STRUCTURE magazine | November 2014 by structuremag

November 2014 Steel/Cold-Formed Steel

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE ®

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FEATURES “Not Just Another Dome Idea”

CONTENTS November 2014

By Matthew Brand and Thomas Tailer A retired physics teacher and a group of engineering students designed and built a prototype dome structure incorporating used carpet as a major structural component. The project’s goal is to provide a safe, economical shelter for people in the poorest communities in the world as they struggle to survive natural disasters.

COLUMNS 7 Editorial Developing Strategies for Growth and Success

Cold-Formed Steel Provides the Strength Needed to Take Sustainable Building to a New Level

11 InFocus

By John Matsen, P.E.

12 Construction Issues

The Convent Hill project is a 10-story senior residence with roof terraces. The terraces are extensive, holding light-weight soil filled to a depth of three inches, ground cover plants and wild flowers, and irrigation systems.

By Carrie Johnson, P.E., SECB

Virtue Ethics, Insight, and Emotions By Jon A. Schmidt, P.E., SECB

Expansion Bolts for Hollow Structural Steel Sections By Ken Hansen, P.E.

16 Building Blocks Standing Strong

NGL Fractionation Plant on the Fast Track

By Mark Warnecke, P.E. Natural gas liquids (NGL) have a higher market value when separated from the natural gas stream and segregated into their individual components in a fractionation facility. Engineers tasked with design and construction of such a facility in Texas, faced challenges like an aggressive schedule, rigorous safety plans, and off-site assembly of process unit components.

ADA Requirements for Historic Properties

By Gail S. Kelley, P.E., Esq.

54 Professional Issues Challenges Facing Young Structural Engineers

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE

By Jessica Mandrick, P.E. and Jason McCormick, Ph.D.

November 2014 Steel/Cold-formed Steel

Springfield Bridge for Western Railroad

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

26 Structural Design Why It’s Good to be a Lightweight

By Peter Debney, CEng

How Big is that Beam?

By Jerod G. Johnson, Ph.D., S.E.

58 Education Issues Missing Cold-Formed Steel Framing By Brent Perkins, P.E., S.E., SECB

67 Spotlight Final Phase of La Plata Stadium Construction By Matthys Levy, P.E.

74 Structural Forum Increasing the Velocity of Knowledge – Accelerated By Gene Frodsham, S.E.

ON THE COVER The 1972 Olympic Main Stadium, Munich. Frei Otto aspired to make modern architecture as light as possible, in both senses of the word. He is well known for the design of fabric structures. The Munich roof achieved his goal by using both a minimum of material and maximum glazing. See more in the Structural Design article on page 26.

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

23 Historic Structures

44 Engineer’s Notebook

DEPARTMENTS 51 Legal Perspectives

By Chuck Knickerbocker

November 2014

46 InSights Current Status of Coated Reinforcing Steel

By David McDonald, Ph.D., P.E.

48 Guest Column Overview of the National Institute of Steel Detailing By Kerri Olsen

IN EVERY ISSUE 8 Advertiser Index 60 InBox 61 Resource Guide (Software Updates) 68 NCSEA News 70 SEI Structural Columns 72 CASE in Point

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Editorial

Developing Strategies for new trends, new techniques and current industry issues Growth and Success By Carrie Johnson, P.E., SECB

eaders are expected to navigate effectively through a wide variety of social and professional situations with a wide variety of people. More often than not, however, engineering firms promote engineers who are successful at the technical requirements of the job into areas that require skills they haven’t been trained for–leadership, business development, public speaking, and conflict management. Shouldn’t we, as a profession, devote more time to the discussion and development of strategies for long-term growth and success, including leadership training and more? Three years ago, NCSEA determined that it would provide a vehicle to help structural engineering firms do exactly that. The 2-day program includes a mix of lectures, panel discussions, case studies, and plenty of time for interaction and networking with fellow attendees. Attendance is limited to structural engineering principals and those in leadership positions, which makes this a unique opportunity. Past attendees have had high praise for both the format and the presentations. Here are a few examples: • “It is one of the best ways to learn skills not normally pursued by engineers even though it is one of the more critical aspects of our practice” – Joseph W. Carone • “A perfect mix of networking and business learning. The Winter Leadership Forum will be on my calendar every year” – Chris Hofheins • “Excellent mix of participants–small, mid & large firms, good geographic mix. The topics were excellent and speakers also. Even the sessions that I thought would not be interesting were, in fact, excellent!” – Jay Shapiro NCSEA’s next Winter Leadership Forum will be held January 29–30, 2015, in Coral Gables, Florida. The theme is Developing Strategies for Growth and Success. The presentations will answer the following questions: • What are your clients really looking for when selecting a consultant? • How can engineering firms increase their value to clients? • Can you ever win when you are competing solely on price? • How do you make sure your whole team is working to provide what your client needs? • Should you grow your firm organically or by acquisition? • What role does your relationship with your banker play in your success? • Should you purchase a firm or pass? A Case Study Our Thursday morning session will answer the first question by introducing the audience to the results of major research performed by the Society for Marketing Professional Services (SMPS) Foundation. The SMPS Foundation interviewed more than 100 buyers and sellers of A/E/C services and asked questions about what works, what doesn’t, and how clients want to be sold. The answers were surprising and thought-provoking. Scott Butcher, an SMPS Foundation Trustee, and Brad Thurman, PastPresident of SMPS, will present the results. We will then delve further into successful business development with three separate panel discussions. STRUCTURE magazine

The first session will be moderated by Robb Dibble, founder of Dibble Engineers. It will explore various ways structural engineers can ensure being a valued member of the team by providing services that they may not have previously considered. The second panel discussion will be moderated by Scott Butcher and will focus on pursuing projects. Pre-positioning, business development, and go/ no-go decisions will be discussed and analyzed. Our final panel discussion for the day will address strategies for building relationships and creating repeat clients. I will be moderating that session and will discuss ways to train your entire staff to be responsive to your client’s needs. Friday will offer four different types of presentations, beginning with a panel session that will evolve into a debate on how best to grow your company: Through organic growth or through growth by acquisition? The debate will be moderated by Jonathan Hernandez, a Partner at Gilsanz Murray Steficek and will provide valuable insights and information on successful tactics that have worked for others. This will be followed by a presentation from Terry Vanderaa, Chairman of Providence Bank and former CEO of an international transportation company that sold for $349 million. He will discuss what to look for when starting a banking relationship, including how to determine if a bank is the right size for your business. Friday afternoon, John Tawresey, former CFO of KPFF Consulting Engineers, will wrap up the program with a case study that digs deep into the question of growth by acquisition. Participants in the session will become members of the Board of Directors of a company being approached by a smaller firm, one that is located in a different geographical market and with expertise in curtainwall design, which the larger firm has never done. The Board will be given information about the smaller firm’s financials, markets, business practices, corporate climate, key employees and owner’s transition, along with alternative valuation models, deal breakers, and other considerations, and some basic decision theory. The question to the Board will be: Should the firm be acquired or should your company pass? If the decision is to acquire, how much is your company willing to pay? I hope you will join us in sunny Florida this January for what promises to be another great event! You will leave with insight on how to run your firm with new-found confidence and excitement. A full description can be found on the NCSEA website, www.ncsea.com.▪ Carrie Johnson, P.E., SECB, is a principal at Wallace Engineering Structural Consultants, Inc., Tulsa OK.

November 2014

Advertiser index

PleAse suPPort these Advertisers

Autodesk, Inc. ......................................... 4 Bentley Systems, Inc. ............................. 75 CADRE Analytic .................................. 49 Canadian Wood Council ....................... 43 Clark Dietrich Building Systems ........... 25 CTS Cement Manufacturing Corp........ 59 Design Data .......................................... 22 Enercalc, Inc. .......................................... 3 Engineering International, Inc............... 49 Gerdau .................................................. 31 ICC....................................................... 57 Integrated Engineering Software, Inc..... 62 Integrity Software, Inc. .............. 32, 52, 56 ITW Red Head ..................................... 10

JMC Steel Group .................................. 37 KPFF Consulting Engineers .................. 27 Lindapter .............................................. 13 LNA Solutions ........................................ 8 New Millennium Building Systems ....... 17 Nucor Vulcraft Group ............................. 9 Powers Fasteners, Inc. .............................. 2 PT-Structures ........................................ 49 Ram Jack Systems Distribution ............. 45 reThink Wood ....................................... 50 RISA Technologies ................................ 76 SEA of IL .............................................. 66 Simpson Strong-Tie......................... 21, 33 StrucSoft Solutions, Ltd. ....................... 19

Editorial board Chair

Brian W. Miller

Chuck Minor

Jerry Preston

Eastern Sales 847-854-1666

Western Sales 480-396-9585

sales@STRUCTUREmag.org

Davis, CA

John A. Dal Pino, S.E.

Degenkolb Engineers, San Francisco, CA

The DiSalvo Engineering Group, Ridgefield, CT

Evans Mountzouris, P.E.

EditoriAl StAff

Mark W. Holmberg, P.E.

Greg Schindler, P.E., S.E.

Executive Editor Jeanne Vogelzang, JD, CAE

Heath & Lineback Engineers, Inc., Marietta, GA

KPFF Consulting Engineers, Seattle, WA

Dilip Khatri, Ph.D., S.E.

Stephen P. Schneider, Ph.D., P.E., S.E.

Khatri International Inc., Pasadena, CA

Roger A. LaBoube, Ph.D., P.E. CCFSS, Rolla, MO

Brian J. Leshko, P.E.

HDR Engineering, Inc., Pittsburgh, PA

BergerABAM, Vancouver, WA

John “Buddy” Showalter, P.E. American Wood Council, Leesburg, VA

Amy Trygestad, P.E.

Chase Engineering, LLC, New Prague, MN

Erratum In A Structural Perspective on Sustainability (STRUCTURE, October 2014), third paragraph, the full name for ACEC was incorrectly listed. The correct name is the American Council of Engineering Companies.

Universal Kits for Faster & Easier Steel Connections ADVERTISEMENT - For Advertiser Information, visit www.STRUCTUREmag.org

A Joint PublicAtion of ncSEA | cASE | SEi Interactive Sales Associates

Burns & McDonnell, Kansas City, MO chair@structuremag.org

CBI Consulting, Inc., Boston, MA

AdvErtiSing Account MAnAgEr

Jon A. Schmidt, P.E., SECB

Craig E. Barnes, P.E., SECB

Structural Engineers, Inc. ...................... 49 Structural Technologies ......................... 47 StructurePoint ......................................... 6 Struware, Inc. ........................................ 49 Soc. of Naval Arch. & Marine Eng. ....... 55 The Steel Network, Inc. ......................... 29 Tekla ..................................................... 65 USP Structural Connectors ................... 15 Wood Advisory Services, Inc. ................ 49 Wood Products Council ........................ 53

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Editor

Christine M. Sloat, P.E.

publisher@STRUCTUREmag.org

Associate Editor Graphic Designer Web Developer

Nikki Alger

publisher@STRUCTUREmag.org

Rob Fullmer

graphics@STRUCTUREmag.org

William Radig

webmaster@STRUCTUREmag.org

STRUCTURE® (Volume 21, Number 11). ISSN 1536-4283. Publications Agreement No. 40675118. Owned by the National Council of Structural Engineers Associations and published in cooperation with CASE and SEI monthly by C3 Ink. The publication is distributed free of charge to members of NCSEA, CASE and SEI; the non-member subscription rate is $75/yr domestic; $40/yr student; $90/yr Canada; $60/yr Canadian student; $135/yr foreign; $90/yr foreign student. For change of address or duplicate copies, contact your member organization(s).Any opinions expressed in STRUCTURE magazine are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C3 Ink, or the STRUCTURE Editorial Board. STRUCTURE® is a registered trademark of National Council of Structural Engineers Associations (NCSEA). Articles may not be

reproduced in whole or in part without the written permission of the publisher.

www.ncsea.com 3

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STRUCTURE magazine

November 2014

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Virtue new trends, new Ethics, techniques Insight, and current industry andissues Emotions By Jon A. Schmidt, P.E., SECB

obert J. Fitterer’s book, Love and Objectivity in Virtue Ethics, published in 2008 by University of Toronto Press, brings together several topics that I have discussed to various extents in past columns: • Aristotelian virtue ethics (“Virtue as a Skill,” May 2012; “Virtuous Engineering,” September 2013; “Virtue Ethics, Judgment, and Engineering,” July 2014). • Bernard Lonergan’s cognitive theory (“How We Know and What It Means,” September 2009; “Engineers Are Persons, Too,” January 2010). • The role of emotions in moral living (“Risk and Virtue Ethics,” January 2014). Fitterer begins with an exposition of Aristotle’s Nicomachean Ethics, affirming that “ethical truth differs from scientific truth and cannot be captured in abstractions such as universally applicable moral maxims.” He invokes cognitive psychology to argue that “the imprecision comes from the prior indeterminacy of the concrete good relative to each individual human who must discern it, combined with the probabilistic nature of human insight when deployed in concrete problem solving.” This does not entail a complete lack of objectivity; rather, good choices are grounded in an individual’s grasp of what is genuinely conducive to human well-being (eudaimonia). How do people come to know this? In the same way that we come to know everything else – by following what Lonergan identified as the “generalized empirical method,” which he summarized as a series of “transcendental precepts” (#4 is my addition): 1) Experience – Be attentive in examining the data presented. 2) Understanding – Be intelligent in envisaging possible explanations. 3) Judgment – Be reasonable in evaluating which is most likely. 4) Deliberation – Be considerate in exploring potential courses of action. 5) Decision – Be responsible in electing to proceed accordingly. Each of these processes is “spontaneously operative” in everyone to some degree, but because the will is involved, we are capable of employing them more intentionally – not only to pursue theoretical knowledge (episteme), as in scientific investigation, but also to develop practical judgment (phronesis) for “the concrete and particular circumstances of human living.” This results in not only insights of fact, but also insights of value; and when implemented conscientiously, it becomes a cycle that is effectively self-correcting: decision leads to action, which leads to new experience against which we reassess our previous conclusions. Unlike insights of fact, insights of value often rely at least partially on emotions. Here Fitterer, following Lonergan, is careful to clarify that he is not referring to bodily states such as tiredness or hunger, or to general moods like depression or irritability. Instead, he has in mind “the emotions such as fear, love, anger, joy, or disgust that accompany some object of thought or perception … feelings that approve or disapprove, that attract or repulse, that evoke a desire to cling or to flee.” These are apprehensions of value that do not merely manifest personal preferences, but constitute “recognition of some object or action that is seen as an intrinsic good” – especially once confirmed by subsequent, reflective judgments of value. STRUCTURE magazine

Of course, emotions are by no means infallible when carrying out this function. Besides producing various kinds of biases that can interfere with our ability to exercise the transcendental precepts properly, they establish our “horizon of concern,” the boundary between what we care about in general and what does not matter to us at all. Furthermore, in going about our daily business, we tend to move among distinct “patterns of experience” (Lonergan) or “salience networks” (Fitterer); that is, we inevitably focus on specific aspects of our current situation, causing other factors to fade into the background. It is phronesis that must determine which of these mindsets is most appropriate in each succeeding set of circumstances that we face. Fitterer concludes by seeking a suitable “background emotion, one that is beneficial to ethical insight induction … a healthy emotion that would predispose us towards an expanding horizon of concern … an emotion that allows us to shift across various limited patterns of experience.” The only viable candidate that emerges is what Lonergan described as “openended altruism, the self-sacrificing love commonly called charity,” which “embodies a concern for the genuine good, both for oneself and for others.” As Martha Nussbaum observed, this kind of love includes “recognition of the unique individuality of persons; reciprocity in human relations; and mediation of mercy and justice through compassion.” This is not to say that we must love everyone in the same way that we love, for example, our families. “Background emotion does not have a proximity to my personal eudaimonia the way feelings about significant people do. It is a fundamental set of concerns, usually operative without our explicit awareness.” Fitterer argues that such love actually fosters a “performative” or “procedural” type of objectivity by “maximizing the probability of sound moral insight occurrences.” Paraphrasing the Apostle Paul, it binds all of the virtues together in perfect unity (Colossians 3:14). This is fully consistent with what I have previously proposed as “The Moral Virtues of Engineering” (May 2013). Objectivity, care, and honesty are complementary components of love-as-compassion. Virtuous Engineers diligently adhere to the transcendental precepts, constantly and consciously expanding their horizon of concern to encompass everyone who might be affected by their projects or products, and then adjust their decisionmaking in each case accordingly.▪

Jon A. Schmidt, P.E., SECB (chair@STRUCTUREmag.org), is an associate structural engineer at Burns & McDonnell in Kansas City, Missouri. He chairs the STRUCTURE magazine Editorial Board and the SEI Engineering Philosophy Committee, and shares occasional thoughts at twitter.com/JonAlanSchmidt. Fitterer on Practical Judgment “Phronesis is not a deductive science (episteme), whereby we derive correct choices from moral axioms. And it is not a techne, whereby direct application of general procedures of art will more or less guarantee correct outcome. Phronesis requires attentiveness to the actual circumstances impinging upon us, a calibration of decisions as the case may demand.” November 2014

ConstruCtion issues discussion of construction issues and techniques

onnecting to steel hollow structural sections (HSS) from a single side has troubled engineers for decades. However, there are now numerous types of fasteners and connection methods for this increasingly popular structural material, other than the norm of welding. This article will look at the benefits and drawbacks of each connection method, to find that expansion bolts for HSS members are a viable option. Often when a designer has opted to use HSS for its bi-axial capacity or the aesthetics of visually appealing symmetric shapes, the question that arises is how to attach another structural member to it. Most often with structural shapes, welding or bolting has been the preferred method as they can handle a high degree of load. But when there exists restrictions in welding or where engineers want to avoid the high costs of labor involved with certified welders, setup, breakdown charges and having to fire protect the surrounding area, engineers turn to mechanical fasteners to get the job done. The American Institute of Steel Construction (AISC) addresses HSS connections in their Design Guide 24– Hollow Structural Section Connections. Within that document, they refer to Part 7 of the AISC manual Special Considerations for Hollow Structural Sections, which discusses various mechanical fasteners that can be used for HSS connections. These include: Through-Bolts are commonly used, but the inherent flexibility of HSS walls typically prevents the use of pre-tensioned fasteners without additional fabrication work, such that joints tend to be designed for static shear only. It also makes connections to opposing faces of a square or rectangular HSS member difficult and timeconsuming to assemble on site. In many cases, stiffeners may have to be welded inside the tube to give it extra support, which would incur an extra cost of shop welding. Threaded Studs can be used on the faces of HSS members, although heavy and unwieldy equipment will have to be used in the form of a weld gun and associated equipment. This will require the same considerations as welding the members together in the first place. This is a process that can be done ahead of time in the fabrication shop before it is sent to the field. In some instances, recessed or counter-bored holes might be necessary to clear the collar that could form where the stud meets the HSS face. The finished product will produce the appearance of a bolted connection but made on only one side of the HSS. Flow or friction-drilling is a method of forming a screw thread within thin material, like sheet metal, using tools that rotate at high speed. The

Expansion Bolts for Hollow Structural Steel Sections By Ken Hansen, P.E.

Ken Hansen, P.E., is a Professional Engineer at Lindapter USA and Hollo-Bolt specialist. Ken has comprehensive engineering experience and the ability to identify practical connection solutions to support the innovative designs of architects and structural engineers. He can be reached at khansen@lindapter.com.

Figure 1. A 3D model illustrates a structural connection and shows how the bolt expands inside the HSS section.

process reshapes the material so that none is lost, with the excess forming a sleeve that is longer than the original thickness of the material, making it possible to create a relatively strong joint in thin material. Unfortunately, friction drilling is not possible in material thicker than about half the hole diameter; and the material must be able to withstand the heat produced, which means that sections that have already been painted or galvanized are often unsuitable and require touch-up. Field installations are only recommended for thicknesses less than or equal to 5/16 inch, and will also require additional field equipment and tools. Blind bolting covers a variety of fasteners that are attached to the HSS from one side only. The majority of blind bolting products are proprietary fasteners, which come in many different shapes and sizes. Per AISC, there is no empirical way of calculating load values for many of these products and, therefore, AISC suggests engineers refer to manufacturers’ literature. Manufacturers therefore have developed bolt strengths via testing and statistical analysis to determine their published values. However, the increased popularity of expansion bolts for structural steel has led to the recent publication of International Code Council’s (ICC) evaluation reports. These independent reports verify third party testing and provide applicable load values that are consistent with the intent of the International Building Code (IBC). The following explores the many types of ‘blind’ fasteners: Singled sided structural fasteners are claimed to have high breaking loads; however, they generally consist of individual parts and require a specific installation tool. The number of separate parts means that installation can be a longer-thanexpected process. In certain circumstances, the tool may require reversing to aid the tightening process, further extending the installation time. Other bolts are available which are claimed to

12 November 2014

Figure 2. A proprietary expansion bolt for structural steel (drawing from the AISC Steel Construction Manual). Courtesy of American Institute of Steel Construction.

be equally as good, but require specialized equipment and a hydraulic supply due to the requirements of the tooling which, again, can impede installation in the field. Toggle bolts, also called flip bolts, have an advantage with the use of nominal fastener clearance holes. The bolt has a pivoted bar, which lies within the bolt shank as it is inserted through a hole drilled in the section. Once the pivoted bar is through the HSS wall and the bolt shank is turned through 180 degrees, the pivot bar swings under gravity and prevents the bolt from being pulled back

out of the hole. However, great care has to be taken during installation. If the pivoted bar is given insufficient space to swing into position, load values can be dramatically reduced. Shear capacities are often those which are proportionate to the threaded shank, and given the wall thickness of most HSS, the shear plane will almost always fall into the slotted zone of the bolt where the capacity will be reduced. Blind threaded inserts are generally available but their use is limited due to the amount of material that they can grip, as they were initially designed for sheet metal rather than structural steel sections. Once again, an installation tool is required that may require some effort if a manual version is chosen. Blind rivets, although suitable for use in situations where access is limited, only tend to be available in small diameters and for light loads. They are not intended for heavy-duty structural connections, and in most instances will require a pneumatic/hydraulic supply for the specialized installation tooling. Expansion bolts for structural steel are mechanical fasteners typically consisting of a bolt, an expansion sleeve, and a coneshaped nut that, when the bolt is tightened, is driven up inside the sleeve to create a wedging effect and expand the fastener (Figure 2). This ‘blind connection’ technique can just as

easily be used to connect to the web of another structural section type, such as a wide flange beam. Unlike conventional bolted or welded connections, expansion bolts can be quickly installed by simply inserting the fastener into a pre-drilled hole and tightening with a torque wrench. Due to the faster installation process, work in the field is reduced and, therefore, the cost and timeframe of the construction project are decreased. These expansion bolts are suitable for structural connections due to their capability to resist loading in both tension and shear. For example, the allowable load values for a ¾-inch diameter bolt are approximately 12,500 pounds for tension and 11,500 pounds for shear. Product sizes range from 5/16- to ¾-inch and the total material thickness clamping range is from ⅛-inch for the smallest diameter to 3⅜-inch for the largest diameter.

An In-Depth Look at Expansion Bolts for Structural Steel Early Product Developments One of the first such fasteners to become widely available was a threaded stud expansion bolt, launched in the United Kingdom (UK) in 1948.

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Issued March 1, 2014 This report is subject to renewal March 1, 2015.

www.icc-es.org | (800) 423-6587 | (562) 699-0543 DIVISION: 05 00 00—METALS Section: 05 05 02—METAL FASTENINGS REPORT HOLDER:

4 Highest resistance to tensile loading in accordance with AC437

LINDAPTER LINDSAY HOUSE, BRACKENBECK ROAD BRADFORD, WEST YORKSHIRE BD7 2NF UNITED KINGDOM 44 (0) 1274 521444 www.lindapter.com www.lindapterusa.com

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

4 Use in Seismic Design Categories (SDC) A, B and C

3 PART AND HOLLO-BOLT

5 PART

1.0 EVALUATION SCOPE Compliance with the following code: ® 2009 International Building Code (IBC)

Property evaluated:

4 Standard HDG product at standard pricing

ICC

4 Available in sizes 5/16” - 3/4” from your local distributor

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

4 Patented High Clamping Force design (sizes 5/8” and 3/4”)

3.1 General: ®

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

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

Page 1 of 6

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

November 2014

Figure 4. There are now many different types of expansion bolts such as this Flush Fit version, popular amongst architects.

Figure 5. Expansion bolts are quick and easy to install.

This bolt was designed to provide a threaded stud that protruded from the HSS to provide an attachment point for lifting equipment during marine salvage operations. It was a success and, still available, remains a popular component within the offshore industry to this day. Although initially developed in the 1950s, the widespread use of HSS did not start until the mid-1960s. Since then, its popularity has continued to increase, with many of today’s contemporary designs making a feature of exposed structural steel profiles to enhance the aesthetics of a building. During the 1980s, various shapes and sizes of HSS became available, and engineers needed a more versatile connection. This led to the development of a product in 1986 that had a fairly similar design to today’s expansion bolt. This product was a two-part assembly consisting of a slotted cylinder and cone, the latter threaded to receive a standard high-tensile fastener. While popular, system installation was not always easy; errors could arise when inserting

the product into the tight ±0.008-inch tolerance hole. Working overhead and/or with the larger sizes of square and rectangular HSS, the required hammer blows could cause chord face flexure and spring-back, sometimes producing incorrect installation of the product and possible hole damage. The use of tools with tapered handles to align beam end plates and column hole centers during steelwork erection was restricted, as the product could easily be displaced.

system. They are manufactured in carbon, alloy or stainless steel and are produced with a variety of finishes, meaning that they can be used in almost any situation: zinc-plated for standard use, hot-dip galvanized where a more robust product is needed, and stainless steel for the most demanding environments. Expansion bolts have been continuously developed to meet the diverse requirements of structural engineers and architects. For example, there is now a flush fit head variant that leaves no protrusion above the surface of the steel section. Recent performance optimizations for structural connections include a patented mechanism that compresses during installation and provides a high clamping force, resulting in a more secure connection.

Figure 6. Expansion bolts are typically installed by following three simple steps.

Figure 7. Expansion bolts secure the stunning HSS-framed roof at The Kimmel Center for the Performing Arts in Philadelphia.

Figure 3. One of the first expansion bolts, launched in 1948.

Recent Product Developments The knowledge gained from several decades of successful manufacture, combined with continuous direct contact with evolving onsite practices, formed the basis for the current expansion bolts designed to satisfy the needs of the steelwork erector in terms of ease and speed of installation. They also provide some tolerance to site abuse, for example hole size and misalignment, providing the construction industry with a robust yet aesthetically pleasing

STRUCTURE magazine

November 2014

Installation Installing expansion bolts is relatively straightforward and requires only basic tools. The steel is pre-drilled with oversized holes, per

the manufacturers’ literature, to accommodate the sleeve and cone-shaped nut. Care must be taken to ensure that the holes are located to allow the product to open within the HSS, meaning that they may not be placed closely together or near the edge. The steel can be fully prepared in the fabrication shop and transferred to site, where the advantage of fast installation can be fully appreciated. It is important to note that the faces of the members to be fastened together must be brought into contact before the expansion bolt is installed. To complete the process, the contractor must grip the expansion bolt collar with a wrench to prevent the body from rotating during installation and must tighten the central bolt to the manufacturer’s recommended torque using a calibrated torque wrench. Limit States

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Conclusion As this article has shown, there are many options available for connecting to HSS. The designer or engineer will have to carefully select the most appropriate connection for their application. The relatively recent acceptance of HSS as a construction material, and subsequent increase in use for structural frames, has no doubt encouraged

completed within an extremely short timeline or if there are restrictions in welding, a designer will need to look at alternative connection methods. Expansion bolts for structural steel are now one of the best choices for making structural connections to HSS. With their capability to handle much higher loads than other single-sided fasteners, such as rivets, and the fact that they can be installed in the field using standard hand tools, unlike threaded studs, you may find yourself taking a serious look at expansion bolts for structural steel.▪

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As expansion bolts for structural steel are proprietary products, the manufacturer’s literature or code reports state the available strength for the expansion bolt itself. It is up to the designer to check the viability of the HSS member from the applied loads imposed on it by the fastener. Per Design Guide 24, for expansion bolts in shear, the limit states for HSS are block shear, if near the end of the HSS, and bolt bearing. For tension applications, the limit states are distortion of the HSS wall and pull-out through the wall of the HSS. Expansion bolts have been independently verified by various approval bodies around the world, including the International Code Council Evaluation Service (ICCES). Specifically, several expansion bolts have been approved by ICC-ES for compliance with the International Building Code to AC437, Acceptance Criteria for Expansion Bolts in Structural Steel. In order to gain this approval, these bolts were tested by an independent certified test laboratory, and the results were used to calculate capacities for both Load and Resistance Factor Design (LRFD) and Allowable Stress Design (ASD) methods under both tension and shear in line with the AISC Steel Construction Manual, 14th Edition.

fastener manufacturers to concentrate their efforts on developing and improving innovative structural fasteners as a faster alternative to conventional methods such as throughbolting or welding. Likewise, the trend for construction developers and contractors to build structures in incredibly short timeframes has also contributed to an upsurge in demand for expansion bolts for structural steel, as it is specifically the speed of installation that is the fundamental benefit of this type of connection. When engineers are faced with a situation that requires a construction project to be

STRUCTURE magazine

November 2014

Building Blocks updates and information on structural materials

Standing Strong Advanced Steel Curtain Walls Provide Enduring Beauty By Chuck Knickerbocker

Chuck Knickerbocker is the curtain wall manager for Technical Glass Products (TGP), a supplier of fire-rated glass and framing systems, along with other specialty architectural glazing products. Mr. Knickerbocker chairs the Glass Association of North America (GANA) Building Envelope Contractors (BEC) Division Technical Committee. He can be contacted at chuckk@tgpamerica.com.

hen San Francisco’s Hallidie Building opened in 1918, its seven-story glass and steel skin launched the era of glass curtain walls. Using the strength of reinforced concrete and structural steel, the building team suspended the glass panes in a steel framing grid to create the illusion of a floating wall. While innovative, early curtain wall systems like the one in the Hallidie Building had shortcomings. One in particular was steel’s vulnerability to corrosion. As a result, aluminum’s lightweight and durable form became the material of choice for glazed curtain wall framing after it was adapted for use in buildings in the mid-20th century. Today, nearly half a century after aluminum entered the curtain wall scene, manufacturing advances are allowing building professionals to capitalize on steel’s strength in interior and exterior glazing applications, such as minimizing sight lines with small mullions and providing large free spans at the podium level of buildings. To achieve these results, manufacturers have developed two fabrication methods. The first uses a roll-forming technique in which continuous steel coils are forced through dies and laserwelded into closed, structural profiles. Under the second method, a laser cuts long length (up to 49 feet) steel plates (0.15 to 1.5 inches thick). Manufacturers then laser weld them into C, T, I, H, or L profiles, or custom shapes, as required. The laser welds are continuous and significantly smaller (radius < 0.07 inches) than conventional fabrication welds, which allow the shapes to be analyzed and used as composite, rather than assembled members. Using the above methods, manufacturers can produce steel frame members in lengths and shapes not previously possible with hollow metal, hot-rolled or welded steel frames. From protection against corrosion to support for highperformance applications, well-designed steel curtain wall systems use this versatility to provide enduring beauty.

Protection from the Elements To preserve the appearance of steel curtain walls, modern manufacturing methods help overcome earlier problems with moisture intrusion and corrosion. Moisture Intrusion To prevent water in the glazing cavity from contacting the steel back members, advanced steel curtain wall systems include a continuous joint gasket across the full width of the frames. Through the gasketing, water is also kept off the

Well-designed steel curtain wall systems use their versatility to provide enduring beauty.

tops of glass units and is directed to the vertical frame members. This is one of the factors that allows water penetration resistance per ASTM E331, Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors and Curtain Walls by Uniform Air Pressure Difference, to reach a minimum of 15 psf. The continuous face gaskets cover the surfaces of the framing in the glazing pocket to provide a critical safeguard against moisture. The installer seals the lapped gasket joints at horizontal-tovertical connections to further aid in preventing water intrusion. In general, steel curtain walls with proper gasketing do not require zone damming, as is typical with aluminum pressure plate systems. This eliminates the need for weeping at every horizontal pressure plate, thus reducing fabrication and installation time as compared to conventional aluminum systems. Once the framing is erected and the gaskets are sealed, these steel systems use more conventional aluminum or stainless steel cover caps and pressure plates to hold the glass to the framing. Self-sealing fasteners penetrate the gasketing, but do not provide access for water penetration. Structural silicone glazing uses sealants specific to the application to retain the glass to the framing in lieu of pressure plates and covers, as is typical with aluminum systems. Weather seals around the perimeter of the framing are made to gaskets at the back of the glazing pocket, to special extrusions or to perimeter details in plane with the glass instead of to the framing. Placing perimeter seals in front of the steel continued on page 18

16 November 2014

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plates to carbon steel back members with stainless steel pressure plate screws. As these metals are in close proximity to each other in anodic polarity, they do not tend to corrode as fast as metals that are further apart on the electromotive scale. The supplier can coat the metals with a non-conductive paint or finish to effectively isolate the two materials.

Support for Demanding Applications

To protect against corrosion, modern steel framing is available with double-sided pre-galvanization and factory-applied finishes.

eliminates any chance of water contacting the material behind the seal. This ensures greater protection from corrosion once the building is completed. Corrosion To preserve the curtain wall’s appearance and protect against corrosion, modern steel framing is available with double-sided pregalvanization and factory-applied finishes. For instance, steel framing may be prefinished with liquid zinc and top-coated with a durable primer and finish color to match virtually any design scheme. A variety of finishes are available, including powder coating and liquid-applied finishes specifically formulated for steel. Typical finishes applied to aluminum, such as liquid applied fluoropolymers, are not suitable for steel. Carbon steel members, when formed from coil stock as described above, are protected from corrosion after production and during fabrication by pre-galvanized finishes applied to the coils before forming. Powder coating or liquid applied finishes can be applied with proper cleaning or blasting, depending on the quality of the required finish. Fabrication is generally completed before finishes are applied to reduce any chance of damaging the finish during sawing, welding, drilling or final assembly. This also ensures minimal coatings are applied on rough edges that would otherwise be exposed during shipping to the jobsite, as well as installation until the building can be “dried in” and protected from water contact. As with any specialty glass and framing system, product nuances vary by manufacturer. Consult the supplier’s documentation for specific installation instructions, particularly for more complex steel systems, such as structural silicone glazed steel curtain walls.

Galvanic Action Galvanizing exterior exposed metal is a recommended best practice; however, it is not ideal to apply finishes over the galvanized surface. The galvanizing tends to bubble the finish, resulting in a rough, usually unacceptable surface appearance. Another option is to form the framing members from stainless steel alloys. Generally speaking, Series 304 is the only alloy currently used in the rolled profile methodology (alloys such as Series 316 are too brittle when rolling). Other stainless alloys require more fabrication time. For example, the 316 Series requires slower saw and drill speeds, thus taking longer to fabricate. As such, checking with fabricators prior to specifying a stainless alloy is recommended. For steel curtain walls with aluminum pressure plates, galvanic action can occur. To reduce corrosion between the two dissimilar metals, suppliers can connect the aluminum pressure

Slender, versatile, and strong, steel framing offers several significant performance advantages over traditional steel and aluminum mullion curtain wall systems. Greater Load Carrying Capacity Steel has a Young’s modulus (E) of about 29 million psi, compared to 10 million psi for aluminum. As a result, steel frames deflect less, providing a substantially greater load capacity. This helps ensure the amount of deflection does not compromise the strength of the steel members, causing bowing, sagging or joint failure. It also aids in protecting glass lites from being forced out of place. These benefits can help building teams preserve the long-term appearance of the framing and reduce maintenance costs. From a functional standpoint, steel’s greater load carrying capacity allows building teams to increase glass sizes in steel frames versus aluminum frames of the same shape. It also enables greater free spans than traditional steel and aluminum systems. For example, given 5-foot mullion spacing at a 30-lb/sf-wind load, an aluminum mullion of 2.5 by 7.5 inches, including the glass and exterior cap, can span 12.5 feet. Due to

Steel’s greater load carrying capacity allows building teams to increase glass sizes in steel frames.

STRUCTURE magazine

November 2014

steel’s strength, a similarly sized profile of 2.4 x 7.6 inches would only deflect one-third as much under the same conditions. As a result, it is possible to increase the length of the steel mullion in this instance to span approximately 16.3 feet – a 30 percent increase over its aluminum counterpart. As with any curtain wall system, variables such as center-to-center location of verticals, span length, and structural loads have an impact on the size of the framing member required to support the project’s performance criteria. Design Versatility Curtain walls that incorporate modern steel frames can support a wide range of design schemes. For instance, steel veneers allow for attachment to virtually any structural component that can support the curtain wall system’s weight and imposed loads (i.e., wind loads, snow loads). As such, they can provide building teams with exceptional design freedom. The strength and versatility of steel mullions also enables curtain walls of various heights and shapes. The maximum allowable height for single- and multi-story steel curtain wall installations depends on factors such as applied loads and thermal expansion and contraction. However, the primary

Steel veneers allow for attachment to virtually any structural component that can support the curtain wall system’s imposed loads.

factor influencing the maximum height is where the curtain wall’s dead load will bear on the structure. For example, in a recently completed sixstory wall, the project structural engineer required each floor to carry the imposed curtain wall dead load, rather than have the ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

STRUCTURE magazine

November 2014

wall’s full weight (approximately 25 psf due to thicker fire-rated glass, not the steel frame) imposed on the structure at the lowest level. The steel mullion was sized at 2.3 x 7.1 x 0.1-inch thick walls, and required a 0.37 inch dynamic splice joint at every floor. The structure of the building had to be increased to

limit the live load deflection to 0.25 inch THERMAL EXPANSION COEFFICIENT at these conditions. In another example, on a project with a 55-foot clear span in an open atrium, the 12.3 steel mullion was sized as a 4 x 17-inch rectangle. It weighed 100 lb/linear foot due to a moderately high wind load and 8.0 wider-than-normal spacing between verti7.3 cal mullions. In this case, the dead load was imposed on the foundation wall at the base 5.0 of the curtain wall, and a moment splice was introduced since it was not possible to fabricate and ship a 55-foot tall mullion as a single piece. Glass Concrete Steel Aluminium It is important to note the project structural engineer offered to design the structure with a moment connection at A comparison of the thermal expansion coefficients of the base of the wall, which would have various comparison materials. reduced the weight of the mullion by 50 percent. However, since the reaction Heat Gain/Loss imposed on the foundation was too great, the mullion stayed robust as described. Many curtain wall framing materials have high thermal conductivity compared to other elements of the building envelope, Energy-Efficient Framing creating assemblies susceptible to summer As the connection point between the glazing heat gain and winter heat loss. To overcome and perimeter details, modern steel frames this challenge, design professionals often pair can help create a sound building envelope. framing systems with low-emissivity (low-e) glass or other energy-efficient glazing. While Condensation Resistance center-of-glass (COG) thermal performance In modern steel curtain wall systems, the values improve, the system’s overall thermal absence of metal in the cold space of the glaz- efficiency remains substantially less effective ing pocket, combined with narrower-frame where the captured or retained glass edge profiles, reduces the potential for heat trans- meets the supporting frames. fer. This, in turn, lowers the risk of interior With a thermal conductivity of approxicondensation. The condensation resistance mately 31 Btu per hour (about 74 percent factor (CRF) for steel curtain walls typically less than aluminum), steel can help reduce ranges from 40 to 63, depending on the type the potential for heat gain and loss between of glazing used. More energy-efficient glazing the glass and frames. Its performance is can help design teams achieve a higher CRF. equivalent to that of thermally broken aluSince curtain walls and windows with a CRF minum frames, allowing the steel frame appropriate for the local climate and building profiles to help reduce heat flow. As an design typically have less interior condensation added benefit, some advanced steel frames (or ‘sweating’) on frames, proper specifica- do not necessitate a traditional thermal tion is crucial. The American Architectural break due to the design of steel profiles. This Manufacturers Association (AAMA) and helps lower the potential for heat transfer other associations provide guidelines for and interior condensation on the frames selecting systems with the appropriate CRF. by providing a significantly smaller area of However, it is important to note the con- steel for heat to pass through. In addition, densation resistance factor they recommend the strength of steel allows for ‘heavy’ triple is a weighted average. It does not take into glazed insulated glass units (IGUs) while account cold spots and other peripheral fac- maintaining the ability to provide large tors. As such, thermal modeling software can glass sizes and minimal sight lines – all provide value for projects where condensation advantages over aluminum. control is a concern, including cold-climate, Thermal Expansion high-humidity applications. These programs factor in numerous variables, including prox- Steel expands and contracts at a rate about imity to perimeter heating elements, to help 50 percent less than aluminum. Its thermal estimate the air temperatures along the inside expansion coefficient of about 12 x 10-6 x 1/K surfaces of the glass and frames. is comparable to glass and concrete, which are 15.0

in/in.°Fx 10-6

10.0

5.0

STRUCTURE magazine

November 2014

approximately 9 and 10 respectively, while aluminum is about 24. Since steel, glass and concrete expand and contract at similar rates, steel can work in close conjunction with its surrounding materials to help ensure a sound building envelope as the temperature changes. This can also reduce the size of perimeter sealant joints, especially at locations where expansion is being addressed. These are crucial specification considerations for buildings in climates with extreme morning-to-midday temperatures and distinct seasonal changes.

Fire Protection Fire-rated curtain walls also benefit from the new generation of steel frames. Using new manufacturing techniques, steel firerated frames can be formed from tubes, instead of hollow metal profiles, and shaped in an extrusion-like process similar to that of other advanced steel frames. This method allows for a wide range of narrow mullion profiles that feature well-defined corners and crisp edges. The result is improved sightlines, views, and smooth integration with neighboring window and curtain wall applications. Fire-rated frames can also be custom painted or powder-coated to complement non-firerated frames, including aluminum, stainless steel, and various color options. Fire-rated frames are currently available with one- and two-hour ratings. They can provide fire protection (against the transfer of flames and smoke) or fire resistance (against flames, smoke, and heat transfer). Framing systems that provide fire resistance do so by resistive insulation. They are tested to ASTM E 119, Standard Methods for Fire Tests of Building Construction and Materials, and Underwriters Laboratories (UL) 263, Fire Resistance Ratings – meeting the fire resistance for walls. As a result, fire-rated frames are suitable for use in various applications, including: • atriums • stairwells • interior separations • storefronts • along shallow lot lines

Conclusion Through good design practices and routine upkeep, building teams can create modern steel curtain walls that are serviceable and attractive for many years to come. As Ludwig Mies van der Rohe said, “We must remember that everything depends on how we use a material, not on the material itself…Each material is only what we make it.”▪

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cLASh prevention SDS/2 checks for interaction with other connections within a common joint. That means adjusting connections for shared bolts, checking driving clearances for bolts, sharing, adjusting and moving gusset and shear plates when required, and assuring erectablity of all members. All adjusted connections are automatically verified based on selected design criteria.

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he Boston and Worcester Railroad, one of the first railroads built in Massachusetts, was chartered in 1831 and opened to Worcester in 1835. This was followed by the Western Railroad, which would begin in Worcester and run to the New York State line, connecting with the Hudson and Berkshire line that ran to Albany, New York, on the Hudson River. The latter line was completed in 1838. The Western Railroad reached the easterly shore of the Connecticut River at Springfield on October 1, 1839. The line of the Western Railroad from W. Springfield to the New York State over the lower Berkshire Mountains was completed on May 4, 1841. To make the connection across the Connecticut River required a long bridge. Up to this time, most wooden bridges were constructed to the design of Stephen H. Long and by Ethiel Town. On the western segment, many bridges were short stone arches. Other early wooden railroad bridges were by Lewis Wernwag over the Monocacy River and Harper’s Ferry over the Potomac River for the B & O Railroad (STRUCTURE, August 2014). Burr’s Trenton Bridge (STRUCTURE, June 2014) across the Delaware was retrofitted for railroad service in 1835 and Moncure Robinson built several long Town Lattice Trusses for the Philadelphia & Reading Railroad as well as the Richmond & Petersburg Railroad in Virginia. (STRUCTURE, October 2014) The engineers for the Connecticut River crossing were William Gibbs McNeil, George Washington Whistler and William H. Swift, who were all early graduates of the United States Military Academy at West Point. They were planning on using Long Trusses by Stephen H. Long for the bridge until William Howe came to them with a new plan that he claimed was superior to the Long Truss. Howe was a millwright from Spencer, Massachusetts, located about 8 miles west of Worcester and on the line of the railroad. He was one of the three inventive Howe bothers. His brother Elias invented the sewing machine and brother Tyler the spring bed. Howe designed many churches and meeting houses, some of which required long truss spans for the roof. They were all entirely of wood with the exception of some iron bolts. Long’s truss was also entirely of wood. At an old church in Brookfield, he saw a truss of wood that was sagging and there was no way of adjusting the sag. He got the idea of replacing the vertical wooden tension members with wrought iron rods that were threaded on both ends, which made it possible to adjust any sag in the truss. This was fully intuitive, as Squire Whipple had not then published nor even developed the method of analytical truss design. It is likely he tried this out on a roof for a church in Warren. He then convinced Swift and Whistler to try his design on a short 70-foot

span across the Quaboad River at Warren, just west of Spencer. It was successful, and they gave Howe the contract to build a much longer bridge at Springfield. Howe received a patent, #1,711, on a bridge William Howe. on August 3, 1840 while he was building the Connecticut River Bridge. It had braces and counter braces crossing two panels, with additional braces at the ends and additional longitudinal member just below mid height. Long claimed that it was a violation of his patent rights, but was unsuccessful in convincing the Patent Office they had erred in granting the patent to Howe. Howe wrote, “The truss-frame which I am about to describe is in many respects similar to the truss-frame for which, under several modifications thereof, Letters Patent of the United States are about to be granted to me, under an application therefor dated the eleventh day of May, 1840; but it differs therefrom in the effecting of the straining up, and cambering, by the operation of iron bars, or rods, furnished with screw nuts, and of wedge pieces so placed as to be rendered effective by the action of said screw rods, or bolts.” He claimed in his patent “The manner in which I have combined the iron bolts, and the wedge pieces against which the braces and counter braces abut, so as to cooperate in increasing the camber to any desired extent, the whole truss-frame being constructed and acting, substantially as herein set forth.” There is no record of a patent issued on May 11, 1840, but there is one, #1,685, dated July 10, 1840 for a much more complex truss with a supporting arch and no iron rods that he claimed could be adjusted by wedges, etc. On both patents, he gives his address as Warren, Massachusetts. A wooden carriage and wagon toll bridge had existed nearby, since 1805, with a length of 1,234 feet and a width of 30 feet. Howe’s design was for seven spans of 180 feet, for a total length of 1,260 feet with masonry piers. Unlike many old bridges where information is lacking, a complete description of Howe’s Bridge was published in The Journal of the Franklin Institute in May 1842 by Lewis M. Prevost, Jr., C. E. He wrote in part, Each truss is formed of a system of main braces, A, A, A, seven inches square, of white pine, inclined from the piers towards the centre of the span, abutting upon white oak shoulders, C, C, C, which are let into the chords D, D, to a depth of two inches; and counter braces B, B, B, of the same dimensions, inclined in the

STRUCTURE magazine

Historic structures significant structures of the past

Springfield Bridge for Western Railroad

First Railroad Bridge across the Connecticut River in Massachusetts 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 19th 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.

Howe patent.

contrary direction, passing between each pair of main braces and also abutting upon the white oak shoulders. The upper and lower chords are composed of planks forming, in all, six horizontal beams of seven by ten inches each. The whole truss is firmly bound together by the iron rods E, E, E, two inches in diameter, passing between the main and counter braces, and through the white oak shoulders; having screws cut on their lower ends, and the lengths adjusted by means of burrs; these suspending rods act in lieu of the king and queen posts usually employed, and sustain the lower chords, on which the girders, F, repose. The spans are 180 feet each, and the deflection of the bridge in the middle of a span, during the passage of a locomotive and train, by careful measurement, was found to be only a quarter of an inch. Some of the principal advantages of this plan are that the stress comes upon the end grain of the main and counter braces, and is in the direction of their length – consequently there is not the same danger of the settling which occurs in lattice bridges, in consequence of the crushing of the pins and the splitting of the lattices at the ends and there being a free circulation of air between the main and counter braces, the bridge is not so liable to the speedy decay which occurs in lattice bridges, wherever the lattices come in contact. There is also less timber required in Howe’s truss than in Town’s. For a bridge of 180 feet span, there are in Howe’s truss frames, 28,636 feet board measure. For a bridge of 180 feet span, there are in Town’s double lattice, 46,080 feet board measure. These quantities of timber have been calculated for the trusses, or sustaining parts only, of the two plans respectively; supposing each to span 180 feet, and the truss depth of the former to be eighteen feet, whilst that of the latter was assumed at nineteen feet

eight inches, both measured from the top of the upper to the bottom of the lower chord: the roof and floor would of course contain the same quantity of timber in both cases, and has therefore not been included, being evidently unnecessary in a mere comparative estimate of the amount of lumber in each; we must, however, observe that the above described trusses upon Howe’s plan, contain the subjoined quantity of iron, – a material not used in the lattice bridges – viz: Approximate weight of iron in the suspending rods and burrs of the two trusses of one of Howe’s bridges, of 180 feet span, 21,100 pounds. Approximate weight of iron in the transverse top ties, 710 pounds. Total, 21,810 or nearly, nine and threequarter tons of wrought iron. The usual cost of the superstructure of covered railroad bridges, upon the plan above described, with long spans, and for a single-track railway, inclusive of all materials, and of the workmanship, is about $22 per lineal foot of floor. In conclusion, the writer will add his conviction, that in bridges with spans equal to, or exceeding, those of the bridge at Springfield, the peculiar truss above described, will be found superior in strength, stiffness, and durability, to those of Town’s double lattice plan. He added struts from the piers up to the first, second and third panel points, with an extra 9- by 12-inch bolster. His panel length was only 7 feet and, with a height of truss of 18 feet, was a little flatter than the preferred 45°. He had wrought iron bars across the tops of the trusses for lateral stiffness. At the ends of his braces and counterbraces he had wooden shoes, white oak shoulders, to transfer the diagonals loading to the top and bottom chords. His braces and 2-inch wrought iron bars were all the same size over the length of the truss as were the chords, so it is obvious he did not fully understand the loading in the members. The trusses were continuous over the piers in the same way

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November 2014

many Long Trusses had been and as the earlier Burr, Palmer and Wernwag bridges were. The bridge opened in October 1841, completing the line linking Boston with the West at the Hudson River. The trusses were covered, not roofed and painted with a whitewash; a layer of tin was placed on the flooring and painted black. The tin was to cut down on the possibility of fire. The bridge was replaced in 1855. With the opening of the Springfield Bridge, the Howe Truss became the bridge truss of choice, given its stiffness, adjustability and lower cost, for many railroads around the country. Whistler left the Western Railroad and went to Russia to build the Nikolayev Railroad in 1842, and built many Howe Trusses on that line as well. Howe’s bridge became known around the world, as technical journals of the time spread the word about advantages of the style. Many were covered and roofed but some were not, and those generally had a life of 15 years or less. The Foxburg, Pennsylvania Bridge for the B&O Railroad over the Allegheny River was double decked and survived until 1921, when a steel bridge replaced it. Most Howe Trusses after the Springfield Bridge were not double intersection and had cast iron shoulders (shoes) to receive the braces rather than wooden ones. On August 28, 1846, he obtained another patent, #4,726, adding an arch to his truss pattern. Many Howe Truss bridges still exist and carry roadways and light duty railroad traffic. What Howe had done was to introduce wrought iron rods for his vertical tension members, enabling bridge owners to keep the camber in their bridges. Squire Whipple, in his 1847 Treatise on Bridge Engineering, gave the engineering profession the ability to design each member of a truss to carry the load it would see in service; this made it possible to vary the size of its members as necessary along the length of the truss. Howe’s brother-in-law, Amasa Stone, built many Howe trusses in the mid-west. On the 150-foot long Ashtabula Bridge, he replaced the top chord wooden members with wrought iron I-beams and the lower chord with wrought iron rods making it an all iron bridge. Unfortunately, the bridge collapsed on December 29, 1876 killing 90 people. In iron, the Pratt Truss over time generally replaced the Howe Truss for both railroad and highway traffic. Howe, however, was able to retire and live off the patent fees he charged for use of his patented truss.▪ This is the last in the series of notable wooden bridges. In the next and following issues, Dr. Griggs will discuss the cast and wrought iron bridges that were dominant between the 1840s and 1880s.

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Structural DeSign design issues for structural engineers

part from the weight, there is nothing lightweight about lightweight structures. With traditional structures, the loads are resisted by the stiffness in the beams, columns, and walls; with tension-only and compression-only structures, the overall form of the structure becomes critical. Get the form right and the structure can span huge distances with minimal material; get the form wrong and you are in trouble. “Students … learned that nonlinear systems were usually unsolvable, which was true, and that they tended to be the exception – which was not true.” James Gleick (1988) We can all remember, in structures 101 lectures, when we were told that a beam could have a pin at one end and a roller at the other, but it could not work if you added a pin in the middle as well. This is true if you want to keep the analysis linear, and not create any horizontal reactions, but is a hopeless approach if you want a bridge to cross 1.5 miles of river. The linear approach just will not work; it’s time to take a nonlinear approach. Many building structures are linear, or at least near enough to not worry about nonlinear effects. The beams and columns are kept within tight deflection limits and they tend to behave in a linear way. The truth is that all structures are nonlinear. It’s just that the simpler linear analysis usually gives answers that are close enough for the majority of engineering design. So what makes nonlinear different from linear analysis? One of the most important things to remember is that with linear analyses you establish equilibrium of the forces on the original geometry, but with a nonlinear analyses you get equilibrium of the forces on the deformed geometry. The problem is, you don’t know what the deformation is until you have resolved the forces and you cannot resolve the forces until you know the deformed shape. All nonlinear analyses thus requires a certain amount of iteration.

Why It’s Good to be a Lightweight Geometrically Nonlinear Structures By Peter Debney, BEng(Hons), CEng, MIStructE

Peter Debney, BEng(Hons), CEng, MIStructE, is a Chartered Structural Engineer and software specialist with over 20 years’ experience specializing in computing applications, half of those in practice and the rest in engineering software, whether BIM, analysis or design. He is an application specialist for Oasys, concentrating on structural and crowd simulation software.

The online version of this article contains a list of subject sources. Please visit www.STRUCTUREmag.org.

Cables While linear structures resist loads with bending stiffness, lightweight nonlinear tensile structures work by deflecting until the forces are in balance. Take a look at a very simple example: a cable supporting a single point load at its centre. For extra simplicity, ignore the self-weight of the cable, strain hardening and strain limits. Concentrate purely on the point load and how the cable responds to it. Before the load is applied, the cable is straight and unstressed. When the load is applied, the cable cannot resist: it has no bending strength,

so it starts to deflect. As it deflects, it begins to stretch and tension is induced. As the cable is no longer perpendicular to the load, there is therefore a vector component of that tension that resists the load. As the deflection increases, so does the induced tension and angle until the deflection reaches the point where the load is exactly balanced by the parallel vector components in the cable tension (Figure 1). This structure is nonlinear, as it has to deflect to carry the load. Don’t forget that all structures have to deflect to carry load, but nonlinear ones such as this have to move a significant distance to reach static equilibrium. Force/Action → Acceleration → Deflection + Resistance → Strain → Stress → Reaction → Equilibrium The nonlinearity in the system is seen by plotting load against deflection (Figure 2). Note that the final axial force in the cable is totally dependent on its final angle. Such a structure is also very sensitive to the support stiffness: as the supports move in, the deflection increases, as does the angle of the cable. This will result in a larger deflection but a lower stress in the cable. If the two parts of the cable become parallel (either by infinite deflection or the more useful option of moving the supports together until they touch), the axial force will be equal to exactly half the applied load. Note also that there is minimal lateral resistance to movement. You have made a pendulum. Conversely, we can reduce the deflection by applying a pre-stress to the cable, so that the higher tension generates the required resistance at a shallower angle. In theory at least, you could achieve zero deflection with infinite pre-stress. Practical structures fall between these two extremes. The picture starts to get more interesting when section and material properties are considered. Initially, one might surmise that the deflection of the cable is independent of the cable stiffness, but the reality is that tension will build faster in a material with a higher stiffness and thus reach equilibrium at a lower deflection. There is also the structure’s behaviour when the stress in the cable reaches the material plastic yield limit: the cable might yield but the structure will still carry the load. Even though the cable cannot carry any more stress, the load is carried by a combination of the stress and the angle of the cables, so any further increase in load results in a much higher deflection. In theory, the cable can carry a load of twice the yield strength of the cable. However, that would require the cable to deflect to infinity; the strain limit will have been reached long before that. So with one point load on a cable you get a V shaped result. Adding more point loads or making the load uniform will pull the cable into the classic catenary shape, familiar to us from suspension bridges.

26 November 2014

Figure 1. Diagram of deflection and load.

Figure 2. Load-deflection.

Cable Nets

Figure 4. Climbing frame.

the 16,146 square yard (13,500 m2) cladding lies a cable net, eﬃcient enough to keep the total weight down to a mere 12 pounds per square foot (60 kg/m2). Despite its lightness, the roof is still stiff enough to keep the lighting from shaking, something that the cyclists would find extremely distracting. The shape also has the advantage of minimizing the volume of the space and thus reduce heating and cooling loads while at the same time maintaining audience sight-lines. On the other hand, spiders instinctively make their webs in a single plane, giving them

a flexibility undesirable in most engineered structures. From the spider’s point of view this is exactly what they need, as they are, like safety nets, designed to catch and absorb the energy from fast moving objects. A double curved spiders web may be too stiff and thus allow flies to bounce off before the glue has a chance to work. As tension structures are very sensitive to movement at the supports, the Velodrome roof needed a stiff steel compression ring, which was in turn borne by raking trusses that also supported the seating. The trusses in turn were rigidly mounted on the concrete

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Velodrome So what does such a double curved surface look like? An excellent example is Expedition’s award winning Velodrome for the London 2012 Olympics, famous for its “Pringle” shaped roof. Beneath STRUCTURE magazine

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A single loaded cable, such as a catenary, is stabilized out-of-plane by gravity and possibly additional factors such as the bridge deck. However, such structures are still vulnerable to sway, whether induced by wind or pedestrians. A solution to this problem (though not normally for bridges) is to have cables going in multiple directions, so sway in one direction is resisted by cables at other angles, providing what is called a cable net. These are actually common structures in nature. It is likely that there are tens if not hundreds in your house and garden, spun by spiders (Figure 3). If such a cable net is horizontal and loaded, it will deflect down with an essentially catenary shape, giving resistance to gravity loads. There is still a problem: what about uplift forces on such a cable net if clad? Suction would be resisted purely by the self-weight of the structure, which is minimal. As catenaries are good at resisting load in the direction of the curve, the solution is to have the cables in one direction curve down to resist gravity loads, and those in the other direction curve upward to resist suction loads. This double-curved hyperbolic surface is characteristic of many cable nets and all engineered fabric structures, as the shape naturally gives stiffness in all directions. The alternative is to provide cables in all directions, which might not give a practical roof but makes for great climbing frames (Figure 4).

Figure 3. Spiders web.

Figure 5. GSA model of Velodrome. Courtesy of Expedition Engineering Ltd.

Element list: P1 Scale: 1:17.63 Deformation magnification: 4.000 Node Loads, Force: 0.5000 kN/pic.cm Output axis: global Resolved Element Translation, |U| Output axis: local 90 mm 80 mm 70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm mm Case: L1 Case: A1 : Analysis Case 1 Contour case

y x

Figure 6. Hyperbolic paraboloid double-ruled mesh.

base structure. Designers used GSA Analysis modeling software (Oasys) throughout the design process, from form finding the cable net to static analysis to checking the vibration characteristics of the completed building (Figure 5).

Element list: P2 Scale: 1:20.65 Deformation magnification: 10.00 Node Loads, Force: 0.5000 kN/pic.cm Output axis: global Resolved Element Translation, |U| Output axis: local 90 mm 80 mm 70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm mm Case: L1 Case: A1 : Analysis Case 1 Contour case

Forming a Hyperbolic Surface Unlike most double curved surfaces, hyperbolic surfaces have a curious property: you can make them entirely out of straight lines. We are all familiar with single-ruled surfaces such as cylinders, where you can define the surface with a series of straight lines all going in the same direction. Hyperbolic surfaces are double-ruled surfaces, meaning that they are formed from two series of parallel lines. The classic version of this is the hyperbolic paraboloid, or hypar for short, which you can form by twisting a rectangular plane (Figure 6). Although the Velodrome roof is a hyperboloid, it is slightly different as the cables were at 45° to the ruled surface (Figure 7). Both options have the same surface and about the same quantity of material, but the latter is twice as stiff due to the curved profile of the cables, halving the deflection. This means that the longer span cables actually deflect less. Rigid hyperboloid structures were first used by the Russian engineer Vlaadimir Shukhov in the 1890’s with his lattice tower in Polibino, Lipetsk Oblast. He is most famous for his Shabolovka Radio Tower. The form has been subsequently used for architectural towers such as Zhou Ruogu and the Kobe Port Tower (Figure 8), but also to give the humble cooling tower its buckling resistance. Hyperboloids are not the only form of double-curved surface used with lightweight structures. The basic forms also include the Conic and the Barrel Vault (Figure 9). There is also the dome, which will be discussed in Part 2 of this article.

Fabrics The boundary between fabrics and planar cable nets can be a blurred one. Structurally, one of

y x

Figure 7. Hyperbolic paraboloid mesh.

Figure 8. Shabolovka Tower, Zhou Ruogu, Kobe Port Tower.

Figure 9. Hypar, Conic, and Barrel forms.

the most important differences is that fabrics are woven while cable nets tend to be layered. This gives rise to the fabric’s warp-weft interaction, which means that when you tension one direction more than the other, the fibres in that direction straighten and increase the kink in the other. This gives fabrics both an unusual stressstrain relationship and Poisson’s ratio. Fabrics are thus sensitive to the balance of pre-stresses in the two principle directions; the fabric will wrinkle as a whole if the pre-stress is much higher in one direction than the other (Figure 10).

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November 2014

Figure 10. Fabric weave.

continued on page 30

Figure 11. 2008 Olympic Aquatic Centre, Beijing. Courtesy of Arup.

Figure 12. Masyas. Courtesy of Arup.

Because of this arrangement, fabrics are principally stiff in the warp (principle fibre) and weft/fill (secondary fibre) directions, and have minimal stiffness diagonally. Coating the fabrics can increase this stiffness, but the low shear stiffness does aid the fabric’s ability to twist into the required double curved surfaces.

Munich 1972

Foils A step further on from fabrics are foils, which are isotropic plastic sheets made from materials such as ETFE (ethylene tetrafluoroethylene) and in use on iconic structures such as The Eden Project and Beijing 2008 Water Cube (Figure 11). Foils are generally used in inflated pillows, so each cladding panel is actually two or three separate layers supported by pressurized air. Wind loads on one surface are carried through the contained air to load the opposite face, so the whole remains in tension. The air can be heated to prevent snow loads. Unlike fabrics, foils have a good shear strength; they have to yield under load to achieve their final form, though form finding and determining the correct cutting patterns goes a long way to minimize this.

Edge Conditions Because the pre-stress is crucial to ensure the tension and hence stability of fabrics, it is important to consider how to achieve this pre-stress. Fabrics require an edge support, which can either be solid, such as a beam, or flexible, such as a cable. With flexible edges, the cable’s curvature (or “set”) is dependent on the balance in the pre-stress between the cable and fabric. Apart from structural considerations, this set has quite an impact on the aesthetics of the fabric structure. The balance of the pre-stress in the fabric is also crucial and must be in harmony with the fabricated surface. A correctly tensioned fabric will be smooth, as can be seen in Arup’s Marsyas sculpture at the Tate Modern in London. Unbalanced tensions will cause wrinkles in the surface, known as Heugen’s Tension Fields (Figure 12).

The modern science and engineering of fabric structures was pioneered by Frei Otto, with his roof to the Munich Olympic Games being a major landmark in the industry. In rejection of the heavy wartime architecture of Nazi Germany, Otto aspired to make modern architecture as light as possible, in both senses of the word. The Munich roof achieved this by using both a minimum of material and maximum glazing (Figure 13). Frei Otto’s seminal work has continued to inspire and influence Olympic architecture. While the end effect is quite different, Mott MacDonald’s 2012 Shooting Gallery façades in London are based on exactly the same principles. Otto and his team needed to determine the geometry using physical models, with careful measurements feeding into hand calculations. Mott MacDonald, on the other hand, was able to use Oasys GSA for both the form finding and subsequent static analysis.

Tensegrity So far we have looked just at tension structures, but now let’s start to mix in compression with the rather interesting group of structures known as Tensegrity. Buckminster Fuller coined the term as a portmanteau of Tension and Integrity, and described them as an “island of compression in an ocean of tension” (http://bfi.org). Rene Motro went a little further when he said that,

Figure 13. 1972 Olympic Main Stadium, Munich.

“A tensegrity is a system in stable self-equilibrated state comprising a discontinuous set of compressed components inside a continuum of tensioned components.” And artist Kenneth Snelson (http://kennethsnelson.net) went further still with “Tensegrity describes a closed structural system composed of a set of three or more elongate compression struts within a network of tension tendons, the combined parts mutually supportive in such a way that the struts do not touch one another, but press outwardly against nodal points in the tension network to form a firm, triangulated, prestressed, tension and compression unit.” Now we see tensegrity at work in superb structures like Brisbane’s Kurilpa Bridge (Figure 14). It’s a cantilever beam, but where is the compression flange? Each element is either in pure tension or pure compression (ignoring the small bending on the struts from the selfweight), so the load path is not conventional. Like cable nets, pre-stress is essential to the stability of these structures to give them sufficient stiffness. You can make the simplest

Figure 14. Award-winning tensegrity in Brisbane’s Kurilpa Bridge. Courtesy of Kenneth Snelson.

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November 2014

continued on page 32

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(a)

(b)

(c)

Figure 15. Tensegrity units.

tensegrity work with just one strut and four cables (Figure 15a) or slightly more complex with two struts (Figure 15b). You can then start to combine these basic units to create more complex forms (Figure 15c). While these are stable in plane, they are unstable out of plane, so you will need additional cables or a full wheel (Figure 16). With a suitable compression ring, tensegrity structures have the ability to cover huge spaces such as stadia with minimal weight, usually by forming inscribed hoops, each one supporting the next. There are two classic forms to tensegrity roofs, known as the Geiger, where the cables are arrayed radially, and the Fuller, which is triangulated for improved stiffness.

for each stage in tensioning the cable hoop, and then erection of each lighting rig and the fabric roofing (Figure 18).

Conclusion Though their lower stiffness or deflection requirements do not make them suitable for every application, lightweight nonlinear structures already enable us to span huge distances with minimum materials. Part 2 of this article will look into the world of compression-only structures.

Figure 16. GSA tensegrity roof. Courtesy of Arjan Habraken, TU Eindhoven.

Acknowledgements My thanks go to Matthew Birchall and his team at Buro Happold for the information on their 2012 Olympic Main Stadium. My thanks also go to Andrew Weir at Expedition for the information on their 2012 Olympic Velodrome, the various engineers at Arup that I have worked with over the years, and especially to my colleagues at Oasys for both creating the GSA software and for answering my many questions.▪

2012 Olympic Stadium

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An excellent and rather subtle version of the tensegrity roof is Buro Happold’s 2012 Olympic main stadium. Here the fabric infill panels disguise the boldness of this structure, with a single main cable loop tensioned and supported by radial cables from the steel frame. This cable, in turn, supports the 14 lighting rigs, each weighing 50 metric tons. These rigs are stabilized by back stays and a tension ring of their own (Figure 17). The programme did not allow for complete scaffolding of the compression ring, which was not stable until it was complete, so each stage in the erection sequence required separate GSA analyses to ensure stability and also to determine the locked-in stresses to take into the next stage. Further analyses were also required

Figure 17. London 2012 main stadium. Courtesy of ODA.

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Figure 18. Main stadium GSA model. Courtesy of Buro Happold.

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November 2014

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“Not Just Another Dome Idea” Micro Tilt-Up Construction for Super Low Cost Structures By Matthew Brand and Thomas Tailer

Overview of Cementitious Materials Used In this article, the term “cement” was used throughout, referring to various cementitious materials. The first Dome was built with a standard non-structural mortar mix that can be purchased at any retail home improvement store. The panels can be fabricated with any number of cementitious mixes, including grout, mortar and concrete. The second Dome is under construction using a grout mixture with excellent results. Additional materials will be tested in conjunction with the carpet in the future.

Figure 1. Completed structure. Courtesy of Meghan Holland.

very year approximately 160 million people are affected by natural disasters, with poverty identified as a major contributor of vulnerability to catastrophic events (WHO 2014). In addition, 4.7 billion pounds of carpet are discarded each year, accounting for 2% of all waste generated in the United States, with only 3.8% of the materials recycled (EPA 2012). The objective of this project was to design a low cost, high strength structure incorporating used carpet as a major structural component. Thomas Tailer, a local retired physics teacher, along with engineering students at the University of Vermont, designed and built a prototype dome structure in the shape of a truncated icosahedron. The goal of this project is to provide a safe, economical shelter intended to help people in the poorest communities in the world to survive natural disasters.

Construction Methods The Dome’s design objectives include simple construction, minimal material use, and utilizing locally available materials and labor. Construction does not require sophisticated calculations, measuring devices, or tools. The goal was to achieve a fabrication tolerance of +/- 0.25 inches during the design process; however, during assembly, misalignments of up to three inches occurred while maintaining

Figure 2. Diagram of dimensions. Solidworks drawing courtesy of Victoria Rude.

STRUCTURE magazine

structural integrity. The Dome’s span is fourteen feet and reaches seven and a half feet in height (Figures 1 and 2). 2- by 4-inch wire mesh fence, laid eight inches within the panel joints, connects the individual panels together. The Dome was designed by Thomas Tailer of Essex, Vermont using a compass to achieve the desired angles during planning and construction. The forms were placed on flat ground and lined with scrap plastic to hold the cement. The bottoms of the forms were lined with masonry cement by semi-skilled laborers, as seen in Figure 3. A carpet-cement laminate was constructed using two layers of carpet reinforcement surrounded by cement, with 14 gauge galvanized fencing wire bonded to the cement extending four inches out of individual panels to provide the panel connections (Figure 4). The carpet reduces the amount of cement necessary to make the panels, and also acts as tensile reinforcement. During loading events, the carpet will deform elastically; after the event occurs, it will have a tendency to return to its original shape. Each panel takes the shape of a pentagon or hexagon, weighing approximately 100 to 240 pounds, with a thickness of one and a half inches and with a side length of thirty inches. The Dome assembly uses a layering technique with three steps of construction. The first step starts at ground or base level, and connects the panel edges to each other by twisting together the protruding wires. The second step requires cantilevering panels from the ground level panels and temporarily supporting them until three sides can be wired to the structure as displayed in Figures 5 and 8 (page 36 ). After the supported panel is wired into the structure, the temporary supports can be removed and used in attaching the next panel. The center piece is lifted into place by the use of temporary cribbing in the center of the dome. The temporary supports and cribbing are removed after all pieces are connected. Masonry cement is added between the joints, acting as a waterproofing feature and a reinforcing structural element. In addition, it prevents the wires from untwisting during large loading events. The Dome comfortably fits nine people (Figure 6 , page 36 ), and would provide adequate shelter from extreme weather events. A chimney, stove, and external vent inserted into the structure allow for a cooking area, ventilation, and a heat source. A team of students from the Governors Institute of Vermont and the University of Vermont’s Engineers Without Borders Chapter assembled the Dome. The students were unfamiliar and unskilled in construction. It took approximately 100 person hours to construct and assemble the panels and their forms. However, a semi-skilled team of laborers with greater strength, or laborers with more experience using the system, could likely fabricate a dome in 50 person hours. The material cost of the structure is approximately US $200, with the major cost being masonry cement.

November 2014

Figure 3. Panel formation of first layer. Courtesy of Hannah Marshall.

Figure 4. Attachments between the panels before addition of masonry between joints. Courtesy of Megan Strand-Jordan.

Construction Challenges Numerous challenges arose during construction of the Dome, mainly during the assembly of the panels. The first major problem emerged while trying to close the circular base of the dome. The base would not completely close due to misalignment, and the panels were extremely difficult to adjust by hand. Closure of the bottom panels was needed before the second level of panels could be placed. Construction completely stopped until the issue was resolved. A system of levers was designed to wedge the base into place and allowed the first layer to close. In order to avoid construction delays, future designs will feature the construction of a foundation before interlocking the base panels to ensure closure. The weight of the top panel was a major issue during the assembly process. The panel’s thickness made it much heavier than other panels used. Styrofoam aggregate added to the cement mixture was not successful in substantially reducing the weight of the panel. This issue required the assembly of cribbing in the interior of the Dome to support the top panel while it was wired into the entire structure (Figure 7, page 36 ). The top panel rose slightly higher than the total height of the structure and was lowered onto the lightly supported second level panels by removing part of the cribbing to allow for the final wire attachments. With the roof panel in place, the structure achieved the rigidity needed to stand unsupported. To avoid this situation in future construction, designs will use smaller panels that weigh no more than 100 pounds. Significant problems with the structural integrity of the panels arose during construction of the second level. A hexagonal panel cracked in half during transit from the mold to the structure because material shortages forced the use of subpar carpet during construction. The panel was severely damaged as an individual piece, and could not support its own weight. The integrity of the entire structure was called into question as a result of this panel failure. With winter fast approaching, entire replacement of the panel was not possible. The damaged panel was subsequently attached to the dome with the crack oriented vertically. It was believed at the time that the structure’s strength resides in its edges, and that it was unlikely that a single cracked panel would cause the failure of the entire structure. In addition, the placement and orientation of the crack took advantage of the compressive lateral forces provided by the dome shape to negate the damage done to the panel by the crack. The dome has remained standing STRUCTURE magazine

successfully for one year with its structural integrity intact, surviving significant snow loading during the harsh 2013-14 Vermont winter and repeated freeze thaw cycles, with no apparent signs of structural damage or deterioration.

Applications/Conclusion Conventional construction systems for housing in third world countries use reinforced masonry that is expensive both environmentally and economically, and often do not provide enough protection from earthquakes and other natural disasters. The goal of this project was to develop a new system using resources that are currently wasted or underutilized to help provide shelter to the world’s poorest people severely affected by natural disasters. The system and construction process has application to many other structures that could be built at reduced costs. For instance, this concept has the potential of creating a composting toilet from local materials for only a few hundred U.S. dollars, and the opportunity to create a useable product from waste generated within a community. A Quonset hut type structure can provide larger clear spans and more useable floor space for classrooms, workshops, or storage areas for a significantly lower cost than traditional methods, such as corrugated steel or timber structures. continued on next page

Figure 5. Temporary supported 2nd level. Courtesy of Megan Strand-Jordan.

November 2014

Figure 6. Nine people comfortably seated inside dome. Courtesy of Megan Strand-Jordan.

This system is a green technology which supports the concept of sustainable development. The system enables slender sections resulting in less cementitious materials in the members. Approximately 5% of global CO2 emissions are contributed by the production of cement and concrete (WBCSD 2008). According to many scientists worldwide, global warming is the most destructive problem humans now encounter. This system will result in benefits from cost savings, lower embodied energy and reduced CO2 emissions when compared to conventional approaches. Using the structural analysis laboratory at the University of Vermont, basic structural property tests such as bending and buckling resistance were conducted on test panels. The results from these tests will be used in a computer model to be constructed this fall and spring, for earthquake resistance analysis.

the UVM campus, not only to attract the public’s attention, but also to get new UVM students involved in engineering projects. Finally, new structures using the carpet cement material are being designed, constructed, and tested for applicability in Vermont. The hope is to custom tailor designs to the regions of the world where these structures will be built. Disclaimer: The Dome was built with other safety systems in place that were not included in the article for brevity. Anyone who wishes to replicate this work should exercise caution. The Dome is patent pending. The hope is that, with a patent, the work will be protected and licensing of pre-engineered structural designs to non-profits and non-governmental organizations for use in relevant countries will be feasible.▪

What’s Next?

Matthew Brand is an undergraduate Environmental Engineering student at the University of Vermont studying the impacts of climate change on infrastructure. He can be reached at mwbrand@uvm.edu.

The most applicable places to build these structures would be in locations such as Haiti and other earthquake prone areas with easy access to cement. A pilot project is underway in which student volunteers from UVM will travel to Haiti with the Vermont Haiti Project and teach Haitian students how to build a structure using Dome materials and how to implement it in their communities. In addition, the team envisions a dome-like structure built right on

Figure 7. Inside view of interior cribbing/scaffolding. Courtesy of Megan Strand-Jordan.

STRUCTURE magazine

Thomas Tailer has worked for the last eight years with the International Earth Science Olympiad and observed firsthand the impact of disasters such as earthquakes, typhoons, and fires on low income communities in developing nations. He can be reached at tbtailer@hotmail.com.

Figure 8. Second level panel supported and wired into place. Top panel with chimmney supported by cribbing in the foreground. Courtesy of Megan Strand-Jordan.

November 2014

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Cold-Formed Steel Provides the Strength Needed to Take Sustainable Building to a New Level Green Terraces Present Design Challenges in a 10 -Story Senior Housing Complex By John Matsen, P.E. Figure 1. The terraces, totaling 12,000 square feet, are each support entirely by cold-formed steel.

round 1900, the School Sisters of Notre Dame settled on a wooded hill in Milwaukee. According to the Milwaukee Journal Sentinel, the nuns built “a little pioneer home hidden under mighty trees.” More than a century later, greenery crowns another home built on the same hill: Convent Hill, a $9.9 million, 10-story senior residence with roof terraces filled with day lilies, spirea, phlox, shrubs and grass. The terraces are extensive. They hold lightweight soil filled to a depth of three inches, ground cover plants and wild flowers, and irrigation systems (Figure 1). The street level is retail, the second floor houses the offices for the facility, and the 3rd through 10th floors are senior residential apartments. The upper eight stories are cold-formed steel framed bearing walls and C-joists with Levelrock gypsum concrete fill on metal deck. The second story and below are hot-rolled steel framed with post-and-beam construction. However, the joists are cold-formed steel C-joists (Figure 2).

The foundation walls, lower slab and footings are cast-in-place concrete. The main lateral resisting systems are cast-in-place reinforced concrete stairs and elevator cores. The cast-in-place concrete cores served to resist the lateral loads resulting from both wind load and seismic load. The concrete core was chosen over discrete bracing or cold-formed steel shear walls due to building height restrictions. The concrete core also aided in detailing and fire rating of the shafts. The City of Milwaukee had the Convent Hill complex built in 1959. For the present redevelopment, the city wanted to take advantage of the latest environmentally friendly building designs. The structure, which features 12,000 square feet of green roofs, represents “a new level of sustainable and green technology,” states the Milwaukee Journal Sentinel. But how could the structure support the green roofs without a large and significant use of structural steel? Matsen Ford Design Associates, Waukesha, Wisconsin, engineered the project’s cold-formed steel system, which comprises the majority of the structure’s support system.

Design Solution and Special Considerations

Figure 2. Hot-rolled steel with cold-formed steel joists were used strategically for only the first two floors.

STRUCTURE magazine

Cold-formed steel framing is the primary load-carrying structure for the upper residential stories. Cast-in-place concrete was used for the foundation walls, lower slab and shallow footings. The main lateral resisting system is cast-in-place reinforced concrete stairs and elevator cores. The combination of concrete and some structural steel with cold-formed steel supports 120 senior apartments and five rooftop garden terraces. From the second floor upward, the structure features cold-formed steel joists that were prefabricated into panels to shorten construction times and eliminate on-site labor. These joists leverage the strength and formability of coldformed steel with punched web holes to accommodate HVAC, mechanical, plumbing and sprinkler runs. The perimeter of the web holes had rolled edge stiffeners to add web strength and stiffness over the entire span of the joist.

November 2014

Figure 3. The design features pre-fabricated cold-formed steel joists, rim track and structural blocking.

Figure 4. The 10-story Convent Hill senior housing complex features a new level of sustainable and green technology.

The roof joists are cold-formed steel C-sections, 10-inch deep x 2-inch wide flange x 54 mil thickness, spaced at 24 inches on center for the 15-foot spans. Joist bridging was typically at 6 to 7 feet on center. Double C-sections 12-inch deep x 2-inch flange x 97 mil thickness where used for the longer 24-foot spans and 8-inch deep x 15/8-inch wide flanges x 43 mil thickness were used to span the corridors. The roof membrane is a screw fastened 1½-inch B deck with tapered insulation and ballasted EPDM roofing. The cold-formed steel joist roof structure at Convent Hill has the strength and stiffness to support five terraces each filled with a variety of greenery. The floor joists are cold-formed steel C-sections, 10-inch deep x 2-inch wide flanges x 54 mil thickness spaced at 16 inches on center. The joists were fastened into pre-punched tabs on ClarkDietrich Building System’s “Trade-ready” rim track (Figure 3), which facilitated maintaining the 16-inch center-to-center joist spacing. The rim track was also used in many locations to eliminate the need for load bearing headers. The rim track was fastened to the wall stud flange with either screws or welds. The floor framing supported a 0.6 C-deck with Levelrock gypsum concrete fill cover which served as the horizontal diaphragm to transfer lateral loads to the concrete cores. The wall framing, 6-inch deep C-sections with thicknesses from 97 to 43 mil having either 15/8-inch or 2-inch wide flanges, were used at interior locations; at the exterior wall locations the 6-inch deep

C-section thicknesses varied from 68 to 43 mils. The wall stud bridging was strap and blocking or channel with clip angle. To expedite the construction process, the walls were prefabricated on site. To ensure proper seating of the stud into the track, the stud panels were compressed to achieve tight seating of the wall stud. Typically, fabrication was done with welding because screw fastening of the thicker steel members proved too difficult. Development of a load path proved to be a design challenge. First, for vertical wall loads, the floor deck did not have sufficient web crippling strength; thus, deck crushing at the inter-story load transfer was a design concern. To resolve the inter-story load path, a steel-to-steel stud connection was used. However, this steel-to-steel connection resulted in a discontinuity for the diaphragm. The diaphragms had to be broken and additional perimeter fasteners used to ensure diaphragm continuity. Also, angles as drag struts were required at some locations to accomplish the diaphragm load path. Second, the marriage of the two systems, the concrete towers and the cold-formed steel framing, was necessary. Floor diaphragm forces were provided for inclusion in the design of the towers. The School Sisters of Notre Dame would be proud. The little hill in Milwaukee where they had built their home remains verdant and filled with life. The owner, too, is proud of the green contribution Convent Hill makes to Milwaukee’s Park East corridor (Figure 4).▪ John Matsen, P.E., is a Principal in the firm of Matsen Ford Design Associates. He also participates in multiple committees of the American Iron & Steel Institute’s Committee on Framing Standards. John may be contacted at john@matsenford.com.

Project Team Structural Engineers: Norris & Associates Cold-Formed Steel EOR: Matsen Ford Design Associates Developer: Housing Authority of the City of Milwaukee Architect: Zimmerman Architectural Studios General Contractor: Gilbane Building Company Cold-Formed Framing Contractor: Worthington Building Systems

Figure 5. Exterior cold-formed steel framing the primary load-bearing system for the top eight floors.

STRUCTURE magazine

November 2014

NGL Fractionation Plant on the Fast Track

Off-Site Assembly Reduces Schedule, Enhances Safety, and Cuts Costs By Mark Warnecke, P.E. Figure 6: Completed module erection overview.

omestic gas fields are rejuvenated using technologies such as hydraulic fracturing and horizontal drilling, which can substantially increase the supply of natural gas. Many formations also contain heavier hydrocarbons such as ethane, propane, butane, and gasoline. These natural gas liquids (NGL) have a higher market value when separated from the natural gas stream and segregated into their individual components in a fractionation facility. Burns & McDonnell performed an Engineer, Procure, Construct contract for a new NGL Fractionation Plant for ONEOK Hydrocarbon, L.P. located in Mont Belvieu, TX. An aggressive schedule and rigorous safety plans encouraged off-site assembly of process unit components. Pipe racks were selected for modular construction, with completed modules shipped to the site and set directly from the truck. Assembly of modules in a controlled yard environment significantly enhanced safety by allowing work closer to grade in a less congested area.

Module summary.

Module Summary Module size selection is largely dependent upon the shipping method and overall crane lift weight. Although the project location is close to port facilities, the last 30 miles is an overland route. Modules transported overland must balance road/bridge height and weight restrictions, road width limitations, and associated permit processes against the largest assembly that can be safely lifted at the site. A detailed transportation study, coupled with an on-site crane lift study, is an effective tool to summarize the module size opportunities and limitations. In this case, the project team decided that two practical module outto-out dimensions were 16 x 61 feet and 20 x 61 feet. Module height was constrained by bridge clearance. The lowest beam of the pipe rack module rests upon the transport trailer, which is typically about three feet above the road. Module heights up to 15 feet from bottom of column overhanging the trailer to top of highest object are shippable. Module design for the NGL project was a three-tier system. “A” and “C” modules have two levels of piping and/or cable tray, while “B” modules have a single level of piping. “D” modules are relief valve access platforms, with the majority of the piping and valves installed in the shop. The Table on this page summarizes the NGL project modules. In addition to the customary design plans, elevations, and connection details, module design analysis and drawings include lifting requirements, transportation arrangements, overall weights, and center-of-gravity information. STRUCTURE magazine

Number of Modules

Steel (tons)

Pipe Rack 100 (Modules 101 A/B/C to 108 A/B/C)

165

Pipe Rack 200 (Modules 201 A/B/C to 206 A/B/C/D)

120

Pipe Rack 300 (Modules 303 A/B/C to 309 A/B/C )

160

Pipe Rack 400 (Modules 401 A/B/C to 403 A/B/C & 402D)

Pipe Rack 500 (Modules 501 A/B to 504 A/B)

Pipe Rack 1100 (Modules 1102 to 1104)

Pipe Rack 1200 (Modules 1201 to 1204)

Pipe Rack 1300 (Modules 1301 to 1303)

TOTALS

675

Modules

Connections Modular construction’s effectiveness is related to the system of connections and whether they are made in the fabrication shop, module assembly shop, or field. In general, bolted connections are lower-cost than welded connections, with all costs increasing in the field. A mix of welded and bolted connections is typically selected for module assembly yard connections. Moment connections in the transverse and longitudinal directions are designed with full-penetration bevel welds at the transverse moment frames (Figure 1) to obtain the required strength without the need for bolted extended end plate connections. Bolts associated with such connections at the lowest beam would interfere with the field assembly of module-to-module connections. Bolted connections also require larger shop fireproofing blockouts, increasing fireproofing’s total installed cost.

November 2014

Figure 1. Transverse direction moment frame connection.

Figure 2. Longitudinal direction weak-axis moment frame connection.

Longitudinal weak-axis moment connections with extended stiffener plates (Figure 2) at interior columns eliminate the requirement for temporary bracing to resist lifting and transportation loads, as well as the final pipe rack thermal loads. Pipe turnouts may be placed anywhere along the module, thus minimizing pipe runs to the process equipment. Careful attention to detailing and fabrication is required. Consideration should be given to oversizing the gap between extended stiffener plates to beam depth plus 1/8-inch, then installing shim plates to facilitate module shop fit-up and allow for fabrication tolerance. Simple shear connections at module exterior column lines create “clean” columns with no stiffener plates when setting the adjacent module; however, high axial loads in the stringers require clip angle connections. The solution is installing an angle beam seat in the web of the exterior column. The beam seat is sized for transportation and lifting loads and assembled at the module shop. Clip angles with through-bolted connections to the adjacent module are installed in the field prior to release from the crane. A “temporary” bent (green steel in Figure 3) is provided for module assembly, transport, and erection. Temporary connections are bolted for easy removal after module-to-module pipe welding is complete (Figure 4). Plates attached to the tops of all columns facilitate attachment of reusable lifting lugs. Bolts are replaced per the American institute of Steel construction’s (AISC) guidelines, but the lifting lugs may be reused many times with visual inspection of welds between lifts, reducing module costs.

Figure 3. Typical module stack-up model.

Fabrication & Assembly Schedule flexibility is important to manage design of various pipe racks with input dependencies from multiple sources. The NGL project opted to purchase the steel directly from a fabricator and ship it to a protective coatings subcontractor, then on to the module assembly subcontractor’s yard. Protective coatings include a requirement for fireproofing meeting a UL-1709 two-hour rating for all steel within 30 feet of grade. The NGL project team selected a combination of intumescent fireproofing for the A modules and supporting columns, and an epoxy/urethane paint system. Primer and finish coats are the same for fireproofed and non-fireproofed steel, with only the tie-coat varying to simplify module yard and field touch-up.

Steel piece mark identification issues had to be overcome. Application of protective coatings requires removal of shop-applied tags. Initially, a metal tie wire and paper tag system replaced the steel shop tag during protective coating. However, paper tags did not perform well during transport or handling at the module assembly shop. The solution was to apply a steel stamp in a location that would be visible after painting and shop fireproofing, such as the edge of splice plates or top of beams. This eliminated lost tag issues and provided piece orientation for the erection crews independent of the erection drawings. continued on next page

Figure 4. Module-to-module connection.

STRUCTURE magazine

November 2014

The protective coatings subcontractor’s yard is the staging point to align the steel fabrication, protective coating and module assembly schedules. Use of a lump-sum protective coatings subcontract for shop, module yard, and job site coating provides incentive to maximize shop work at the bid stage and create value for the client. Modular construction imposes lift and transportation forces from frame twist, bending and bearing on the transport trailer. Intumescent fireproofing was selected for several advantages, including: • Strength/durability during handling and erection, • Long-term reliability, • Maximizing shop-applied material, • Steel assembly estimated as 25% more efficient by the erection team, • Competitive total installed cost. Protective coatings are shop-applied to the maximum extent possible prior to shipping to the module assembly yard. Module assembly includes welding of bents at the column rows at grade, and assembly into modules via stringer beams bolted into the weak-axis moment connections at the interior beams and the beam seats at the exterior columns. Piping is installed and connections other than module-tomodule are patched prior to shipping to the job site.

Lifting, Transport and On-Site Erection Modules are checked for loads created by lifting and transportation operations. Engineers must analyze and design transportation and lift plans for each module, applying factors to gravity loads in all three directions to model potential acceleration, rapid braking, and impact forces. One source for guidance is Cargo Securement Rules: USDOT Federal Motor Carrier Administration (2004). A rigging analysis is performed to calculate the assembled module center of gravity. Transport and lifting studies depend upon accurate pipe, valve and fireproofing weights and centers of gravity. Three-dimensional modeling tools provide the inputs. “Stick-built” columns, associated stringers, and vertical bracing that support the modules are erected along the entire length of a given pipe rack. Transverse bracing of the stick-built columns is omitted, since the moment frame is created as soon as the first module is bolted in place. Minor transverse lateral loads imposed by erection operations for the A modules are transferred to the foundation with the inherent moment resistance from the four-bolt base plate configuration. Modules are set from bottom to top. Incoming modules “rest” on the stringers below at the previous module end, and on a column splice plate atop the stick-built column or module post at the open end (Figure 5). Up to three modules per day were set at peak production, while targeting eight modules per week. Quality fabrication and maintaining assembly tolerances of plus or minus 1/8-inch any direction ensured flawless erection. Additional stick-built steel for access platforms, ladders, and pipe supports was field-erected using traditional methods to complete the pipe racks. See Figure 6 (page 40) for an overview of the plant with modular pipe racks erected.

Figure 5. Erection of typical module.

as much off-site assembly of components as possible. Pipe rack modules with proven functional connection design features and protective coating systems, along with a highly effective subcontracting strategy, made it possible to deliver and set 92 modules, relocating approximately 2,100 linear feet of pipe rack assembly off-site. Careful module fabrication, assembly, and erection resulted in a flawless safety performance and shaved two months from the project duration.▪

Schedule, Cost, and Safety Benefits Modular construction is favored by industry for its schedule advantages, inherently safer process, and reduced total installed cost. The Burns & McDonnell ONEOK project team was challenged to deliver an NGL Fractionation plant in an aggressive time frame while maintaining the highest standards of quality and safety, encouraging STRUCTURE magazine

Mark Warnecke, P.E. (mwarnecke@burnsmcd.com), is an Associate Structural Engineer in the Process & Industrial Group at Burns & McDonnell. He serves as the Lead Structural Engineer for the ONEOK Mont Belvieu program.

Project Team Engineer of Record: Burns & McDonnell, Kansas City, MO Steel Fabricator: Markle Manufacturing Co. Inc., San Antonio, TX Protective Coatings Subcontractor: PK Industrial, Augusta, KS and Houston, TX Protective Coatings Materials: International Paint Module Pipe Fabrication: Turner Industries Group, L.L.C, Baton Rouge, LA Module Assembly: Turner Industries Group, L.L.C, Port Allen, LA and Corpus Christi, TX Module Erection: Turner Industries Group, L.L.C, Baton Rouge, LA

November 2014

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s practitioners in structural design, we sometimes scratch our heads in bewilderment with new code provisions. Usually, with a little homework, we can understand the logic behind the changes and see how they lead to better performance of the end product. Unfortunately, beneficiaries of our efforts sometimes see that end product and jump to the “engineers gone wild” conclusion, accusing us of grossly overdesigning the structure when we have simply provided one that meets code. A good example of this can be found in the ANSI/AISC 341-10 Seismic Provisions for Structural Steel Buildings, Sections F1.4a and F2.3. Among other criteria, they require beams intersected by braces to be designed for the expected strength of the braces in tension, counteracted by only 30% of the expected strength in compression of the adjoining braces. In other words, a beam intersected by the braces in a conventional “V” or chevron configuration must be designed for an enormous vertical seismic load at its midpoint. The result is a beam that at first glance seems too large to reflect a pragmatic design. Where past code provisions might have allowed a W24x76, it is now not uncommon to see a W33x241 or even larger. What is really happening in this scenario? Fundamentally, the logic does make sense. Simple nonlinear modeling serves to illustrate the concept and the benefit of this code provision. Consider Figure 1. Other than the obvious geometrical differences between Frames 1 and 3, one might conclude that they are essentially equivalent. Indeed, their weights are equal, and modal analysis calculates the exact same periods and mode shapes. These frames will thus behave the same in an earthquake, right? The answer is a qualified ‘Yes’ if no braces buckle in compression, and a definitive ‘No’ if any braces do buckle; and in contemporary seismic design, brace buckling may be characterized as

How Big is that Beam? The ‘X’ Brace vs. ‘V’ Brace Conundrum By Jerod G. Johnson, Ph.D., S.E.

Jerod G. Johnson, Ph.D., S.E. (jjohnson@reaveley.com), is a principal with Reaveley Engineers + Associates in Salt Lake City, Utah.

Unfortunately, beneficiaries of our efforts sometimes … accuse us of grossly overdesigning the structure when we have simply provided one that meets code. a forgone conclusion. In fact, many detailing provisions in ANSI/AISC 341-10 require that frames be configured to allow and even encourage a specific mode of buckling. What then is the primary difference between Frames 1 and 3? Frame 3 is geometrically configured with four braces, rather than two braces intersecting the beam. As such, the braces themselves provide most of the counteracting resistance required by the aforementioned sections of ANSI/AISC 341-10, and the beam size is not significantly affected. A simple pushover analysis demonstrates this concept. Frame 2, also shown in Figure 1, is geometrically equal to Frame 1, but with beam sizes increased to address the unbalanced load requirement of ANSI/AISC 341-10. Figure 2 depicts pushover curves for the three frames that have been analyzed and subjected to equivalent procedures of piecewise monotonic displacement while measuring the base shear and accounting for compression buckling, tension yielding, and beam bending in the frames. For this scenario, the only difference between Frames 1 and 3 is the geometry, yet a marked difference is evident in the nonlinear performance. Both behave elastically up to about 0.75 inches of rooftop displacement, at which point the first braces buckle at the lower level. From this point forward, the behavior diverges significantly. For Frame 1, the beam (W24x76) is subjected to an unbalanced force for which it does not

44 November 2014

have adequate strength and stiffness. As a result, the frame does not regain its strength as shown with increased displacements on the pushover diagram. Frame 3, on the other hand, has braces at the upper level configured to counteract the unbalanced forces from braces at the lower level. It has the ability to regain capacity, as measured by the base shear, roughly equal to the force at which the first brace buckled. This frame can be displaced even farther, through buckling of other braces, until reaching the point where tensile rupture of braces occurs and base shear measurements suddenly diminish. Frame 2 of Figure 1 depicts beam sizes that might be utilized to maintain the chevron configuration, yet satisfy the seismic design provisions. These very large, very heavy beams have a flexural stiffness commensurate with the counteracting braces. As such, they can readily handle the unbalanced forces and develop a pushover curve as shown in Figure 2, capable of regaining capacity after initial buckling of braces as demonstrated by the base shear measurements. In summary, Frame 1 is ill-equipped for significant nonlinear behavior as demonstrated in Figure 2. Frames 2 and 3 are better equipped for nonlinear behavior,

Figure 2.

but the weight of Frame 2 is nearly double that of Frame 3, and Frame 2 must accommodate very deep beams with flanges in excess of 15 inches wide. Clearly, the ‘X’ configuration is the best approach using conventional framing members. Alternative approaches for potentially mitigating these pitfalls include “zipper columns,” which distribute the unbalanced

forces across multiple levels of beams and bracing, and advanced technologies such as buckling restrained braces.▪ A similar article was published in the Structural Engineers Association-Utah (SEAU) Monthly Newsletter (November, 2011). Content is reprinted with permission.

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InSIghtS new trends, new techniques and current industry issues

oated reinforcing steel is widely used to provide corrosion protection to reinforced concrete against the effects of deicing and marine salts and carbonation. In North America, approximately 10 percent of all reinforcing is coated. Coated reinforcing steel utilizes the existing reinforcing bar stock and is available in sizes from 0.375 to 2.25 inches and in strengths from 40 to 80 ksi. Due to the relatively low cost of coating technologies, distributed manufacturing is possible. Over 35 epoxy coating facilities are currently certified by the Concrete Reinforcing Steel Institute (CRSI) and many galvanizing plants are available.

Types of Products ASTM recognizes the following types of coated bars, wire and welded-wire reinforcement: • Epoxy-coated (ASTM A775, A884, A934) • Galvanized (ASTM A767) • Dual-coated (ASTM A1055) • Vinyl-coated (ASTM A933) Epoxy-coated reinforcing steel is the most widely used coated bar in North America. It is manufactured by passing cleaned and heated steel through a cloud of epoxy powder. This powder is drawn to the bar surface by electrostatic forces where it fuses, forming a continuous coating layer. Most manufacturing plants in North America are certified by CRSI, which randomly inspects manufacturing facilities to ensure that they have processes, staff and equipment to produce high quality materials. ASTM standards have developed during the past 40 years by including thicker coatings and appropriate surface cleanliness and roughness properties. Vinyl-coated bars are coated in a similar manner to that of epoxy-coated bars, except that the coating material consists of a vinyl polymer. However, these bars have not found significant commercial utilization. Dual-coated bars are manufactured by spraying prepared reinforcing steel with a zinc alloy, then coating the bars with an epoxy, in a similar manner to that of epoxy-coated reinforcing steel. Several agencies have chosen to use these bars in standard specifications, including Florida and Vermont. Demonstration projects are also being conducted in many states. Galvanized reinforcing steel is manufactured by placing properly prepared reinforcing bars into molten zinc. The finished product consists of various zinc-iron and zinc layers. Several plants outside North America use a process that applies zinc alloy coatings to reinforcing steel in a continuous process, and an ASTM specification for this process is under development.

Current Status of Coated Reinforcing Steel By David McDonald, Ph.D., P.E., FACI

David McDonald, Ph.D., P.E., FACI, is the Managing Director of the Epoxy Interest Group of Concrete Reinforcing Steel Institute. David has been active in technical committees including ACI, NACE, ASTM and PCI. David can be reached at dmcdonald@epoxy.crsi.org.

Stainless steel clad reinforcing bars have been utilized in concrete structures, but these are not currently commercially available. Laboratory work has also been conducted on ceramic-coated reinforcing bars, but as of yet have not been utilized in concrete structures. CRSI recently produced a Specialty and Corrosion-Resistant Product Guide, which is a useful reference for available reinforcing products.

Research Significant research has been conducted on the effectiveness of coated reinforcing steel. It is recognized that a weakness of coated reinforcing steel is damage to the coating. Generally, research on these products has been conducted using bars that are damaged prior to placement in concrete. In comparing the two leading types of coating, laboratory research has found that epoxy-coated reinforcing steel performs better than galvanized reinforcing bars when subjected to deicing salts. Notwithstanding, both types of coated bars perform better than uncoated reinforcing steel. Field studies in Bermuda found good performance of galvanized steel (Kinstler, 1999); however, mixed conclusions were reached in Iowa when it was compared with epoxycoated reinforcing steel (Kraus, et al., 2014). This may be largely due to the effects of steel and concrete chemistry on the formation of passivating layers in these materials. The continuously processed galvanizing product has not been extensively used, and it is too early to determine how this product performs compared with other products. Field and laboratory research on A1055 dualcoated bars is limited, but preliminary data shows improved performance compared with other products (Accardi, 2010) due to protection provided by the zinc to the underlying steel at coating damage locations. Several agencies, including Florida and Vermont Departments of Transportation permit use of the dual-coated bars under certain circumstances and many other agencies have demonstration projects using this product. In the 1980s, concerns were raised regarding the performance of epoxy-coated steel in Florida; however, these performance concerns were isolated to certain structures where poor concrete and poorly applied reinforcing bar coatings were used (Sagüés, et al., 2009). The studies also found that the observed corrosion distress was isolated to less than 10 bridges out of the 300 bridges in Florida containing epoxy-coated reinforcing in their substructures. The majority of these structures are predicted to have a 100-year design life. The observations of distress in Florida in the 1980s prompted review of coated materials by

46 November 2014

other agencies. Recent reports from New York, Michigan and Nebraska DOTs on the performance of epoxy-coated reinforcing steel all indicate substantial long-term benefits (Agrawal, 2006; Boatman, 2010; Hatami, 2012). For example, statistical analyses by Boatman on almost 1800 Michigan bridges estimated the life of bridges using uncoated bars would be 35 years compared with 70+ years for decks containing epoxycoated reinforcing. Bond of coated reinforcing in concrete is as important as the type of coating material, and this has been extensively researched. The governing conclusion is organic coatings do not adhere to concrete as well as metallic coatings. Most design codes provide for increased development length for organic-coated reinforcing steel including epoxy-coated, dual-coated, and vinyl-coated bars.

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Future research on organic coatings will focus on increased toughness, surface adhesion to steel and flexibility. These systems are largely based upon epoxy materials that are currently available to the steel pipeline industry and include use of multiple coats of epoxy materials that have different flexibility and abrasion properties. The ongoing research of metallic coatings will expand to various types of passive materials and ceramic coatings, for their durability and low cost of the raw materials. Future research on coated bars will also focus on the long-term field performance of these products, as it is difficult to determine product life from shortterm laboratory tests. Several studies have been conducted using state bridge inventory data and statistical methods, such as Markov Analysis, to determine the life of coated reinforcing compared with that of uncoated bars. Other studies are being conducted as part of the current FHWA Long Term Bridge Project, which includes extensive evaluation of decks around the country. Additional data is also being collected as bridges age. This is particularly true for epoxy-coated reinforcing bars as the oldest bridges containing epoxy-coated bars are only 40 years of age and very few have deteriorated in that time.▪ The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

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STRUCTURE magazine

November 2014

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Carbon Fiber System

Future Directions

Guest Column dedicated to the dissemination of information from other organizations

ounded in 1969, the National Institute of Steel Detailing or NISD is an organization which fosters a professional approach to doing business as a steel detailer in the construction industry. The mission of the group is to create a better understanding of the importance of steel detailing services, by advocating improved quality, education and certification.

Certification Many steel detailers are self-taught beyond the limited offerings of trade schools. Some are mentored by more experienced self-taught steel detailers, creating drawings according to steel fabricator preferences. As such, they do not have full knowledge of standard detailing practices or business practices which work to support other related industry professionals. This is a common history for steel detailers and has been the reason for lack of consistency with drawing editing, presentation and business practice. Industry professionals are in search of talented detailers who have the knowledge and capability to produce quality shop detail drawings within the framework of various codes, specifications and contract documents. The NISD created the Individual Detailer Certification Program or IDC in response to the industry’s need to determine the skill level of individuals performing steel detailing services. The IDC program offers worldwide certification in two disciplines: Bridge and Structural/Miscellaneous. The IDC program examines and evaluates an individual’s detailing knowledge and issues a certificate attesting to that level of knowledge. Currently, the NISD is working to establish an industry-wide professional standard of practice in conjunction with the Quality Procedures Certification Program for Companies. Individuals applying for certification must meet the following requirements:

Overview of the National Institute of Steel Detailing By Kerri Olsen

Kerri Olsen is the Marketing Chair of the NISD. She may be contacted at kerriolsen@steeladvice.com. The NISD may be contacted at www.nisd.org.

Senior Detailer (Class 1)

completed a formal training program. These applicants are required to submit detailed experience history and a letter of recommendation with their application. The letter of recommendation may be from a steel fabricator, an IDC Certified Senior Detailer, or an NISD National Director. Individuals may apply to take both the Bridge and the Structural/Miscellaneous test; however, separate applications must be submitted for each discipline. The open-book examination period can take as long as eight hours and is comprised of true/false and multiple choice questions, together with workout calculations. It is a test of ability, with the knowledge base supported by the current American Institute of Steel Construction (AISC) Steel Construction Manual and the Detailing for Construction Manual. The questions and problems are the type which steel detailers encounter in everyday work experience.

Quality Procedures Program The NISD Quality Procedures Program certifies that recognized quality assurance procedures are established so the end result will be quality detailing services available to the steel construction industry. This program provides a method to ensure uniform levels of procedures for detailing firms through a nationwide system for defining and recognizing quality assurance procedures, and a firm’s commitment to quality. Evaluation and on-site inspections are conducted by a registered professional engineer approved by the committee. The program consists of an initial audit, with triennial audits thereafter. The intervening years require a written self-audit based on the standard program checklist. Procedures Checklist (partial) • Are detail drawings checked by qualified personnel? • Are jobs field checked? • Are design changes and revisions to shop drawings reviewed by a responsible agent? • What is your procedure for clarification of design problems? Application • A listing of representative projects completed in the last 10 years • Letter of recommendation from two clients served in the past 12 months • Resumes and job description of all principals and full or part-time employees • Company policy statement • Organizational chart and processing procedures

This classification is for applicants who have a minimum of 10 years detailing experience in addition to some checking experience. These applicants are required to submit detailed experience history and a letter of recommendation with their application. The letter of recommendation may be from a steel fabricator, an IDC Certified Senior Detailer, or an NISD National Director. Detailer (Class II) This classification is for applicants who have a minimum of 5 years detailing experience, or who have 3 years detailing experience and have satisfactorily

Membership Currently, the National Institute of Steel Detailing is a world-wide organization,

48 November 2014

offering several categories for membership serving the individual steel detailer, detailing firms or corporations, associate and Member Emeritus memberships for businesses and individuals outside of the steel detailer’s umbrella.

The NISD Industry Standard Derived from the consensus understanding of the steel detailing industry, the NISD Industry Standard is a document which exists to improve understanding and communication between members of the detailing community and construction industry as a whole. This document works to: • Provide background and history of the steel detailing industry and the National Institute of Steel Detailing • Identify and define the role of the steel detailing firm in the construction project • Present the business, technical and professional values and practices of the detailing industry • Provide an authoritative reference by defining terms, concepts and principles which have been adopted by the detailing industry

• Outline the rights and responsibilities of the steel detailing firm with respect to the client and the construction team • Provide model documents and illustrations useful in establishing business and technical practices This information resource defines the steel detailing industry’s practices and procedures, and is an essential addition to reference libraries for steel construction managers, contractors, architects, structural engineers, as well as steel detailing firms. In addition to the Industry Standards, the NISD also provides guidelines for successful presentation of steel design documents. This document is intended to support the AISC Code of Standard Practice for Steel Buildings and Bridges, which sets forth the minimum requirements for completeness in contract drawings. These guidelines are intended to impress upon all team members the importance and value of adhering to the AISC code.

The NISD Difference The exciting part for any steel fabricator and design team is to realize the benefits of utilizing steel detailers certified to NISD standards.

The steel fabricator and design team’s work and worry is cut to a minimum as an otherwise problematic process is transformed into a workable project. Adequate shop detail drawings minimize the approval processing time for designers. With the use of NISD certified detailers, reviewers may expect to see the following advantages, to name a few: • Due diligence to the RFI process • Approval submittal drawings which have been checked and are fabrication ready • Shop detail and erection drawings which provide all the necessary information • Efficient and industry-correct part and piece marking system • Efficient and industry-correct revision history maintenance and reference Since its founding in 1969, the NISD has been the only voice to speak on behalf of the steel detailing community. We continually work to maintain a high level of professional ethics and standards. NISD has a close working relationship with AISC and the Steel Erectors Association of America (SEAA), and endeavors to improve the steel detailing industry and its relationships with engineers, erectors and fabricators.▪

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discussion of legal issues of interest to structural engineers

LegaL PersPectives

ADA Requirements for Historic Properties By Gail S. Kelley, P.E., Esq.

n enacting the Americans with Disabilities Act of 1990 (ADA), Congress found that individuals with disabilities continually encountered discrimination in the form of architectural barriers. To address this discrimination in privately-owned facilities, Title III of the ADA mandated that all commercial facilities and places of public accommodation constructed after January 26, 1993, be “readily accessible to and usable by” individuals with disabilities. The Department of Justice (DOJ) was charged with writing regulations to implement the ADA requirements with respect to construction. Under the DOJ regulations for Title III, codified in the Code of Federal Regulations (CFR) at 28 CFR Part 36, new construction and additions must comply with the ADA Standards for Accessible Design. The current standards are the 2010 Standards and consist of the DOJ regulations and the 2004 Americans with Disabilities Act Guidelines (ADAAG). The ADAAG is published by the United States Access Board, a federal agency that promotes equality for people with disabilities through the development of accessibility guidelines. As defined in the DOJ regulations, a place of public accommodation is a privatelyowned facility that offers goods or services to the public. This includes hotels, restaurants, bars, theaters, concert halls, museums and libraries. Commercial facilities are other nonresidential facilities such as office buildings, factories, and warehouses whose operations affect commerce. Any alteration affecting the usability of an existing place of public accommodation or commercial facility must comply with the ADA Standards to the maximum extent possible. In addition, public accommodations in existing buildings must remove architectural barriers and communication barriers that are structural in nature, when it is readily achievable to do so. Readily achievable is defined as easily accomplished and able to be carried out without much difficulty or expense. Barrier removal is required for all public accommodations, even if no alterations are being done to the building.

Questions sometime arise as to whether alterations to historic properties are required to comply with the ADA, and if so, to what extent. The short answer is: yes, alterations to historic properties must comply with the ADA, but there are exceptions when compliance would threaten or destroy the historic significance of a feature of the building.

ADA Requirements for Alterations Under the DOJ regulations, alterations must comply with the ADA Standards unless it is technically infeasible to do so. Technical infeasibility is a fairly high bar. Something is technically infeasible only if it would require removing or altering a load-bearing member that is an essential part of the structural frame, or because other physical constraints prevent modification or addition of features to comply with the ADAAG requirements. The fact that compliance would be extremely expensive does not mean it is technically infeasible. However, the ADAAG includes certain exceptions for alterations. For example, in new construction, ramps on accessible routes cannot have a slope steeper than 1:12. In existing buildings, ramps can have a slope of 1:10 when the rise is not more than 6 inches and 1:8 when the rise is not more than 3 inches, if such slopes are necessary due to space limitations. (ADAAG §405.2). Path of Travel When an alteration affects a primary function area, the alteration must provide an accessible path of travel from the altered area to the entrance and to the bathrooms, telephones, and drinking fountains serving the area, if it is technically feasible to do so. A primary function area is defined as any area where a major activity for which the building is intended takes place. This includes both the customer services areas and work areas in places of public accommodation, and all offices and work areas in commercial facilities. Alterations to provide an accessible path of travel are only required to the extent that the costs do not exceed 20

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November 2014

percent of the cost of the original alteration. (28 CFR 36.403(f )).

ADA Exceptions for Historic Properties Many buildings in the United States have details of architectural significance, or have historic significance because of events that took place in the building. In the context of the ADA, historic properties are those that are either listed or are eligible for listing in the National Register of Historic Places, or are designated as historic under state or local law. Although all alterations must comply with the ADAAG to the maximum extent feasible, §202.5 of the ADAAG allows additional exceptions for historic properties. There are exceptions for accessible routes (ADAAG §206.2.1 Exception 1 and §206.2.3 Exception 7); entrances (ADAAG §206.4 Exception 2); and toilet facilities (ADAAG §213.2 Exception 2). If an entity believes that following the usual standards would threaten or destroy the historic significance of a feature of the building, the entity should consult with the State Historic Preservation Officer (SHPO). Use of an exception will be allowed only if the SHPO agrees that compliance with the usual standards would threaten or destroy the historic significance of a feature. Accessible Route Exceptions Per the ADAAG, accessible routes are limited to walking surfaces with a running slope not steeper than 1:20, doorways, ramps, curb ramps excluding the flared sides, elevators, and platform lifts. The ADAAG requires that there be an accessible route from the accessible parking spaces, the public streets or sidewalks, and the public transportation stops. Under ADAAG §206.2.1 Exception 1, only one accessible route from a site arrival point to an accessible entrance is required for a historic property. The ADAAG requires that all stories and mezzanines be connected by an accessible route. However, under §206.2.3 Exception 7, historic properties are only required to have an accessible route on the level of the accessible entrance. continued on next page

An A/E involved in alterations to a historic property must be aware of both the ADA requirements and the exceptions allowed by the ADAAG. Entrances Exception The accessible entrance to a historic property does not have to be the entrance used by the public. The entrance can be an unlocked entrance that is not used by the public or a locked entrance with a notification system or remote monitoring. Toilet Facilities Exception Under ADAAG §213.2 Exception 2, only one accessible toilet facility is required for a historic property and it can be unisex. Alternative Methods to Provide Access In the rare case that complying with even the additional exceptions will threaten the historic significance of the building, alternative methods to provide access can be used. The alternative methods are those used to provide access when barrier removal is not readily achievable. As an illustration, if a historic house is being altered to be used as a museum, widening the door to one of the rooms in accordance with ADAAG requirements would destroy historic features of the door frame. Instead of widening the door, the museum could create a video of the items in the room and show the video in a nearby room that is accessible.

Barrier Removal

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The DOJ regulations (28 CFR §36.304) require public accommodations in existing buildings, including qualified historic properties, to remove architectural barriers and communication barriers that are structural in nature when doing so is readily achievable.

However, the ADA takes the national interest in preserving significant historic structures into account. Installation of a platform lift in a historic facility that has been preserved because of its unique architecture would not be required if it would destroy architecturally significant elements of the building. In contrast, installation of a lift in a building that has historic significance only because of events that occurred in the building may be readily achievable if it does not destroy the historic significance of the building and the cost is reasonable. Whether the cost of barrier removal is reasonable depends on the nature and cost of the action, its impact on the operation of the business, and the overall size and financial resources of the facility, its owners and affiliates.

Publicly-Owned Historic Properties Title III of the ADA only applies to privately-owned facilities; facilities owned by state and local governments are covered under Title II of the ADA. Title II does not directly address construction, but access to buildings is covered under a broad mandate that prohibits a public entity from denying a disabled individual the benefits of the entity’s services, programs, or activities. The DOJ regulations for buildings owed by state and local government, codified at 28 CFR 35 Subpart D (28 CFR §35.149 -§35.151), are the same as those for privately-owned buildings – new construction and alterations must comply with the 2004 ADAAG and barriers must be removed when it is readily achievable to do so. The standards are somewhat higher for public entities, however; under 28 CFR §35.150(b)(3), public entities are required to give priority to methods that provide physical access to individuals with disabilities. Properties owned or leased by the federal government are not covered by the ADA. Instead, they are covered by the Architectural Barriers Act of 1968 (ABA) and by Sections

501 and 504 of the Rehabilitation Act of 1973. The ABA stipulates that all buildings designed, constructed, and altered by the federal government, or with federal assistance, must be accessible. The Guidelines for the ABA (ABAAG) are slightly different from the ADAAG, but the same exceptions are allowed for historic properties. The Rehabilitation Act requires recipients of federal financial assistance to make their programs and activities accessible to everyone. Recipients can make their programs and activities accessible by altering their building, moving their programs and activities to accessible spaces, or making other accommodations.

Conclusion An A/E involved in alterations to a historic property must be aware of both the ADA requirements and the exceptions allowed by the ADAAG. Although various federal and state preservation agencies have developed guides to making historic buildings accessible, many of these guides are based on the original (1991) ADAAG, which can be confusing. There are some differences between the exceptions allowed under the 2004 ADAAG (used by the 2010 Standards) and the exceptions allowed under the 1991 ADAAG. In addition, the section numbers are different; whereas the exceptions for historic properties are listed in §202.5 of the 2004 ADAAG, they were listed in §4.1.7 of the 1991 ADAAG. The 2010 ADA Standards are available on the United States Access Board website: www. access-board.gov/guidelines-and-standards/ buildings-and-sites/about-the-ada-standards/ ada-standards. The Access Board website also contains other useful ADA references, including a guide to the standards.▪ Gail S. Kelley, P.E., Esq., is a LEED Accredited Professional as well as a licensed attorney in Maryland and the District of Columbia. She is the author of Construction Law: An Introduction for Engineers, Architect, and Contractors, published in 2012 by John Wiley & Sons. Ms. Kelley can be reached at Gail.Kelley.Esq@gmail.com.

Disclaimer: The information and statements contained in this article are for information purposes only and are not legal or other professional advice. Readers should not act or refrain from acting based on this article without seeking appropriate legal or other professional advice as to their particular circumstances. This article contains general information and may not reflect current legal developments, verdicts or settlements; it does not create an attorney-client relationship.

STRUCTURE magazine

November 2014

Professional issues

issues affecting the structural engineering profession

Challenges Facing Young Structural Engineers Why Are They Important and What Needs To Be Done? By Jessica Mandrick, P.E., LEED AP and Jason McCormick, Ph.D., with the SEI Young Professionals Committee

s current leaders in structural engineering approach the end of their careers, it is increasingly important that young professionals take active measures to step into leadership roles. Leadership transition plays a vital role in the profession, but always brings with it challenges that differ from those of past generations. This article highlights select challenges identified by the ASCE Structural Engineering Institute’s Young Professional’s Committee.

Challenges Facing Young Professionals in Practice Structural Engineering is a High Responsibility Profession Of paramount concern to structural engineers is the safety of the public. Many recent graduates feel nervous at their first jobs because of the high level of responsibility. Mistakes in practice can have high costs; meanwhile, clients expect quick responses. Each engineering firm should set standards on the internal technical review of projects. Also companies must strike a balance between the level of detail of work, including internal reviews, and the budget restrictions of a project. Training and mentorship are needed at all levels to encourage young professionals to develop quality work, gain confidence, and eventually step into management roles themselves. Codes and standards set minimum safeguards for the profession. However, as codes grow more complex, they become increasingly susceptible to misinterpretation and misapplication. This is evident in the range of solutions that SEI receives for its trial design problems each year. Young practitioners need to develop familiarity with dense volumes of codes without the advantage of having utilized the codes in their simpler earlier forms. Even though the ultimate responsibility for design falls on the practitioner, external reviews are helpful to verify that standards are properly followed. The extent of external review currently required varies regionally. As a comparison of the two largest cities in the country, Los Angeles requires that engineers submit drawings

and calculations to a building department and conducts a review of both items; New York City requires submission of drawings, but does not require calculations or peer review except for critical projects. Young practitioners in many jurisdictions have never received feedback from outside their offices. Although the susceptibility of the West Coast to earthquakes prompts its strict enforcement of structural codes, densely populated areas could also benefit from more thorough reviews. Action Items: • Develop a consistent standard of care within the industry. This may involve increasing the rigor of external project review by local building departments, publishing guidelines on how to internally review projects, and increasing the understandability of codes and standards. • Train young professionals how to lead. As a profession in which those who excel technically often ascend into management, firms should provide instruction on business and supervisory responsibilities through training sessions, recommended reading, or mentorship by firm leaders. Young professionals must similarly take leadership roles within project teams, guiding clients and architects towards cost saving and creative solutions. • Involve young professionals in professional committees. Codes and standards committees should actively seek out the involvement of young professionals. Young professionals would learn the origins of code provisions, meet critical industry leaders, and prepare themselves to lead future committees. • Licensure of structural engineers. In the interest of public safety, encourage states to license structural engineers as a distinct discipline with certain qualifications beyond those required for professional engineering licensure. Structural Engineering is Not Set Up to Accept Late Entrants A structural engineering education typically includes a required four year baccalaureate

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November 2014

with the strongly suggested addition of a master’s degree. Admissions requirements for master’s programs are largely based on coursework such as structural analysis, reinforced concrete, and steel design. Applicants with undergraduate degrees in related fields (physics, mathematics, computer science, etc.) are often required to take these classes with no credit towards their master’s degree, increasing their time commitment and debt. Similar professional degrees, including medical, legal, business, and architecture, offer more flexibility as they are accredited at the masters level and can be entered through a variety of undergraduate fields. Furthermore, those without undergraduate degrees in engineering, who later achieve a master’s degree in structural engineering, continue to face adversity professionally. Many state licensing boards base experience requirements on an ABET accredited bachelor of engineering degree. This basis is likely due to the dearth of ABET accredited master of civil engineering degrees. Although the penalty varies by state, those without the equivalent bachelor’s degree may require eight years of experience prior to licensure rather than the typical four years. This additional experience requirement further sets late entrants in structural engineering behind their peers. Engineers who were educated abroad face similar extended experience requirements. As younger generations seek non-traditional career paths, more flexibility in education and at the workplace is required to attract talent to structural engineering. Action Items: • Restructuring of engineering education. ASCE and the National Academy of Engineering are both exploring making the master’s degree in structural engineering a professional degree. Additionally, internship or co-op programs can expose students to the profession. • Post-Baccalaureate programs for structural engineering. Postbaccalaureate programs could provide the additional coursework necessary to confer a general engineering bachelor’s

November 2014

RCHITECTS LA

RINE ENG MA I

STRUCTURE magazine

There is a need for better collaboration between structural engineering professionals in practice and those in academia, as is often done in Europe and Japan. Collaboration between practitioners and academics can lead to quicker adoption of new technology and methods developed through research, as well as research motivated by the immediate needs of the structural engineering profession. These opportunities could take the form of industry funding as outlined above or more simply, the creation of conduits for the exchange of information. However, young structural engineering professionals in practice and academics often find it difficult to make these types of connections due to a focus on establishing their career, limited interaction with those on the other side, and lack of knowledge of where to look or who to talk to about developing such collaborations. Part of what inhibits collaboration is a lack of knowledge of the research being conducted and how it might benefit those in practice. While universities often subscribe to a variety of academic journals, structural engineering firms often do not. As students, academic publications provide a resource to help solve problems; however, these resources are not widely available to young professionals after graduation. Although articles are available online for a fee, it is difficult to know from the abstract whether the content will be useful to a practicing engineer, leading to potentially costly searches. Collaboration is one way to keep both parties informed of the state-of-the-art and the needs within structural engineering, setting a precedent for young professionals to follow. Action Items: • Provide a forum for those in academics and practice who have interest in

As more universities express interest in growing into top tier research institutions, there is increased demand for research resources that are not growing at the same pace. The National Science Foundation and Department of Defense provide funding for research in the area of structural engineering.

Fostering Collaboration between Practitioners and Academics

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Challenges Facing Young Professionals in Academia

However, funding from these agencies for structural engineering related projects tends to lag behind other more prominent fields. The goals of these projects are not necessarily focused on the direct current needs of the structural engineering profession, but on transformative topics that can have high impact in the future. Also, the increasing number of overall faculty seeking out funding from these agencies, which have seen only a limited increase in available funds, has made it difficult for both young and established faculty to obtain funding. Funding is also available from other agencies such as the Federal Highway Administration, State Departments of Transportation, American Institute of Steel Construction, and American Concrete Institute. These agencies fill a critical need and are a great resource for researchers, but they typically focus on a particular need relative to their mission. Available funds are often smaller than those from federal agencies. The need to obtain supplemental funds requires contacts that young faculty may not have and takes time away from other areas, such as publishing, necessary for tenure. One of the main problems within the structural engineering field is the lack of other sources for significant funding. In 2011, 5,400 civil engineering graduate students at doctorate-granting institutions were supported through institutional funds and 2,301 through Federal grant money. Meanwhile, only 1,078 students were funded through non-federal domestic or foreign support. As a result, the total amount of money for structural engineering research is limited and the lack of industry involvement limits the ability for research to have an immediate impact. Action Items: • Concerted effort from industry to fund research. Young professionals would benefit from more engagement of industry in structural engineering research. Funding is critical, but even in-kind professional support and donation of materials or services can result in significant future partnerships that can be beneficial to both parties. • Increased effort from industry to adopt new technology and methods. Faster adoption of new technologies and methods coming out of research will increase the impact of research and the public perception of the need for research in structural engineering. By increasing the impact of current research, it will provide incentive for increased funding from government and private agencies.

• THE ERS S NE

degree. Such programs are commonly used for pre-medicine studies, serving as a conduit both for those who take a late interest, and for educationally disadvantaged students (including underrepresented minorities) who enter college with insufficient math and science backgrounds to begin a science or engineering degree. Prospective hosts for such a program could be the universities that provide the latter portion of a 3-2 program. In 3-2 programs, students take three years of fundamental math and science at a liberal arts college and then two years of study in an engineering discipline at a research university. A similarly structured one to two year “post-bac” approach could be utilized for late entrants. • Pursuit of online master’s degrees for reentry into the profession. Graduates of civil engineering bachelor’s programs, who chose to pursue careers in other professions, could enroll in part-time online master’s programs to refresh and advance their engineering skills. Care must be taken that online degree programs are developed to incorporate all of the requirements, accreditation or otherwise, to meet the needs of the profession. • Reevaluate experience requirements for professional engineering licensure. State licensing boards should set similar experience requirements for graduates of structural engineering master’s programs as for their colleagues who possess undergraduate engineering degrees. This could be rectified through the accreditation of master’s programs or the acceptance of master’s degrees from schools with accredited undergraduate engineering programs. The accreditation of more colleges abroad, or reciprocity between foreign accreditation bodies and ABET, should also be pursued.

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collaboration. A location that provides information on the interests of those willing to collaborate across the academic-industry boundary is necessary, particularly for young professionals. The forum would provide a means of introduction to people across the profession. • Broader availability of academic journals to the engineering community at large. Many journals can be obtained for free from local libraries through interlibrary loan programs, but these often take time that may not be available. Journal publishers should want their publications to be available to the engineering community and should develop platforms for practitioners to explore journals without prohibitive costs. Papers could also be published in more colloquial forms highlighting the potential for future incorporation by industry. A model of converting research into practice is seen in the Applied Technology Council (ATC). • Professional interaction between academics and practitioners. Practitioners should be willing to seek out Academics when situations arise where their background and research capabilities will be helpful. Likewise, Academics should make a more concerted effort to reach out to practitioners to determine the research needs of the structural engineering profession. This research could be similar to wind tunnel studies conducted at universities or include the testing of engineering materials, assemblies, dampers, vibration studies, etc. • Better communication of current practice and the structural engineering industries’ needs. Practitioners should openly share technical presentations

and blog posts online to increase knowledge within the structural engineering community. Lack of Public Awareness/ Acknowledgment of the Structural Engineering Profession In order to attract the best and the brightest young professionals to the structural engineering profession, whether it is in practice or academia, a stronger effort is needed to make the public aware of the importance of the profession. Far too often, structural engineering makes headlines only when something catastrophic occurs, and far too little recognition is given to some of the greatest accomplishments of structural engineers in the public domain. Often the work of structural engineers is taken for granted or hidden behind an extravagant architect. A more concerted effort is needed to promote the extraordinary things that structural engineers accomplish on a daily basis. Bringing the structural engineering profession to the forefront of society in a positive light will help to attract the next generation of structural engineers, who will lead the profession in the future. The United States lacks political leaders in Congress with engineering backgrounds. There is a need for increased advocacy on national issues such as aging infrastructure and the work that structural engineers are doing to draw attention to and solve these problems. Young structural engineering professionals will be driving this profession forward and need to be mindful of the need for better public awareness. Action Items: • Take advantage of political interest at the undergraduate level. Extend ASCE’s annual Legislative Fly-In and government outreach programs to members of ASCE student chapters. Starting political interest early will help motivate engineers to shed light on the needs of society and show the structural engineering profession as the solvers of these problems, not the creators. • Increase public understanding of the importance of structural systems. Make the ASCE Infrastructure Report Card more personal by including letter grades for particular sites that people use on a daily basis. Assign letter grades to Philadelphia’s rail network, New York City’s subway lines, California’s bridges. People may respond more to the report card if a structure in their own locality receives a poor grade. We also need to

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November 2014

highlight what structural engineers are doing to rectify the problem. • Further outreach to the public. Although magazines like STRUCTURE® are great for disseminating information within the profession, articles need to be more accessible to the public to increase awareness of structural engineering. Structural engineers need to take up roles as public servants/public informers and communicate to the public on a level that will affect them. • Open up Structure’s Congress or high profile projects to the public. Create a day at the Structure’s Congress with presentations geared towards the general public, with reduced registration fees, to serve as a conduit for interested members of society, government, and high schools to learn about structural engineering. For example, the American Astronomical Society had two public days for the first time at their conference in 2013. • Promote structural art. Incorporate coursework in aesthetics in engineering education so engineers become greater contributors to design.

Conclusions If we are to meet the ASCE Vision 2025 goal that civil engineers will be master builders, stewards of the environment, innovators, managers of risk, and leaders in the community, we will need young engineers on board, tackling these issues.▪ Jessica Mandrick P.E., LEED AP, is an Associate at Gilsanz Murray Steficek in New York City and a member of the SEI Young Professionals Committee. Jessica may be reached at jessica.mandrick@gmsllp.com. Jason P. McCormick, Ph.D., is an Associate Professor in the Department of Civil & Environmental Engineering at the University of Michigan, Ann Arbor, and a former member of the SEI Young Professionals Committee. Jason may be reached at jpmccorm@umich.edu. A more extensive report will be published by the SEI Young Professional’s Committee in the future. The online version of this article has detailed references and information resources. Please visit www.STRUCTUREmag.org.

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Education issuEs

core requirements and lifelong learning for structural engineers

Missing Cold-Formed Steel Framing Should Cold-Formed Steel Coursework be Included in the Structural Engineering Curriculum? By Brent Perkins, P.E., S.E. Unlike the United States Constitution, the National Council of Structural Engineers Associations (NCSEA) recommended structural engineering curriculum suggested by practitioners for structural engineers is a living document that engineers need to review on a regular basis. In some cases, such as in technical writing, the monitoring by our profession and academic institutions results in a modification to the program. Academic institutions have found ways to incorporate technical writing, which is simply a title for the need for engineers to communicate in an effective way on a technical and lay person level. A short while ago, member organizations and readers of STRUCTURE were exposed to suggested modifications to the two-part Concrete Curriculum. Generally speaking, these suggestions were to make Concrete 1 the “Introduction to Reinforced Concrete”, and Concrete 2 the “Advanced Level of Reinforced Concrete”. Pre-stress and Post-tension Concrete would be a separate three-credit course that would be offered by schools as an elective. In that regard, the mission of NCSEA would be to inform practitioners of the potential change, and learn from those practitioners if a twocourse concentration in reinforced concrete was more beneficial than the current curriculum, or perhaps become a geographic alternate dependent on particular practitioner needs. The following article, authored by Brent Perkins, P.E., S.E., on behalf of the Basic Education Committee and in response to comments from industry, practitioners, and other stakeholders, is a suggested course on Cold-Formed Steel. A subsequent article currently being prepared by Professor Kevin Dong, P.E., a long-term member of the Committee, combines Timber and Masonry. Combining these two programs is a response to practitioners suggesting there is a real need on the part of young engineers to have academic exposure before joining the workforce, and a nod to academic institutions that may not have the resources to provide two (2) full three-credit courses. In another area, Professor Judy Liu of the Committee and Professor Dong are suggesting an update to the course content for Structural Steel I and II to reflect a University perspective. Please stay tuned to STRUCTURE and other communication outlets as the Basic Education Committee of NCSEA reaches out for stakeholder and practitioner input.

Craig E. Barnes, P.E., SECB

s it time to include cold-formed steel coursework as part of the structural engineering curriculum recommended by the National Council of Structural Engineers Associations (NCSEA)? Since 2002, the Basic Education Committee for NCSEA has recommended a core 12-course schematic as the Structural Engineering Curriculum (Figure 1). This curriculum includes subject matter deemed necessary by the profession for all structural engineers. In the years since the implementation of this schematic, the NCSEA Basic Education Committee has received questions as to how or if coldformed steel should be included. The current curriculum recommendations do not include cold-formed steel design. NCSEA has continually sought input concerning the curriculum since its inception. As practicing engineers and educators, do you believe cold-formed steel design coursework (Figure 2) should be part of the recommended curriculum?

Cold-formed steel framing is obviously no longer being used exclusively for exterior curtain wall framing and interior non-load bearing partition wall framing. Cold-formed framing systems are now being implemented as the primary vertical and lateral load carrying systems for complex single and multi-story cold-formed structures. How did you or your colleagues obtain a competent level of understanding for cold-formed steel design? Did you attend a technical cold-formed steel design presentation? Did you teach yourself the American Iron and Steel Institute (AISI) North American Specification for the Design of Cold-Formed Steel Structural Members? Is it appropriate for NCSEA to not include cold-formed steel design coursework recommendations regardless of the changes that have occurred in cold-formed steel construction? It may sound as if the Basic Education Committee is strongly encouraging a response from practicing engineers and educators to

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November 2014

Structural Engineering Curriculum Analysis I Analysis II Matrix Methods Dynamic Behavior Steel Design I Steel Design II Concrete I Concrete II Timber Masonry Foundation Design/Soil Mechanics Technical Writing Figure 1. NCSEA 12-Course recommended structural engineering curriculum.

Cold-Formed Steel Design Topics 1. 2. 3. 4. 5. 6. 7.

Materials, shapes, and standard sizes. Building codes and specifications. Buckling behavior of CFS members. Design of tension members. Design of flexural members. Design of compression members. Design of combined axial and bending members 8. Design of connections. 9. Design of trusses. 10. Design of shear wall systems. Cold-Formed Steel Design Objectives 1. Use structural principles, material properties, current codes, and specifications to analyze and design cold-formed steel members and connections. 2. Use structural principles to configure cold-formed steel framed structural systems. 3. Use cold-formed steel manufacturer’s technical literature and software to aid in the design of cold-formed steel elements. 4. Correctly specify and detail coldformed steel components and systems. Figure 2. Example of cold-formed steel design recommended coursework.

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FA S T ER STRONGER MORE DURABLE 3000 PSI IN 1 HOUR Figure 3. Cold-formed steel framing. Courtesy of Equilibrium Engineers, LLC.

at the NCSEA Annual Conference, articles in STRUCTURE magazine, and discussions with practitioners and educators. Now the committee needs input from a broader spectrum of professionals to move forward and make a formal recommendation. Tell us what you think. Should the curriculum remain unchanged or be modified to include coldformed steel design? Provide feedback to the Basic Education Committee by contacting Brent Perkins, NCSEA Basic Education Committee Chair, at bperkins@dwase.com.▪

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support the addition of cold-formed steel design as part of the recommended curriculum. However, this is not necessarily the case; the committee recognizes that the future structural engineer’s college education path is already filled with recommended coursework that is a challenge for students to complete. How can another curriculum recommendation be added? Should some of the recommended curriculum be revised to elective courses – if so which ones? Should some of the recommended curriculum be combined or eliminated – if so which ones? Or should the recommended curriculum remain as it was originally introduced without cold-formed steel design? The Basic Education Committee has repeatedly sought feedback concerning the recommended curriculum through forums

INBOX

letters to the editor

Code Complexity DeFriez STRUCTURE, July and September 2014

I applaud the author’s opinions on code complexity, as it is a very important topic for our industry. With pressure to keep engineering fees and design schedules increasingly tight, we just don’t have the time to process what has become overly complex code-required wind and seismic loading scenarios. When I started as a structural engineer, the New York State Building Commission simply gave you wind pressures in psf based on the building height. Simple but effective – I have not heard of a single structure failing due to wind load. The current code requirements (ASCE and IBC) are ridiculously complex for the typical one story structures that I think make up the significant portion of engineering work for most firms. I find it interesting that snow loading determination has remained relatively simple. Personally, I have seen/heard of far more roof snow failures than wind failures. Similarly, the approach to dead and live loads remains simple. The basic approach with these loadings is to provide a conservative level of confidence in the loading (despite the potential variability) to prevent failure. This level of analysis should be similarly applied to wind and seismic loadings. I would agree that, if we are designing multi-story, especially skyscraper, type structures, more significant and rigorous determination and distribution of wind and seismic loads is absolutely necessary – for both safety and cost savings. However, for single story basic structures, let’s be given the option to use a conservative but easy approach to determining these loads so we can move on with the design. We simply don’t have hours or days of fees for the current complexity on these types of design projects. In addition, it seems ludicrous to go through so many calculations with various factors and adjustments to determine loads to the equivalent of a decimal point which in nature are so highly variable and unpredictable. Whether the old basic approach or the current complexity, the desired outcome is essentially the same – determine a pressure or load that to a high degree of probability (say 99%) will provide adequate protection to the public against failure. Despite adding more factors and adjustments in the name of accurately determining loadings, we will never be able to completely predict nature.

The recent Structural Forum columns by Craig DeFriez, How Code Complexity Harms Our Profession – Parts 1 and 2,, were exceptional and right on target. Finally, a voice for simplicity! Uncomplicated can be as good as (if not better than) bigger and more complex. As a sole practitioner, I often wonder how to keep up with all that is new. One of my dilemmas is living and working in a fairly large metropolitan area where there are several different contiguous selfgoverning municipalities. Most have different time frames for adoption of applicable codes. Try explaining to a client and/or contractor why it now has to be done this way when yesterday, or next door, it could still be done simply, as it has always been done. The articles mentioned continuing education, a very important part of being an engineer. I attended a seminar that was designed to help the engineer “transition” from one code edition to the next. I asked the instructor, a nationally recognized expert, why codes were continuing to “improve” to the pain and detriment of the little guy, many of whom struggle to keep up and/or compete. My summary of his response is: most code committee members are not practicing engineers, but rather upper-level managers who no longer crunch the numbers. That is probably also right on target. It is also unfortunate. I have never written a letter to any editor before, but wanted to commend this particular piece. My thanks to Mr. DeFriez for expressing his opinion and insightful thoughts, David M. Buck, P.E., MLSE dmbuck@swbell.net

Deconstructing Bridge 92297 Salmon and Elliott, STRUCTURE, January 2014 A colleague recently sent me the article on Deconstructing Bridge No 92297 as I am interested in the use of the Turner ‘Mushroom Flat Slab’ system in Australia. Hugh Ralston Crawford, an engineer and architect, acquired the Australian patent rights for the Turner Mushroom Flat Slab system and, in 1909, used it for the design of the 5 story Snider & Abrahams cigarette factory in Melbourne. In 1938, he used the same system when two more floors were added to the building. Crawford used the Mushroom Flat Slab system on a number of other buildings he designed. These additional buildings were built in various States in Australia. Some of the buildings, including the Snider & Abrahams building, still exist. I have been unable to find out how Crawford acquired the Australian patent rights for the Turner system. If anyone has that information, I would be grateful to receive it. STRUCTURE magazine

John. F. Collins, P.E., M. ASCE As far as I am aware, Turner’s Mushroom Flat Slab system was not used for any bridges in Australia. Early reinforced concrete bridges in the State of Victoria were designed using the Monier arch patent system, which had been acquired by Sir John Monash & his partner, Joshua Noble Anderson. Between 1897 and 1903, eighteen Monier arch bridges were built. Monash then developed a T-girder bridge system that his firm used to build at least 45 bridges between 1904 and 1915. David Beauchamp, MIE Aust, MICE davidbeauchamp75@gmail.com

November 2014

news and information from software vendors

Software UpdateS

ADAPT Corporation

Autodesk, Inc.

CADRE analytic

Phone: 650-218-0008 Email: florian@adaptsoft.com Web: www.adaptsoft.com Product: ADAPT-PTRC 2014 Description: An indispensable production tool for the fast and easy design of concrete slabs of any form, beams, and beam frames. Uses equivalent frame method to design posttensioned or conventionally reinforced projects. Easily switch between PT and RC modes.

Phone: 720-459-6830 Email: charlyn.mccallum@autodesk.com Web: www.autodesk.com/advancesteel Product: Autodesk® Advance Steel 2015 Description: Built on Autodesk AutoCAD® platform, Autodesk Advance Steel provides 3D modeling tools to help you accelerate design and detailing. The latest release includes more powerful integration with Autodesk Revit® and Autodesk Navisworks®, and documentation tools that help save time and reduce rework on shop drawings. Free trial at website.

Phone: 425-392-4309 Email: cadresales@cadreanalytic.com Web: www.cadreanalytic.com Product: CADRE Geo 6.2 Description: Geodesic design application for generating a wide variety of geodesic and spherical models for CAD or FFA applications. Output are clean DXF files suitable for structural analysis applications. Produces detail design data for domes such as hub and panel layouts, dimensions, dihedral angles, volume, surface area. Multiple breakdown method supported.

Bentley Systems

Concrete Masonry Association (CMACN)

Phone: 800-236-8539 Email: katherine.flesh@bentley.com Web: www.bentley.com/structural Product: STAAD.Pro Description: The structural engineering professional’s choice for steel, concrete, timber, aluminum, and cold-formed steel design of virtually any structure including culverts, petrochemical plants, tunnels, bridges, piles, and much more through its flexible modeling environment, advanced features, and fluent data collaboration.

Phone: 916-722-1700 Email: info@cmacn.org Web: www.cmacn.org Product: CMD12 Design Tool 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 through 2013 CBC or 2003 through 2012 IBC and 1999 through 2011 Bldg. Code Requirements for Masonry Structures (TMS 402/ACI 530/ASCE 5).

Product: ADAPT-Builder 2014 with Column Design Description: Builder Suite for the integrated and efficient design of concrete buildings. Streamline your process using one model to run gravity and lateral designs. Don’t waste time by maintaining separate data for your slab, foundation, column and wall designs. Designs post-tensioned and mild reinforced projects. Seamlessly integrates with Revit Structure.

American Wood Council Phone: 202-463-2766 Email: info@awc.org Web: www.awc.org Product: Connection Calculator Description: Provides users with a webbased approach to calculating capacities for single bolts, nails, lag screws and wood screws per the 2005 NDS. Both lateral (single and double shear) and withdrawal capacities can be determined. Wood-to-wood, wood-to-concrete, and wood-to-steel connections are possible. Product: Span Calculator Description: Performs calculations for all species and grades of commercially available softwood and hardwood lumber as found in the NDS 2005 Supplement. Joists and rafter spans for common loading conditions can be determined. A “span options” calculator allows selection of multiple species and grades for comparison purposes.

Applied Science International, LLC Phone: 919-645-4090 Email: tdigirolamo@appliedscienceint.com Web: www.appliedscienceint.com Product: SteelSmart System 7.0 Service Pack 1 Description: SP1 updates include: “Special Seismic Design” in the Shear Wall Module. “Fastener Design” in the Curtain Wall Module, 2013 Hilti fastener database, “Bridging Connection” design for studs, Jambs with Standard section database now includes both back-to-back and toe-to-toe layouts, ASCE 7-10 wind maps now correspond to Building Risk Category.

Product: STAAD Foundation Description: A comprehensive foundation design program that offers the ability to model complex or simple footings, including those specific to Plant facilities such as octagonal footings supporting vertical vessels, strap beam foundations supporting horizontal vessels, ring foundations supporting tank structures, and drilled or driven pier foundations. Product: RAM Concept Description: ISM enabled, RAM Concept is the ultimate structural designer’s solution for post-tensioned and conventionally reinforced slabs, mats, and rafts. RAM Concept empowers structural engineers to design floor systems much more cost-effectively than with other tools, and with exceptional visibility into the compliance, efficiency, and practicality of the design. Product: RAM Connection Description: A steel connection design application, is fully integrated with RAM Structural System, RAM Elements, and STAAD.Pro and coming soon with ProStructures! RAM Connection can check or design connections in seconds. All Resource Guide forms for the 2015 Editorial Calendar are now available on the website, www.STRUCTUREmag.org. Listings are provided as a courtesy. STRUCTURE® magazine is not responsible for errors.

STRUCTURE magazine

November 2014

Decon USA Phone: 707-996-5954 Email: frank@deconusa.com Web: www.deconusa.com 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. 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.

Design Data Phone: 402-441-4000 Email: doug@sds2.com Web: www.sds2connect.com Product: SDS/2 Connect Description: Enables structural engineers using Revit Structure for BIM to intelligently design steel connections and produce detailed documentation on those connections. 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. continued on page 63

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news and information from software vendors

Software UpdateS

Devco Software, Inc.

Integrity Software, Inc.

Phone: 541-426-5713 Email: rob@devcosoftware.com Web: www.devcosoftware.com Product: LGBEAMER v8 Pro 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.

Phone: 512-372-8991 Email: sales@softwaremetering.com Web: www.softwaremetering.com Product: SofTrack Description: Saves you money by accurately controlling usage all your Bentley® applications. SofTrack’s solution is unique because it tracks usage by the Bentley Product ID code(s) activated during application usage including those activated by MDL applications. Version and Feature Strings set by the Municipal License Administrator are also tracked.

Digital Facilities Corportation Phone: 978-455-0441 Email: sjames@digital-corp.net Web: http://dfc-sc.net Product: WallPro- E-Data Description: Wall inspection software for documenting as built construction, facade condition inspections, building inventory assessments.

ENERCALC, Inc.

ENERCALC

Phone: 800-422-2252 Email: info@enercalc.com Web: www.enercalc.com Product: Structural Engineering Library Version 6 Description: Software system applied to most aspects of structural engineering design for all but the largest structures. We’re also deep into our Cloud based system which promises to be revolutionary. Huge capabilities combined with sensible pricing and great support make for a 31 year veteran system.

Hilti, Inc. Phone: 800-879-8000 Email: us-sales@hilti.com Web: www.us.hilti.com Product: PROFIS Anchor and PROFIS DF Description: Hilti offers two design programs for structural engineers. 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: info@iesweb.com Web: www.iesweb.com Product: VisualAnalysis Description: Model what you need to build, applying loads (yes, you are skilled), get quick results for your design, with great reports to make you shine. In this way, your work is fast, solving problems is a blast; VisualAnalysis helps you get engineered success: no sweat.

Losch Software Ltd Phone: 323-592-3299 Email: LoschInfo@gmail.com Web: www.LoschSoft.com Product: LECWall – Concrete Sandwich Wall Panel Design and Analysis Description: Prestressed and/or mild reinforcing. Flat, hollow-core or double tee configurations. Column design, handling analysis, multi-story capability, zero to 100 percent composite. Free 30 day trial.

National Concrete Masonry Association Phone: 703-713-1900 Email: ncma@ncma.org Web: www.ncma.org Product: Direct Design Software Description: Updated to the 2013 edition of TMS 403 (referenced by the International Building Code and Residential Code) this software allows users to generate final structural designs for whole concrete masonry buildings in minutes. Product: Structural Masonry Design Software Version 6.1 Description: Now updated to include the 2012 International Building Code and the 2011 MSJC. Includes new larger allowable stresses per code. Design walls, lintels, columns and much more.

Nemetschek Scia Phone: 410-290-5114 Email: dan@nemetschek.net Web: www.scia-online.com Product: Scia Design Forms Description: Imagine being able to write checks that linked to your FEA software. Easily script custom engineering calculations and output professional reports that show the exact formulas used to derive the check. Checks can be run as stand-alone, or linked to Scia Engineer. Explore the power, download the free trial.

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November 2014

Product: Scia Engineer Description: Plug structural analysis and design into today’s 3D workflows. Easily take larger projects with advanced non-linear and dynamic analysis. Design to multiple codes or script your own custom checks. Plug into BIM with IFC 2x3 and links to Revit, Tekla and Rhino and others. Request a FREE tryout.

Pile Dynamics, Inc. Phone: 216-831-6131 Email: info@pile.com Web: www.pile.com/pdi Product: GRLWEAP Description: GRLWEAP Wave Equation Analysis of Piles: simulates pile driving, predicts driving stresses, hammer performance, the relation between bearing capacity and net set per blow and total driving time. Helps select job-adequate hammers. 800+ preprogrammed hammers, several analysis options. Offshore Piles version available. Codes may allow leaner design with GRLWEAP analysis.

POSTEN Engineering Systems Phone: 510-275-4750 Email: sales@postensoft.com Web: www.postensoft.com Product: POSTEN Multistory Description: With sophisticated proprietary post-tensioning algorithms, POSTEN automatically and efficiently designs the tendons and rebar (no hours fiddling with drapes) for multistory buildings. The only post-tensioned concrete software that includes design of moment frames, seismic & wind, columns, torsion, and truly sustainable design (with automatic LEED documentation).

Powers Fasteners Phone: 800-524-3244 Email: engineering@powers.com Web: www.powers.com Product: Power Design Assist (PDA) Anchor Software Description: Approved mechanical anchors: Power-Stud+ SD2 (carbon steel), SD4 (304 SS), SD6 (316 SS), Power-Bolt+, Wedge-Bolt+, Snake+, Vertigo+ and Atomic+ Undercut. Approved adhesive anchors: Pure110+, PE1000+ and AC100+ Gold. continued on next page All 2014 Resource Guides are available as references on the website, www.STRUCTUREmag.org. Listings are provided as a courtesy. STRUCTURE® magazine is not responsible for errors.

Software UpdateS RISA Technologies

news and information from software vendors

Structural Engineers Inc.

Phone: 949-951-5815 Email: amberf@risa.com Web: www.risa.com Product: RISAFloor ES Description: Offers all of the capabilities of RISAFloor, plus the ability to design floors as elevated concrete two-way slabs. The design of elevated concrete slabs includes optimization of rebar, full code checks including punching shear, elastic deflection analysis, and T-beams.

Simpson Strong-Tie Phone: 800-999-5099 Email: web@strongtie.com Web: www.strongtie.com Product: Simpson Strong-Tie® Joist Hanger Selector Web App Description: Web app that makes it easier than ever to select the most cost-effective hanger for projects based on the type of installation, sizes and loads. The clean, visual interface enables engineers to quickly select the members and configuration for their desired connection, and print the results. Product: Simpson Strong-Tie® Steel Deck Diaphragm Web App Description: Enables engineers to quickly and efficiently identify the best design and fastener solutions for steel decks given shear and uplift loads. The app, which is accessible from any web browser, provides diaphragm shear strengths of a steel deck when using Simpson Strong-Tie screws.

FloorVibe Phone: 540-731-3330 Email: tmmurray@floorvibe.com Web: www.floorvibe.com Product: FloorVibe v2.20 Description: Provides structural engineers an analysis tool to check floor vibration serviceability. Floors subject to walking or rhythmic excitation or supporting sensitive equipment can be evaluated using the procedures in the AISC Design Guide 11 and the new SJI Technical Digest 5, 2nd Ed. Design guidance is available for all input parameters. StructurePoint Phone: 847-966-4357 Email: info@structurepoint.org Web: www.StructurePoint.org Product: spColumn and spWall Description: spColumn – for design of shear walls, bridge piers as well as typical framing elements in buildings and structures. spWall – for design and analysis of cast-in-place reinforced concrete walls, tilt-up walls, ICF walls, and precast architectural and load-bearing panels. Product: spMats and spSlab Description: spMats – for analysis, design and investigation of commercial building foundations and industrial mats and slabs on grade. spSlab – for analysis, design and investigation of reinforced concrete floor systems.

Struware, LLC

Strand7 Pty Ltd Phone: 252-504-2282 Email: anne@beaufort-analysis.com Web: www.strand7.com Product: Strand7 Description: An advanced, general purpose, FEA system used worldwide by engineers and analysts 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.

StrucSoft Solutions Phone: 514-731-0008 Email: info@strucsoftsolutions.com Web: www.strucsoftsolutions.com Product: MWF Advanced Floor Description: Extend the power and reach of Revit® & MWF with MWF Advanced Floor. This upgrade to the popular framing extension allows engineers and estimators to engineer and determine optimum joists for their projects. Take advantage of a finite element analysis engine and the almost limitless configurations you expect from MWF.

Phone: 904-302-6724 Email: email@struware.com Web: www.struware.com Product: Struware Code Search Description: Get all pertinent wind, seismic, snow, live and dead loads for your building in just minutes. The program simplifies ASCE 7 & IBC by catching the buts, ifs, insteads, footnotes and hidden items that most people miss. Demo at website. Current users: a new update is available for download.

Tekla Phone: 770-426-5105 Email: kristine.plemmons@tekla.com Web: www.tekla.com Product: Tekla Structures Description: Create and transfer constructible models throughout the design lifecycle. From concept to completion, Tekla Structures allows you to create accurate and information-rich models that reduce RFIs and enable structural engineers proven additional services. Used for drawing production, material take offs and collaboration with disciplines like architects, consultants, fabricators and contractors.

STRUCTURE magazine

November 2014

Product: Tedds Description: A powerful software that will speed up your daily structural and civil calculations, Tedds automates your repetitive structural calculations. Perform 2D Frame analysis, utilize a large library of automated calculations to US codes, or write your own calculations while creating high quality and transparent documentation. Product: Fastrak Description: Automates the design and drafting of steel buildings. From concept to final design, achieve designs faster than ever before. Design both simple and complex buildings to US codes and then export models direct to BIM compatible software, such as Tekla Structures to increase efficiency and design confidence.

USP Structural Connectors Phone: 952-898-8772 Email: uspcustomerservice@mii.com Web: www.uspconnectors.com Product: USP Specifier™ Description: Simplifies access to information on over 3,000 structural connectors through an intuitive and graphical desktop interface. Looking up connector capacities, viewing code evaluation reports and even mapping from competitor products to USP products is quick and easy. Free download from USP website.

WoodWorks® Software Phone: 800-844-1275 Email: sales@woodworks-software.com Web: www.woodworks-software.com Product: WoodWorks® Design Office Suite Description: Conforms to the 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 stories; automatic load patterning. CONNECTIONS: Wood to: wood, steel or concrete. Canadian version available.

All Resource Guide forms for the 2015 Editorial Calendar are now available on the website, www.STRUCTUREmag.org. Listings are provided as a courtesy. STRUCTURE® magazine is not responsible for errors.

We’ve evolved. We’ve become Tekla. Our world looks a little different, but our focus is still on creating innovative software. CSC has always been about pioneering software and responding to the real world challenges of structural engineers. Joining forces with like minded people, like Tekla, is the next step in our evolution.

Find out how we’ve evolved at www.tekla.com

SEAOI

SE Exam Refresher Course October 27, 2014 – April 2, 2015 The Most Comprehensive Review Course Available RAVES FROM PAST PARTICIPANTS: “Thank you for having an amazing SE Review Course. I have taken the exam a few

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award winners and outstanding projects

Spotlight

Final Phase of La Plata Stadium Construction By Matthys Levy, P.E. Weidlinger Associates, Inc. was an Outstanding Award Winner for the La Plata Stadium project in the 2013 NCSEA Annual Excellence in Structural Engineering awards program (Category – International Structures over $100M).

onstruction of the 53,000-seat soccer stadium in La Plata, Argentina, was interrupted in 2001, after the concrete bleachers had been poured on the earth berm and the steel-trussed compression ring had been erected to support the twin-peaked Tenstar Dome™ developed by Weidlinger Associates. Nearly a decade later, in 2012, the cable dome and an annular section of its fabric cladding were constructed, leaving a figure-eight-shaped opening in the middle of the roof. The success of the project in hosting the Copa América and, later, the inaugural Rugby Championship led to the realization that the stadium would be even more useful if the central opening were covered with translucent fabric cladding. This possibility is currently under consideration by the owners, the Buenos Aires Province. In its final configuration, the roof will feature two peaks, each with an umbrella roof covering its ventilation openings, completing the competition-winning design by architect Roberto Ferreira. Although initially conceived as a grass pitch on earth, the final playing field consists of an asphalt surface covered with removable pallets of natural grass turf. This scheme permits

the rapid replacement of worn areas, and the removal of all pallets for non-sporting events such as concerts, public gatherings, and the circus. The triangulated structure of the Tenstar Dome has been shown to be extremely adaptable, allowing each node to support a variety of hanging loads and accommodate the suspension of unique lighting, banners, and sound systems and the rigging needs of circus acts and special events. This has been amply demonstrated over the past 25 years at the Georgia Dome, which was the first stadium to feature the Tenstar Dome concept. A unique characteristic of the La Plata stadium is its reliance on natural ventilation, which is provided through an open perimeter behind the seats and boxes and, in the final configuration, a 15-meter-diameter

(49-foot) opening at each of the two peaks. When the fabric cladding is completed, tentlike cupolas will cover each of these holes to keep out rain or the infrequent snowfall. Two options are presently under consideration for the center cladding: the same PTFE fabric that was used for the completed section of the roof or clear, air-inflated ETFE pillows. The latter option would result in a virtually transparent center roof section. Since the cable structure is already in place, the installation of this final section of the roof will be a simple matter using scaffolding hung from the existing cables and nodes. The stadium is the centerpiece of a park that was designed by the architect as a part of the original competition, to provide the local residents a gathering place and recreational area. As a world-class entertainment complex, the site provides playing fields for both professional and amateur teams and is a frequent venue for sporting and cultural events. When the roof is finished, it will be the only completely covered stadium in South America, making it a year-round venue irrespective of the weather.▪ Matthys Levy, P.E., is chairman emeritus of Weidlinger Associates, Inc., and former director of its Building Design Group. Levy is the recipient of numerous professional awards. He is also the author of many popular books on structures and climate effects, including the classic Why Buildings Fall Down. He can be reached at matthyslevy@gmail.com.

STRUCTURE magazine

November 2014

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Your Profession, Your Choice

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NCSEA News

News form the National Council of Structural Engineers Associations

Barry Arnold, NCSEA Board President As a boy, I read about people with vision and passion and was amazed by their accomplishments. People committed to a cause have changed the world; the root of their success was a vision of what could be and a desire to create it. Capturing a vision can be difficult. A picture I enjoy by Pawel Kuczynski shows a person warming himself by a small fire in the shadow of a long, tall wall. Beyond the wall is bright blue sky and presumably greater opportunities. Against the wall rests a tall ladder with the bottom ten rungs cut off and being burned as firewood thus rendering the ladder useless. It is a self-created prison. The message is clear: Opportunities are plentiful for those willing to use the ladder to look over the wall and envision a new future instead of using its rungs as firewood. The desire to create is frequently found in many, but especially prevalent in engineers. I once received a totem pole with a face carved into each of its four sides; each face displays a different emotion. The totem pole is a reminder that we have the opportunity to create our day every day. We create our day by choosing our attitudes, opinions, and focus. Each day, whether we consciously make a choice or not, we make a choice in how we create our day. Knowingly making a decision to not create our day is as binding as making a decision to take control of our destiny and create our day. Each day we choose whether to dine at the big banquet table and partake of the bounty our profession has to offer, or to dine on crumbs. The choice is ours – everyday. Franklin D. Roosevelt said it best when he wrote, “Men are not prisoners of fate, but only prisoners of their own minds.” The structural engineering community needs to understand and embrace the idea that we can create, improve, and modify our profession. We have been given charge of a trusted profession and we have a responsibility to all we serve to choose a destiny that will benefit us all. We have an obligation to our profession to choose to look over the wall and create a better future. But change can be difficult and engineers are traditionally suited to resist change. In our professional work we must adhere to the content of codebooks – a laborious checklist of do’s and don’ts. Our codebooks give us answers that we do not have to think about because someone else has, we assume, done the thinking for us. It is easy. We like that. The problem is that the desire for easy answers creates an addiction to dogma. Adherence to dogma is alluring because at its core is the ‘do-nothing alternative’. The do-nothing alternative is an economics principle that uses doing nothing as a baseline when comparing options. The sirens-call of the do-nothing alternative varies but often is verbalized as, “No one cares”, “It will take time”, “It will cost money”, or “They won’t let us.” Especially persuasive to those addicted to dogma are the phrases, “But that’s the way we’ve always done it.” and, “No one’s dead yet.” It is easy to follow dogma because someone else has, we assume, already done the thinking for us. It’s easy to fall into the do-nothing alternative trap, but it may, in the long run, be doing us more harm than good. Imagine what the world would be like if people like Susan B. Anthony, Gandhi, STRUCTURE magazine

Martin Luther King, Abraham Lincoln, George Washington, and John F. Kennedy had chosen the do-nothing alternative. Each was willing to ask the question: “What if…?” Those of you that enjoy clean running water, flush toilets, and electric lights should be grateful that someone broke with the norm, chose to look over the wall, and asked themselves, “What if...?” The codes we use are revised every few years to dump outdated dogma and update our understanding of how a particular type of structure or material behaves. Should our profession also have a regular review and update? When is the last time we looked at our profession by climbing the ladder and looking into the future and asking, “What if…?” When is the last time we looked at our profession and wondered if we couldn’t and shouldn’t create something better, something that suits where we want to be ten or fifty years into the future? Should we pause and ask ourselves: Is this the direction we want to go? Or, is there a better way? We have the opportunity to create our lives and our profession every day. Not only do we get to choose our future but we also get to create it. We have an obligation to take that responsibility seriously and not seek the ease and comfort of the do-nothing alternative. We should use the ladder to peer into the distant future and make decisions that will guide us to a better destiny and provide those using our services with a better experience. NCSEA is in the process of developing a strategic plan to outline the direction the organization will take for the next five years. We are using the ladder to peer over the wall and look into the future. We are gathering the information needed to create a better profession and safeguard the public. It is your profession and you are invited to participate in that process by supplying input. Email me at barrya@arwengineers.com or any NCSEA Board member with your suggestions. Making a choice to provide your insights and thoughts will help us create a better future for structural engineering and the public.

NCSEA Webinars November 20, 2014 Tilt-up Eats Hurricanes for Breakfast - Five Things Every Engineer Should Know When Designing Tilt-Up Panels Jeff Griffin, Ph.D., P.E., P.M.P., structural engineer and project manager, LJB Inc. December 4, 2014 2012 IBC, ASCE 7 & 2008 SDPWS Seismic Provisions for Wood Construction Michelle Kam-Biron, P.E., S.E., SECB, M.ASCE, Director of Education, American Wood Council (AWC) More information on the webinars can be found at www.ncsea.com. These courses will award 1.5 hours of continuing education. Approved for CE credit in all 50 States through the NCSEA Diamond Review Program. Time: 10:00 AM Pacific, 11:00 AM Mountain, 12:00 PM Central, 1:00 PM Eastern. 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.

November 2014

January 29 – 30, 2015, Hyatt Regency Coral Gables, Florida How Can Engineering Firms Increase Their Value to Clients? This panel discussion will focus on ways to increase billable hours, increase and provide more comprehensive services, and improve specialties.

Sessions will include:

Banking Relationships Bank Chairman Terry Vanderaa How engineering firms and banks can develop relationships that benefit both parties, and how banks value firms.

2014 NCSEA Annual Conference exhibitors: LNA Solutions MiTek Builder Products, USP Structural, Hardy Frame NCEES Nemetschek Scia New Millenium Bldg. Systems Nucor Ecospan Nucor Vulcraft Powers Fasteners Side Plate Systems RISA Technologies Simpson Strong Tie Steel Joist Institute Steel Tube Institute Strand7 SECB Tekla USG Vector Corrosion Tech

More detailed information on the Winter Leadership Forum sessions and speakers can be found in the editorial on page 7.

NCSEA thanks the sponsors of the 2014 NCSEA Annual Conference: Platinum

Gold September 19, 2014

Silver

Copper

Designates NCSEA membership

DiBlasi Associates, P.C. • Euclid Chemical Sound Structures

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For information on exhibiting at the 2015 trade show, contact Susan Cross, scross@ncsea.com.

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American Concrete Institute AISC Atlas Tube AZZ Galvanizing Bekaert Blind Bolt Cast Connex Chance Civil Construction CFSEI Delta Structural Technology Design Data Engineers Alliance for Arts Euclid Chemical Fabreeka International Five Star Products Fyfe Company Headed Reinforcement Hilti Holcim Independence Tube Corp. International Code Council ITW Red Head, Ramset & Buildex ITW Trussteel Lindapter USA

Case Study: To Purchase or To Pass? By John Tawresey An interactive case study will focus on whether or not to acquire another firm. Attendees will function as the Board of Directors making this decision.

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Organic Growth vs. Growth by Acquisition This panel discussion will focus on the avenues for firm growth, their pros and cons, and understanding which approach, if any, is right for your firm. The session will include a debate on the two approaches.

STRUCTU

AEC Business Development: The Decade Ahead By Scott Butcher, Vice President, JDB Engineering Inc., SMPS Foundation Trustee and Co-Chair of Thought Leadership Committee. Information is vital to anyone selling design and construction services – what works, what doesn’t and how do clients want to be sold? The SMPS Foundation interviewed more than 100 buyers and sellers of A/E/C services to answer these questions and will share their findings with attendees.

How To Get Your Firm Hired and Retain Relationships Part 1 will address pre-positioning, business development, and go/no go decisions. Part 2 will address strategies for building relationships and creating repeat clients.

News from the National Council of Structural Engineers Associations

How do you provide additional value to your clients? What are the buyers of your services thinking, and what are they looking for? When do you compete on prices? What is your banker thinking, and how does a bank value an engineering firm? These questions and more will be addressed at NCSEA’s third Winter Leadership Forum. Structural engineering leaders and firm principals will gather to discuss the issues confronting engineering firms in today’s environment. The Forum will feature roundtable discussions, presentations from firm principals and professionals in banking and finance, and a debate between structural engineering leaders on “How to Grow.” The topics of this year’s Forum will focus on ways to grow your firm and provide additional value, as well as on issues relating to acquisition and finance.

NCSEA News

NCSEA 2015 Winter Leadership Forum

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The Newsletter of the Structural Engineering Institute of ASCE

Structural Columns

Geotechnical & Structural Engineering Congress 2016

Become an SEI Sustaining Organization Member

February 14–17, 2016, Phoenix, AZ

Raise recognition for your organization in the structural engineering community, and increase visibility to more than 25,000 SEI members via www.asce.org/SEI, SEI Update e-newsletter, and STRUCTURE magazine. Learn more at www.asce.org/SEI-Sustaining-Org-Membership.

Call for abstract and session proposals now open… We are seeking dynamic sessions and presentations on topics addressing both Geotechnical and Structural Engineering issues. Final papers are optional and will not be peer reviewed. Consider submitting either session proposals or single abstracts related to the topics and subtopics of interest to both professions. The 2016 Congress will feature a total of 15 concurrent tracks: there will be tracks based on traditional GI and SEI topics, and tracks on joint topics. In addition, we will be offering interactive poster presentations within these tracks. All proposals must be submitted by April 7, 2015 (no extensions). Visit the joint conference website at www.asce.org/SEI for more information.

New ‘Make Your Mark’ Poster Now Available Inspire and encourage students to MAKE YOUR MARK pursue structural engineering as a career with the new Make Your Mark poster, produced by the National Council of Structural Engineers Associations (NCSEA) and SEI. Include this free tool in your outreach efforts with local students. Limited supplies of the complimentary poster are available upon request to Suzanne Fisher at sfisher@asce.org. Be sure to include the number of posters you are requesting and where they should be sent. The job of a structural engineer is both an art and science.

GO THE DISTANCE

Structural engineers design the buildings where we live, work, go to school, and play, and the bridges we cross everyday. As buildings reach greater heights and bridges span further distances, structural engineers must design these structures with materials such as steel, concrete, masonry, and timber to resist all forces. These forces include gravity, earthquakes, hurricanes, explosions and much more. All of this is considered to create the architect and client’s vision while creating a safe place for the public.

Make your mark by visiting

Errata

www.ncsea.com and www.asce.org/SEI

’s Brid Calatrava

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 Jon Esslinger at jesslinger@asce.org.

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Serraiocco

Achieving the Vision: Structural Engineers as Leaders & Innovators SEI Announces New Student Video Competition Your student team is invited to participate in the 2015 SEI Student Video Competition. • Show your pride and vision for structural engineering. • Compete for the opportunity to network and learn with the best and brightest at Structures Congress. • Gain recognition for your team and university. Produce a short video on your team’s interpretation of the theme “Achieving the Vision: Structural Engineers as Leaders and Innovators” from the SEI Vision for the Future of Structural Engineering and Structural Engineers: A Case for Change.

The winning video will be shown at Structures Congress April 23-25, 2015 in Portland, Oregon. The winning team will receive complimentary registration for up to five students and their faculty advisor to participate in the full program at Structures Congress, including special opportunities for students to meet and mix with industry and academic leaders. Entries are due December 12. Learn more and apply on the SEI website at www.asce.org/SEI.

Young Professional Scholarship Second ATC-SEI Conference Improving the Seismic Performance of Existing to 2015 Structures Buildings and Other Structures

Portland, Oregon, April 23 – 25, 2015 Applications due December 12

December 10-12, 2015 Hyatt Regency San Francisco

SEI is committed to the future of structural engineering and offers a scholarship for Young Professionals (age 35 and younger) to participate and get involved at Structures Congress. Many find Structures Congress to be a career-changing and energizing experience, opening up networking opportunities and expanding horizons to new and emerging trends. The scholarship includes complimentary registration sponsored by the SEI Futures Fund. Enter by visiting the SEI website at www.asce.org/SEI-Young-Professional-Scholarship. STRUCTURE magazine

Call for abstracts and session proposals now open Organized by the Applied Technology Council (ATC) and the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE), this conference will be dedicated to improving the seismic performance of existing buildings and other structures. All proposals must be submitted by January 22, 2015 (no extensions). See the conference website at www.atc-sei.org for more information. November 2014

Gain valuable professional and networking experience, compete for cash prizes, and raise visibility for your team and university. Awards include complimentary registration, sponsored by the SEI Futures Fund, to participate and present finalist projects at Structures Congress April 23-25, 2015 in Portland, Oregon. Learn more and enter at www.asce.org/SEI-Student-Competition by January 5, 2015.

accomplished SEI members as leaders and mentors in the structural engineering profession. The benefits of becoming an SEI Fellow include recognition via SEI communications and at the annual Structures Congress along with a distinctive SEI Fellow wall plaque and pin, and use of the F.SEI designation. SEI members who meet the SEI Fellow criteria are encouraged to submit application packages online by December 1 to advance to the SEI Fellow grade of membership and be recognized at Structures Congress, April 23-25, 2015 in Portland, Oregon. Apply at www.asce.org/SEIFellows.

Search for New SEI Director strategic plan with Board of Governors’ approval; and networking with other similarly aligned organizations and identifying opportunities to partner. Ideal candidates will have a degree in civil engineering plus an advanced degree. An advanced degree in structural engineering is highly desirable. Candidates must possess or be able to shortly become a registered professional engineer. Ten to fifteen years’ experience in structural engineering with demonstrably increasing responsibility is required. Association management experience would be considered a plus but is not required; however, candidates are expected to be familiar with the many products and activities developed by SEI. See the ASCE website at http://asce.applicantpro.com/jobs/ for more information.

2015 Fazlur R. Khan Lecture Series at Lehigh University

New Structural Publications from ASCE

Lehigh University is proud to announce the speakers for the 2015 Fazlur R. Khan Distinguished Lecture Series. The series, co-sponsored by the Departments of Civil & Environmental Engineering and Art, Architecture & Design, honors Dr. Fazlur Rahman Khan’s legacy of excellence in structural engineering and architecture. • Friday, February 20, 2015 – 4:30 pm William Pedersen, Founding Design Partner, Kohn Pedersen Fox Associates, New York, NY Balancing • Friday, March 20, 2015 – 4:30 pm Glenn R. Bell, Chief Executive Officer, Simpson Gumpertz & Heger, Waltham, MA Structural Engineering at Mid-21st Century: Reengineering Our Roles • Friday, April 17, 2015 – 4:30 pm Peter Marti, Professor of Structural Engineering, ETZ Zurich, Zurich, Switzerland Science and Art of Structural Engineering New for 2015 – The Structural Engineering Institute-Lehigh Valley Chapter will be awarding 1 PDH credit for each lecture to eligible attendees. Visit the Lecture Series website at www.lehigh.edu/~infrk for additional information about the Fazlur R. Khan Distinguished Lecture Series. STRUCTURE magazine

Snow-Related Roof Collapse during the Winter of 2010–2011 Implications for Building Codes This report describes an investigation into nearly 500 roof collapses and snow-related roof problems that occurred in the northeastern United States during the winter of 2010–2011. Engineering Investigations of Hurricane Damage Wind versus Water This book provides civil engineers with the background and guidance necessary to conduct engineering damage investigations of structures following hurricanes, focusing particularly on distinguishing between wind damage and water damage. Guideline for Condition Assessment of the Building Envelope Standards ASCE/SEI 30-14 Standard ASCE/SEI 30-14 provides a guideline and methodology for assessing the condition and performance of existing building envelope systems and components. Visit the ASCE Bookstore at www.asce.org/Bookstore to purchase these books and browse the many other structural publications available.

November 2014

The Newsletter of the Structural Engineering Institute of ASCE

The American Society of Civil Engineers (ASCE) is currently searching for a Director to manage the day to day and strategic operations of ASCE’s structural engineering specialty institute, SEI, creating value added products and services, and ensuring its programs are responsive to the needs of its members and consistent with the overall mission and vision of the Institute. Responsibilities include: managing overall operations of the institute; developing staff; establishing budgets; developing and implementing programs in conjunction with institute leadership – i.e. conferences, publications, and standards; managing technical, educational, professional activities and facilitating committee work in those areas; developing and implementing

Structural Columns

Enter the 2015 SEI Student Advance To SEI Fellow Structural Design Competition The SEI Fellow grade of membership recognizes

CASE in Point

The Newsletter of the Council of American Structural Engineers

CASE Contracts – Now Available! CASE #6 – Commentary on AIA Document C141 Standard Form of Agreement Between Architect and Consultant, 1997 Edition and AIA Document C142 Abbreviated Standard Form of Agreement Between Architect and Consultant, 2009 Edition This document provides a form letter of agreement to be used with adoption by reference to AIA Document C401. This Agreement is intended for use when the owner-architect agreement is an AIA B-series. A scope of services is included. The purpose of the commentary is to point out provisions that merit special attention. CASE #6A – Commentary on AIA Document B-141 Standard Form of Agreement Between Owner and Architect with Standard Form of Architect’s Services, 1997 Edition The purpose of this Commentary is to point out provisions which merit special attention, or which some have found to contain “pitfalls”.

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 a committee ready for your service: • Toolkit Committee: Develops and maintains documents such as business practices manuals and policies for engineers under CASE’s Ten Foundations for Risk Management. 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, and • 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! STRUCTURE magazine

CASE #8 – An Agreement Between Client and Specialty Structural Engineer for Professional Services This document is pertinent when structural engineering services are provided to a contractor or a sub-contractor for work to be included in a project where you are not the Structural Engineer of Record, but you are a specialty structural engineer. Your contractual relationship differs from the norm and the typical contract forms will not suffice. The CASE #8 document is tailored to this particular situation. CASE #9 – An Agreement Between Structural Engineer of Record and Testing Laboratory The Structural Engineer of Record may be required to include testing services as a part of its agreement. If a testing laboratory must be subcontracted for this service, CASE # 9 may be used. It can also be altered for use between an Owner and a testing laboratory. These publications, along with other CASE documents, are available for purchase at www.booksforengineers.com.

CASE Risk Management Convocation in Portland, OR The CASE Risk Management Convocation will be held in conjunction with the Structures Congress at the Doubletree by Hilton Downtown Hotel and Oregon Convention Center in Portland, OR, April 23-25, 2015. For more information and updates go to www.seinstitute.org. The following CASE Convocation sessions are scheduled to take place on Friday, April 24: 7:00 AM – 8:15 AM CASE Breakfast: The Future of Structural Engineering Sue Yoakum, Donovan Hatem 8:30 AM – 10:00 AM Addressing Hidden Risks in Today’s Design Contracts Speakers – Rob Hughes, Ames & Gough; Brian Stewart, Collins, Collins, Muir & Stewart 10:30 AM – 12 Noon How to Succeed Without Risking It All! Moderator – John DalPino, Degenkolb Engineers 1:30 PM – 3:00 PM Lessons Learned From Structural Cases in Litigation Speaker – Jeffrey Coleman, The Coleman Law Firm 3:30 PM – 5:00 PM SE Practice for Quality and Profitability – Panel Discussion Moderator – Stacy Bartoletti, Degenkolb Engineers November 2014

Increase your decision-making skills now at ACEC’s Small Firm Council’s (SFC) annual Winter Meeting, February 20-21 in Nashville. Speaker, Coach and Author, Shelley Row, P.E., of Shelley Row Associates LLC will ignite an interactive exploration of complex decision-making based on her personal interviews with over 70 leaders. The data confirms that the most effective leaders make decisions by gathering information while trusting their intuition. That remarkable combination is what Shelley calls infotuition™. Don’t over-think it! Join the discussion today. Infotuition… You’ve got it. Are you using it? SFC was established to protect and promote the interests of the smaller firms within ACEC. Its winter meeting provides an exclusive forum for small firm principals to attend seminars, network with peers, address key issues affecting their firms, learn and share new ideas. Attendees provide valuable input that helps SFC direct the business and legislative agenda for the coming year. To learn more about SFC, visit www.acec.org/sfc.

ACEC Business Insights NEW AMAZON PORTAL Knowledge is power – and your firm’s greatest asset. Whether it’s keeping ahead of the competition or improving your bottomline, beefing up your firm’s know-how can only help. And laying your hands on trustworthy A/E and business resources is about to become a whole lot easier. In mid-August, ACEC launched its new webstore, the ACEC Business Resource Center, on the Amazon e-commerce platform. Now ACEC members, as well as A/E professionals worldwide,

can enjoy fast access to hundreds of engineering and general business resources published by ACEC and other publishers through one convenient hub. As an added benefit, current Amazon Prime members can continue to enjoy the privileges of Prime membership – including free 2-day shipping – when making purchases at the ACEC Business Resource Center. Visit the ACEC Business Resource Center at www.ACECEngineeringBookCenter.org.

Standard Form of Public-Private Partnership Agreement Published Public-private partnerships (P3) are a way for governmental entities to leverage the expertise, resources, and financing of the private sector to implement needed public improvements. Because developing P3 contracts from scratch can be very time-consuming and expensive, the Engineers Joint Contract Documents Committee (EJCDC), of which ACEC is a sponsor, recently published its new document EJCDC P3-508, PublicPrivate Partnership Agreement. EJCDC P3-508 is the first standard P3 contract form for use in the United States developed by a non-profit, industry professional organization. Under a P3 contract, the private entity is retained to design, build, finance, operate, and/or maintain a public improvement for a concession term that usually extends for many years. EJCDC P3-508 addresses these items, together with provisions on revenue to which the private entity will be entitled, revenue STRUCTURE magazine

adjustments during the concession term, management, future improvements, and other topics relevant to P3 contracts, but is sufficiently-flexible to allow users to tailor it to the specific needs of each separate P3 contract. Where enabled by law, P3s can be used for implementing improvements such as public utilities, transportation infrastructure, schools and other public buildings and structures, and others. EJCDC created EJCDC P3-508 in recognition of the growing number of government entities seeking private partners in jurisdictions where laws and regulations allow P3s. While it can be used with a variety of design and construction or design-build documents, EJCDC’s Design-Build (D-Series) documents are well-suited for use in conjunction with EJCDC P3-508. Visit www.acec.org/bookstore and click the “Contracts” link for EJCDC P3-508 and the full library of EJCDC documents.

November 2014

CASE is a part of the American Council of Engineering Companies

Does your company have data but lack insight? Is the rapid pace of change a challenge to timely decision-making? Is valuable time wasted searching for just one more piece of data? As a leader of a small firm, you face increasingly complex decisions – decisions that are filled with ambiguity, uncertainty and risk. To remain competitive, you can’t wait for complete data and certainty. To save time and money you must decide and decide now. It’s easy. Successful leaders know the secret. They gather as much information as feasible and they pay attention to intuition – gut feelings. Powerful decisions come from balancing cognition and intuition in a skilled internal calculus. New research in neuroscience reveals the proven processes your brain uses to perform that calculus. Now you can harness that power for the management of your firm and development of future leaders. Through these sessions, discover practical skills that put neuroscience to work for you and your business so that you can avoid the pitfalls of over-thinking; sidestep analysis paralysis; learn techniques to simplify complex decisions; and develop future leaders who are both smart and insightful.

CASE in Point

Strengthen your Competitive Edge: Increase your Decision-Making Skills

Structural Forum

opinions on topics of current importance to structural engineers

Increasing the Velocity of Knowledge – Accelerated By Gene Frodsham, M.S., S.E.

n article in the August 2013 issue of Scientific American, “Learning in the Digital Age,” addresses the abilities of gaming technology ported over for educational use in Massively Online Open Courses (MOOC). Sugata Mitra, BBC news (www.bbc.co.uk), noted that students in rural Africa can use Skype to get the best teachers. These stories address the availability of knowledge, not the presentation of knowledge for comprehension, speed of transfer, or integration, and are chained to the twodimensional world. The idea that I presented in my previous Structural Forum column, Increasing the Velocity of Knowledge (July 2013), is that an immersion in organized interactive knowledge with programmed or live tutors allows the fastest transfer of knowledge; a virtual world in 3D space where we can experience simulated reality. We now present knowledge at a set rate, then grade on how much is learned at that rate. The interactive emergent system allows the student to choose tutors and a preferred method of presentation for really learning. The brain is modeled crudely, and Internet tools are not optimized. We cannot know the limits of the mind; all we can do is continually remove constraints to learning. The ancient Greeks recognized the difference between “memory” and “recollection,” what we know and what is referenced; immersion in organized interactive knowledge will extend recollection, blurring the line between it and memory, and thus accelerating learning. Lawrence Lessig, in The Future of Ideas, describes the commons where everyone can contribute and the efforts of society are coordinated. Lessons and courses can be used by others to provide variations or new uses without the constraints of the patent and copyright systems restricting the flow of knowledge. It is not necessarily free information, but freely available for use and reuse. It will take the coordinated effort of societies to complete the massive project for the display of human knowledge in a 3D, interactive, integrated format. It takes a commons to create the framework to make the next great step in human knowledge. Mr. Lessig provides this

idea in which to develop an emergent system for the collection and extension of knowledge. Conrad Wolfram (www.computerbasedmath. org) has an idea for math that can be expanded to the 3D world. The site states, “The importance of math to jobs, society, and thinking has exploded … Meanwhile, math education is in worldwide crisis – diverging more and more from what’s required by countries, industry, further education … Computers are key to bridging this chasm: only when they do the calculating is math applicable to hard questions across many contexts. Real-life math … education needs this fundamental change … to redefine math education … toward real-life problem-solving situations that drive high-concept math understanding and experience.” Imagine real-life problems with 3-D representation, mathematics displayed with equations and methods in an interactive calculation format, with a tutor (live or programmed) and references surrounding the student. Being knowledgeable is not the same as being adept. Schooling gives knowledge, but provides little basis for engineering judgment. With presentation in 3D immersion, students can see projects from conception to construction; from analysis and design to field engineering, troubleshooting, and problem solving. A programmed tutor or live professor can guide them in the development of engineering skills. It will not replace experience or mentoring, but offers a huge advantage by saving and transmitting experience. What is applicable for structural engineering is true for electronic design, chemistry, the mechanical arts and the trades, history, geography, and ideas in general. Imagine donning goggles and special gloves to capture hand motion, and then overhauling a motorcycle. A tutor of the student’s choice disassembles a bike, describing every step, specification and tolerance along the way. Students then pick up virtual tools and dismantle and inspect every part, repairing as needed, and then reassemble the bike. A new taxonomy is needed for presentation of the required adjunct knowledge, as the traditional preparatory education is replaced

by associated knowledge that is given as it is required. It is inherent in the emergent commons that its measurement and modification will become the grounds for the study of human intellectual capabilities and the testing of educational theories, rather than the hundreds of millions now spent on “educational research.” The danger is that an oral culture could develop in the 3D world, unconstrained by the exactness of the written word as the uneducated masses, deprived of the traditional preparation, get a chance to learn. Gresham’s Law – “bad money drives out good” – also applies to information, and the prevention of the sheer mass of noise is necessary. A commons must still be governed. The first step is programming the 3D space, then making virtual equipment and materials for each discipline and trade with the programming needed for creating classes. The rules for the commons and for governance can be developed in parallel. Much of the coding for this has already been created, and the hardware is now off-the-shelf. It only remains to organize the knowledge of the human race. We battle time. Tools matter; slide rules to calculators to computers to a virtual reality of knowledge allow us to fight this enemy. The gigabit internet and 5G phone systems being developed will provide high-speed access and computing ability everywhere, making deployment possible. With the equipment in a small briefcase, a child anywhere could access the best laboratories, teachers and classes for any of the sciences, arts and trades; an educational commons for the world. We are now in possession of the tools to accomplish this as never before. It is the work that we can do as a society and a generation to free us from the tyranny of ignorance and time. In the words of the poet, Delmore Schwartz, “Time is the fire in which we burn,” and all can have the opportunity to burn brightly.▪ Gene Frodsham, M.S., S.E., is a structural engineer practicing in Nevada. Gene can be reached at gfrodsham1@gmail.com.

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

November 2014

Strong Structures Come From Strong Designs

With RAM™, STAAD® and ProStructures, Bentley offers proven applications for:

Build it with Bentley! Integrated projects, teams and software. Bentley’s Structural Software provides you the tools you need for strong designs and supports an integrated workflow all the way around. Having all the applications you need for the tasks at hand, along with the ability to easily synchronize your work with the rest of the project team, helps you get your job done right, fast and profitably.

Visit www.bentley.com/Structural to learn more! © 2014 Bentley Systems, Incorporated. Bentley, the “B” Bentley logo, ProjectWise and MicroStation are either registered or unregistered trademarks or service marks of Bentley Systems, Incorporated or one of its direct or indirect wholly owned subsidiaries. Other brands and product names are trademarks of their respective owners.

• Metal Buildings • Steel/Steel Composite • Aluminum • Reinforced Concrete • Foundation Design • Steel Connections • Structural Drawings and Details

… all easily coordinated with the Architect and other team members and their design applications – such as AutoCAD, Revit, MicroStation® and more.

STRUCTURE magazine | November 2014

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