNDATION Description: Design, analyze and detail foundations with S-FOUNDATION, a complete foundation management solution. A stand-alone application, or utilize S-FRAME Analysis’ powerful 2-way integration links for a detailed soil-structure interaction study. Automatically manages the meshed foundation model and includes powerful Revit and Tekla BIM links.

Product: Structural Office R11 Description: Model, analyze and design robust structures regardless of geometric complexity, material type, loading conditions, nonlinear effects, or design-codes. Integrated steel, concrete, and foundation design solutions have efficient data sharing and include powerful two-way Revit and Tekla BIM links and comprehensive DXF file import capabilities.

Simpson Strong-Tie Phone: 925-560-9000 Email: web@strongtie.com Web: www.strongtie.com Product: Simpson Strong-Tie® CFS Designer™ Software Description: Software for cold-formed steel designers automates product selection and helps navigate the complicated design provisions of AISI, while offering more robust design tools. The program has an upgraded user interface that makes input faster and more intuitive. CFS Designer is the new version of LGBEAMER software.

Product: Simpson Strong-Tie® Joist Hanger Selector Web App Description: This web app makes it easier than ever to select the most cost-effective hanger for your projects based on the type of installation, sizes and loads. The clean, visual interface enables users to quickly select the members and configuration for their desired connection, and print the results.

Product: Window Glass Design 5 Description: Performs all required calculations to design window glass according to ASTM E 1300-09, ASTM E 1300 02/03/04, ASTM E 1300-98/00 and ASTM E 1300-94. GANA endorses WGD5 as best tool available in designing window glass to resist wind and long-term loadings.

Strand7 Pty Ltd Phone: 252-504-2282 Email: anne@beaufort-analysis.com Web: www.strand7.com Product: Strand7 Description: Advanced, general purpose, FEA system used worldwide for a wide range of structural analysis applications. Strand7 can be used as a standalone system, or with Windows applications such as CAD software. It comprises preprocessing, solvers (linear and nonlinear, static and dynamic) and postprocessing.

Structural Engineers Inc.

FLOORVIBE

Phone: 540-731-3330 Email: tmmurray@floorvibe.com Web: www.floorvibe.com Product: FloorVibe v2.20 Description: Proposed floor designs can be analyzed to determine if they meet the AISC Design Guide 11 and the SJI Technical Digest No. 52nd Ed. using FloorVibe v2.20. Floor framing can be hot-rolled, joists, or built-up sections. Expert advice provided for all required input and results.

StructurePoint Phone: 847-966-4357 Email: info@structurepoint.org Web: www.StructurePoint.org Product: spWall and spColumn Description: spWall – For analysis design and investigation of reinforced concrete, precast, ICF, tilt-up, retaining and architectural walls. spColumn – design and investigation of rectangular, round, and irregular concrete columns including slenderness effects.

Product: spSlab and spMats Description: spSlab – For analysis, design, and investigation of elevated reinforced concrete beams, joist, one-way, two-way and slab band systems. spMats – For analysis, design and investigation of concrete foundations, mats, combined footings, pile caps, slabs on grade, underground and buried structures.

Product: Tilt-up Walls and CMU Walls Description: Tilt-up analyzes wall strips, CMU analyzes solid walls for out of plane loading, but both will also analyze panel legs next to openings by automatically calculating loads to the wall leg from vertical and horizontal loads at the opening. Demos at website.

Product: Struware Code Search Description: Provides all pertinent wind, seismic, snow, live and dead loads for your building in just minutes.

Simplifies ASCE 7 & IBC (and codes based on these) by catching the buts, ifs, insteads, footnotes and hidden items that most people miss. Demos at website.

Tekla Inc. Phone: 770-426-5105 Email: info.us@tekla.com Web: www.tekla.com Product: Fastrak Description: Dedicated software to automate the design and drafting of steel buildings. Design simple and complex buildings to US codes and then export models directly to BIM compatible software, such as Tekla Structures.

Product: Tedds Description: Perform 2D frame analysis, access a large range of automated structural and civil calculations to US codes and speed up your daily structural calculations.

USP Structural Connectors Phone: 800-328-5934 Email: uspcustomerservice@mii.com Web: www.uspconnectors.com Product: USP Specifier Description: Simplifies access to information on over 3,000 structural connectors. Looking up connector capacities, viewing code evaluation reports and even mapping from competitor products to USP products are a snap with just a couple of clicks. Download the FREE USP Specifier software at the website.

WoodWorks® Software Phone: 800-844-1275 Email: sales@woodworks-software.com Web: www.woodworks-software.com Product: WoodWorks Design Office 10 Description: Conforms to IBC 2012, ASCE7-10, NDS 2012, SDPWS 2008; SHEARWALLS: designs perforated and segmented shearwalls; generates loads; rigid and flexible diaphragm distribution methods.

SIZER: designs beams, columns, studs, joists up to 6 spans; automatic load patterning. CONNECTIONS: Wood to: wood, steel or concrete.

Not listed? Visit www.STRUCTUREmag.org and submit your information for upcoming guides!

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STRUCTURE magazine

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August 2014

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Structural ForenSicS investigating structures and their components

Figure 1. View showing the widespread damage that occurred though this suburban neighborhood following the Waldo Canyon fire.

E

l Paso County, Colorado is located approximately 70 miles south of Denver, has a land area of 2,127 square miles, and had a 2012 population of approximately 645,000 (representing 12 percent of the population of Colorado). Although the majority of the El Paso County population is concentrated in Colorado Springs and along the Interstate 25 corridor, densely-populated areas also exist at the east edge of the Pike National Forest where the Rocky Mountain Foothills meet the Front Range. With only a few exceptions, all of the structures built within El Paso County are within the jurisdiction of the Pikes Peak Regional Building Department.

On Saturday, June 23, 2012, a fire ignited in Waldo Canyon inside the Pike National Forest, approximately four miles northwest of Colorado Springs. The fire was given the namesake of its origin canyon, and burned eastward engulfing approximately 18,250 acres of land and destroying 346 homes. Two fatalities were reported. The wildfire was fully contained by July 10, 2012. At last report, the insurance claims for the wildfire exceeded $450 million.

The Black Forest community in El Paso County is known for wide-spread moderately-dense Ponderosa Pine trees. The Black Forest area is located along the north edge of El Paso County, northeast of Colorado Springs. Structures built in the Black Forest community were mostly single family homes situated on ½- to 4-acre lots. On Tuesday, June 11, 2013, a fire started near the east edge of the Black Forest community and began to burn eastward. The Black Forest fire burned approximately 15,500 acres, destroyed 511 homes, and damaged 28 other structures.

Two fatalities were reported. The Black Forest fire was fully contained by June 20, 2013. At last report, the insurance claims for the wildfire exceeded $295 million.

In response to the Waldo Canyon fire, the Pikes Peak Regional Building Department developed four scenarios to assist those who lost or experienced damage to their home. The four scenarios were as follows: 1) Use of existing foundation, same house: “If Regional Building has the original plans, the only document required will be a letter from a licensed engineer stating that existing foundation is acceptable for rebuild. RBD will issue, at a minimum fee, a demolition permit for removal of fire debris. This permit is required to monitor removal activity and be sure fall protection is installed around the open foundation as required by code (2011 PPRBC).

The single family dwelling shell can be constructed according to the plans on file with the issuance of a new remodel permit (434)… The interior finish portion of the house may not be required to meet all current structural or design criteria of the 2009 IRC, but will be required to meet all life/safety requirements and other design provisions that benefit the owner such as, but not limited to, State Electrical Code, smoke and CO detectors, energy conservation, etc.”

2) Non-use of existing foundation, same house: “If Regional Building has the original plans, the documentation required will be a letter from a licensed engineer stating that foundation is not safe for rebuild and submittal of a new foundation plan for review/approval. RBD will issue a wrecking permit at a minimum fee for total removal of foundation and all fire debris. continued on next page

STRUCTURE magazine

Engineering Evaluation of Fire Damage to Concrete Foundations

57

By Peter Marxhausen, M.S., P.E.

Peter Marxhausen, M.S., P.E., is a Senior Staff Forensic Structural Engineer with Higgins & Associates, Inc. in Morrison, Colorado. He is also an adjunct faculty member with the University of Colorado Denver Civil Engineering Department.

Peter may be reached at Peter@HigginsAssoc.com.

Figures 2 and 3. Views showing how heat-damaged concrete exhibits low strength and crumbles easily when struck four to six times with a hammer. The rebar is exposed, and the fractures are through the paste, not the aggregate. Without conducting any further testing, this foundation is considered not suitable to be re-used in reconstruction of the structure.

This permit is required to monitor removal activity and to be sure the foundation excavation is backfilled or protected according to code (2011 PPRBC)… The construction of the foundation must comply with all applicable provisions of the 2009 IRC. Inspections may be made by the engineer of record. The remaining portion of the structure located above the foundation may be constructed as outlined in # 1 above.”

3) Building new home (different from original) at existing location: “Process will be the same as any new single family dwelling plan/permit submittal currently in place… One set of plans, including engineered foundation, site plan, all construction docs and duct design components to comply with 2009 IRC.” 4) Repair of existing structure due to fire damage: “Process will be the same as any remodel for an existing residential structure.”

Scenarios 1 and 2 above required a licensed engineer to evaluate the remaining foundation to confirm it could be reused or to determine it was damaged to an extent that required replacement. Scenario 3, construction of an entirely new and different home, required the involvement of a licensed engineer to develop the new foundation plans, since El Paso County is an area known to contain expansive soils. Lastly, Scenario 4 typically required the involvement of a licensed engineer to evaluate the extent of the fire damage to the structure, and to develop reconstruction plans that could be submitted to the building department for the normal permitting/structural repair process. The guidelines for evaluation and repair of structures developed by the Pikes Peak Regional Building Department

following the Black Forest fire were similar to those outlined above.

Structural engineers are frequently hired after disasters to evaluate the damage. As it pertains to both the Waldo Canyon and Black Forest wildfire events, insurance companies, owners, and contractors sought help from the Colorado engineering community to evaluate numerous structures to determine the extent of the damage. Specifically, most of the assigned tasks were to evaluate the remaining portions of the masonry and concrete foundations to determine whether the foundations could be reused.

Over a decade ago, the author of this article would typically obtain concrete cores of a damaged foundation, then submit these samples to a third party testing agency to conduct a chemical analysis, compressive strength tests, and a microscopic/petrographic analysis. Testing like that would often take four to six weeks and could cost $3,500 to $6,000, depending upon ease of site access and the number of cores to be extracted and evaluated. The results of the laboratory examinations were beneficial; however, after years of evaluating damaged concrete and CMU, the author was able to develop methods for quickly and economically evaluating concrete slabs and foundations for fire/heat damage.

The rapid methods for evaluation were useful following the Waldo Canyon and Black Forest Fires, and helped property owners achieve faster resolution with less expense.

Evaluation The four methods used to rapidly evaluate a concrete or concrete masonry unit (CMU) foundation for heat damage included the following: Visual A visual assessment is conducted to review the foundation for patterns of scorch marks,

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heat exposure, cracks, a change in color, surface spalls, and/or leaning/tilting of the walls. Tilting and leaning may not be due to heat damage, but can occur from the loss of diaphragm support after a structure is consumed by a fire. Wall tilts/leans, as well as cracks, may have pre-existed the fire event or may have been induced by the fire.

Regardless of cause, cracks and leaning walls should be considered by the structural engineer in determining whether a foundation is reusable for construction.

Typically, normal concrete is not significantly altered or damaged below a temperature of 500 degrees Fahrenheit; however, rapid heating of the concrete can cause pore water to rapidly boil, which can cause surface spalls. Surface spalls can also result from sudden cooling/contraction after being sprayed by a fire fighter’s hose.

Spalled areas should be carefully examined to determine whether they are a sign of widespread heat damage or an isolated occurrence that could be addressed with a targeted repair patch.

The color of the concrete paste should also be reviewed since a color change may indicate exposure to temperatures of greater than 550 degrees Fahrenheit. Concrete exposed to temperatures greater than approximately 570 degrees often turns a shade of pink, associated with chemical changes of the iron-containing compounds in the aggregates and paste matrix. At much higher temperatures, which are not commonly encountered during typical structure fires, the concrete can turn back to a light gray and then eventually to a yellowishbrown color. Concrete that has turned pink is damaged and should be replaced.

Smoke stains and scorch marks serve as a good indication of areas that were exposed to high heat when comparing to areas exposed to less heat, indicating further evaluation by methods 2 and 4 outlined below.

Audible/Sound Changes A sounding hammer, typically a framing hammer with a hardened steel handle, can be used at various exposed surfaces to strike the surface and listen for subtle sounds in how the hammer rings. In general, healthy, undamaged concrete will cause a hammer to have a highfrequency ringing sound when struck. Concrete that has a consistent dull/thud or soft noise can indicate damaged or poor-quality concrete.

Fracture Mechanics Healthy, undamaged concrete will typically fracture in a plane through the aggregate. In heat-damaged concrete, the paste matrix is often much weaker than the aggregates; therefore, the fracture plane will break around the aggregate pieces. In order to facilitate an evaluation of the fracture mechanics, the edge of the concrete can be struck with a framing hammer. Undamaged concrete will typically be very difficult to break, which may be an indication there is no damage.

By comparison, heat-damaged concrete will crumble away with a few rigorous hits. Once broken, an experienced engineer can get a feel for the quality of the concrete and gain access to a fracture face for closer examination. Severely damaged concrete will unreservedly fall apart with a few arduous blows of a modest-sized hammer, often exposing the rebar and a paste matrix that has a chalky consistency.

A review of the distress in Figures 2 and 3 shows the effect of four to six hammer strikes on an area of heat-damaged concrete. Healthy, undamaged concrete would have likely required the better part of a day to accomplish the same damage using the same hammer.

Relative Concrete Strength A Schmidt hammer, also known as a rebound hammer or a Swiss hammer, is a calibrated device that is used to measure the elastic properties or surface strength of the concrete.

Although the results of the Schmidt hammer can be used to determine an approximate concrete compressive strength through use of empirical tables, the original as-built design compressive strength is often not known and therefore is of minimal benefit.

As with nearly all of the aforementioned evaluation methods, especially the Schmidt

hammer evaluation, more meaningful data is obtained by a comparison of test results from at least four areas of the foundation. One way to do this is to conduct a Schmidt hammer test below grade at an excavated surface (where it was protected from heat by the soil) or at a lower inside foundation corner to obtain a baseline value for areas that were exposed to minimal/less heat. If areas of the foundation that were obviously exposed to high heat exhibit a 20 percent or more decrease in concrete strength compared to areas that were not exposed to heat, those results should be reported to the client and considered in the analysis of whether to reuse the foundation.

The homes consumed in the Colorado wildfire events typically exhibited a concrete compressive strength of less than 2000 psi and a 30 to 50 percent reduction in strength compared to areas generally protected from exposure to heat.

In the event 50 percent or more of the foundation system exhibits damage, the entire foundation is typically removed and replaced.

However, on occasion, an owner may want to preserve as much of the foundation as possible.

This scenario may present itself in the case of historical buildings or an owner with minimal insurance coverage. In that event, additional evaluation, which would likely include laboratory analysis and/or non-destructive location of the embedded rebar, may be necessary to determine if the structure is safe to support the anticipated loads and what repairs are needed to fortify deficient areas. It is beyond the scope of this article to discuss those types of repairs.

Conclusion Ultimately, each client involved with the wildfire events was seeking clarification and information as to whether their foundation was undamaged, could be repaired, or required replacement. Since the Waldo Canyon and Black Forest wildfires were historical firsts in Colorado in terms of damage magnitude, minimal guidance was available from the local building department.

However, a pattern quickly emerged that, where the structures had burned without any effort to extinguish the fire or control the temperatures, the sustained exposure to high heat was ultimately deleterious to the

Figure 4. View showing the characteristic pink hue of heat-damaged concrete. The signature pink color is a strong indicator the concrete is severely damage and cannot be re-used for reconstruction.

concrete and masonry, requiring complete foundation replacement.

It was this author’s experience that photographs taken before and after striking the concrete foundation with a hammer provided the most benefit to clients who had severely damaged foundations. Photographs showing the concrete could be dislodged to expose the rebar with two to six hits with a framing hammer quickly convinced homeowners who may have wanted to preserve/reuse their foundation to choose otherwise. Additional documentation, including the visual assessment, Schmidt hammer tests, and sounding hammer reports, helped augment and convey the extent of the damage. Using the aforementioned methods, engineering documentation regarding the extent of foundation damage was provided to the clients involved in less than a week.

It should be noted that structure fires are typically extinguished by firefighting professionals before the concrete is heated to an extent that it becomes damaged. Where structure fires are rapidly extinguished, the aforementioned evaluation methods can help determine whether a foundation is safe to be reused in the repair of a structure. These evaluation tests for heat damage to concrete can help determine a “go” or “no go” rapid evaluation for fire-damaged foundations.

Specifically, it can quickly categorize the concrete as positively undamaged, positively damaged, or questionable requiring a further detailed analysis. Test results at buildings where these methods yield mixed, inconclusive, or borderline results should be further evaluated by laboratory analysis.▪

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Education issuEs

core requirements and lifelong learning for structural engineers

Awakening Young Minds to Structural Engineering

By Craig E. Barnes, P.E., SECB and Jennifer dos Santos, Associate A.I.A., MCPPO

T

he process of awakening young minds to the beauty and excitement of structural engineering is not as complicated as one might think. What are the necessary ingredients?

• A classroom of young minds.

• A cooperating school.

• An engineer willing to speak to young minds.

• A classroom assistant (perhaps a parent of one of the children).

• Graphs, easily downloaded from the web, of interesting projects.

• Paper, foam board (cardboard), glue, toothpicks, gum drops, etc.

• One to 1½ hours of time in the classroom (which will be quickly filled), an hour or two of preparation time the evening before, and a cooperating individual to help prepare student gift bags filled with materials to construct a bridge.

Young children will find almost anything entertaining as long as there is activity.

The key is to make that activity pertinent to their environment and tie it in some fashion to science and engineering. The following example, we believe, achieves both of those objectives. In this program, the teacher had paved the way for the presentation by having the students undertake basic research into elements of bridge construction. The classroom example was an unnamed child walking over a brook on a board or a log. A log supported on the bank (buttress) of the brook becomes a bridge.

One can’t be more descriptive for a young mind than that. However, the simple bridge allowed for an opportunity to extend basic concepts through sketches and photographs to real-world situations.

no need to have a professional drawing. The kids wouldn’t understand the detail in any case. The paper in this case, 8½ x 11 inches, is used simply to illustrate the principle of stiffness created by folding the paper. That same piece of paper can be used to illustrate how changing the shape of materials can also change what they are able to do. In this example, a sheet of paper was simply thrown. Without surprise, it went nowhere but down. The students were then, with their own piece of paper, asked to fold it to resemble that childhood paper plane that you certainly made years ago. Much to the authors’ surprise, much of the class had not experienced making a simple paper plane.

The paper plane, when thrown, achieved

In the Classroom In the case of our classroom example, the real-world case experience was the Leonard-Zakim Bridge in Boston. For the classroom experience, it was convenient to have a whiteboard or an easel for quick sketches with magic markers. Remember, you are speaking to an audience where quick sketches are as good in their minds as the ones they make…there is absolutely STRUCTURE magazine

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a much greater distance than the plain sheet of paper. The study was extended a little further; with a few more folds, and some staples in the nose of the “plane” to change the aerodynamic characteristics. The students saw how minor design changes, using the same piece of paper, could really improve the flight of their ‘777’. A note of caution, best to save this example to the end of the class…you can speculate as to why. That piece of paper appears later in a hand-sketch symbolically on the white board to illustrate how structural engineers participate in the airplane industry. By the time they are ready for that description, they will have received a brief discussion about trusses and how trusses work.

With the white board handy, the basic elements of bridge construction (piers, buttress, cables, tension and compression members, etc.) can be illustrated. Prepare ahead with simple combinations of popsicle-sticks, glue joints, or popsicle-sticks with pin joints to illustrate the elements of truss construction. Use the white board to quickly describe a variety of bridges: truss, girder, arch, cable, etc. Children become bored easily when looking at too much placed on a board in front of them; therefore, intersperse your white board activity with photographs and/or some of the examples you have made to illustrate concepts. We found a simple combination of toothpicks and small Styrofoam

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Jennifer L. dos Santos, Associate A.I.A., MCPPO, is an Assistant Project Manager at CBI Consulting Inc. in Boston, Massachusetts. Ms. dos Santos can be reached at jdossantos@cbiconsultinginc.com.

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Craig E. Barnes, P.E., SECB, is the Founding Principal of CBI Consulting Inc. He also is a member of STRUCTURE’s Editorial Board. Mr. Barnes can be reached at cbarnes@cbiconsultinginc.com.

RINE ENG MA I

Part of the back story in a successful presentation is the involvement of the school and the parents. Somebody needs to put that package together to make it appear attractive to a school. Remember, no grade-school teacher or superintendent of a school that I can remember will have much awareness of structural engineering, and most of them won’t have the faintest idea of what a structural engineer does.

Also it is helpful if the children have some prior interaction with the concepts that will be presented. In this case, the teachers had prepared learning packages for the students which contained vocabulary words, objectives, and descriptions of the projects that the students would be executing. The vocabulary primer included words such as pier, abutment, span, suspension, and included simple definitions.

The students were also assigned a bridge to research on third-grade appropriate websites (Wikipedia was not an allowable resource for this project). The bridges included the local Leonard P. Zakim Bunker Hill Bridge and the famous Akashi-Kaikyo Bridge in Japan. Upon completion of their research, the students had to create an informational “brochure” regarding their bridge, including such information as the Designer of the bridge, the duration of the construction, the type of bridge (they had to select from cable, span, suspension or arch), the location, the year built and the question that proved to be a bit tricky (at least for the author’s child) was to explain why this type of bridge was selected.

Another project that the students executed was with an assigned partner where they were given materials in class (popsicle sticks, foam board, tooth picks, glue, etc.) and had to

ETY OF NAV A CI O

The Back Story

engineer and construct a bridge that was able to span a certain distance and withstand the weight of 3 cups of steel bolts. It also had to allow cars to pass independently, without the assistance of the students. This project was especially enjoyable to most of the students.

In addition to the in-class bridge education, the students also really enjoyed the class presentation. It offered them a broader exposure to structural engineering and showed them a number of exciting things that engineers might work on, such as airplanes (which all children love!) and some interesting structures other than bridges!

There may be students in those very class rooms that will remember this introduction to engineering in a few years when it is time for them to select a college major!▪

• THE ERS S NE

bridge sample on the book buttresses for illustration purposes.

&

balls quite useful. In one case, toothpicks and Styrofoam balls were pushed together to form a string in front of the student.

A similar example using Styrofoam balls and toothpicks, inserted in quick- setting glue, was used to illustrate tension characteristics and cable analogy. Popsiclestick glue joints, prepared ahead of time, or with the use of quick-setting glue in class, can illustrate the difference between rigid connections and pin connections.

Clearly, some of these concepts will be lost because the children will not understand the application; however, they will be able to visualize how joints work.

In our case, the teacher required the students to write a report on their observations of the presentation, and to describe items of interest and what they had learned. Most of the students were intrigued by the concept that a ¼-inch piece of foam board would not support a stapler (the stapler was described as loading on the brook bridge), versus two layers of foam board where there was greater capacity, yet the stapler still touched the water. Using glue, turning those two pieces of simple layers into composite construction, the foam board could then be a functional bridge supporting the stapler, amazing the children. I used the foam board, the stapler, and two books symbolizing two buttresses over our imaginary river; this illustrates that the simplest of materials can be utilized to great benefit in a presentation of this sort.

If you are in a program of long duration and have sufficient time to make your toothpick and gum-drop truss bridge, go to it in the classroom environment. If you don’t believe you will have enough time, prepare in advance little gift bags of the truss with a hand sketch of what it will look like when completed for the students to take home. Put your preassembled gumdrop

Professional issues

issues affecting the structural engineering profession

Deferred Submittals Part 2: When is Final…Final?

By Dean D. Brown, S.E.

I

n Part 1 of this series, the importance of proper routing review of a deferred submittal was highlighted. Pre-engineered wood trusses were used as a case study and, while this topic is obviously an issue directly affecting the Engineer of Record (EOR), it impacts the Building Official and their ability to properly enforce the building code. We, as building designers, typically assume building officials properly understand their respective responsibilities and that their adopted policies are compatible with the engineered system. That is not always the case and this issue has puzzled the author for many years as he has dealt with a multitude of Building Officials.

As a rule, we make explicit statements, sometimes in the general notes or on the building detail sheets that deferred submittals are to be reviewed by the EOR before construction proceeds. In spite of these instructions, often times the designer is not afforded an opportunity to review Truss Design Drawings and is forced to adjust assumptions made during the initial design.

One can suppose contractors get busy and forget to follow protocols. One can also suppose many Building Officials think an EOR’s involvement in the design ends once the stamped set of construction documents has been submitted for permit. This can be a difficult issue to enforce, as most designers have no direct contractual link to the contractor or the truss designer.

To satisfy his own curiosity, the author conducted a brief simple written survey of five questions with chief Building Officials across a relatively small state (which shall remain anonymous and to which will be referred to as the “Survey State”). The survey considered all of the main city and county jurisdictions, and the state was one in which the author was not licensed. Also, pre-engineered wood trusses are commonly used throughout the Survey State and would be an engineered system with which Building Officials had experience.

The main goal of the survey was to determine any common state-wide consensus (call it “standard-of-care”) on review procedures among Building Officials.

Below, the responses are summarized along with the author’s commentary.

Question 1: Are Deferred Submittals required to be listed on contract documents and/or on the permit application?

Responses to Question 1 • “Yes, Deferred Submissions are to be listed on the contract documents and the building permit.”

• “Typically our city does not allow Deferred Submittals. Deferred Submittals are to be provided at the time of building permit application.”

• “Deferred Submittals are not allowed.”

Commentary – if deferred submittals are not allowed, are pre-engineered wood trusses not being used? This engineered system is commonly used on residential and commercial projects.

How can deferred submittals be completed “at the time of building permit application?”

Question 2: Does the (EOR), when stamping plans, typically provide any notation adjacent to the stamp that the design is ‘Preliminary’ (or comparable notation) indicating that the design needs to be later checked by the EOR? Responses to Question 2 • “When the building permit is issued, all plan documents must be construction ready.”

• “No…no notation is provided indicating that the information is ‘Preliminary’. Any revisions to plans would require resubmittal of changes.”

• “Yes, a note is provided that submittal design is for ‘Design Purpose Only’.”

Commentary – “Construction ready” implies that the design is final. For “Design Purpose Only’ infers that the submitted design is an interim design.

Question 3: Are Final Deferred Submittals provided at the time of building permit application?

Responses to Question 3 • “Deferred Submittals are not allowed.”

• “Submittals are to be provided at the time of building permit application.”

• “A preliminary deferred submittal is to be submitted upon a building permit application. Many manufacturers will not provide P.E. stamp on the Deferred Submittal design until the PRODUCT has been paid for.”

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• “No, the Deferred Submittal documents are provided at the time of inspection.”

• “Deferred Submittals are never submitted upon building permit application. They are listed as a Deferred Submittal. Framing inspections are not provided until all the Deferred Submittal documents are received, reviewed, and approved.”

• “Proposed Deferred Submittal packages are required to be submitted for plan review, to verify loads are being addressed. Inspections of the structure are made from stamped Deferred Submittal Package. There are occasional deviations from the ‘Preliminary’ vs. ‘Final’.”

Commentary – Regarding the 3rd bullet point, trusses are often purchased after the building permit has been issued and are not finalized until a purchase order has been received from the contractor. Anything submitted prior to this time would be considered ‘preliminary’ or ‘proposed’.

The last bullet point does verify that there can be “deviations” between that of the original design to the final design.

Question 4: How does the EOR provide indication that they have provided (independent) Responsible Charge review of the Deferred Submittal documents?

Responses to Question 4 • “EOR typically provide generic details not stamped except for larger commercial projects, bracing and erection details are stamped.”

• “EOR are responsible to provide correct details upon submission for building permit application and will often use Truss Plate Institute truss industry bracing details.”

• “The building department does not require independent analysis of Deferred Submittal design (i.e., permanent bracing), but the EOR is asked to make Responsible Charge review where requirements are above the building code minimums.”

• “The city generally has the structural inspector briefly review the truss engineering and then the inspector compares it to the structural engineer’s stamped drawings. In cases where the

truss engineering doesn’t appear to be compatible or if something doesn’t seem correct, the inspector would notify the plan reviewer and the design professional in responsible charge would be contacted.”

Commentary – The building official in the last comment implies that the EOR’s review role is completed upon building permit application.

In other words, it’s up to the building official’s discretion to decide when to involve the EOR, contrary to IBC 107.3.4.2.

Question 5: For projects containing Deferred Submittal submission, does the EOR typically make amendment (or changes) once they have reviewed the Truss Submittal Package?

Responses to Question 5 • “No.” • “There are a few instances where the EOR makes changes to the original building design (when using a preliminary truss design). The EOR does review changes to the design before submittal to building official.”

• “The EOR is required to re-review the original design with respect to load bearing. Issues identified during field inspection are brought to the attention of the registered design professional.”

Commentary – How is it that in some jurisdictions there are no revisions to the Structural Design Drawings and then in others, there are?

Disparities in these responses were alarming, given that these individuals are tasked with enforcing the building code. A Building Official’s simple directive is to enforce the code, provide interpretations as to the intent of code, and to adopt policies as to the code’s application. They are not authorized to override the design intent as rendered by the EOR. (2009 IBC, Section 104.1) For one city surveyed (4 th question, last bullet point), the author subsequently informed the building department of their deficient practice and was initially met with push-back (i.e., no agreement with the conclusions). The mayor was then contacted to apprise him of the situation and he responded with, “Based on a review of the City…adopted building code and our current practices, we have asked all of our building plan reviewers and inspectors to now require that a letter be stamped by the engineer in responsible charge indicating that the deferred submittals from truss manufacturers and others are in general conformance to the design of the building before any Certificate of Occupancy is issued.”

It is obvious that there is no state-wide consensus among Building Officials regarding the use and review of deferred submittals. Most of these submittals have a direct impact on the Lateral Force Resisting System of a building and are therefore part of the Life/Safety mandate of the IBC and the state’s Rules of Professional Practice.

This affects the practice of professional engineers (i.e., does not the practice of Building Officials …at least on this issue…impact the professional engineer in responsible charge duties?). Perhaps, if there has been any ambiguity on roles and responsibilities with engineers, it has been, in part, because some Building Officials do not fully understand their role.

Standard-of-Care (for Professional Engineers) in the Survey State is defined as, “Each Licensee and Certificate Holder shall perform in accordance with the standard of care for the profession and is under duty to the party for whom the service is to be performed to exercise such care, skill and diligence as others in that profession ordinarily exercise under like circumstances” (emphasis added). Given that practices differ from building department to building department, is standard of care confined to local regional practices (i.e., city-to-city or county-to-county)? Obviously the statute is defined for state-wide practices, but in reality standards of practice can vary more locally.

When it also states “…as others in that profession…”, is that what others in that state are currently practicing or what they “should be” practicing by building code and truss industry standards?

Given the conflict that occurs among Building Officials, this was brought to the attention of the respective Survey State’s Board of Professional Engineers. Their brief response alarmed the author even further, stating “The Board is under no obligation to inform a building official of any conflict.

This is so because the building official, in and of itself, does not practice engineering.

The processes, practices, or methodology that the building official employs regarding plan approval …for metal or wood trusses or any other matter has nothing to do with the practice of engineering by engineers. If there are discrepancies in plan approvals, those discrepancies are the policy of the building official. Further, there was no information that exists suggesting ... that the health, safety or welfare was a risk due to a systematic failure of the review process.” They went on to elaborate that they did not see any deficiencies with current state statutes or that of building officials requirements

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for professional engineers (i.e., the status quo properly defines an engineer’s role and responsibility). Ironically, this state’s regulations reads, in part, “All Licensees … shall at all times recognize their primary obligation is to protect the safety, health and welfare of the public in the performance of their professional duties.”

If and when a city contracts with a Professional Engineer for peer review services (involving deferred documents), the State Board informed the author that the engineer is under “no obligation to remedy the city (client)” plans review process or practices. If there are discrepancies of some kind in the plans review and approval processes, those discrepancies are the policy of the city and building officials and not the responsibility of the peer review engineer.

Does not the proper practice of building officials impact that of the professional engineer? Are not the two roles tied together? If building officials are not properly enforcing the review of deferred submittals, does that not reflect on the engineering community at large and a professional engineer’s responsible charge and primary obligation?

In this one case, a city mayor (who is a non-industry individual) clearly understood the issue with his own building department and acted to align policy with practice. The State Board chose to ‘kick the can down the road’ and Building Officials couldn’t see the existing problem.

As engineering professionals, we can’t afford to design within a bubble any longer. In this age of integration, there needs to be faster and more efficient alignment between all stakeholders. State Boards regulating Professional Engineers need to work with Building Officials on a state-wide basis. There needs to be an examination as to conflicts between state statutes and building code language.

Each state’s structural engineering association would do well to lead this effort and thereby serve their own interests.

In Part 3 of this series, the author will discuss a specific conflict … using the Survey State as an example.▪ Dean D. Brown, S.E., is a Professional Structural Engineer in the state of Utah.

He works as a senior structural engineer for Lauren Engineers & Constructors in Dallas, TX. He can be reached at browndean57@yahoo.com.

INBOX

letters to the editor

Are Sustainable Structures Compactible with Common Sense?

March 2014

T

he March 2014 Structural Forum column baffled me.

The author has not documented the basis of his assertion that “sustainable” buildings are only one percent better than “standard” buildings, nor did he explain why he “ignored the energy used to run buildings” even though, of the total energy used to construct and maintain a building over its lifetime, operation typically accounts for about half. We are left with the somewhat self-congratulatory argument that anything an engineer touches is better than prior designs because of increased structural efficiencies; or perhaps that what some call “sustainable” design really is not sustainable.

It’s been a couple of years since the last semi-credible “climate skeptic” examined the evidence and said that not only was he convinced, but things are worse than originally thought. While public agencies are preparing for rising sea levels, more frequent droughts, etc., maybe we should examine the definition of “common sense” as well as “sustainable.” Instead of designing an “efficient” new bridge to widen a highway, we could replace the highway with a mass transit system; instead of state-of-the-art and “efficient” McMansions, we could design multi-family housing with equally efficient structures, preferably using truly renewable materials.

We have enormous challenges ahead of us. LEED won’t meet them in time; that does not mean we should abandon the goal of sustainability, but rather that we should reset our entire outlook on what we should build, and how.

Thor Matteson, S.E. Berkeley, CA Response from the Author My admittedly outrageous statement that current “sustainable” structures are little different from normal structures is based on the following assumptions: • It is essential that engineers lead the way in reducing impact on the environment and depletion of non-renewable resources. See Building for a Sustainable Future: An Engineer’s Guide, published in February 2014 by the Institution of Structural Engineers.

• My comments were limited to what engineers can do once the decision has been made to construct something; i.e., their normal job.

• The energy used to operate buildings is not part of structural design; also, the end of a structure’s life and potential for recycling are not within the engineer’s control.

• Structural engineering design codes, augmented by value engineering, generally result in near-minimum-weight and -cost structures.

• For a typical large building, say 50,000 square feet, the choice is between steel and concrete frame, with similar floor structures. Stripped to structure only – foundations, cores, columns, beams, floor slabs – there is virtually no difference, in terms of cost, weight and embodied energy, between steel and concrete options; rather, the differences are smaller than STRUCTURE magazine

those that arise out of project-specific and commercial circumstances – the precise sources of construction materials, their transport to site, required speed of construction, preferences and experience of contractors, etc.

Many studies have demonstrated this.

• The outcome of whole-life embodied energy calculations depends entirely on the assumed life of the structure, which is generally arbitrary; this always lies in the assumptions given in the small print of such calculations.

Bill Addis, Ph.D., MCIOB Closure Thanks to Mr. Addis for clarifying this, and for his other contributions toward sustainable design. His first point, that engineers should lead the way in reducing environmental impacts, suggests that we need to shift our approach to his other five points by influencing the following: • Deciding what we construct – e.g., suburbs, exurbs, and freeways vs. well-planned, high-density housing areas with no need for private automobiles.

• Using materials that result in lower operating energy – e.g., steel-framed houses with poor thermal performance vs. wood-framed.

• Measuring on a “per need” basis, not a per square-foot basis – e.g., the couple who asked me to design a 5,000-square-foot retirement home, glowing about how energy-efficient it was, should have been guided toward a much smaller home or apartment.

• Thinking beyond the structural core – e.g., can the structure be adapted to future uses, or can components be easily reused or recycled?

• Designing for true resource efficiency, not just to meet artificial goals subject to redefinition for the convenience of the owner or design team.

Every building material sector tells you how theirs is the most sustainable to use. The truth is, unless some 7 billion other people can build just the same way you are, and never reduce the supply of raw materials, your building is not sustainable. The last time we practiced truly sustainable construction was before we started mining coal. We don’t need to regress, but we definitely need to change course swiftly, while we still can.

Thor Matteson, S.E. Berkeley, CA

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letters to the editor

Vertical Turbine in an Urban Environment February 2014

I just came across this article in STRUCTURE magazine. Drum turbines do have some of the best turbine coefficients (Ct). They do produce more efficient power then horizontal turbines in urban areas. They will capture up to 95% of air mass going through, while horizontal turbines at best will capture 40% of air mass going through. But there are a few down sides, such as: vertical assembly has weight issues, the entire assembly sits on one gear box which carries both the weight and rotation of the turbine. And secondly, wind flows both on the force and drag side of the turbines; blades have to be aerodynamically shaped to capture wind on the one half and reduce drag on the other side as blades are rotating into the wind. Bahari Energy, LLC, has developed a new technology which overcomes all the issues with both vertical and horizontal. It is called the Wind Tower technology. This is a game changer technology in capturing wind energy for the urban environment.

Design Deficiencies in Edge Barrier Walls in Parking Structure April 2014 Thank you for your excellent article in STRUCTURE magazine on “’edge barrier walls” in parking structures. We need more of these type practical articles – this is especially important for young structural engineers. In Figure 1, the #4 standard hook is not developed in a six inch wall – reference CRSI Reinforcing Bars: Anchorages and Splices. In the past twenty years or so, I have investigated parking structure problems and found most serious structural issues to be related to connections. Thanks again and good luck.

Larry G. Mrazek, P.E., S.E. Chesterfield, MO

Regards, Habib Bahari Rockville, MD ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

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August 2014

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Spotlight

Recognizing Outstanding Structural Engineers

T

he Structural Engineering Institute (SEI) proudly recognized the following recipients at the Structures Congress 2014 in Boston, Massachusetts on April 3, 2014:

Structural Engineering Institute Awards 2014 Chapter of the Year Award The 2014 SEI Chapter of the Year Award was given to the SEI Philadelphia Chapter. The Philadelphia SEI Chapter has been very active in a variety of activities including technical presentations, conferences, tours, student outreach events, and networking opportunities.

Gene Wilhoite Innovations in Transmission Line Engineering Award The Gene Wilhoite Award honors an individual who has made significant contributions to the advancement of the art and science of transmission line engineering. The 2014 Gene Wilhoite Award was given to Michael Miller, P.E., P.Eng, M.ASCE. Mr. Miller has more than 25 years of experience in the design, analysis, and testing of high-voltage transmission structures. Mr. Miller is the current chair of the ASCE/SEI Electrical Transmission Structures Committee.

Dennis L. Tewksbury Award The Tewksbury award recognizes an SEI member who has advanced the interests of SEI. The 2014 award was presented to Sam Rihani, P.E., F.SEI, F.ASCE. During his 36-year professional career, Mr. Rihani has specialized in the structural analysis and design of steel framing systems and buildings. Mr. Rihani has been an active member of ASCE since 1975, serving on the Executive Committee of the Structural Engineering Institute’s Business and Professional Activities Division, was a member of the ASCE Technical Region Board of Governors, and served as President of SEI from 2011 through 2013.

Walter P. Moore, Jr. Award This award is presented for significant contributions to the development of codes and standards.

The 2014 Walter P. Moore, Jr. Award was given to Ronald Hamburger, S.E., SECB, F.SEI. Mr. Hamburger has nearly 40 years of experience in design, failure investigation, research and building code and standards development. He has also given of his time to serve on many SEAOC, AWS, and NCSEA committees.

SEI President’s Award The SEI President’s Award recognizes exemplary contributions to the success of SEI. The 2014 President’s Award was given to Stan R. Caldwell, P.E., SECB, F.AEI, F.SEI, F.ASCE. Mr. Caldwell’s Award winners (left to right): Mike Miller, Todd Helwig, experience includes the structural Maria Pia Repetto, Sherif El-Tawil, Sam Rihani, Herbert design and management of more Mang, Don Dusenberry, Stan Caldwell, Taka Kimura, Ron than 800 projects over his 40 year Hamburger, Lou Geschwindner, Chia-Ming Uang, Satish career. He has been very active in Nagarajaiah, Jennifer Goupil. professional organizations including ASCE. Mr. Caldwell was a member of the in the September-October 2012 issue of the SEI Board of Governors, participated in bet- Journal of Bridge Engineering. tering the Structural Engineering Certification Nathan M. Newmark Medal Board, helped form the Structural Engineering The Nathan M. Newmark Award is presented Licensure Coalition, and helped in the creation jointly by the Engineering Mechanics Institute of the SEI Futures Fund. and Structural Engineering Institute for outstanding contributions in structural engiAmerican Society of Civil neering and mechanics. The 2014 medal was Engineering Structural Awards awarded to Herbert A. Mang, Ph.D., F.ASCE. A 40 year ASCE member, Dr. Mang has made Shortridge Hardesty Award outstanding research contributions in the area The Shortridge Hardesty Award may be given of nonlinear continuum and computational annually to individuals who have contributed mechanics that clarified the cause of collapse substantially in applying fundamental results of of important concrete structures and quantiresearch in the field of structural stability. The fied the influence of bending on the initial 2014 award was given to Todd Helwig, Ph.D., post-buckling behavior of metallic structures.

P.E., M.ASCE. Dr. Helwig is currently in his Raymond C. Reese Research Prize 20th year of teaching and conducting research in The Raymond C. Reese Research Prize is the design and behavior of steel structures with awarded for a paper published by ASCE that an emphasis in structural stability and bracing. presents structural engineering research that Ernest E. Howard Award can be applied to design. The 2014 prize was The Ernest E. Howard Award recognizes an presented to Maria Pia Repetto, Ph.D., and ASCE member who has made contributions to Giovanni Solari, Ph.D., P.E., F.EMI, M.ASCE, the advancement of structural engineering. The for their paper titled “Closed-Form Prediction 2014 award was given to Louis Geschwindner, of the Alongwind-Induced Fatigue of Ph.D., P.E., M.ASCE. Dr. Geschwindner was Structures,” published in the September 2012 a faculty member at Penn State for more than issue of the Journal of Structural Engineering.

40 years. He has published books on structural George Winter Award analysis and structural steel design, and is active Candidates for the George Winter award in writing and presenting continuing education must be highly accomplished civil engineers programs for the American Institute of Steel who are also proficient in the arts or have Construction (AISC). made social contributions to the community.

Moisseiff Award Armen Der Kiureghian, Ph.D, M.ASCE, was The Moisseiff Award recognizes a paper con- presented with the 2014 award in recognition tributing to structural design, including applied of his contributions to structural engineering, mechanics, as well as the theoretical analysis or painting, and humanitarian work. Dr. Der construction improvement of structures. The Kiureghian’s research deals with development 2014 award was presented to Hyoung-Bo Sim, and application of probabilistic methods to Ph.D., and Chia-Ming Uang, for the paper solve civil engineering problems. Dr. Der titled “Stress Analyses and Parametric Study on Kiureghian was fundamental in the creation Full-Scale Fatigue Tests of Rib-to-Deck Welded of The American University of Armenia Joints in Steel Orthotropic Decks,” published (AUA) and is an accomplished painter.▪

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NCSEA News

News form the National Council of Structural Engineers Associations

NATIONAL

State NCSEA SEER Programs Assist with Disaster Evaluations All too often after a disaster, affected communities are left on their own to struggle with assessing damage and determining whether buildings can be safely reoccupied. When evaluations are not performed in a rapid fashion by properly qualified individuals, residents can and most likely will reoccupy potentially unsafe buildings.

The key to adequately evaluating the extent of damage to a community and keeping residents from occupying unsafe structures is to ensure that sufficient numbers of qualified “2nd responders” exist to rapidly and appropriately perform building damage evaluations. In an effort to help, NCSEA’s State SEER programs are taking the lead on compiling lists of engineers trained and qualified to provide post-disaster structure condition evaluations.

Background

For the last 25 years, engineers and a hand full of architects have been serving as Structures Specialists (1st responders) on FEMA and State Urban Search and Rescue (US&R) teams.

Structures Specialists are a select group of highly trained first responders working with FEMA and State US&R teams spread throughout the US. More recently, in the wake of numerous widespread natural disasters, two organizations have begun training 2nd responders to work with communities dealing with disasters. These 2nd responders are design professionals and code officials trained to perform post-disaster structure condition evaluations to National Incident Management System (NIMS) standards.

The goal of NCSEA’s State SEER programs is to locate and compile lists of these 2nd responder engineers so that they can be made available to Emergency Operations Managers, Building Officials and community leaders dealing with disasters.

Training Programs

The International Code Council (ICC) and the California Office of Emergency Services (CalOES) have developed recognized 2nd responder training programs. Based in part on ATC’s 20 & 45 manuals, these training programs also include concepts of operations and operating in disaster environments.

The ATC 20, titled: Postearthquake Safety Evaluation of Buildings is a widely accepted standard for post earthquake safety review and tagging of structures. The ATC 20 was utilized in the wake of the 1989 Loma Prieta and 1994 Northridge California earthquakes.

The ATC 45, titled: Safety Evaluation of Buildings after Windstorms and Floods was developed for the purpose of evaluating damage to buildings resulting from hurricanes, tornadoes and floods. This manual was developed in part based on the success of the ATC 20 and in response to the hurricanes of the 1990s, which included Hurricane Andrew, Hurricane Fran, and Hurricane Iniki.

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Currently, these documents serve as the basis for ICC’s Disaster Response Inspector (DRI) program and CalOES’s Evaluator and Coordinator training programs. NCSEA’s Structural Engineers Emergency Response (SEER) plan is also based in part on these manuals.

Credentialing Efforts

While comprehensive, the ICC and CalOES programs are only one of the criteria that exist to participate as a 2nd responder.

A credentialing process is being developed at a national level through NIMS whereby properly qualified, trained and experienced volunteers can become certified. Having adopted this national credentialing model, The Florida Structural Engineers Association’s SEER programs have developed a summary of the qualifications required of 2nd responding professionals. The basic affiliation and training requirements of the Florida program can be found on the NCSEA website under both the SEER Committee page and under Resources/Emergency Response.

To further expand the number of qualified 2nd responders, the NCSEA SEER committee is working with other stakeholders (ASCE, AIA, APWA, ICC, CalOES and FEMA) on a publicsector-driven certification program to validate and database the qualifications of individuals who wish to comply with the FEMA/National Incident Management System (NIMS) Resource Typing for Structure Condition Evaluators. This Resource Typing is essentially a ‘performance specification’ for assets (personnel and equipment) that may be requested by a municipality following a disaster. The specific Resource Type that this Certification will address is posted at www. fema.gov/media-library-data/20130726-1918-25045-1327/ structureconditionevaluator.pdf

Getting Involved

To participate you need to be rostered, and to become rostered you need to be trained. To obtain training you can contact: ICC at www.iccsafe.org/Education/Courses/Pages/default.aspx, CalOES at www.calema.ca.gov/trainingandexercises/pages/ training.aspx or FEMA at https://training.fema.gov/IS/ NIMS.aspx. NCSEA also provides this training in the spring and fall as a full day of webinars. Following completion of your training, please register at the NCSEA SEER database homepage www.ncsea-seer.com/ in order to receive information regarding upcoming deployment opportunities and training updates.

For more information on becoming rostered as a resource to Emergency Operations Managers, Building Officials and community leaders, please contact your State’s NCSEA SEER program coordinator.

William C. Bracken, P.E., S.I., President of Bracken Engineering, Florida, is licensed in 33 states as a professional engineer, is a Special Inspector in Florida, serves as Vice-Chair on Florida’s Board of Professional Engineers and serves as a member of NCSEA’s Structural Engineers Emergency Response Committee.

He is also certified as a FEMA/USACE StS2, an ICC DR Inspector and a CalOES Evaluator and Coordinator.

Scott G. Nacheman, MSc.Eng., AIA, is a Vice President in the Chicago office of J.S. Held. He is Chair of NCSEA’s Structural Engineers Emergency Response Committee as well as a Structures Specialist with FEMA Urban Search and Rescue, State of Illinois US&R and MABAS Technical Rescue. He is certified as a FEMA/ USACE StS2 and CalOES Evaluator and Trainer.

August 2014

8:00 - 5:00 8 a.m. - 12 p.m.

5:30 - 6:30 p.m.

6:30 - 8:30 p.m.

Committee Meetings NCSEA Board of Directors meeting Young Engineer Reception SECB Reception

Friday, September 19

Visit www.ncsea.com for more details!

Register & reserve your hotel room today!

News from the National Council of Structural Engineers Associations

8:00 - 10:00 Member Organization Reports 8:00 - 10:00 Vendor Product Presentations 10:30 - 12:00 Student to Teacher – Gaining

Competency after the University, a panel

discussion led by the NCSEA Young Member Thursday, September 18

Group Support Committee 8:00 a.m.

Welcome & Introduction 1:00 Trade Show closes 8:15 – 9:45 Keynote: Prepare Your Practice – Why 1:00 - 1:45 The Most Common Errors in Wind

Your Strategic Plan is Doomed to Fail,

Design & How to Avoid Them, Emily

Kelly Riggs, President, Vmax Performance Group Guglielmo, S.E., Associate, Martin/Martin 9:45 - 10:45 Prepare for the Future - Where Codes 1:45 - 2:30 The Most Common Errors in Seismic

& Standards are Heading, NCSEA

Design & How to Avoid Them, Tom

Code Advisory Committee

Heausler, P.E., S.E., Heausler Structural 11:00 - 12:00 Prepare for the Unthinkable –

Engineers, member of ASCE 7 Seismic

Designing Buildings for Tornadoes,

Provisions Committee

Bill Coulbourne, P.E., Director of Wind & 3:00 - 4:00 Practical HSS Design with the Latest

Flood Hazard Mitigation, Applied

Codes & Standards, Kim Olson, P.E.,

Technology Council

Technical Advisor, Steel Tube Institute and 1:00 - 2:15 A. ACI 562 Building Code for Repair

Structural Engineer, FORSE Consulting

of Existing Concrete Structures, 4:00 - 5:00 Practical Steel Connection Software Concurrent Keith Kesner, Ph.D., P.E., S.E., Senior Associate, Design Using 2010 AISC Standard, Sessions: WDP & Associates, Chair of ACI 562

Steve Ashton, P.E., SECB, Principal,

B. Wind Engineering Beyond the Code, Ashton Engineering & Detailing, SDS/2

Roy Denoon, Ph.D., CPP Wind Engineering

Engineering Representative for Design Data Consultants 6:00 - 7:00 Awards Reception (formal attire encouraged) 3:00 - 4:00 A. 2012 National Design Specification 7:00 - 10:00 NCSEA Banquet & Awards Presentation,

for Wood Construction Overview,

featuring the NCSEA Excellence in

Michelle Kam-Biron, P.E., S.E., SECB,

Structural Engineering Awards and the

M.ASCE, Director of Education, American NCSEA Special Awards Concurrent Wood Council Saturday, September 20 Sessions: B. Three Diverse Adaptive Reuse/ 8:00 - 12:00 NCSEA Annual Business Meeting Renovations, Bill Bast, P.E., S.E., SECB, 12:30 - 2:00 NCSEA Board of Directors Meeting

Principal, Thornton Tomasetti 4:00 - 5:00 A. AISI Standard & Tech Notes,

Vince Sagan, Chairman, P.E., Cold-Formed NCSEA Webinars Concurrent Steel Engineers Institute Sessions: B. High Roller Observation Wheel, August 19, 2014

Jason Krolicki, ARUP San Francisco Parking Garage Repairs: Identification, Evaluation, the 6:30 - 8:30 Welcome Reception on Trade Show floor Process, and the Repair David Flax, Euclid Chemical Co.

NCSEA News

Wednesday, September 17

August 26, 2014 Principles of Ground Movement Design James Hussin, P.E., Director, Hayward Baker, Inc. October 2, 2014 The AISC Direct Analysis Method Dr. Leroy Emkin, Ph.D., P.E. Logos, credits, time, etc.

GINEERS

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NCSEA offers three options for NCSEA webinar registration: Ala Carte, Flex-Plan, and Yearly Subscription. Visit www.ncsea.com for more information or call 312.649.4600.

STRUCTU

Platinum Sponsors:

COUNCI L

Electrical Transmission & Substation Structures Conference 2015

Structural Columns

The Newsletter of the Structural Engineering Institute of ASCE

Call for Abstracts Closes September 10, 2014 The conference will provide a forum for transmission and substation engineers to exchange ideas, concepts, and philosophies, while providing new engineers with the opportunity to learn more about the art and science specific to transmission lines and structures, substation structures, and foundation engineering.

The Conference Steering Committee is currently accepting abstracts of papers to be presented in technical sessions, with case studies strongly encouraged. A poster session format may also be provided.

Visit the SEI website at www.asce.org/SEI for more information and to submit your proposal. All proposals are due September 10, 2014.

ASCE-171 ETS2015 CONFERENCE WEB/EMAIL BANNERS

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ELECTRICAL TRANSMISSION & SUBSTATION STRUCTURES CONFERENCE 2015

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| September 27- October 1

Branson, Missouri

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| September 27- October 1

Grid Modernization – Technical Challenges & Innovative Solutions

ASCE is seeking members to update existing SEI/ASCE Standard 32-01, Design and Construction of Frost-Protected Shallow Foundations. The intent of the standard is to address the design and construction of frost-protected shallow foundations in areas subject to seasonal ground freezing.

This Standard includes foundation insulation requirements to protect heated and unheated buildings from frost heave presented in easy-to-follow steps with reference to design tables, climate maps, and other necessary data to furnish a complete frost-protection design. The intended outcomes of the application of this standard include improved construction efficiency over conventional practices, increased energy efficiency, minimized site disturbance, and enhanced frost protection.

Interested parties may submit an application at www.asce.org/ codes-standards/applicationform/ to join this new committee

by August 23, 2014. For more information, please contact James Neckel at jneckel@asce.org, Codes and Standards Coordinator.

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SELC Website Launched The Structural Engineering Licensure Coalition has launched a new website covering all aspects of the initiative. Featured on the site are case studies and presentations that make the argument for licensure. In addition, there is a calendar of events, relevant news articles, and the status of SE licensure by state. Visit the website at www.selicensure.org/ to learn more.

2014 Ammann Fellowship Winners and Call for Nominations In 2014 the SEI Technical Activities Division Executive Committee awarded five O.H. Ammann Research Fellowships in Structural Engineering. SEI continues to receive an increasing number of high-quality applications each year. This year’s winners are: • Mahdi Arezoumandi, Missouri University of Science and Technology • Donna Chen, University of Calgary • Julie Fogarty, University of Michigan • Adam Richard Phillips, Virginia Tech • Ravi Kiran Yellavajjala, University of Notre Dame See the SEI website at www.asce.org/SEI for more information about the winners and their research.

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The O. H. Ammann Research Fellowship in Structural Engineering is awarded annually to a member or members of ASCE or SEI for the purpose of encouraging the creation of new knowledge in the field of structural design and construction. All members or applicants for membership are eligible.

Applicants will submit a description of their research, an essay about why they chose to become a structural engineer, and their academic transcripts.

This fellowship award is at least $5,000 and can be up to $10,000. The deadline for 2015 Ammann applications is November 1, 2014.

For more information and to fill out the online application visit the SEI website at www.asce.org/SEI. August 2014

The SEI Professional Activities Committee (PAC) is currently seeking membership applicants for this important national committee. The PAC works on initiatives, policies and tasks focusing on structural licensing, regulation, and professional development.

If you are interested in communicating with professionals throughout engineering and related fields, or working behind the scenes in developing supporting documentation, visit the SEI website at www.asce.org/sei/join-business-and-professional-activities/ to apply.

The ASCE Committee on Cold-Formed Members is co-organizing the 2014 International Student Competition on Cold-Formed Steel Design. The competition promotes higher education in cold-formed steel structural design and encourages students to use creative thinking skills to solve engineering problems. Please encourage full time students (high school through graduate degrees) to participate. Submissions are due by September 30, 2014 and the top prize is $600. See the competition website at http://cfscompetition.unt.edu for more information.

Call for 2015 SEI/ASCE Award Nominations Nominations are being sought for the 2015 SEI and ASCE Structural Awards. The objective of the Awards program is to advance the engineering profession by emphasizing exceptionally meritorious achievement, so this is an opportunity to recognize colleagues who are worthy of this honor. Nomination deadlines begin October 1, 2014 with most deadlines falling on November 1, 2014.

Visit the ASCE Awards and Honors page at www.asce.org/leadership-and-management/awards/ for more information and nomination procedures. See the Spotlight on page [67] to read about the 2014 honorees.

Second ATC-SEI Conference Improving the Seismic Performance of Existing Buildings and Other Structures December 10-12, 2015 Hyatt Regency San Francisco Call for abstracts and session proposals will open in Fall of 2014.

Geotechnical & Structural Engineering Congress 2016 February 14-17, 2016 Phoenix, AZ Special Joint Event: The 2016 congress will feature a total of 15 concurrent tracks: 5 tracks will be on traditional GI topics, 5 tracks on traditional SEI topics, and 5 tracks on joint topics.

In addition, we will be offering interactive poster presentations within these tracks. Call for abstracts and session proposals will open on October 15, 2014.

First International Conference on Sustainable Infrastructure Call for Speakers on Technical Join ASCE for the inaugural International Conference on Sustainable Infrastructure 2014 in Long Beach, California November 6-8, 2014. The full conference program includes short courses, special events with riveting keynote speakers, and a technical tour. It promises to be an event you will not want to miss. Visit the conference website to learn more http://content.asce.org/conferences/icsi2014/.

Errata SEI posts up-to-date errata information for our publications at www.asce.org/SEI. Click on “Publications” on our menu, and select “Errata.” If you have any errata that you would like to submit, please email it to Paul Sgambati at psgambati@asce.org.

STRUCTURE magazine

Topics for SEI Local Group Events Share your technical knowledge and expertise with local SEI Chapters, Graduate Student Chapters, and Structural Technical Groups. The SEI Speaker Bureau Committee is looking for experienced structural engineering professionals (consulting or academic) to give presentations on technical topics to SEI local groups. The Committee is seeking to expand its resource list of qualified speakers willing to give technical presentations on a voluntary basis, and make the list available to SEI local groups via their SEI e-room. If you would like to be included on the Speaker Bureau resource list, please complete the online form at www.asce.org/speakers-bureau/.

Potential speakers are welcome to approach their local SEI Chapter/Technical Group directly to give a technical presentation. Any solicitation for personal or business gain is strictly discouraged.

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The Newsletter of the Structural Engineering Institute of ASCE

Save the Dates

Structural Columns

Professional Activities Committee Student Competition on ColdCall for New Members Formed Steel Design

CASE in Point

The Newsletter of the Council of American Structural Engineers

CASE Contracts – Now Available!

CASE #14B – Standard Form for Request For Information (RFI)

CASE #16 – An Agreement Between Client and Structural Engineer for a Structural Condition Assessment

The purpose of this document is to provide the design team with a standard Request for Information (RFI) form that can be included in the bid documents and used by all contractors and subcontractors on the project.

The purpose of this Document is to provide a sample Agreement for structural engineers to use when providing a structural condition assessment directly to a client. Examples are – earthquake evaluation, seismic retrofitting, fire or wind damage, changes in occupancy or historic preservation.

CASE #15 – Commentary on AIA Document A201 General Conditions of the Contract for Construction, 1997 Edition

You can purchase all CASE products at www.booksforengineers.com.

The purpose of this Commentary is to point out sections and paragraphs of AIA document A-201 which, in the opinion of CASE, merit special attention, or which other reviewers have found to contain “pitfalls.” (See also CASE Contract Document 6.)

Follow ACEC Coalitions on Twitter – @ACECCoalitions.

Member Firm CEOs to Forecast 2015 at ACEC Fall Conference in Hawaii, October 22–25 Three leading Member Firm CEOs will provide their forecasts of the 2015 business environment for engineering firms during the ACEC Fall Conference in Waikoloa, Hawaii, October 22-25.

On the panel will be Jon Carlson, CEO, Braun Intertec Corp., Minneapolis; William Siegel, president/CEO, Kleinfelder, San Diego; and Donald Stone, CEO, Dewberry, Fairfax, Va. Also speaking at the Conference will be Business Stategist Erik Wahl, Political Analyst Charlie Cook, FERC Commissioner Tony Clark and a panel on Opportunities in Booming Energy Markets featuring Larson Engineering’s Steve Bakken, Pennoni Associates CEO Tony Bartolomeo, and Freese and Nichols Principal Kendall King.

The Conference also features more than three dozen bottomline-focused educational sessions; CEO roundtables; exclusive

CFO and CIO tracks; the CASE Convocation; and numerous ACEC coalition, council, and forum events.

For more information and to register, http://conf.acec.org/.

WANTED

Engineers to Lead, Direct, and Get Involved with CASE Committees!

If you’re looking for ways to expand and strengthen your business skillset, look no further than serving on one (or more!)

CASE Committees. Join us to sharpen your leadership skills – promote your talent and expertise – to help guide CASE programs, services, and publications.

We have two committees ready for your service: • Contracts Committee: Responsible for developing and maintaining contracts to assist practicing engineers with risk management.

• Toolkit Committee: Develops and maintains documents such as business practices manuals and policies for engineers under CASE’s Ten Foundations for Risk Management.

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Expectations and Requirements To apply, you should • be a current member of the Council of American Structural Engineers (CASE) • be able to attend the groups’ two face-to-face meetings per year: August, February (hotel, travel reimbursable) • be available to engage with the working group via email and conference call • have some specific experience and/or expertise to contribute to the group Please submit the following information to htalbert@acec.org • Letter of interest • Brief bio (no more than 2 paragraphs) Thank you for your interest in contributing to your professional association!

August 2014

CASE in Point

ACEC Business Insights 20 th Senior Executives Institute Class Now Open for Registration For 20 years, ACEC has offered the premier executive leadership course designed specifically for the A/E/C community – the ACEC Senior Executives Institute (SEI). SEI is an intensive 18-month program taught by recognized experts and instructors from The Brookings Institution, national universities and business consulting organizations. The classes meet for five separate four or five-day sessions.

The next class, SEI Class 20, is now open for registration and will begin in September, 2014.

For more information, contact Dee McKenna, Deputy Director, ACEC Business Resources & Education Department, at dmckenna@acec.org or 202-347-7474.

October 22-25 ACEC is holding its Fall Conference at the Waikoloa Hilton Village, Hawaii. CASE will be holding a convocation on Thursday, October 23rd. Sessions include: Addressing Hidden Risks in Today’s Design Contracts – Brian Stewart, Collins, Collins, Muir & Stewart; James Schwartz, Beazley; Rob Hughes, Ames & Gough The Five Commandments of A&E Risk – Dan Buelow, Willis A/E Learning from the Past, Ready for the Future: Managing the Emerging and Enduring Risks of Professional Practice – Karen Erger, Lockton

Upcoming ACEC Online Seminars – September Seize the Day! Strategies for Email Success

Tuesday, September 2, 2014; 1:30pm to 3:00pm Eastern The Average person can spend up to 40% of their eight hour work day sending and receiving up to 200 messages a day!

Some reports say people at work check their email and average of 35 times an hour!

It’s no wonder that many of us always feel behind on projects and struggle to finish our work in a typical work day! Wouldn’t you like to have some of that time back in your day? Everyone can benefit from learning to control and manage email to improve productivity.

This lively, interactive presentation provides strategies and solutions to boost productivity and efficiency with your email system and practices. You’ll walk away with tips you can use the same day as the training. Participants will: • Learn how to minimize email overload • Improve your inbox management skills • Develop more realistic response times • Learn tips and trick to utilize email more efficiently and effectively • Learn productive email etiquette strategies You can register for these and other ACEC online seminars at www.acec.org/acecmainsite/education/webinars.

STRUCTURE magazine

Find the Lost Dollars: 6 Steps to Increase Profits in Architecture and Engineering Firms

Wednesday, September 3, 2014; 1:30pm to 3:00pm Eastern Learn to get the most from people, processes and technology to gain a competitive edge and increase your firm’s profitability.

This session will provide valuable best practices and advice that will show you how to improve your firm’s performance and prepare the firm’s future leaders to successfully take the reins.

Legal Issues Unique to Design-Build

Wednesday, September 10, 2014; 1:30pm to 3:00pm Eastern Everyone knows that design-build and EPC projects are different from traditional construction, but very few people can identify and understand the differences. In this program, nationally noted design-build expert, Mark Friedlander, will identify and describe the business and legal issues that make design-build and EPC projects unique. In simple language, with no legalese, he will explain how the standard of care, change orders and warranties are different in design-build and EPC jobs, and will describe how the legal and business relationships among the parties change when the Engineer and Contractor form a design-build team. As part of the presentation, he will teach the participants how to prepare and negotiate design-build teaming agreements with contractors, and provide a checklist of issues that need to be discussed and resolved.

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CASE is a part of the American Council of Engineering Companies

CASE Convocation at the ACEC Fall Conference

Structural Forum

opinions on topics of current importance to structural engineers

Certification as a Bridge to Structural Licensure

By Timothy M. Gilbert, P.E., S.E., SECB

A

s an engineer, I believe that our highest obligation is to provide for the public welfare. Most jurisdictions and many professional societies express this obligation in their laws, rules or bylaws. In keeping with this, the NCSEA Structural Licensure Committee believes that the public would be better protected by establishing structural licensure in all jurisdictions – legislation requiring a licensed Structural Engineer to be in responsible charge for the design of significant structures.

It will probably take several years of diligent work to achieve this goal, particularly when faced with opposition and ambivalence. In a previous article (Opposition to Structural Licensure, STRUCTURE®, January 2014), I explored some reasons for such resistance.

In the interim, prior to achieving our goal, should we be content with the status quo? No. We have the option to take affirmative action through professional certification.

Certification is a process used by many professions to recognize proficiency within a specific field. Medical doctors might be the most familiar profession that extensively uses certification. Generally, states license doctors to practice medicine without designating a particular area of practice. The American Board of Medical Specialties certifies doctors in one or more of 37 specialties and 132 subspecialties. Since its inception in 1933, it has become the accepted standard for doctors to demonstrate their capabilities. Project managers and program managers may choose to seek one of six different certifications available through the Project Management Institute.

For environmental engineers, the American Academy of Environmental Engineers and Scientists offers nine different engineering certifications, and the American Society of Civil Engineers offers certification in three areas: water resources; coastal, port and ocean engineering; and geotechnical engineering.

These are all instances where practitioners have taken it upon themselves to establish, administer and promote professional certification for the benefit of their clients and profession. Along these lines, structural engineers have two options available: the NCEES MLSE designation and SECB certification.

Members of the National Council of Examiners for Engineering and Surveying (NCEES) are from the licensing boards of the 50 states plus the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands.

NCEES develops, administers and scores engineering and surveying licensing examinations.

Its unique membership gives it the status to make recommendations to the jurisdictions, and it publishes model laws and rules for their consideration. Additionally, its Standard for Licensure as a Model Law Structural Engineer provides structural engineers with the option, for their records, to indicate compliance with the standard. Although the Model Law Structural Engineer (MLSE) designation does not actually grant licensure in any jurisdiction, it may speed the process since many of its requirements parallel state requirements.

Additionally, MLSE designation is likely to aid in obtaining a structural license in jurisdictions that choose to adopt one in the future.

Briefly, to obtain the MLSE designation, a candidate must: • Hold an active NCEES Record; • Obtain a degree from an EAC/ABETaccredited program including at least 18 semester hours of structural analysis and design, at least nine of which are in structural design; • Pass the NCEES FE exam; • Pass 16 hours of qualifying structural engineering licensure exams; o NCEES 16-hour Structural exam o NCEES Structural II and another NCEES Structural exam (prior to January 1, 2011) o A 16-hour, state-written exam (prior to January 1, 2004) o NCEES Structural II and an eighthour, state-written exam • Complete four years of structural engineering work; and • Maintain a record free of disciplinary action.

More information about the MLSE designation is available at www.NCEES.org.

In 2003, NCSEA established the independent Structural Engineering Certification Board (SECB) to provide the public with a means to identify qualified structural engineers based on a common national standard. Similar to

certification bodies in other professions, SECB does not grant licenses to practice structural engineering. However, it does promote a common standard that carries more weight as the ranks of SECB-certified engineers grow.

Similar to licensure, certification is based on education and examination, with experience also taken into account. An abridged summary of the SECB certification requirements is as follows: • Successful completion of one or more specific exam combinations totaling 16 hours or more; and • Attainment of a B.S. degree in an engineering discipline with no less than 36 semester hours in six of nine subjects significant to structural engineering.

As with many professional licenses, maintaining SECB certification requires continuing professional development though education or other professional activities; 15 hours are required annually. A more complete discussion of the requirements is available at www.secertboard.org.

Although structural licensure is not yet established in many jurisdictions, certification is an avenue for us to demonstrate our commitment to protecting the public. By obtaining, displaying and discussing these certifications, we can raise the profile of our profession and work towards the goal of structural licensure.▪ Special Opportunity For a limited time, normal SECB exam requirements are waived for NCSEA and SEI members who are licensed professional engineers practicing structural engineering. The license must have been awarded on or before July 1, 2005 and must have remained valid continuously through the time of application. In addition, the application fee is reduced from $350 to $200.

Timothy M. Gilbert, P.E., S.E., SECB (TGilbert.PE@gmail.com), is a Project Specialist with TimkenSteel in Canton, Ohio. He is also a member of the NCSEA Structural Licensure Committee, and a Director and the Licensure Committee chair for the Structural Engineers Association of Ohio (SEAoO).

A similar article was published in the SEAoO Newsletter (January, 2014).

Content reprinted with permission.

Structural Forum is intended to stimulate thoughtful dialogue and debate among structural engineers and other participants in the design and construction process. Any opinions expressed in Structural Forum are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C 3 Ink, or the STRUCTURE® magazine Editorial Board.

STRUCTURE magazine

74

August 2014