STRUCTURE magazine | May 2016 by structuremag

May 2016 Masonry

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE ®

Masonry solutions OWER

TES

BORA

PowerStud+® SD1

PowerStud+® SD4/SD6

WedgeBolt+®

Lok-Bolt AS®

Tapper+®

Hollow Set

ToggleBolt

StrapToggle

✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔

AC100+ Gold® Pure110+®

Gas Pins

Powder Pins

✔ ✔

ESR-3200

ESR-2966

ESR-1678

ESR-3196

ESR-3275

✔

IC REG

I C AT

OWER

TES

✔ ✔

LIF

Grouted CMu

BORA

✔ ✔ ✔ ✔ ✔ ✔ ✔

ESR-3200

ESR-3275

✔

IC REG

OWER

TES

I C AT

BrICK

LIF

uNGrouted CMu

BORA

✔

AC100+ Gold® Pure110+®

✔ ✔ ✔ ✔

PowerStud+® SD1

PowerStud+® SD4/SD6

WedgeBolt+®

Powers 7th edition technical Manual is now available! Please contact your local Powers Field Engineer at 800-524-3244 to schedule a Lunch & Learn and receive your new Tech Manual.

Lok-Bolt AS®

Tapper+®

Hollow Set

D R I V E N

ToggleBolt

StrapToggle

Gas Pins

Powder Pins

E N G I N E E R E D

THE CONCRETE SOLUTION

™

701 E. Joppa Road, Towson, MD 21286 (800) 524-3244 • www.powers.com

Introducing Trimble’s Structural Software Suite Powerful Structural Software to: Analyze, Design, Detail and Construct Buildings Tekla Tedds

- Calculation Production Suite - Automate all your structural calculations & deliver high quality documentation

Come see us at: NCSEA Convention Booth 149 tek.la/ncsea2016

Tekla Structural Designer -Analysis & Design Suite -Focused Analysis & Design for Steel & Concrete Buildings

Tekla Structures -BIM Solution for Structural Engineers -Produce construction documents and shop drawings from one solution

“Tekla Structures is the most exhautive form of communication that we require on our projects. Just as important, Tekla has shown a willingness to incorporate the needs of designers, such as making it easier to produce construction documents from models” — Stephen E. Blumenbaum, Walter P Moore TRANSFORMING THE WAY THE WORLD WORKS

Transform the way you work with Tekla’s complete software suite:

http://tek.la/eng

SGA / IBI Group Architects in joint venture with Will Alsop Cast node photograph: Dieter Janssen

Experience this design in Augmented Reality

If you could make structural steel take any shape, what would you have it do? Download the free Augment app

Fill screen with this ad & scan with Augment

innovative components for inspired designs

STRUCTURE

May 2016 30

FEATURE

Louisiana Sports Hall of Fame and Northwest Louisiana History Museum

34 EDITORIAL

7 The Summit Experience

BUILDING BLOCKS

By David L. Kufferman, P.E. In 2003, the Louisiana Sports Hall of Fame was accepted into the Louisiana State Museum system, which set the stage for the creation of a new museum building. The most distinctive feature of the new building, completed in 2013, is the undulating cast stone surface on both its interior and exterior.

39 More Than Square By Laurel Fritz and

INFOCUS

9 Creating a Roadmap for Professional Success By Barry Arnold, P.E., S.E., SECB LESSONS LEARNED

11 Hybrid Masonry Connections and Through-Bolts By Gaur Johnson, Ph.D., S.E. and Ian Robertson, Ph.D., S.E. TECHNOLOGY

14 Finite Element Modeling, Analysis, and Design for Masonry By Samuel M. Rubenzer, P.E., S.E. STRUCTURAL ECONOMICS

20 Efficiency and Economy in Bridge and Building Structures – Part 1 By Roumen V. Mladjov, S.E. CODE UPDATES

Meghan Elliott, P.E. HISTORIC STRUCTURES

43 Wheeling Suspension Bridge

FEATURE

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

Restoring the Foundation of Justice

P.E., P.L.S. INSIGHTS

46 Staying within the “Circle of Trust” on DB/IPD/EBD Projects By Joseph Rietman SPOTLIGHT

By Thomas E. Forsberg, P.E. When the roof on the historically significant County courthouse leaks, what do you do? Of course, you patch it. When the “patch method” no longer works, a new approach is to thoroughly examine the roofing and dome structure and recommend corrective work, and, remove and restore Justitia (the Statue of Lady Justice) perched atop the County courthouse dome.

51 Did You Say, “Build it with Mushrooms”? By Shaina Saporta, P.E. and Matt Clark, C.Eng., P.E. STRUCTURAL FORUM

58 Public Perception of Structural Engineers By Dilip Khatri, Ph.D., S.E.

25 Significant Changes between ACI 318-11 and ACI 318-14 – Part 2 By S. K. Ghosh, Ph.D.

On the cover ‘When Virtual becomes Reality: Cast Stone Meets the Information Age in Louisiana’… The cast stone atrium of the Louisiana Sports Hall of Fame and Northwest Louisiana History Museum. See the feature article on page 30.

IN EVERY ISSUE 8 Advertiser Index 48 Noteworthy 49 Resource Guide (Steel/CFS) 52 NCSEA News 54 SEI Structural Columns 56 CASE in Point

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

May 2016

Editorial

The new trends, Summit new techniques Experience and current industry issues The Perspective of Young Engineers

The following article is a reflection of Brian Petruzzi’s experience at the 2015 NCSEA Summit, with contributions provided by Jera Schlotthauer.

here has been an ongoing conversation within NCSEA over the last few years on the importance of Young Member Groups. Articles written in this publication have not only discussed the benefits of Young Member Groups but also stated the importance of Young Member Groups as a valuable investment for the next generation of structural engineers. As a founding board member and a past Chair of the Structural Engineers Association of Metropolitan Washington Young Member Group (SEAMW-YMG), I could not agree more with those articles. However, I’d like to take this opportunity to discuss the importance of encouraging young engineers to get involved in the structural engineering profession at the national level, particularly by attending structural engineering conferences such as the NCSEA Structural Engineering Summit. As a first time attendee of the NCSEA Summit last year, I was impressed by the conference’s intimate feel (as far as national conventions go) and NCSEA’s commitment to cater programming to the practicing engineer. As one of the ‘young engineers’ in attendance, I was also fascinated by the noticeable effort to make young engineers feel welcome. National conventions can be a daunting scene for young engineers to navigate; however, between the Young Engineers Welcome Reception, the session designed to foster conversation about generational differences in the workplace, and special ‘Young Member’ ribbons on our name tags, it was clear to me that NCSEA is making a concerted effort to welcome young engineers to their conference. During a conversation with one of the “more seasoned” structural engineers, it was impossible not to sense the irresistible excitement in their voice – people were genuinely delighted we were there. Arguments for attending conferences typically sound something like this: “Conferences provide an opportunity to expand your technical knowledge, improve your soft skills, and network with others in your field.” Although these statements are true, perhaps the most impactful part of attending the NCSEA Summit for me was the overall sense of community I felt at the conclusion of the conference. To me, meeting other people in the structural engineering profession is like meeting your neighbors. Neighbors look out for each other and together share the responsibility to take care of the neighborhood. Leaving the NCSEA Summit, it was hard not to feel this sense of responsibility for the structural engineering community. The people I just met were the people taking care of our profession. If not for them, who would do it? Perhaps more relevant, if not for young engineers like myself, who will do it in the future? A culture of personal accountability, where employees possess the confidence and the courage to take ownership over their success, is the most powerful characteristic of a successful work environment. Attending conferences such as the NCSEA Summit surrounds young engineers with people who are taking accountability for their careers by stepping outside of their workplace to strengthen

STRUCTURE magazine

themselves and their profession. Environments like this are contagious and allow young engineers to develop into future leaders that will take accountability for both their personal success back at the office and the structural engineering community as a whole. It is impossible for an office environment to recreate the energy generated at a conference. Young engineers directly out of school often have a lot of energy and enthusiasm. They are starting a new chapter in their lives and are eager to learn and establish themselves amongst their peers. After a successful transition to the workplace, many young structural engineers are driven to obtain their P.E. (or S.E.). However, after a few years, sitting in the same chair within the same cubicle, talking to the same people, can keep them from maintaining this energy. Attending conferences such as the NCSEA Summit allows young engineers to break out of their comfort zone and be exposed to like-minded people who are willing to take time away from the office and are enthusiastic to learn something new. This renewed energy is one of the many tangible benefits that young engineers can bring back to the office. Beyond what I shared in this editorial, there are countless reasons why young engineers should be involved with their profession outside of their office walls. For whatever reason one decides to attend the NCSEA Summit this fall, I’m confident that, as each young engineer returns home, he or she too will feel the support and sense of community that I experienced and will be empowered to care for and ensure the success of the structural engineering profession in the future. This year’s NCSEA Summit is in Orlando, the magical home of Disney, a place that embraces the creativity and successes of the people that built it, and that has been inspiring future generations for over 40 years. What better combination – the NCSEA Summit and Disney – to bring everyone in our profession together? Regardless of age, we hope that you will join us – and your neighbors – in Orlando for the 2016 NCSEA Structural Engineering Summit.▪ Brian Petruzzi is a Project Engineer for Thornton Tomasetti and Founding Member and Past-Chair of the Structural Engineers Association of Metropolitan Washington Young Member Group. Brian may be contacted at BPetruzzi@ThorntonTomasetti.com. Jera Schlotthauer is a Structural Engineer, EIT II for Martin/ Martin Wyoming and the current Chair of the NCSEA Young Member Group Support Committee. Jera may be contacted at Jschlotthauer@mmwyo.com. For more information on the NCSEA YMGSC, please visit www.ncsea.com/members/younggroups.

May 2016

ADVERTISER INDEX

PLEASE SUPPORT THESE ADVERTISERS

Anthony Forest Products Co. ................ 29 Applied Science International, LLC....... 59 ASDIP Structural Software ...................... 8 Bluebeam Software .................................. 6 Cast ConneX........................................... 4 Clark Dietrich Building Systems ........... 23 CTP Inc. ............................................... 37 Design Data .......................................... 50 Dlubal Software, Inc. ............................ 48 Halfen USA, Inc. .................................. 10 Hardy Frame ......................................... 47 Heckmann Building Products, Inc. ....... 27

Hohmann & Barnard, Inc. .................... 24 Integrated Engineering Software, Inc..... 42 Integrity Software, Inc. .......................... 15 KPFF Consulting Engineers .................. 41 Legacy Building Solutions ..................... 38 Lindapter .............................................. 45 Powers Fasteners, Inc. .............................. 2 RISA Technologies ................................ 60 Simpson Strong-Tie............. 13, 18, 19, 33 Structural Technologies ......................... 17 Trimble ................................................... 3 Williams Form Engineering .................. 21

STRUCTURE

ADVERTISING ACCOUNT MANAGER INTERACTIVE SALES ASSOCIATES sales@STRUCTUREmag.org Eastern Sales Chuck Minor 847-854-1666 Western Sales Jerry Preston 480-396-9585

EDITORIAL STAFF Executive Editor Jeanne Vogelzang, JD, CAE execdir@ncsea.com Editor Christine M. Sloat, P.E. publisher@STRUCTUREmag.org Associate Editor Nikki Alger publisher@STRUCTUREmag.org Graphic Designer Rob Fullmer graphics@STRUCTUREmag.org

Erratum The author of the article Rethinking Seismic Ductility (Building Blocks, STRUCTURE, March 2016) discovered an error after publication. The following corrections have been made: Table 1 • The caption should read, “Maximum lateral tie…” • The “minimum” to the right of Pile Location and Condition should be “Maximum” Table 2 • The caption should read, “Maximum lateral tie…” • The “minimum” to the right of Pile Location and Condition should be “Maximum” Text • The reference to Table 1 in the text should read “…the maximum spacing of the transverse steel is specified in Table 1.” • The reference to Table 2 in the text should read “Maximum spacing of the transverse steel is specified in Table 2.” All corrections have been made to the online version of the article, and to the associated downloadable/printable PDF.

Web Developer William Radig webmaster@STRUCTUREmag.org

EDITORIAL BOARD Chair Barry K. Arnold, P.E., S.E., SECB ARW Engineers, Ogden, UT chair@structuremag.org Jeremy L. Achter, S.E., LEED AP ARW Engineers, Ogden, UT John A. Dal Pino, S.E. Degenkolb Engineers, San Francisco, CA Dilip Khatri, Ph.D., 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 Jessica Mandrick, P.E., LEED AP Gilsanz Murray Steficek, LLP, New York, NY Brian W. Miller Davis, CA Mike Mota, Ph.D., P.E. CRSI, Williamstown, NJ Evans Mountzouris, P.E. The DiSalvo Engineering Group, Ridgefield, CT

ADVERTISEMENT - For Advertiser Information, visit www.STRUCTUREmag.org

Greg Schindler, P.E., S.E. KPFF Consulting Engineers, Seattle, WA Stephen P. Schneider, Ph.D., P.E., S.E. BergerABAM, Vancouver, WA John “Buddy” Showalter, P.E. American Wood Council, Leesburg, VA C3 Ink, Publishers A Division of Copper Creek Companies, Inc. 148 Vine St., Reedsburg WI 53959 Phone 608-524-1397 Fax 608-524-4432 publisher@structuremag.org May 2016, Volume 23, Number 5 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) or email subscriptions@STRUCTUREmag.org. Note that if you do not notify your member organization, your address will revert back with their next database submittal. 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 magazine

May 2016

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.

InFocus

Creating a Roadmap for Professional Success new trends, new techniques and current industry issues By Barry Arnold, P.E., S.E., SECB

ave you heard or read about engineers becoming dissatisfied with the profession, their employer, or their career and pursuing employment in other occupations? Some suggest the source of dissatisfaction is a result of a conflict between the work the engineer is engaged in and their values and passions. In his book Built to Last: Successful Habits of Visionary Companies, author Jim Collins encouraged companies to ask themselves, “What do we stand for and why do we exist?” That is sound advice for companies wanting to be successful and long lasting. It is critical advice for individuals wanting a satisfying, rich, and rewarding career. Losing an engineer to some other occupation is a great loss to the profession. It is also expensive for companies and organizations. An engineer’s career consists of years of education and experience, as well as the accumulation of knowledge – all of which are difficult and expensive to replace. Many companies recognize the cost and difficulty associated with training engineers, so they painstakingly vet potential employees to find candidates whose values and passions parallel those of the company. However, even the best companies find this difficult to do consistently and the results are usually hit and miss. Discovering what inspires and motivates an engineer is not easy. A person can attend exotic retreats, sit in sweat lodges, or practice yoga for months and not discover their core values or passions. Discovering these can take considerable effort and commitment. The best way to simplify the process is to write down your thoughts and compile them into a manifesto. A manifesto – a personal creed – is useful for defining one’s values and passions, and helpful in establishing boundaries to avoid conflicts. The use of a manifesto has diminished in recent years because of the rise of vision and mission statements; however, a manifesto is fundamentally different. While vision and mission statements are generally vague and company-centric, a manifesto focuses on a person’s own core values and passions and provides direction when making decisions. A manifesto is more than a list of rules. Once implemented, it becomes a personal brand – a kind of personal vision and mission statement – differentiating you from your peers. Many companies have had great success using manifestos. To reinforce his values, beliefs, and brand, Frank Lloyd Wright used an Apprentice Manifesto which reads: “An honest ego in a healthy body; An eye to see nature; A heart to feel nature; Courage to follow nature; The sense of proportion (humor); Appreciation of work as idea and idea as work; Fertility of imagination; Capacity for faith and rebellion; Disregard for commonplace (inorganic) elegance; and Instinctive cooperation.” Many successful people have used a manifesto as a guide to keep them aligned with their core values and passions. In June 1938, Edmund N. Carpenter, at the age of seventeen, wrote an inspiring manifesto (www.wsj.com/articles) titled Before I Die, highlighting the kind of person he wanted to become, the things he wanted to accomplish, and the experiences he wanted to have to live a full and rewarding

STRUCTURE magazine

life. Using such a powerful manifesto as a guide, it is not surprising that Carpenter won the Bronze Star during World War II, graduated from Harvard Law School, and was president of a law firm. Using his manifesto as a guide, he no doubt enjoyed a successful professional career and deep personal satisfaction. My first manifesto was provided by an admired professor at graduation. It is short and direct: “Don’t Kill Anyone.” It was simple and easy to remember but lacked depth and breadth. After a few years of experience and exposure to a variety of situations, I changed my manifesto to read, “Don’t kill anyone as a result of ignorance, arrogance, negligence, or indifference.” After thirty years of experience, the key points of my current manifesto include: • Own your career. Your goals, vision, mission, and destiny are yours to decide. • Be a professional. Your responsibility is to the health, safety, and welfare of the public, and the environment – not to a deadline or profit margin. Before applying your professional seal and signature to any document, pause and reflect on your ethical contract with society. • Don’t just belong to the profession, contribute to it. Serve the profession with spirited dedication. • Nurture your creative and technical mind. Ask: What if…? and Why…? • Be inquisitive. Education never stops. Doubt. Question. Verify. Prove. • Endeavor for a clear conscience. A clear conscience is the most valuable award, benefit, or acknowledgment you will receive. A manifesto is a personal roadmap for professional success. A manifesto is about values and passions – period. Nowhere do I declare the titles I want to have, the positions I want to hold, or the amount of money I want to make. They do not belong in a manifesto. Instead, a manifesto focuses on areas that will provide lasting benefits and personal rewards. Having a manifesto will not guarantee professional success. However, my experience has shown that, when followed, a manifesto will keep a person aligned with their values and passions and provide clear guidance. Best of all, it is a potential antidote for dissatisfaction with one’s profession, employer, or career. What are your thoughts? Do you have a manifesto? Would you like to share it? The discussion continues at www.STRUCTUREmag.org.▪ Barry Arnold (barrya@arwengineers.com) is a Vice President at ARW Engineers in Ogden, Utah. He chairs the STRUCTURE magazine Editorial Board and is the Immediate Past President of NCSEA and a member of the NCSEA Structural Licensure Committee.

May 2016

Appalachian State University (ASU) Boone, NC

Masonry has a New Edge. And it’s called HALFEN FK4. Introducing a new adjustable shelf angle with a thermal break.

ALFEN FK4 brickwork supports transfer the dead load of the outer brick veneer to the building’s load-bearing structure: an eﬀcient construction principle developed with the experience of over 80 years of lasting technology.

Adjustability HALFEN FK4 brickwork supports provide continuous height adjustment of +/- 13/8” which compensates for existing tolerances of the structure as well as installation inaccuracies of wall anchors.

Reduced Thermal Bridging The HALFEN FK4 brickwork supports are oﬀset from the edge of slab allowing insulation to pass behind. Minimal contact with the building structure means reduced thermal bridging and lower energy loss.

Efficient Design As the demand for higher energy efficiency in commercial buildings continues to increase, the cavity between the brick veneer and the substrate is getting larger to allow for more insulation and air space. Along with this increased cavity size, the traditional masonry shelf angle, used to support the brick veneer at the slab edge, is also getting larger and subsequently heavier and more expensive to install. Architects & engineers are looking for a more efficient support solution. The HALFEN FK4 brickwork supports use a thinner, light weight shelf angle, eliminating brick notching while also allowing for a wider cavity.

Structural Eﬃciency The HALFEN FK4 brickwork supports allow eﬃcient anchoring of brickwork facades in connection with HALFEN cast-in channels.

Quality By using HALFEN FK4 brickwork supports, you proﬁt from an approved anchoring system, excellent adjustment options and a complete product program covering all aspects of brickwork facade. Many advantages with one result: HALFEN provides safety, reliability and eﬃciency for you and your customers.

HALFEN USA Inc. · PO Box 547 Converse · TX 78109 Phone: 800.423.9140 · www.halfenusa.com · info@halfenusa.com

s voluminous as our codes have become, they do not provide guidance to all situations. Students in structural design classes often ask the professor, “What is the procedure I need to follow?” The question they should be asking is “What is the underlying behavior?” Only then will they begin to develop engineering judgment and be able to correctly implement code provisions in their designs. Experienced engineers know that there are many instances in which engineering judgment is needed to move a design forward; the code allows for judgment based on a “rational analysis.” The underlying structural behavior informed by fundamental engineering principles can be used to build on a code provision. An engineer’s willingness to provide a client a design based on a rational analysis will be subject to the perceived risks and benefits associated with the design. The following are lessons learned from a limited number of tests performed on structural connections between steel and masonry elements of hybrid masonry seismic structural systems. The goal of this article is to help practitioners gain a better understanding of the behavior of throughbolted masonry connections so that they can appropriately implement existing code provisions into designs prior to more data being developed.

Hybrid Masonry Overview Hybrid masonry was introduced as a structural system concept in 2007. The system is composed of a structural steel frame and reinforced concrete masonry panels. Hybrid masonry offers a design alternative to braced frames and moment-resisting frames that are appropriate for low and mid-rise construction. It is best suited for cases where a structural steel framing system and masonry walls would naturally be chosen due to structural and architectural efficiency. Hybrid masonry includes three distinct types of load transfer, which are shown in Figure 1. In Type I Hybrid Masonry (Figure 1a), steel connectors transfer in-plane shear between the steel frame and the top of the masonry panel. These connectors can be either rigid link plates or ductile fuse plates. The connectors do not transfer any vertical

(a)

load to the masonry wall, but their design can have a significant influence on the overall performance of the system. In Type II and III Hybrid Masonry (Figure 1b and Figure 1c), headed studs are used to transfer shear from the beam and/or columns to the masonry panel. Vertical load is also transferred directly through contact from the beam to the top of the masonry panel. In its simplest form (Type I), hybrid masonry consists of reinforced concrete masonry panels connected to the surrounding steel frame such that story shears can be transferred from the floor beams to the masonry. The masonry panel is constructed in-plane with the steel frame, supported on the floor beam or foundation below the panel. Steel connector plates between the masonry panel and the floor beam above the panel transfer only horizontal story shears (Figure 1a). The masonry does not make contact with the upper beam or columns other than through-bolts in vertically slotted holes in the connector plates, which are designed either as ductile “fuse” or elastic “link” connectors. The structural masonry panel acts as a surrogate-bracing member and can be reinforced both vertically and horizontally to resist in-plane and out of plane lateral forces. Hybrid Masonry Types II and III are designed to transfer both shear and vertical load from the steel beam to the top of the masonry panel and, in the case of Type III, to transfer shear between the panel and the steel columns (Figure 1b and Figure 1c). Shear transfer is achieved through the use of headed studs welded to the beam and columns and embedded in the grouted cells, or formed bond beams, of the concrete masonry panel. All inelastic activity is focused in the masonry panel, while the steel frame and headed studs are designed with an overstrength factor to remain elastic during a design level seismic event.

Lessons Learned problems and solutions encountered by practicing structural engineers

Hybrid Masonry Connections and Through-Bolts

Through-Bolt Connectors The performance of hybrid masonry is highly dependent upon the performance of the connectors. Therefore, much of the research on hybrid masonry

(b)

(c)

Figure 1. Hybrid Masonry Systems: (a) Type I; (b) Type II; (c) Type III.

STRUCTURE magazine

By Gaur Johnson, Ph.D., S.E. and Ian Robertson, Ph.D., S.E.

Gaur Johnson is an Assistant Professor at the University of Hawaii at Manoa. Gaur can be reached at gaur@hawaii.edu. Ian Robertson is a Professor of Structural Engineering in the Department of Civil and Environmental Engineering at the University of Hawaii at Manoa. Ian can be reached at ianrob@hawaii.edu.

has uncovered some important information on the performance of masonry connectors that are not directly addressed in the masonry standard or building codes. Due to space considerations, this article will only address through-bolted connections. However, Part 2 of the article, in an upcoming issue of STRUCTURE, will address hybrid masonry steel plate connectors and headed studs in bond beams. The practicing engineer, whether designing hybrid masonry or conventional reinforced masonry, will find that added information useful.

Through-bolt test data statistics.

Limit State

Low Pcr/Pn

High Pcr/Pn

Mean Pcr/Pn

COV

Masonry Breakout TMS 402-13

0.402

0.723

0.583

0.164

Masonry Crushing TMS 402-13

1.029

2.659

1.652

0.330

Bearing TMS 402-13

0.883

2.282

1.500

0.299

Shear of Unreinforced Masonry TMS 402-13

0.729

2.459

1.525

0.345

Shear Loading of Anchors ACI 318-14

1.232

2.152

1.708

0.150

Local Failure of Masonry at Through-bolts For the hybrid masonry system to function correctly, it is essential that through-bolt connections between the masonry panel and the connection plates are able to transfer the required load without premature failure. However, many engineers also use throughbolts for conventional masonry construction. Local masonry failure mechanisms caused by a horizontal point load introduced into a bond beam via through-bolts is not addressed by any code. Is it appropriate to extrapolate existing provisions for anchors which load one face of the wall to the through-bolts? A test setup which monotonically loaded a single through-bolt toward the end of a CMU wall was used to estimate a lower bound capacity of the masonry. Figure 2 shows one of the wall specimens after two tests. Damage on the right was caused when a through bolt in

Figure 2. Through-bolt test specimen.

the second cell from the end of the wall was loaded towards the right. Damage on the left was caused by the load applied to the left at the side plates and through-bolt shown. Details of the test setup, results and discussion

Figure 3. Limit State Geometry.

STRUCTURE magazine

May 2016

can be found in an upcoming TMS Journal article titled Capacity of Masonry Loaded by Through-Bolts in Double Shear and other reports and conference proceedings. The results were compared with code specified limit states from TMS 402-13 and ACI 318-14 which could potentially be used with engineering judgment. The TMS 402-13 limit states of masonry breakout at anchors, masonry crushing at anchors, bearing, and shear were considered. The ACI 318-14 limit state of shear loading of anchors was also considered. The formulation for each limit state can be found online at www.STRUCTUREmag.org. Figure 3 illustrates each limit state as implemented for through-bolts. Figure 4 shows a plot of the predicted capacity of each limit state considered, versus the test data corresponding to the first cracking load observed during testing. Points to the left of the diagonal line indicate a conservative under-prediction of the capacity while points to the right indicate an overprediction. The data series labeled Maximum Test Load shows the reserve or additional strength beyond the first cracking for each specimen. The TMS 402-13 limit state equation for masonry breakout clearly and consistently overpredicts the capacity. Indeed, in most cases, the prediction also exceeds the maximum test load which is shown in the figure and indicates

Build Your Career with Us

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

Figure 4. Test data versus predicted capacity from various specifications.

the additional observed strength beyond first cracking during the tests. The TMS limit states of masonry crushing at anchors and bearing are both a function of the bolt diameter and number of bolts – they do not appear to limit the connections capacity. Prediction using shear of unreinforced masonry generally was less than the actual tested capacity; however, it was an unconservative prediction in two cases. The ACI shear loading of anchors limit state provided a consistently conservative prediction. This data is not definitive especially considering the limited number of tests; however, it is instructive to know that the masonry breakout limit state equation is severely overpredicting capacity. For each limit state evaluated, the Table gives the low, high and mean ratio of the first cracking load to the predicted nominal capacity (Pcr/Pn) as well as the coefficient of variation. Values of Pcr/Pn less than 1.0 indicate that the predicted nominal capacity is unconservative. The ACI shear loading of anchors and the TMS masonry breakout of anchors limit states have a significantly lower coefficient of variation compared to the other limit states. The observed failures are consistent with the theoretical failure shown in Figure 3.

Conclusions Practitioners who use through-bolt connection details described in this article will not be able to find code language or limit states that directly

address the behavior, boundary conditions and loading which can make these connections cost effective for hybrid masonry systems. They must rely on engineering judgment and should consider the following information. Local Masonry Failure at Through-Bolts • Based on the limited test data, TMS 402-13 masonry breakout of anchors and ACI 318-14 shear loading of anchors appear to provide the best correlation to the likely failure mechanism of masonry when a through bolt is installed near an edge. However, only ACI 318-14 shear loading of anchors can be used unaltered – it will provide a conservative result (the mean failure of the tests performed is 171% of the predicted nominal capacity). • The TMS 402-13 masonry breakout of anchors limit state should be reduced significantly prior to it being applicable to predict the capacity at these connections. The mean failure of the tests performed is 58% of the predicted capacity which means that, even after using the strength reduction factor of 0.60, there will still be a 50% probability of failure at the design level load. • Engineering judgment is required to incorporate these into a design. Further testing is needed to justify any specific code provisions being adopted for these connections.▪

STRUCTURE magazine

May 2016

Take your career in a new direction. Engineers at Simpson Strong‑Tie affect building construction on a massive scale – helping our customers design and build safer, stronger structures all over the globe. We have multiple openings for structural engineers who enjoy working on innovative and challenging projects, giving presentations and being on jobsites. Learn more and apply at strongtie.com/engineerjobs.

Strong-Tie Company Inc. SSTENGIN16

TECHNOLOGY information and updates on the impact of technology on structural engineering

Line elements. | Plate/shell elements. | Solid (brick) element.

oftware programs for structural engineers continue to escalate in complexity, as engineers become increasingly reliant on those tools to increase accuracy in analysis and efficiency during design. To solve complex problems efficiently, and to gain a more in-depth understanding of the elements being analyzed, structural engineers are using Finite Element Analysis (FEA). Of course, each of the different FEA programs has their idiosyncrasies, all of which require designers to pay close attention when using these programs. What exactly is finite element analysis? It is the process of reducing (simplifying) a problem with infinite degrees of freedom to a finite number of elements with unique material properties. FEA programs can resolve even the most complex problems in a reasonable amount of time. The process of finite element modeling and analysis is an approximate solution which closely mimics an actual structure in a way that allows structural engineers to design for the stresses, forces, and deflections that are determined using the FEA method. Some of the more commonly used software programs for FEA with masonry design are RAM Elements (soon to be released as STAAD(X) from Bentley Systems, Inc.), as well as RISA Floor and RISA 3D (from RISA Technologies). Other FEA programs with high-end analysis features, such as SCIA Engineer, are important tools for structural engineers because they offer more options for

Finite Element Modeling, Analysis, and Design for Masonry By Samuel M. Rubenzer, P.E., S.E.

Samuel M. Rubenzer is the founder of FORSE Consulting and assists with designs on a variety of projects and building types. He has also been the structural engineering consultant to Structural Masonry Coalitions in several states. He can be reached at sam@forseconsulting.com.

Node Ty Rz Tz

General Comments about Finite Element Modeling Finite element models are created by modeling line, plate/shell, and solid (or brick) elements, with associated end nodes. Complicated three-dimensional elements, such as solid (or brick) elements, are not usually available in most commercial design software. In structural engineering, most problems can be modeled with one-dimensional line elements, or two-dimensional plate or shell elements, and result in reasonably accurate solutions. When creating a model, the line and plate/ shell elements with their associated properties are defined, and the end nodes are defined with translational or rotational degrees of freedom. The properties assigned to the line and plate elements must be defined to associate a reasonable stiffness with each element. Columns and beams (not masonry lintels) can be modeled with line elements, and walls and slabs can be modeled with plate/shell elements. Many software programs allow you to define the geometric boundaries of entire wall panels from movement joint to movement joint (a movement joint is either an expansion joint in brick or control joint in concrete masonry) and discretize those large geometries into smaller finite elements by a process called meshing. Sometimes meshing is a manual process, and other times software programs will offer automatic meshing.

Wall Element

Ry R

creating elements that more closely represent a structural component’s behavior.

Properties: • Axial • Vertical Bending • Horizontal Bending • Torsion • Vertical Shear • Horizontal Shear

Node degrees of freedom and wall element properties.

14 May 2016

Example of bending modification factors available in SCIA Engineer. Wall Geometry with opening. | Wall discretized into ﬁnite elements example of automatic meshing from RAM Elements.

Pre-Processing and Masonry Modeling

Important news for Bentley Users ®

Prevent Quarterly Overages when you use SofTrack’s automated license usage control of all Bentley® applications. ContaCt us now: (866) 372 8991 (USA & Canada) (512) 372 8991 (Worldwide) www.softwaremetering.com

SofTrack controls Bentley® usage by Product ID code and counts (pipe, inlet, pond, and all others) and can actively block unwanted product usage SofTrack also supports Autodesk® Cascading Licensing and

Additionally, SofTrack provides software license control for all your applications including full workstation auditing of files accessed and websites visited. Many customers also benefit from SofTrack’s workstation specific logon activity reporting. © Integrity Software, Inc. Bentley is a registered trademark of Bentley Systems, Incorporated

STRUCTURE magazine

May 2016

SofTrack directly reports and controls ESRI® ArcGIS license usage

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

Many of the analysis procedures used today assume thin plate theory and linear elastic behavior for the plate elements. The elasticity of the material is described by a stress-strain curve, which shows the relationship between internal force per unit area and the relative deformation. Linear elasticity is a simplification, assuming linear relationships between the components of stress and strain. This simplification is valid only for stress states that do not produce yielding or fracture. Reinforced masonry and reinforced concrete elements are not linearly elastic because once a concrete element cracks, steel reinforcement is engaged. Of course, masonry is made up of several different components which closely mimic this behavior when it is reinforced. Many times, finite element software provides element modification factors to account for the reduced stiffness of the masonry or concrete element once it has cracked. In some programs this factor is automatically applied, sometimes it must be manually defined, and in others, it is not an option. Some programs offer multiple element modification factors including bending in each direction, torsion, shear, and axial deformations. The engineer must confirm that the element modification factor in the program accounts for the reduced stiffness from cracking and only applies to the bending stiffness in the direction of the cracked behavior, and is not used with the shear stiffness or the axial stiffness of the element. When the analysis program does not have an appropriate element modification factor, an adjustment to the actual properties of the element might be necessary. An adjustment may mean modifying the elastic modulus of the element. The elastic modulus is used to determine the stiffness for the element in each of the deformation categories. Therefore, an adjustment will

impact the element in all properties of bending, shear, and axial deformation. This type of modification must be used with caution, and may not always be appropriate. Masonry is unique in that it is often reinforced in the vertical direction, but unreinforced in the horizontal direction. Therefore, the element may only span horizontally if it remains uncracked in that direction. If the anticipated design demand stresses are beyond the allowed cracking stresses, the engineer should consider reducing stiffness by using a reduced element modification factor. Again, this emphasizes the need for the modification factors to be considered separately in each orthogonal direction. When all of the factors are equal, the slab

element behaves as an isotropic material, a material having the same properties in all directions. When the factors are different from each other, the slab elements behave as orthotropic materials, having different properties along three perpendicular axes. Caution is prudent when using stiffness factors. With certain combinations of factors, the structure can become unstable and the results can become unreliable. Also, the interaction of the stiffness factors may be more complex than it appears upon first inspection. Masonry design also requires custom material types be used to account for attributes that are unique to the material, such as grouting only reinforced cells (partial grouting). Partial grouting affects both the loading aspect (from the self-weight contribution) of the finite

Image from RISA showing wall areas, image to the right of RAM Elements showing wall strips.

element model, as well as the stiffness of the masonry finite elements. There are some programs, such as RISA 3D, which account for partial grouting of the masonry wall. For programs that do not, modifications must be made to the finite element properties (such as altering the thickness of the element). There are advantages and disadvantages associated with modifying the thickness of an element to accommodate for the actual condition of partially-grouted masonry. The axial and shear stiffness of the wall may be accurately modified; however, the reduction to the bending stiffness of the finite elements would not be accurate and result in elements that are much weaker than they are in a real partially-grouted wall. Therefore, engineering judgment must be used when the software does not account for partial grouting, and the engineer is required to make modifications which may bring unintended consequences. It is also important to recognize that overall geometric wall modeling for masonry walls must account for the physical separation between walls due to control joints. RAM Elements allows for quickly separating linked wall panels (panels that share end nodes) into separate wall panels with unique end nodes. Whether there is a tool to create this separation, or the walls are manually modeled separately with unique end nodes, separation in the finite element model is required to ensure each wall can act independently. There are a few items to consider regarding finite element meshing. Finite element programs are based on plate elements that are quadrilateral (four nodes per plate/shell), and the ideal shape is a square. Without going into the theory of why this is ideal, it is important to know that the further plate/shell elements are from a square, the less accurate the finite element approximations become. When considering the ideal size of the plate/shell elements when meshing a wall geometry (manually or by auto meshing), the designer must consider the accuracy of the results, computational processing time, and the material being modeled. When considering accuracy,

the finer the mesh (smaller plates/shells and more of them) the higher the probability that the elements will be square. This is especially true in complex models. However, the smaller the mesh, the more plate/shells and nodes, and larger the demand for computation. Even with the advances in software, finite element models with a very fine mesh can result in unreasonable computational times. Lastly, consideration should be made for material properties. It could be argued that masonry and concrete have an inherent minimum element size due to what is referred to as the “chunkiness” of concrete. It is unreasonable to have differential movement between nodes that are closer together than the thickness of the masonry element. This is similar to evaluating one-way shear no closer than the depth of element away from a support. Considering all of these size recommendations, there is also the point of diminishing return. When a model’s approximate solution starts to converge, using a finer mesh doesn’t result in any significant changes to the final solution. In general, the recommended maximum plate/shell size would be the span distance divided by ten and the minimum plate size should be no less than the thickness of the masonry wall. For example, a twelveinch thick, thirty-foot tall wall would have a minimum plate size of twelve inches and a maximum plate size of three feet [span/eight]. Of course, there may be unique situations when these guidelines must be re-evaluated but, in general, they have been found to be

Example of complete finite element model with masonry walls, which has concrete slabs, steel beams connecting to the walls (model from SCIA Engineer).

STRUCTURE magazine

May 2016

a good starting point for determining plate/ shell size in finite element models for walls. Care should be exercised when modeling masonry wall systems with finite element analysis programs to ensure all of the boundary conditions, the stiffness of the elements, and weights of the elements are accurately accounted for in the development of the finite element model. Some may wonder if it is worth this amount of effort for a masonry wall. It is necessary if the engineer wants to understand the true behavior of complex wall systems, such as in-plane shear wall capacity of perforated shear walls (wall panels with openings in the middle), and gain an even better understanding of the out-of-plane behavior in walls with openings. Of course, modeling masonry finite elements is also essential in the following lateral analysis scenarios: • Lateral dynamic analysis for any building with masonry lateral-resisting elements. Appropriate load and stiffness is required to understand the true dynamic behavior, which yields building fundamental periods. • Lateral analysis load distribution (through rigid or semi-rigid diaphragms) between masonry and other systems or materials, such as concrete or structural steel frames.

Post-processing and Design The next challenge involves taking the results from the finite element model and analysis and converting them into information that can be compared to code-defined maximum stresses or forces that determine the capacity of the masonry wall. Finite element programs for masonry combine the results of several plate/shell elements within geometric areas or strips of the model, as defined by the user. Areas above openings are rationalized into an area that will be checked against lintel capacities. Engineers must study software programs and the combination (summation) of finite element results, and make modifications when necessary. Generally, structural engineering software will check for in-plane bending and shear capacity, out-of-plane bending and shear capacity, and axial capacity of masonry walls. Lintel shear and bending capacities must also be evaluated. Lintels (not in a finite element model) have traditionally been checked by assuming a simply supported “beam” element. Finite element approximation and design of the area above the openings are fundamentally different, as the plates/shells in this area are interlocked by sharing nodes with the other surrounding elements

State-of-the-Art Products STRUCTURAL TECHNOLOGIES provides a wide range of custom designed systems which restore and enhance the load-carrying capacity of reinforced concrete and other structure types, including masonry, timber and steel. Our products can be used stand-alone or in combination to solve complex structural challenges.

V-Wrap™

Carbon Fiber System

DUCON®

Micro-Reinforced Concrete Systems

VSL

External Post-Tensioning Systems

Tstrata™

Enlargement Systems

Engineered Solutions Our team integrates with engineers and owners to produce high value, low impact solutions for repair and retrofit of existing structures. We provide comprehensive technical support services including feasibility, preliminary product design, specification support, and construction budgets. Contact us today for assistance with your project needs.

www.structuraltechnologies.com

+1-410-859-6539 To learn more about Structural Group companies visit www.structuralgroup.com DUCON® trade names and patents are owned by DUCON GmbH and are distributed exclusively in North America by STRUCTURAL TECHNOLOGIES for strengthening and force protection applications. VSL is the registered trademark of VSL International Ltd.

STRUCTURE magazine

May 2016

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

of the wall. When evaluating bending moment in walls, software programs often evaluate only vertical bending and do not evaluate horizontal bending and shear. Therefore, the engineer is left to manually check the horizontal bending moment against an unreinforced masonry bending capacity. If horizontal bond beams are used within a masonry wall, the horizontal bending moment may be manually checked against the allowable bending capacity of a reinforced element. Some software programs may or may not be able to correctly define the finite element model. If it does not, the designer must decide if manual modifications can be made to the model without adversely affecting other attributes and the results. Further, evaluation of the post-processing design features of programs and design checks show that programs are not always complete, and must be supplemented with manual checks of the analysis results. Ultimately, careful evaluation when selecting software that is best suited for the scenario at hand is required. Supplementing with additional calculations may be needed. Therefore, it is recommended the engineer thoroughly review the element response to applied forces. The simplest and most revealing check can be made by animating the deflections of the elements. For example, a simply supported wall element should have a deflected animated shape that is a simple curve, and a wall with moments fixed at the top or with a parapet (cantilevered element above the roof ) should have a compound curved. To review the forces in the element, a quick manual calculation should be within 20-25% of the anticipated forces in any particular element within a finite element model. Lastly, reviewing the reactions to the applied forces is a good study to make sure the elements have been modeled properly. The finite element models structural engineers create often contain other materials and elements that connect to the masonry wall elements. It is important to consider how those elements connect to the masonry. Areas to watch for include: Should the beams (line elements) framing into the wall be modeled as pinned or fixed? Should the end of the beam be offset from the centerline of the masonry wall panel to model eccentricities? Are the shell/plate slab elements pinned or fixed to the masonry walls? There are many items to consider when using FEA software programs to model masonry walls. However, there are very good software options available which make using FEA programs more accurate and more efficient, and make us better engineers once we learn how to use them correctly.▪

The Power to

Barclay Simpson started our company with a simple belief—help customers solve problems. Barc did just that when he created our first joist hanger for a customer in 1956. Today, we continue to help solve construction challenges with our full product offering of structural connectors, fasteners, fastening systems, anchors, lateral systems, software, and concrete repair, protection and strengthening systems.

We’re ready with the products and support to help give you the power to build. Learn more by calling your local rep at (800) 999-5099 and visiting strongtie.com/powertobuild.

Strong-Tie Company Inc. SST15-E

Structural EconomicS cost benefits, value engineering, economic analysis, life cycle costing and more...

Akashi Kaikyo Bridge

fficiency and economy of structures are important parts of structural engineering. This is not a new idea. Many remarkable bridges and buildings have been built under strict financial constraints. The need for selecting an efficient structural system is valid for any structure, except some very rare cases when the owner possesses virtually unlimited funding and is more interested in building a monument than in efficient construction. In this 2-part article, more attention is given to bridge vs. building structures for two reasons: first, the cost of the structure in a bridge is the predominant part (about 90 to 98%) of the total cost, while for a building the structural cost is only about 12 to 18% of the total. Second, in bridges the structural engineer has much more influence on the final decision. However, further observations, data, and conclusions for bridge structures are also valid in general for building structures. One can find discussions on the economy of materials and costs as early as the first century BC in Vitruvius, The Ten Books on Architecture, Book I, Chapter II. Although the well-known motto of Mies van der Rohe “Less is More” was intended for architecture, it is perfectly valid for any structure in terms of cost and materials. Later, in 1990, David Billington of Princeton University defined the three principles of good bridge design as Efficiency (of materials), Economy (of cost and time) and Elegance (slenderness, elegance, and good proportions). It is even more important to have efficient construction in periods when a country’s economy is experiencing difficulty. In addition to new bridge construction resulting from increased demand, existing bridges are examples of an aging infrastructure not only in terms of years of service but also by falling behind the complex modernization of the transportation industry. The US Department of Transportation has found that at the end of 2015 more than 142,900

Efficiency and Economy in Bridge and Building Structures Part 1: A Study for Structural Efficiency and Economy in Construction By Roumen V. Mladjov, S.E.

Roumen V. Mladjov has more than 50 years in structural and bridge engineering, and in construction management. He lives in San Francisco and his main interests are structural performance, efficiency and economy. He can be reached at rmladjov@gmail.com.

The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

20 May 2016

highway bridges in the country are structurally deficient or functionally obsolete. This is about 27% of all bridges (based on a percentage of their deck areas). The situation is even worse in some states. For example, in California, the deficient bridge area is 33.2%, in New York State, 58.9%! Despite the desire of political leaders to improve our infrastructure, the allocated funding will not suffice to repair or upgrade so many structures. Using efficient, economic structures is essential for better use of limited funding and for a faster improvement of the overall condition of the bridge infrastructure in this country. Also, environmental-best-practices, like using fewer materials in construction and reducing carbon footprints, place an increased importance on economics and efficiency.

Rating the Efficiency of Structures To analyze structural economy, it is first necessary to determine how to rate and compare the efficiency of structures. The RS Means Construction Cost Data provides the cost range for different types of buildings around the country; however, these are average values for completed buildings and to the author’s knowledge there is no established normative for the efficiency of building and non-building structures. Designers, like owners and developers, are interested to know in advance the range of cost and material expenses needed to build a structure for a project of a certain magnitude, but such information is generally not available. The main goal of efficient and economic design is to build a specific building, bridge or other structure for the lowest possible cost, with fewer construction materials while providing a high level of functionality and safety based on design criteria and code requirements. The problem is the complexity of the task. For a single-family house, one measure is the cost per square foot. But even with this simple method, the task is very complex. The cost varies and depends on multiple program factors that include the built area, number of rooms and

levels, macro and micro-geographic location, climate, nearby transportation, the proximity of good schools and stores, quality of construction and finish materials. Similarly, estimating the cost of a bridge or other long-span structure is also very complex. It depends again on multiple project size factors: the structure’s usable area (defined as A, which is the total length, ∑L, multiplied by the usable width, B), length of structure span(s) L, height of structure above base level, seismic or hurricane prone areas, structural system, quantity and properties of used structural materials, country of construction (with its local material and labor cost, currency), year of construction, construction methods and technology (fabrication, transport and erection). Usually, construction using less material should be more economical, but this is not always correct. Lighter but more complicated structures, while saving materials, may require more labor, therefore resulting in higher cost. Also important is the professional knowledge and information level of the owner, and the design and construction team, about available rational structural systems, and the team’s ability to select an appropriate efficient system. For example, if a specific project site requires a bridge with a minimum main span of 1,312 feet (400m), there are only a few known

Eﬃciency/Economy Coeﬃcients Efficiency Element

Per area (square meter)

Cost

$/m2

Efficiency/Economy (E/E) Coefficient, or element quantity/ structural unit $/(m2 x L)

Structural Materials and related Carbon Footprint: Structural Steel

kg/m2

kg/(m2 x L)

Concrete

m3/m2

m3/(m2 x L)

Reinforcing Steel

kg/m2

kg/(m2 x L)

Total Self-Weight

kg/m2

kg/(m2 x L)

Construction Time

days/m2

days x103/(m2 x L)

Note: Shown in metric units. Alternatively, U.S. units can be used.

systems that have already satisfied such spans: steel cantilever trusses, steel arches, cablestayed and suspension bridges. The cantilever truss will likely be rejected as not being labor efficient. Unless an arch bridge is preferred from an aesthetic point of view, the most efficient and appropriate option will be either a cable-stayed or a suspension bridge, and the final selection will require further study based on these two systems. In many cases, the selection of the most efficient system may be much more complicated. To select the most appropriate and efficient

system, engineers need a sufficient database and established criteria to rate and compare different types of structural systems. Very often in professional publications or in the jury’s comments for awarded projects, the structure is credited for its efficiency. Unfortunately, such a statement is rarely backed by technical and economic data, and it is almost never compared with other structural systems. Even more ironic, some of the highly awarded bridge projects are often among the least efficient. continued on next page

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

DESIGNED not to be seen

Multi Strand Anchor

Systems

Williams Type B System Extruded Free Stress Length Typical Strand Anchor – PTI Class II

For Suface Stabilization

Williams Systems Include:

Corrosion Protection:

• The most technologically advanced extrusion equipment for the manufacture of permanent and temporary anchors.

• The anchor system is manufactured in accordance with the PostTensioning Institute’s Recommendations for Prestressed Rock and Soil Anchors.

• Strand Anchors are typically produced from 0.6" diameter, 7 wire strand [fpu = 270 ksi, 1862 N/mm2] meeting ASTM A416. • Anchors arrive to the jobsite fully fabricated and packaged in coils to allow for installation in areas where there are clearance issues or bench width constraints. • Williams C4.6 and C7.6 Wedge Plates (anchor heads) have been prequalified by Caltrans, with approval #40114a and #40114b respectively, for prestressed ground anchor construction.

• Williams Strand Anchors are supplied with either PTI Class I or PTI Class II classification.

Applications: • Foundations • Dam Tie-Downs

• Landslide Mitigation • Temporary Excavation Support

• Permanent Tieback Systems • Slope Surface Stabilization

Williams Form Engineering Corp. has been a leader in manufacturing quality products for the customer service, for over 80 years. Belmont, MI 616.866.0815

Lithia Springs, GA 770.949.8300

Kent, WA 253.854.2268

San Diego, CA 858.320.0330

Portland, OR 503.285.4548

London, ON 515.659.9444

Golden, CO 303.216.9300

Collegeville, PA 610.489.0624

16120_WILLIAMS_Multi-strand_Structures_half_page_ad.indd 1

STRUCTURE magazine

For More Information Visit:

williamsform.com

May 2016

3/30/16 2:30 PM

It is time to establish criteria for structural efficiency that will allow professionals to estimate the achievement of a specific project objectively and to select solutions with less expensive structures. This requires assembling a large database for different structures – bridges, large span buildings, office buildings, tall buildings, etc. Such an informational base should be continuously expanded with new data contributions by design and building professionals, city and state building officials, and academia. This database is mainly needed for use by engineers and their clients in conceptual and preliminary design to help with the selection of the most appropriate and efficient structural system. It will also be an instrument for motivation and improvement toward more efficiency. The competition for improvement has always been a powerful tool for progress in engineering and in the development of society in general. Related to environmentally-friendly projects, the use of less material can reduce the carbon footprint and therefore works toward “saving the planet.”

Elements of Structural Efficiency What is structural efficiency and economy? We usually consider a structure to be efficient and economical when it is built with fewer materials, for a lower cost and in a shorter time than an average structure of the same type and similar size. Therefore, the efficiency and economy of a structure can be measured by the construction cost, the quantities of main materials used, the weight of the finished product and the construction time per structural unit. A structural unit is defined as the product of the area covered by a specific structure times the average structural span (or the height for tall buildings). The elements of efficiency and economy in structures include: • Cost (total construction and “soft” costs) • Main structural materials (structural steel and cables, concrete, reinforcing steel/stressing tendons) • Total weight of the bridge or building, excluding foundations (and abutments) • Construction time The cost is supposed to incorporate all other elements and should have been sufficient for comparing the efficiency of structures if we had one universal currency used all around the world and the same local costs (for material and labor). However, this condition is not realistic. There are more elements of efficiency, such as the maintenance cost during the lifespan of the structure and the structure’s capability for future upgrade or modification.

Although not a part of this article, detailed information on this subject can be found in Bridge Management by Bojidar Yanev. David P. Billington’s main principles for good bridge design, efficiency, economy, and elegance are useful general directions, but they neither provide a specific normative for efficiency, nor for economy or elegance. While ele- Self-anchored suspension (SAS) on the main span of the East gance could be a very subjective Span of Bay Bridge. element, the efficiency coefficients for structures can be used as an objective mea- the code-prescribed forces from live loads and sure of efficiency and economy. the natural elements (gravity, wind, earthThe principle less is more (meaning better) is quake, snow, ice), and shall have sufficient valid for all elements of efficiency. For example, stiffness to keep the deformations below some the quantity of steel or concrete per unit area established code limits. All structures shall be for a well-designed structure could be consid- in compliance with these basic requirements ered as a measure of the necessary material to as a given; therefore, the strength and stiffbuild this specific structure. However, this is ness are not considered further in this article. helpful only in comparing building or bridge The total self-weight coefficient is a simplistructures with the same type of structure, fied coefficient of performance (COP). The with the same or very close range of spans. COP is the ratio of the design live loads versus Every additional length added to the span (or the total self-weight of the completed conto the height) increases the material quantity struction. The larger the COP (larger ratio and the material per unit area. No valuable of live loads versus self-weight), the better, or information is provided if one tries to compare, more efficient, the structure. Because the live for example, the structural steel per square loads are prescribed by codes and are the same foot (ft2) of a 328-foot (100m) bridge span for a given type of structure (bridge or buildwith the one used for a 3,281-foot (1000m) ing), it is easier and simpler to compare the span. A simple approach to overcoming this self-weight of completed projects directly. Put difficulty is to use the “efficiency/economy another way, the higher the total self-weight coefficients” introduced in this article. These coefficient per the Table (i.e., the heavier the efficiency/economy coefficients (E/E coeffi- self-weight), the lower the efficiency of the cients) are determined by dividing the quantity structure. In its simplest form, a lighter strucof material, or the construction time, by the ture supporting specific live loads is more area times the average span of the structure, efficient than a heavier structure supporting etc. The efficiency coefficients are shown in the same live loads. the Table (page 21). It should be noted that a lighter structure The value of L is the span of a single-bay means less steel or concrete, or both, and structure or the average span for structures of therefore a smaller carbon footprint. Using two or more spans. The efficiency/economy lighter structures better preserves the envi(E/E) coefficients are equal to the element ronment. Perhaps society will soon start quantity per square foot (or meter) divided prioritizing more projects built with fewer by L, the average span of the structure, or in materials when this helps protect the envitall buildings, divided by the height (H ) of ronment, as the more complicated structures the structure. would require higher cost. The general rule is that the smaller the E/E This article provides some basics for measurcoefficient, the higher the efficiency of the ing the efficiency and economy of structures structure. This is valid for all E/E coefficients with the introduced Efficiency/Economy – cost, materials, self-weight and construction coefficients. Part 2, in an upcoming issue time. Once the construction industry reaches of STRUCTURE magazine, will provide a consensus about the equivalent carbon tables with information on the efficiency and footprints for steel, concrete and timber struc- economy of bridges, bridge systems, constructures, carbon footprint (or green) efficiency tion time, and also efficiency and economy of coefficients will probably play an additional long-span bridges and tall buildings. Part 2 important role in the rating of structures. also includes the author’s recommendations What do we expect from a structure? The for further development of the database for most important requirement is that the struc- efficiency and economy, and its use in engiture shall provide sufficient strength to resist neering practice.▪

STRUCTURE magazine

May 2016

CONNECT WITH US TODAY. [CONNECT THIS TOMORROW.]

FastBridge™ Clip

FastClip™ Slide Clip

Holdown Clip

Moment Clip

CLARKDIETRICH CLIP EXPRESS. It stands alone as a

product line, support service and single-source philosophy. And now, with new clips to cover more installation needs, the industry’s widest selection of steel framing connections is even wider. As always, overnight shipping options keep your projects on the fast track. Plus, getting the whole system—studs, tracks, accessories and more—from one trusted name keeps you working smart. STRONGER THAN STEEL. SM

Interior Framing ∙ Exterior Framing ∙ Interior Finishing ∙ Clips/Connectors ∙ Metal Lath/Accessories∙ Engineering

clarkdietrich.com

Does YOUR brick veneer anchor

PASS THE TEST? NFPA 285: Standard fire test method for evaluation of fire propagation characteristics of exterior non-load-bearing wall assemblies containing combustible components.

or bef

o bef

Aft

X FAIL

PASS

COMPETITOR’S PLASTIC WING:

HOHMANN & BARNARD’S STEEL REINFORCED WING:

When exposed to NFPA 285 testing conditions, plastic-only clip-on wings melt causing complete disengagement of the wire hook. Failure to maintain structural connection between veneer and back-up can possibly lead to catastrophic failure with the veneer falling off the building.

By using a steel core with UL94 plastic coating, the 2-SEAL™ THERMAL WING NUT ANCHOR stands up to NFPA 285 testing. This results in an anchor that will always maintain structural connection of the wire hook; satisfying industry-wide building code requirements for veneer anchors even in the most extreme conditions.

Test results from a modified NFPA 285 test prove that the only SAFE and effective choice for your wall system is the H&B Thermal Wing Nut Anchor.

WHEN PLANNING YOUR NEXT JOB, ASK: “DOES YOUR BRICK VENEER ANCHOR PASS THE TEST?”

U.S. Patents: 7,415,803 8,613,175 D702,544 D706,127

2-SEAL™ THERMAL WING NUT ANCHOR

www.h-b.com/ther malst5 800.645.0616

he American Concrete Institute (ACI) published the Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14) in the Fall of 2014. ACI 318-14 has been adopted by reference into the 2015 International Building Code (IBC). There are very significant organizational as well as technical changes between ACI 318-11 and ACI 318-14. This is the second of a two-part article on these changes: Part 1 (STRUCTURE, April 2016) described the organizational changes, and this Part is devoted to the technical changes.

Overview of Technical Changes In view of the effort involved in the complete reorganization of ACI 318-14, the initial expectation was that the number of technical changes in ACI 318-14 would be minimal. However, it did not end up that way. ACI 318-14 contains a number of significant technical changes, with some of the most significant ones discussed below. Chapter 1 – General The new Section 1.5 – Interpretation is an important addition to Chapter 1. This section tells the user how to properly interpret ACI 318 provisions. Chapter 2 – Notation and Terminology A new sentence has been added to the definition for “hoop.” It reads: “A closed tie shall not be made up of interlocking headed deformed bars.” The term “special seismic systems” has been newly defined as: “structural systems that use special moment frames, special structural walls, or both.” Chapter 4 – Structural System Requirements This new chapter contains sections on: Materials, Design Loads, Structural System and Load paths, Structural Analysis, Strength, Serviceability, Durability, Sustainability, Structural Integrity, Fire Resistance, Requirements for Specific Types of Construction, Construction and Inspection, and Strength Evaluation of Existing Structures. Most of these sections refer to other chapters in ACI 318-14. The section on Construction and Inspection, for instance, refers to Chapter 26. ACI 318-14 does not have specific requirements concerning sustainability and fire resistance. The section on Sustainability permits the licensed design professional to specify sustainability requirements in the construction documents. The strength, serviceability, and durability requirements of ACI 318-14 are required to take precedence over sustainability considerations. In the section on Fire Resistance, ACI 318 refers to the fire protection requirements of the general building code, which is the legal code used by the authority having jurisdiction over the structure.

Chapter 5 – Loads For many code cycles, ACI 318 retained provisions for service-level earthquake forces in design load combinations. Any reference to service-level earthquake forces has been deleted from ACI 318-14. A requirement to include secondary moments was rightly included in the ACI 318-11 section on Moment Redistribution but was not included anywhere else. Since secondary moments are a significant consideration in member design even when moments are not redistributed, they should be included in the member chapters. Also, the effects of reactions induced by prestressing include more than just secondary moments. Thus, Section 5.3.11 now states: “Required strength U shall include internal load effects due to reactions induced by prestressing with a load factor of 1.0.” In the chapter on one-way slabs, Section 7.4.1.3 now requires: “For prestressed slabs, effects of reactions induced by prestressing shall be considered in accordance with 5.3.11.” Sections 8.4.1.3 and 9.4.1.3 have similarly been added to the chapters on twoway slabs and beams, respectively.

Code Updates code developments and announcements

Significant Changes between ACI 318-11 and ACI 318-14

Chapter 6 – Structural Analysis ACI 318-11 and prior editions were silent on the use of finite element analysis (FEA). Chapter 6 has added a new Section 6.9 with provisions that are intended to explicitly allow the use of FEA and to provide a framework for future expansion of FEA provisions. The added provisions are not meant to serve as a guide for selection and use of FEA software. The new chapter on Diaphragms and Collectors makes an explicit reference to the use of FEA. This made it imperative for ACI 318 to recognize the acceptability of its use. Chapter 8 – Two-Way Slabs ACI 318-11 Section 18.9.1 required a minimum area of bonded reinforcement to be provided in all flexural members with unbonded tendons. ACI 318-14 Section 8.6.2.3 requires the same minimum bonded reinforcement in slabs with unbonded or bonded tendons, except that the area of bonded tendons is considered effective in controlling cracking. The structural integrity requirements in ACI 318-11 Section 18.12.6 applied to two-way posttensioned slab systems with unbonded tendons only. The structural integrity requirements in ACI 318-14 Section 8.7.5.6 apply to two-way post-tensioned slab systems with unbonded as well as bonded tendons. Chapter 9 – Beams An extensive PCI-sponsored experimental and analytical research program was conducted at

STRUCTURE magazine

Part 2: Technical Changes By S. K. Ghosh, Ph.D.

S. K. Ghosh is President, S. K. Ghosh Associates Inc., Palatine, IL and Aliso Viejo, CA. He is a long-standing member of ACI Committee 318, Structural Concrete Building Code, and its Subcommittee H, Seismic Provisions. He can be reached at skghoshinc@gmail.com.

The online version of this article has detailed references. Please visit www.STRUCTUREmag.org.

Figure 1. Knee joint with headed beam reinforcement.

North Carolina State University. The results of this research demonstrated that properly designed open web reinforcement is a safe, effective, and efficient alternative to traditional closed stirrups for slender precast spandrels. A simple, rational design procedure was developed. This proposed procedure significantly reduces reinforcement congestion, especially in the end regions of slender spandrels, while maintaining a desired level of safety. This led directly to the inclusion in ACI 318-14 of new Section 9.5.4.7, which reads: “For solid precast sections with an aspect ratio h/bt ≥ 4.5 [bt = width of that part of cross section containing the closed stirrups resisting torsion, in.], it shall be permitted to use an alternative design procedure and open web reinforcement, provided the adequacy of the procedure and reinforcement have been shown by analysis and substantial agreement with results of comprehensive tests. The minimum reinforcement requirements of 9.6.4 and detailing requirements of 9.7.5 and 9.7.6.3 need not be satisfied.” Chapter 12 – Diaphragms ACI 318 has, for many editions, contained design and detailing requirements, found in ACI 318-14 Section 18.12, for diaphragms in structures assigned to Seismic Design Category (SDC) D, E, or F, defined in ACE 7-10. ACI 318-14 has, for the first time, added design provisions in the new Chapter 12 for diaphragms in buildings assigned to SDC C and lower. The new chapter applies to the design of nonprestressed and prestressed diaphragms. The diaphragms may be castin-place as well as precast with or without topping. The topping may be composite or non-composite with the precast units. Chapter 18 – Earthquake Resistant Structures Some of the most important technical changes are found in Chapter 18, Earthquake Resistant Structures, and include the following:

Figure 2. Compression strut in joint with high aspect ratio.

1) Confinement requirements for columns of special moment frames with high axial load or high concrete compressive strength are significantly different for the regions of potential plastic hinging at the two ends. The changes are in recognition of the dependence of the amount of required confinement on the magnitude of the axial load imposed on a column and on the strength of concrete in the column. The new requirements also recognize the fact that longitudinal reinforcement that is well distributed and laterally supported around the perimeter of a column core provides more effective confinement than a cage with larger, widely-spaced longitudinal bars. The new confinement requirements will be the subject of a separate paper in a subsequent issue of the STRUCTURE magazine. 2) For beam-column joints of special moment frames, the new items are (a) restrictions on joint aspect ratio, (b) requirements for knee joints with headed beam reinforcement, (c) hooking of beam reinforcement within a joint, and (d) requirements for headed longitudinal reinforcement within joints. a) The case of knee joints with headed beam reinforcement (Figure 1) requires special consideration. ACI 318 joint design provisions are based on the assumption that joint shear strength is provided mainly by a diagonal compression strut that develops across the joint. Joint transverse reinforcement confines the concrete strut, enabling it to

STRUCTURE magazine

May 2016

Figure 3. Bending of hooks into a joint.

resist shear under force reversals. The strut is most effective if the joint aspect ratio hbeam/hcolumn (Figure 2) is close to 1.0. ACI 318-14 Section 18.8.2.4 restricts hbeam/hcolumn to a value of two or less. b) In such joints, joint failure can occur by a diagonal crack that extends beyond the headed bars, or by top-face blowout above the beam bars. ACI 318-14 Section 18.8.3.4, therefore, requires that in such joints, “the column shall extend above the top of the joint a distance at least the depth h of the joint. Alternatively, the beam reinforcement shall be enclosed by additional vertical joint reinforcement providing equivalent confinement to the top face of the joint.” c) The tail of 90-degree hooks is now required to be bent into the joint (Section 18.8.5.1), as shown in Figure 3. d) ACI 318-14 now explicitly permits use of headed reinforcement in beam-column joints of special moment frames and permits the clear spacing in such joints to be as small as 3db for bars in a layer (Section 18.8.5.2). 3) Section 18.10, previously Section 21.9, has been extensively revised in view of the performance of buildings in the Chile earthquake of 2010 and the Christchurch, New Zealand earthquakes of 2011, as well as performance observed in the 2010 E-Defense full-scale reinforced concrete building tests.

4) In these earthquakes and laboratory tests, concrete spalling and vertical reinforcement buckling were at times observed at wall boundaries. Wall damage was often concentrated over a wall height of two or three times the wall thicknesses, much less than the commonly assumed plastic-hinge height of one-half the wall length. Out-of-plane buckling failures over partial story heights were also observed; this failure mode had previously been observed only in a few, moderate-scale laboratory tests. Design requirements for special shear walls have changed in significant ways in ACI 318-14 in view of the above observations. These changes will also be the subject of a separate paper in a subsequent issue of the STRUCTURE magazine and are not discussed here any further. Chapter 19 – Concrete: Design and Durability Requirements ACI 318-11 Table 4.2.1 – Exposure Categories and Classes is now ACI 318-14 Table 19.3.1.1. A number of changes have been made in this table.

e) The column titled “Severity” has been deleted from the table. f ) Conditions describing Exposure Classes F1, F2, and F3 have changed. “Occasional exposure to moisture” has been replaced by “limited exposure to water.” g) “Continuous contact with moisture” has been replaced by “frequent exposure to water.” h) Exposure Classes P0 and P1 (P for Permeability) are now W0 and W1 (W for contact with Water) because permeability is not an exposure condition. ACI 318-11 Table 4.3.1 – Requirements for Concrete by Exposure Class is now Table 19.3.2.1. The maximum water-cementitious materials ratio and the minimum compressive strength requirements for Exposure Classes F1 and F3 have changed. The cementitious materials types that are allowed in concrete assigned to Exposure Classes S1, S2, and S3 have changed because ASTM C595 has included requirements for binary (IP and IS) and ternary (IT) blended cement since 2009. New Commentary Section 19.3.3.2 clarifies that ACI 318 requirements for air content

apply to fresh concrete sampled at the point of discharge from a mixer or a transportation unit upon arrival on site. If the licensed design professional requires sampling and acceptance of fresh concrete air content at another point, appropriate requirements must be included in the construction documents. Chapter 20 – Steel Reinforcement Properties, Durability, and Embedments Section 3.5.3.2 of ACI 318-71 through 318-08 defined the yield strength of reinforcement “with fy exceeding 60,000 psi” as the stress corresponding to a strain of 0.35%. ACI 318-11 defined the yield strength of reinforcement “with fy at least 60,000 psi” as the stress corresponding to a strain of 0.35%. This definition has changed in a major way in ACI 318-14. For reinforcement without a sharply defined yield point, it is now 0.2 percent proof stress (Figure 4, page 28), as in ASTM Specifications. A third supplementary requirement is now added for ASTM A615 Grade 60 reinforcement to be permitted for use in special moment frames and special shear walls. The minimum elongation in 8 inches must now be the same as that for ASTM A706 Grade 60 reinforcement. continued on next page

PERIOD!

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

TESTED & COMPLIANT...

Pos-I-Tie® ThermalClip® Passes NFPA 285 testing as part of the CavityCompleteTM Wall System!

Knowing that a product has been tested & witnessed by some of the top laboratories in the country provides a very high level of peace of mind. The Pos-I-Tie® ThermalClip® was fully tested in 2014, as part of the CavityCompleteTM Wall System which passed NFPA 285 Fire Testing. That’s GOOD news for Architects, Specifiers, & Contractors... BAD news for the competition!

Pos-I-Tie ThermalClip® ®

Actual Photo From Official NFPA 285 Test

Tests Conducted By: Architectural Testing, Inc. (ATI) Tests Witnessed and Listed By: Underwriter Laboratories, Inc. (UL)

www.HeckmannAnchors.com STRUCTURE magazine

May 2016

Figure 4. Definition of yield strength of high-strength reinforcement.

The stress in prestressing steel at the stage of strength, fps, can be calculated based on strain compatibility, or is permitted to be calculated in accordance with Eq. (20.3.2.3.1) for members with bonded prestressed reinforcement if the effective prestress is no smaller than one-half the tensile strength of the prestressing reinforcement. ACI 318-14 now requires that all prestressing reinforcement be located in the tension zone for Eq. (20.3.2.3.1) to be applicable. Chapter 22 – Sectional Strength For prestressed members, a new equation for the nominal axial strength at zero eccentricity, Po, has been introduced in Section 22.4.2.3. ACI 318-14 has also added Section 22.4.3.1, which requires that the nominal axial tensile strength of a nonprestressed, composite, or prestressed member, Pnt, be taken greater than Pnt,max, calculated by the new Eq. (22.4.3.1). In ACI 318-14, the two-way shear provisions are all expressed in terms of stress (vn, vc, vs, used in ACI 318-11 for slab-column connections subject to axial load and moment), never force (Vn, Vc, Vs, used in ACI 318-11 for slab-column connections subject to concentric axial load only). Section 22.6.4.2 now reads: “For two-way members reinforced with headed shear reinforcement or single- or multi-leg stirrups, a critical section with perimeter bo located d/2 beyond the outermost peripheral line of shear reinforcement shall also be considered. The shape of this critical section shall be a polygon selected to minimize bo.” The last sentence is new in ACI 318-14 (Figure 5). Chapter 25 – Reinforcement Details Two changes are made in ACI 318-14 Table 25.3.2 to eliminate the difference between the required tail extension of a 90-deg or 135-deg standard hook (6db in ACI 31811) and that of a seismic hook (6db, subject to a minimum of 3 inches). The 3-inch

Figure 5. Critical section for two-way shear around discontinued punching shear reinforcement (adapted from ACI 318-14 Figures R22.6.4.2a and R22.6.4.2b).

minimum requirement now applies to standard hooks as well. Mechanical or welded splices with strengths below 125% of the yield strength of the spliced reinforcing bars are no longer permitted. The associated stagger requirements have been deleted. Thus, there is no longer a need to specify “full” mechanical or “full” welded splices. ACI 318-11 referred to the 17th Edition of the AASHTO Standard Specification for Highway Bridges (2002) for the design of local zone reinforcement in post-tensioned anchorage zones. However, AASHTO is no longer updating the Standard Specification for Highway Bridges. Therefore, in Section 25.9.4.3.1, reference is now made to the AASHTO LRFD Bridge Design Specifications. Chapter 26 – Construction Documents and Inspection There was no direct counterpart to this chapter in ACI 318-11. The first paragraph of the Commentary to Chapter 26 gives a very good idea as to what the chapter is about: “…This chapter establishes the minimum requirements for information that must be included in the construction documents as applicable to the project. The requirements include information developed in the structural design that must be conveyed to the contractor, provisions directing the contractor on required quality, and inspection requirements to verify compliance with the construction documents. In previous editions of the Code through 2011, these provisions were located throughout the document. Starting with the 2014 edition, with the exception of Chapter 17, all provisions relating to construction have been gathered into this chapter for use by the licensed design professional. Construction and inspection-related provisions associated with anchors are in Chapter 17 and are called out within Sections 26.7 and 26.13, as appropriate.”

STRUCTURE magazine

May 2016

There are some substantive changes made to the ACI 318-11 provisions covered in Chapter 26. The ACI 318-11 (Section 3.5.1) language “Discontinuous deformed steel fibers shall be permitted only for resisting shear under conditions specified …” has been interpreted to restrict other applications in which discontinuous deformed steel fibers could potentially be used. The wording has been improved to indicate that ACI 318-14 only addresses the use of deformed steel fibers for shear. Other applications are not prohibited, but rather fall under ACI 318-14 Section 1.4. ACI 318-11 Sections 5.3 – Proportioning on the basis of field experience or trial mixtures, or both, 5.4 – Proportioning without field experience or trial mixtures, and 5.5 – Average compressive strength reduction contained prescriptive requirements for mixture proportioning. These requirements are no longer found in ACI 318-14; instead, ACI 301-10, Specifications for Structural Concrete, is referenced from Section 26.4.3. Requirements for post-tensioning ducts and grouting have also been removed as being outdated. The Commentary now provides specification guidance.

Conclusions Contrary to the widely held perception that in view of a complete reorganization of ACI 318-14, technical changes were held to a minimum, ACI 318-14 contains a number of significant technical changes, some of the most important of which are found in Chapter 18, Earthquake Resistant Structures, and Chapter 19, Concrete: Design and Durability Requirements.▪ This article was originally published in the PCI Journal (March/April 2016) and this condensed version is reprinted with permission.

Power Beam® | Power Joist® | Power Preserved Glulam® | Power Pine® msr lumBer | 2400F Glulam

A DURABLE SOLUTION.

ANTHONY POWER PRESERVED GLULAM® BEAMS AND COLUMNS Strong, long lasting, cost-effective solutions for decks, raised floor construction, coastal boardwalks and pier/beam foundations. Learn more. Request or download a brochure today.

Strength in People. Strength in Products. 800.221.2326

w w w. a n t h o n y f o r e s t . c o m Anthony Forest Products Company, LLC

LOUISIANA SPORTS

HALL OF FAME

& NORTHWEST LOUISIANA

HISTORY MUSEUM

By David L. Kufferman, P.E.

Figure 1. Cast stone entry façade. Courtesy of Timothy Hursley.

n the small Northwest Louisiana town of Natchitoches, there now stands a striking building to house both the Louisiana Sports Hall of Fame and the Northwest Louisiana History Museum. (Figures 1 and 2) The Hall of Fame, created in 1958, honors athletes who are either from Louisiana or have played for teams based there. Its roll of inductees includes football greats such as Y.A Tittle, Terry Bradshaw, and Archie Manning, basketball stars such as Pete Maravich and Shaquille O’Neill, and many other standouts from the sports world. The Northwest Louisiana History Museum examines how diverse groups of people, including the Caddo Indians, French and Spanish settlers, and free and enslaved Africans created the unique culture of the region. Natchitoches is the oldest municipality in the state, founded by the French in 1714. The Sports Hall of Fame had been housed in a section of Northwestern State University’s Prather Coliseum since 1971. In 2003, the Hall of Fame was accepted into the Louisiana State Museum system, which set the stage for the creation of a new museum building. The project was funded with a $12.6 million construction budget in 2007. Trahan Architects of New Orleans were ultimately selected to design the building. Construction began in 2010 and was completed in 2013. The Hall of Fame/Museum is a two-story box-like structure enclosing about 28,000 square feet. The structural system of the building is a braced steel frame with composite concrete metal deck slabs. The ground floor is a slab-on-grade. The building is founded on auger cast piles. Lane Bishop York Delahay, Inc. (LBYD) of Atlanta, Georgia was the structural engineer for the building frame. The most distinctive feature of the building is the expressive undulating cast stone surface which defines both its interior and exterior. The architect wanted the building to evoke the meandering rivers of STRUCTURE magazine

Figure 2. Cast stone atrium. Courtesy of Timothy Hursley.

May 2016

degrees of adjustability, and often ‘blind’ as well. In the end, over two dozen ‘typical’ panel connection types had to be developed, depending on 1) whether the panels were stacked, bolted up, hung, or some kind of hybrid thereof, 2) whether the panel was interior or exterior, and 3) whether the connection was accessible or ‘blind’. Still, many completely unique connections had to be developed on a case by case basis. As the original digital surface in the Trahan model was ‘panelized’ in five sequences by CASE Inc., the project’s Building Information Model (BIM) consultants, using CATIA CAD/CAM software, the Shaped Surface Support Steel (SSSS) design team took over. The ‘SSSS’ design team consisted of David Kufferman Structural Engineers working Figure 3. Complete Rhinoceros model of cast stone and SSSS. Courtesy of Method Design. jointly with Method Design, the cast stone support steel geometry consultants, Craft Engineering the region. David Kufferman Structural Engineers was awarded the Studio, the structural analysis consultants, and Total Global Steel task by Advanced Cast Stone, the cast stone fabricator, of designing Detailing, the steel shop drawing detailers. Kufferman worked the shaped surface supporting steel structure (SSSS) for the cast with Method Design to develop the structural geometry of the stone panels. supporting steel frame in digital space. Using the appropriate panel The cast stone surface can be described as a 1,051 piece three- connections developed by Kufferman, Method Design developed a dimensional jigsaw puzzle that weighs about 700 tons, with each digital model in Rhinoceros three-dimensional modeling software piece separately made according to its own unique, digitally created by creating automated steel framing geometry definitions using pattern, therefore having a different size and shape from any other Grasshopper, a graphic algorithmic editor that is tightly integrated piece. At the beginning of the design process, it was realized that with Rhinoceros. Such algorithms were developed based on prethe puzzle could only be properly assembled if all the pieces were liminary framing element shapes and their location parameters, as nearly perfectly made. Otherwise, the pieces would not fit together specified by Kufferman. Panel anchor type and locations were fully correctly. The task was further complicated by the fact that this defined, and this information was passed back to CASE so that massive three-dimensional jigsaw puzzle had to be supported by a final panel shop tickets could be generated for cast stone panel steel space frame. In turn, the frame had to be supported either by production. Kufferman and Method Design worked together to vary the ground floor slab-on-grade, which is essentially rigid, or by the such parameters until an acceptable frame geometry was obtained second-floor framing, which would deflect under load, thereby caus- that would minimize the number of complex mitered butt welded ing a change in the puzzle’s geometry as load is applied or removed. ‘kinks’, but without allowing steel framing elements to either get Again, if some panels moved too much, while others moved little if too close or too far from the back surface of the cast stone panels. at all, the pieces of the puzzle would no longer fit properly. A brittle Every single connective element specified by Kufferman was defined material like cast stone cannot tolerate much movement without in the Building Information Model by Method Design. Over 2,150 the risk of cracking. separate panel connections were needed for the project, with each Early in the design process, it was hoped that the great compressive connection providing support to any number of panels, ranging strength of the cast stone might be exploited through shell action, from one to four (Figure 3). but the overall surface was far too irregular to allow for this kind of The resulting ’SSSS’ frame was then analyzed under load using Robot, behavior to happen. This was only possible in cases where panels a three-dimensional structural analysis program. Method Design used could be stacked into a wall that was more or less vertical, though yet another plug-in program called Geometry Gym to convert the they still had to be tied back to the steel framing to keep them stable. Rhinoceros model into a Robot input file. Kufferman, in collaboraFar more often than not, the panels had to be fully supported by the tion with structural analysis consultants Craft Engineering Studio in steel framing hidden behind them. Indeed, movement connections New York City, refined the Robot models, modifying support and were required in nearly all panels, specifically to prevent shell action, connective conditions so as to best simulate what was to be expected since accumulating forces flowing from panel to panel through their in reality. After over-stressed or excessively flexible elements in the anchor bolts would have failed these bolts had the panels been fully model were beefed up, and under-stressed elements were lightened restrained. Ceiling panels that were close to horizontal could only be to reduce steel weight, the structure was reanalyzed. Once an acceptsupported by hanging them from the steel frame. Most other panels able SSSS was fully developed, the Rhinoceros model was updated, were somewhere between these two conditions and had to be bolted and converted into SDS/2, a steel detailing program, so that shop directly to the steel frame using connections with a large degree of drawings could be generated. adjustability to allow for the ever varying geometry. In some cases, Steel was fabricated and erected by Champion Steel of Louisiana connections were easily accessible for welding, but in other cases, and Commercial Metals Company (CMC) of South Carolina. A total the erection sequence would have made access to some connections station theodolite, that was digitally referenced to the BIM, was used impossible, so ‘blind’ connections had to be developed. In areas to locate steel during erection such that any point on the steel had to exposed to the weather, it was feared that hot fragments from field be within one-half inch of the specified location. The same system welding might damage the waterproofing below the connection, was used to precisely locate the cast stone panels as they were erected which necessitated fully bolted and galvanized connections with six by the installer, Masonry Arts. continued on next page STRUCTURE magazine

May 2016

Figure 4. Exterior steel showing galvanized channel section ‘blind’ cast stone panel connectors. Light gauge metal framing of weather wall not yet installed. Courtesy of VCC.

Figure 5. Atrium steel framing with one of two pre-deflection ballast tubs in the foreground. Courtesy of VCC.

The precise specification, fabrication and erection of the SSSS became especially critical during the second sequence, which included all of the exterior cast stone panels. Since the panels were considered to act as a rain screen rather than a waterproof barrier, the steel elements had to be installed prior to the waterproofing system, which had to occupy the space between the cast stone and the SSSS. The panels could only be installed after the waterproofing was complete. This meant that the galvanized connection elements, to which the cast stone panels had to be bolted, as well as the galvanized stand-off tubes that penetrated the waterproofing, had to be precisely shop-welded to the SSSS frame, with no possible provision for field-modification afterward. Galvanized clips with long slotted holes and galvanized A325 slip-critical bolts had to be used to accommodate all tolerances. Open slotted holes were used for ‘blind’ connections (Figure 4). In the case of the final sequence, which was the cast stone surface defining the atrium and the monumental stair, concern was raised about deflections due to the fact that the SSSS that provided support for the 165 tons of cast stone in this area was completely carried by the second-floor framing. The Robot analysis of this sequence included the floor beams so that an accurate estimate of the deflections could best be achieved. It was indeed found that the overall flexibility of the system would lead to panel fitment problems if no compensating action was taken during panel installation, despite the fact that code mandated deflection criteria was easily satisfied. A structure that does not deflect under load is, quite simply, a physical impossibility. Theoretically, the only way to get the geometry perfect would be to pre-deflect the SSSS frame using ballast equal to the cast stone panels in both weight and distribution. Because of the practical problems surrounding the procurement and installation of 165 tons of ballast over about 500 connections, an alternative approximate means of pre-deflection was devised using two concentrated loads totaling 24 tons, hung from temporary frames. As panels were erected, panel positions were continuously monitored so that the pre-deflection loads could be reduced appropriately. This procedure successfully minimized the racking and distortion problems that were anticipated, while using ballast equal to only 15% of the final panel weight (Figure 5).

The Louisiana Sports Hall of Fame opened to the public on June 28, 2013, at a gala to celebrate both the astonishing new building as well as the induction of basketball legend Shaquille O’Neill and tennis star Chandra Rubin, among several other outstanding athletes. Since then, the project has won numerous major design awards, including the 2015 American Institute of Architects (AIA) National Interior Architecture Honor Award, the 2014 Chicago Athenaeum American Architecture Award, the 2013 Architect magazine Honor Award, and the 2013 Interior Design magazine Best of Year Award. In 2013, Azure magazine named it the Top Project in the World. Not too bad for a small town museum in west Louisiana.▪

STRUCTURE magazine

Project Credits Client: State of Louisiana, Office of Facility, Planning & Control Structural Engineer: LBYD Cast Stone Support Steel Engineer: David Kufferman, P.E. w/ Craft Engineering, NYC Architect: Trahan Architects, New Orleans Interior Designer: Lauren Bombet Interiors M/E/P/FP Engineer: Associated Design Group Civil Engineer: CSRS Geotechnical Engineer: GeoConsultants General Contractor: VCC Landscape Architect: Reed Hilderbrand Associates BIM Manager and Technology Consultant: CASE Cast Stone Support Steel Geometry: Method Design Acoustics: SH Acoustics Waterproofing: Water Management Consultants & Testing David L. Kufferman, P.E., is President of David L. Kufferman Structural Engineers, Fairfield, CT. He can be reached at david.kufferman.pe@sbcglobal.net.

May 2016

Field Adjustable Can be field trimmed and drilled

EASY TO SPECIFY

INSTALL INSPECT

Stronger Wall Narrow panel widths have higher loads Shear Transfer Plate for Header/Top Plate Attachment Ships with every wall and installs with nails

More Applications Residential, multi-family and light-frame commercial construction

Code Listed ICC-ES ESR-2652 and City of L.A. RR 25730 evaluated to the 2015 IRC/IBC

Easy to Install Front, back and side access for easy installation and inspection

The new Strong-Wall® Wood Shearwall has arrived and is better than ever. Standing up to 20 ft. tall, the new walls have significantly higher allowable loads than our original prefabricated wood walls and are now much easier to install and inspect. With visible ttps://widendtp.com/ssttoolbox/uqnjmzfgnn/metal_plate_look_36percent.psd?res=proxy front, back and side access for anchorage attachment, and a simplified top-of-wall connection, they can be installed before or after framing. Learn more about our new high-performance, field-trimmable Strong-Wall Wood Shearwalls ( WSW ). Call (800) 999-5099 and visit strongtie.com/wsw.

Strong-Tie Company Inc. WSW16

Restoring the

FOUNDATION OF JUSTICE By Thomas E. Forsberg, P.E.

Figure 1. Dome shrouded in a scaffolding tower.

he foundation of Justice in the County of Lancaster, Pennsylvania is once again stable and poised for another century of oversight. Justitia (the Statue of Lady Justice) is re-perched on a new structural framework atop the County courthouse dome. The 1850s-era wood-framed dome structure suffered the primary long-term effect of water intrusion: rot. A broad and vague term, “rot” defines merely a symptom, but does not convey any degree of extent. Atop the courthouse dome, the rot can only be described as severe.

History When the roof on a historically significant piece of your county’s architecture leaks, what do you do? Of course, you patch it. And many attempts were made to do exactly that. However, there is a point where the “patch method” no longer works; when you’re repatching patches, it’s time for a better solution. In 2014, the County’s Facilities Management department decided that they needed a new approach. At nearly 80 years of age, the copper roofing was, literally, wearing thin. Too many applications of incompatible materials aimed at preventing ongoing water infiltration were doing more harm than good. Prompted by observations of water leaks and signs of damage to the wood framing,

the County retained Schradergroup Architecture, LLC, to thoroughly examine the roofing and dome structure, develop a report describing the conditions, and recommend corrective work to restore and preserve the dome. Further, the County decided to remove and restore the Statue. The current copper version, installed in the 1920s, is the second Statue to grace the top of the courthouse dome; the original was made of wood (Figure 2). This work required a scaffold tower around the dome reaching nearly 140 feet above the sidewalks and streets below. Fortunately for the team, the scaffold would facilitate the examination and subsequent restoration work (Figure 1).

Examination

Figure 2. Profile of original (1850s) wooden Lady Justice head.

STRUCTURE magazine

May 2016

Able to proceed with a hands-on examination of the exterior roofing surfaces, the inspection team quickly observed that the copper skin was in poor condition along with evidence of an entire system failure: pan seam overstress, material deterioration, loose and missing fasteners, leaks, and failed repairs resulting from inappropriate patching materials applied to the copper. By its geometry and construction, the upper portion of the dome’s interior was inaccessible for visual inspection. However, based on the overwhelming evidence of leaks and deterioration in the copper roofing system,

the examination continued with invasive probes to assess the underlying structure. There was no question whether there was any structural damage, only the extent to which the damage had reached. The evidence from several probes overwhelmingly showed that the dome structure had been compromised. Wood decking was rotted so severely that it could not retain the fasteners that held the copper roofing on the dome nor maintain its connection to the structural framework. Removing the Statue happened concurrently with the examination and evaluation of the dome. In November 2014, the Statue was secured into a steel-framed lifting cage, hoisted from atop the dome, and transported to an off-site studio to begin its makeover. With the Statue out of the way, the upper reaches of the dome structure were exposed and accessible for examination. The final evidence required to conclude the examination was observed, and corrective work was recommended (Figure 3). In a presentation to the County’s decision-makers, the final conclusion of the team’s report was summarized: Movement in the excessively large copper pan’s overstressed seams caused tears and open joints. Further, repairs made with incompatible materials have failed, exacerbating long-term water intrusion and the ensuing structural damage: eroding roofing fasteners and rotting the wood decking and structure. Given the conditions of the roofing system and structural deficiencies, there was no choice but to undertake a wholesale restoration: remove all the copper, repair/replace all of the damaged structural framing, replace the wood deck, and install a new roofing system.

Documentation One of the greatest challenges in this type of work is to know where and when to strike a balance between probing for more evidence and data versus making assumptions and estimates about the work that will need to be done. Perhaps the most successful aspect of this project was the method by which the team worked together, examining the structure and systems, defining what was known, and making a list of unknowns with associated worst-case and worst-cost outcomes.

Figure 4. Looking between dome truss bays at the good condition of existing truss framing.

STRUCTURE magazine

Figure 3. Conditions of wood rot at top of dome structure, underneath statue.

In the end, the Owner had the equivalent of a guaranteed maximum price to perform the work, even though many pieces of the scope were still unknown. Architects and engineers usually manifest their work through the development of construction documents. After all the behind-thescenes work is done – research, calculations, coordination, etc. – plans, elevations, sections, and details are developed and organized as an instruction manual. And by following those instructions, builders bring projects to fruition. For this project, however, developing an accurate set of construction drawings, while not entirely impossible, was both impractical and unnecessary; impractical because of the convoluted and variable nature of the existing construction, and unnecessary for the exact same reason. Therefore, the team agreed that the documentation process would take an as-built approach and be developed as a collection of photographs, field notes, and sketches to reflect the discoveries and corrective work that occurred along the way. continued on next page

Figure 5. Conditions of wood rot at clock base.

May 2016

Figure 6. Transfer posts to facilitate removal and replacement of compression ring.

Simple schematic drawings were used to label various elements such as dome bays, trusses, tension and compression rings, and outriggers. However, these documents were used for establishing consistent nomenclature, tracking the progress of work, and documenting locations of various field repairs, not for bidding purposes or to accurately define the work scope.

Restoration Work began on Monday, December 8, 2014 – not the best time of year to start an 8-month roofing project in the Northeastern US. While there was a broad understanding of how this project would proceed, the team anticipated a wide range of conditions and the

Figure 7. Existing condition of wagon-wheel base framing.

need for real-time, on-the-fly review and resolution. Standard details did not apply here. Moreover, to the greatest practical extent, new structural elements required for either repair or replacement work had to be made on site. With an open roof during winter months, there was no time for a typical shop drawing and fabrication process. The main dome trusses – there are twenty-four in all – were assembled using several pieces of heavy-timber framing. Despite the poor conditions of the wood decking, the underlying structure was largely unaffected and in very good condition (Figure 4, page 35). There were still a number of repairs to be made on a localized basis, but no primary structural elements needed to be removed and replaced in entirety. Removing the copper roofing and wood decking unveiled all of the hidden structural elements and conditions. On Day 1, the team observed cracks and rotten wood in one of the trusses. Fortunately, having both the designer and contractor standing on the scaffolding looking directly at the problems, they were able to talk through various ideas and determine a workable solution that could be implemented immediately. There are four clocks on the main dome, one facing in each of the four cardinal compass directions. Each clock stands proud of the main dome surface and is covered on the top and sides by a dormer-like structure. These elements suffered significant damage from water infiltration, particularly the structural framing under the clocks (Figure 5, page 35) and the main dome compression ring that supports the dome trusses. The compression ring, constructed from multiple layers of heavy timber with offset splices and thru-bolted connections, is critical to the structural integrity of the dome. Repairing it meant removing the rotted wood and rebuilding entire segments. Of primary concern was the relief and transfer of dome truss loads around the damaged portions of the ring. This required a series of transfer posts connected to the structural framing above and below the ring. These elements facilitated unfettered access to the ring for corrective work (Figure 6). Perhaps the worst conditions occurred at the top of the dome. The compromised condition at the base of the Statue allowed years of water intrusion. The wood framing quite literally crumbled to shards as it was removed. However, enough integrity remained to allow the team to document geometry and element sizes to ensure reconstruction occurred in a like manner. Figure 7 illustrates the condition of the original wagon-wheel

Figure 8. Rebuilding the wagon-wheel base.

STRUCTURE magazine

May 2016

Figure 9. Rebuilding the cap structure which supports Lady Justice.

frame underneath the dome cap, and Figures 8 and 9 show its reconstruction progress and the new framework to support the Statue. Not one leak occurred during the restoration of the Lancaster County Courthouse Dome. Working through winter months of rain, snow, sleet and wind is a testament to the quality, craftsmanship, and pride of the restoration crew. A revitalized Lady Justice is once again overseeing the Courthouse, and she has a new weather-tight connection between her base and the top of the dome. Since the connection was the worst flaw in the roofing system, considerable care was taken to ensure the integrity of the joint so that it will no longer be a source of water infiltration. Restoring the dome was accomplished in the manner that every owner desires: ahead of schedule, under budget, and without any change orders. The process of real-time tracking of work and budget allowed the County to perform additional maintenance and repairs on portions of the structure that were not part of the original scope. In the end, this piece of the County’s history is ready for another century of service (Figure 10).▪

Project Team Owner: County of Lancaster, Pennsylvania Restoration Team: Lancaster County Facilities Management Staff Architect & Structural Engineer: Schradergroup Architecture, Lancaster, PA Roofing Consultant: Tricon Building Services, Lititz, PA Roofing Contractor: Ream Roofing, York, PA Supplier: The Garland Company Conservator: Materials Conservation, Philadelphia, PA

Figure 10. Completed restoration of the Lancaster County Courthouse Dome.

Thomas E. Forsberg, P.E., is Principal – Structural Engineering at Schradergroup Architecture, LLC, with offices in Pennsylvania, Maryland, and Delaware. Thomas can be reached at tforsberg@sgarc.com.

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

STRUCTURE magazine

May 2016

MYTH: All fabric buildings are alike

In reality, there are wildly varying quality standards. Let’s start with the strength and agility of fabric and a rigid steel frame. Add the ability to compress a construction schedule plus complete customization and the result maximizes your - and your client’s - business investment for years to come. Legacy Building Solutions was the first to apply fabric cladding to a rigid steel frame. We changed the game in safety, engineering and client satisfaction. Seeing is believing! To see a drone fly-through video visit www.legacybuildingsolutions.com or contact Legacy with your next project requirements.

The Legacy Advantage: • • • • •

Concept to completion project management Patented attachment system to ensure longevity and safety Rapid installation up to 3X faster than conventional delivery Relocatable; construct as permanent then move if required Custom design, in-house engineering and installation services

legacy@legacybuildingsolutions.com 877/259.1528 | www.LegacyBuildingSolutions.com

“I

t wasn’t so long ago that a concrete block would not care to show its face in polite society.” This proclamation formed the lead of an extensive article, “Behold the Lowly Concrete Block,” in the March 1956 issue of the architectural journal, House and Home. The celebratory article argued that concrete block was “one of the most glamorous and flexible building materials at our command.” Today, concrete block is most often associated with utilitarian structures, cost-effective construction, and back-of-house uses where the material is left exposed. However, excitement about a material that could be molded into any shape and combined into any form was a common sentiment both in mid-century architectural journals, and in the 1860s to 1900s, when concrete block was a fledgling alternative. This article provides a short history of the development and use of architecturally designed and exposed concrete block. Two cases in the Minneapolis area represent the two transformational moments in the use of concrete block – a development of single-family and row houses built in 1885, and the 1963 Hoffman-Callan Printing Company building.

Early Years of Concrete Block Concrete block first entered the public market in the 1860s, when a number of proprietary systems for the manufacture of precast concrete blocks were developed on the East Coast (Ann Gillispie, 1979). However, widespread production of the material did not begin until 1900, when Harmon S. Palmer patented a cast-iron block machine with

Building Blocks updates and information on structural materials

Figure 1. A page from the 1915 Sears, Roebuck and Co. Concrete Machinery catalog featuring the various face plates available for purchase for use with concrete block machines.

More Than Square

a “removable core and adjustable sides” (Pamela H. Simpson, 1989). Concrete blocks could be cast with a variety of faces (Figure 1), the most popular being “quarry-faced stone,” which caused the material to be commonly referred to as “imitation stone” during this time period. continued on next page

A Brief History of Architectural Concrete Blocks By Laurel Fritz and Meghan Elliott, P.E., Associate AIA

Laurel Fritz (fritz@pvnworks.com), is an architectural historian and Meghan Elliott (elliott@pvnworks.com), is the founder and principal at Preservation Design Works (PVN), a consulting and project management firm in Minneapolis, Minnesota.

Figure 2. A two-page spread of advertisements for concrete blocks and concrete block machines from a 1907 edition of the Minneapolis Tribune.

STRUCTURE magazine

The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

Figure 3. A single family home and group of row houses built by the Union Stone and Building Company. Both properties are currently recognized as local historic landmarks by the City of Minneapolis.

The development of imitation stone systems was an important innovation in building design and construction. With the purchase of an imitation stone molding machine, individuals had the opportunity to build their own structurally sound and architecturally fashionable homes. Concrete block machines could be found for as little as $12.50 in the early 1900s (approximately $300 in today’s dollars), and were available for order from popular catalogs such as the one from Sears, Roebuck, and Company titled Concrete Machinery (see website link listed in online References). In fact, Sears produced a specialized catalog of this type between the 1900s and the 1920s, touting concrete block and the related production machinery as a sound investment: “The manufacture of concrete blocks and other concrete products is profitable, whether you manufacture them for your own use or for sale. If for your own use you can make them during your spare time, on rainy days or whenever it is impossible to look after your regular work, thus realizing a profit or gain which otherwise might be lost” (Figure 2, page 39). In Minneapolis, these precast concrete blocks appeared in residential construction as a replacement for more traditional (and expensive) stone construction. An early pioneer in concrete block design and construction for the city was the Union Stone

and Building Company, led by local real estate entrepreneur William N. Holway. An article from the October 4, 1885, issue of the Minneapolis Daily Tribune expresses the community’s excitement about imitation stone’s arrival in the area. One of the progressive institutions of the city is the Union Stone and Building Company. The company secured the ‘Pierce Patent’ for artificial stone and immediately opened an extensive factory and yards at Third Street and Twenty-Sixth Avenue North, where they have given employment to 125 men in the manufacture of stone, and 150 more as carpenters, masons, etc. in the building department. In the stone business the company makes a specialty of their building blocks, which are handsome, durable, and cheap, and bound to be the building material of the future. The Union Stone and Building Company proceeded to build a notable development of single family homes and row houses near their yards, now recognized as a local historical landmark (Figure 3). The development was unique in the Minneapolis area, and the same article in a local newspaper described it as both a novelty and an asset: Any one [sic] who will take pains to drive to Third Street and Twenty-Sixth Avenue North will be richly rewarded. Houses of

slate-brown and other colors meet the eye, built of beautiful substantial stone. Odd designs may be seen, such as imitation of log houses, etc. It is well worth a visit, and the company is doing much to build up that section of the city. Of this development, a line of row houses fronting 26th Avenue North and a number of single-family homes along Third Street North and Fourth Street North are extant. Each building was designed by a different architect, but the overall development shares similar architectural details as described in a report by the City of Minneapolis (see website link listed in online References), including their side hall plan, fenestration patterns, multi-gabled roofs, and dormers on primary façades. Another common element, projecting pointed quoins at the corners, are likely the cause of the newspaper’s description of the structures as “odd imitation log houses,” but also foreshadow the flexibility in shape and form of the blocks that architects would realize later. After the initial enthusiasm of the mid- to late nineteenth century, concrete block seems to have faded from favor with the public and the design professions. In the Twin Cities, the use of exposed concrete block in residential structures never gained particular popularity and has since generally been relegated to use in foundations and other covered applications.

Figure 4. The Hoffman-Callan Printing Company Building. Photos by Dan Pratt, courtesy Bader Development.

STRUCTURE magazine

May 2016

Concrete Block at Mid-Century

Concrete Block in the 21st Century The tallest “printed” building was recently assembled in China. A large-scale 3D printer used a mixture of glass fiber, cement, steel, and recycled construction waste to print large modular building components, which were subsequently assembled on site. While the scale is much bigger, the process is not dissimilar from the historic precast block machines of Sears. In a short time, it may be possible to print concrete block specifically designed for a project right on site and in any shape or form – “on rainy days or whenever.” Architects and structural engineers will determine the next transformation of this seemingly humble building material with a glamorous past.▪

Figure 5. Original architectural drawing by James Dresser, showing details of the concrete block construction method for the Hoffman-Callan Printing Company building.

University of Washington Montlake Triangle, Seattle, WA

ACEC 2016

GOLD SUPPORTING AWARD INNOVATION IN ARCHITECTURE

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

STRUCTURE magazine

May 2016

Seattle Tacoma Lacey Portland Eugene Sacramento San Francisco Los Angeles Long Beach

Pasadena Irvine San Diego Boise Phoenix St. Louis Chicago New York

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

Architectural concrete block next came into vogue in the mid-twentieth century. The ANSI modular standard block – commonly known as a concrete masonry unit, or CMU – was introduced in 1946, and standard unit blocks with architecturally designed faces followed shortly after. Pioneering modern architects – such as Frank Lloyd Wright, with his Textile Houses of the 1920s, and Paul Rudolph, with the Colgate University Creative Arts Center – began integrating concrete block into their designs. Contemporary architectural journals soon picked up on the trend, praising the unique patterns, textures, and shapes that could be cast into and built out of concrete block. Concrete block was seen as simultaneously utilitarian and glamorous – a modern architectural ideal. The same journal articles quoted structural engineers who praised the improvements that manufacturers had made in producing concrete blocks of consistent compressive strength, and in developing additives that lightened the overall weight of individual blocks. One engineer went so far as to suggest that concrete block would be a common structural material in the skyscrapers of the future – a partner and structural engineer from Skidmore, Owings & Merrill is quoted (H.Lefer, 1979), noting that “a 50-story building with load-bearing walls made of reinforced concrete block is entirely feasible.” It seems fitting, then, that the block would appear in a progressive design in Minneapolis for a printing company. The Hoffman-Callan Company building (Figure 4) is a unique two-story round structure that was constructed in 1963 to house local entrepreneur Elliott Hoffman’s two businesses, the Hoffman-Callan Printing Company and Motor Travel Services. The Hoffman-Callan Printing Company provided commercial printing services while Motor Travel Services was notable as the publisher of C.A.R., a travel guide in the 1950s and 1960s that listed advertisements for what it described as “a nationwide network of independently owned on-the-highway restaurants.” The building was designed by architect James Dresser of Madison, Wisconsin. Dresser is notable as a Prairie School architect and former Taliesin Fellow who studied with Frank Lloyd Wright in the 1940s. Dresser conceived of the building’s round design as a way to optimize the efficiency of the printing process. The building’s most significant feature is the custom exposed concrete blocks

that make up its exterior walls. The unit construction allowed by the blocks enables the building’s round shape while also providing an intriguing texture to the walls. Each individual block is rectangular, with a pair of blocks taking the form of a recessed pyramid with a truncated top (Figure 5). The pairs of blocks are arranged in vertical columns that extend the full height of the building. The blocks are also visible on the interior, providing an element of architectural interest to those spaces.

“ St��ct�ral desig� is what we do. IES tools help our engineers do it well. ” Structural Software for Fearless Engineers IES VisualAnalysis

Excellent for all your crazy building projects; whatever your clients dream up!

IES, Inc.

800.707.0816 info@iesweb.com

www.iesweb.com

bridge had been proposed at Wheeling for many years to connect the eastern and western portions of the National Road across the Ohio River. The legislatures of Virginia and Ohio incorporated the Wheeling and Belmont Bridge Company in 1816 and authorized them to erect a bridge. The company, in 1836, built a wooden covered bridge from the west end of Zane’s Island to the Ohio shore. Pittsburgh interests were against it, claiming any bridge would impact shipping on the Ohio River. The Company, unable to raise funds necessary for the work, asked the Federal Government for support and received a favorable committee report in the U.S. House of Representatives. On March 4, 1836, Charles Ellet Jr. (STRUCTURE, October 2006 and STRUCTURE, April 2016) received a request to submit a proposal for a suspension bridge from his old friend Congressman G. F. Mercer, who was chairman of the Committee on Roads and Canals. He responded on March 13, 1836, writing in part, Your favor of March 4th, relative to the suspension bridge which it is proposed to erect across the Ohio, at Wheeling, was not received until yesterday. I have since then employed the facts which you have furnished me in developing a plan for that structure, with a view to the preparation of an estimate of the probable cost of its execution. Not being familiar with the proposed site of the bridge, and having no information with regard to the nature and elevation of the banks of the river, I know not what natural advantages may exist to cause a modification of the plan upon which the estimate is predicated. In the absence of authentic information, I have deemed it safest to assume the most unfavorable case, namely, that in which the points of support are to be raised to the full height you have named from the bed of the river, and the ends of the cables must be secured by an artificial construction raised from the same level…The span of the arch, measured between the inner faces of the columns of support, is 500 feet; and between each column and the shore is a stone arch of 100 feet, the extreme or littoral abutments of which arches are constituted of the mass of masonry in which are anchored the cables of suspension…In forming the estimate, I have supposed the width of each carriageway to be twelve feet, and that of the footway six feet: making the whole width of the platform thirty feet…and the estimate for the dimensions, and consequent cost of the cables is made as usual on the presumption that the platform may sometimes be covered by a dense crowd of people, occupying the whole distance between the abutments. This weight exceeds by many tons that which would be produced by droves of cattle, or even a troop of horses…

The platform and its load would be supported by eight, iron-wire cables presenting an actual section of eighty square inches, each of these would measure ten inches in circumference, and would be capable of supporting a weight of 420 tons, which is equivalent to an aggregate force of 3,360 tons, or more than three times the extreme tension which they can be required to resist.” He estimated a total cost of $207,700 and added, “the accompanying plan is to be regarded merely as the result of a half hour’s reflection, and not as the disposition which would actually be adopted after an examination of the site, and mature deliberation on the subject. Mercer included letters by Ellet in a House of Representatives Bill No. 631 on May 17, 1836. Adding, “The character of Mr. Charles Ellet, now a resident engineer on the James river canal, in Virginia, is well known to the chairman of this committee, and his statements are entitled to the highest confidence…” Congress did not fund the construction of the bridge, even though the Committee on Roads and Canals approved it. In 1838, the 25th Congress took up the bridge issue once again with Ellet’s 700-foot span bridge but did not pass the legislation. In 1841, Ellet submitted a second proposal consisting of a single span bridge across the river with a clearance of 86 feet and a reduced cost of $130,000. This design was submitted to the Committee on Roads and Canals of the Congress, which reported a bill to the full Congress, which recommended the bridge should be built at federal expense. The bill was not passed and no funds were appropriated for the bridge. Ellet made another attempt in a letter dated December 29, 1843, recommending “a radical change of plan for the Wheeling Bridge, and leave the river entirely unobstructed.” He wrote in part, The bridge may be built in this style – 86 feet above low water, with arch spanning the whole channel, or from 800 to 900 feet long – at a cost of $130,000... My estimate is for such a work as I now always recommend – plain, but substantial. I take the liberty of sending you a report which I made a few years since in relation to a bridge across the Mississippi, at St. Louis, and also a pamphlet descriptive of the Fairmount bridge. John A. Roebling also sought a contract to build the bridge and presented plans and estimates in 1845. He proposed a bridge with an estimate for construction of $150,000 and, with some reduction of ornamentation, a price of $130,000. The company started talking with both Ellet and Roebling later in 1847. Ellet responded, “I should still be much gratified

STRUCTURE magazine

Historic structures significant structures of the past

Wheeling Suspension Bridge

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

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

Details of the Wheeling Bridge.

to have the execution for that important edifice confided to my care; but I have had, in the course of my experience so much to do with contractors and public works, that I have made up my mind never to enter the lists as a competitor for contracts.” After explaining his fear of contractors, he wrote, “Still I would be exceedingly gratified to have the charge of this work; and if the board should not receive satisfactory proposals from others at a public offering, and will inform me of the fact, I will endeavor to make them an offer on such a plan as I would recommend. It would not be improper to add that my pecuniary responsibility is sufficient to secure the execution of any contract I may make for the edifice; but that I do not wish to put my private fortune in jeopardy by entering the field of competition with every adventurer.” Roebling was in Wheeling on May 28 and again on July 13, at which time he had three proposed plans. One of Roebling’s plans had a pier at mid river giving two 531-foot spans, and a clearance of 100 feet at the eastern abutment and 59 feet at the western abutment. Ellet interviewed the Board on July 2, 1847. Ellet’s main drawing gave his bridge profile showing the cables converging towards midspan, as well as profiles of his two towers and high fill on the island. He had 12 cables, six on each side, with each cable built up with 550 #10 wrought iron wires. His deck carried two walkways, 3½ feet wide, flanking

a 17-foot carriageway. After reviewing the revised plans and estimates by Ellet and Roebling, the Board selected Ellet as their engineer by a vote of 7-1. On October 26, he submitted a long, Report On The Wheeling And Belmont Suspension Bridge, To The City Council Of Wheeling. He began with, The structure is one of the numerous works which characterize the present age, when communities are no longer afraid of enterprises, because in past times they were regarded as difficult, or hesitate to carry out the conclusions of deliberate thought. Transcending the limits within which engineers have hitherto deemed it prudent to confine their arches, this bridge is intended to be of extraordinary length, to cross the Ohio without any intermediate support, and to leave this great highway of commerce without obstruction to its trade or current. No such span has yet been attempted; but its practicability and success are not the less certain because it is the first of its class. On August 13, 1849, the Wheeling Daily Gazette wrote, “The operation of stretching the cables, as well as all the previous operations upon this stupendous structure, are of the most ponderous and Herculean magnitude; but the skill and genius of the Superintendent Engineer, Chas. Ellet, Esq., as well as the skill and intrepidity of his workmen, have rendered them

STRUCTURE magazine

May 2016

comparatively easy, and thus are entirely successful, and unattended by any accident.” The Gazette added, Wonderful as the age is, this is truly one of its most wonderful and majestic works, combining alike the power of art and of science. Nor is it less useful than beautiful and grand…nor is this a work for a day. Centuries will roll away, another and another chain will be thrown over the Ohio and the Father of Waters, yet this work will stand, and throw a halo of glory around the names of those who executed it, and the people in whose midst it was constructed, as the pioneers in the species of improvement. The bridge deck was finished on October 20, 1849, and the Gazette reported, A 10 o’clock A. M., the stars and stripes were planted upon the highest tower on the Virginia side, and in another moment a flag bearing the insignia of Ohio was seen floating from western tower. The crowd on the shores now anxiously awaited the joining of the floor in the middle of the span, the workmen having commenced at both ends and proceeded in laying the timbers toward the centre. At half past 10 o’clock, MR. CHARLES ELLET, the talented and accomplished engineer and superintendent of this structure, and Mr. I. Dickinson, superintendent of the stone and iron work, seated in a one-horse carriage, drove upon the Bridge… The day was beautiful, a brighter one never shone, and certainly never smiled on a scene more triumphant for American genius, skill and enterprise. The longest span ever projected for a bridge, has thus proven successful and, we repeat, it is a triumph of which the people of Wheeling, and indeed of which those in all parts of the United States, may justly feel proud. On November 2nd the Gazette wrote: “The greatest creations of genius, when successfully completed, appear simple, however complex and incomprehensible they may have previously seemed. Such a simple, though huge and magnificent structure does the Wheeling Suspension Bridge now appear to the observer. The light and fairy step of timid women, the heavy tramp of the burthened horse or the crushing wheels of the ponderous car may alike traverse this structure, with the assurance that the platform beneath them is firm, safe and enduring as the rock-ribbed and everlasting hills.” The opening of the bridge was a gala event. The Gazette wrote, “The citizens of Wheeling will long remember the 15th of November, the day appointed for the formal opening of

the Wire Suspension Bridge erected by the citizens of Wheeling over the Ohio river. A continuous train of human beings moved along the work from 3 o’clock until dark… At 6 o’clock, the thousand lamps, hung up on the wires, were lighted almost simultaneously and presented an elegant and graceful curve of fire, high above the river, that was never excelled in beauty.” At a supper toasts were made honoring the bridge and its builders. The first toast was – “The Bridge over the Ohio – One of the most magnificent highways of Art, spanning, like a triumphal arch one of the noblest highways of nature.” The second was to “Charles Ellet, Jr. – The fame of his genius will be as enduring as the towers he has erected, and as pure as the beautiful river he has spanned.” Ellet responded; to “Old Virginia – The land of honorable men and lovely women.” Unfortunately, heavy winds on May 17, 1854, achieved what the Pittsburg interests could not do. The Wheeling Intelligencer wrote, With feelings of unutterable sorrow, we announce that the noble and worldrenowned structure, the WHEELING SUSPENSION BRIDGE, has been swept from its strong holds by a terrific storm, and now lies a mass of ruins! Yesterday morning thousands beheld

this stupendous structure in undisturbed repose and in undiminished strength, a mighty pathway spanning the beautiful waters of the Ohio, a link in the unbroken chain of trade and travel between the East and the West, and looked upon it as one of the proudest monuments of the enterprise of our citizens. Now, nothing remains of it but the dismantled towers looming above the sorrowful wreck that lies buried beneath them! A giant lies prostrate in the Ohio, and against his huge and broken ribs, and iron sinews snapped asunder, the waves are dashing scornfully, ending up a sound the most doleful that ever fell upon the ears of our citizens! The Bridge Company Board met on May 18 and decided to rebuild. They asked Ellet to come to Wheeling, which he did on May 21st. At the time, Ellet thought that while the damage was great he could have it rebuilt within two months on a temporary basis, and in four months ready to carry one lane of traffic across the river. They fished out the cable that dropped into the river and reused as much of the material as possible. The deck was only 10 feet wide, with the carriageway six feet wide and two two-foot walkways. The cost of reconstruction was only $17,000.

Wheeling Suspension Bridge.

His associate, William H. McComas, was the contractor for the reconstruction. Ellet and McComas crossed the bridge in a carriage on July 26, 1854. In 1860, McComas widened the bridge to two lanes and grouped the strands on each side of the bridge into two cables between the towers, and wound them with wrought iron wire, for a total cost of $37,752.23. Later in 1874, Washington Roebling and Wilhelm Hildenbrand rebuilt the bridge adding stay cables, thus “Roeblingizing” it. Over 166 years after it was built, the bridge still carries traffic over the Ohio River.It was named an ASCE National Historic Civil Engineering Landmark in 1968 and was placed on the National Register of Historic Places in 1975.▪

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

Hollo-Bolt

The only expansion bolt with A to F seismic approval Engineers can now specify Hollo-Bolt structural steel connections in Seismic Design Categories A through F in compliance with the 2012 International Building Code. 4 Fast, cost saving installation from one side 4 Designed for HSS and other hollow sections 4 Patented High Clamping Force design 4 Highest resistance to tensile loading in accordance with AC437

ICC

4 All sizes approved (5/16” to 3/4”) 4 Standard HDG product at standard pricing

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

May 2016

InSIghtS

new trends, new techniques and current industry issues

Staying within the “Circle of Trust” on DB/IPD/EBD Projects The Key to Success By Joseph Rietman, CPC

re you being asked to participate in a fast-tracked project? Do you want to get the best results? There are success factors that have been proven on many projects, large and small, including some “mega” projects, across industries from healthcare to retail. One such system works on programs you may be familiar with, such as Design-Build (DB), Integrated Project Delivery (IPD), and Evidence-Based Design (EBD). The key is building your own circle of trust. It has been proven time and time again that the team needs to start with a clear understanding of the owner’s project requirements and project limits. This is the information that the design-build leader (typically the general contractor) and his team of experts, including the structural engineer, uses to remove roadblocks in the design – before they get integrated into the design and make their way to the field. This analysis process is the phase when overall project costs can be lowered significantly, where potential obstacles are overcome and opportunities exploited. Applied correctly, the team can turn a project that might have otherwise hit minimum yield requirements into an uber success. But it all starts with the circle of trust. In one case, at the programming stage on a recent mega project, armed with the owner’s project requirements, the design-build leader analyzed the risks to the project by leveraging the knowledge and skills of his team of master builders, structural engineers, and industry trade partners (the sub-contractors). The team found that the construction of the structural podium would be on the critical path no matter how the pours were sequenced. The team relied on the expertise of the structural engineer, but also encouraged frank discussions between the structural engineer and the trade subcontractors to find the best overall solution. Instead of just saying “no” to a proposed idea or alternative, which is a common reflexive reaction, the structural engineer respectfully considered the alternative proposals and provided clear reasoning as to why the proposal would or would not be acceptable. Once the reasoning and underlying principles of the structural engineer’s objections were understood, the

subcontractors altered their approaches and price proposals to make them acceptable to all parties. This was an exciting and exhausting undertaking, but one in which constant questioning of ideas and team members was necessary. This approach must be in an atmosphere of mutual respect if you are to build a circle of trust environment. What’s the point? Well, it is critically important to the success of all delivery types, be it DB, IPD or EBD, that the team can rely on each other, and recognize that it is worth the time and considerable effort to discuss and dissect early design assumptions, the various design schemes, and the ramifications of decisions to the designers as well as the subcontractors. Think of it as operating a circle of trust. Putting your own self-interest in front of the team goals or not showing mutual respect are easy ways to exit the circle of trust. As the line in the movie, Meet the Parents, aptly states, “once you’re out of the circle of trust you can’t get back in.” For example, on a past project, the team had to be shielded from one of its members who offered no value, was “shady” in his dealings, and in turn warranted no respect. Watch out for these types of individual glory seekers, as they will sink the best high performing teams in no time. If done correctly, the design-build leader, working within the circle of trust, will be able to bid the structural package as early as the 100% schematic design stage. This may seem very early to most structural engineers who think of fast-tracked in terms of an early foundation package, but it is the key to getting the worked started early and on a fast pace. Obviously, changes will need to be made and the structural design will be revised as the designs of the other disciplines are advanced, but it is worth the additional cost to the design-builder and owner. As the structural engineer, expect to be engaged in this bidding process. The structural engineer brings to the table the continued understanding of the engineered limits of the design and his/her invaluable experiences with the various bidders on past projects. The circle of trust amongst the team is vital to project success.

STRUCTURE magazine

May 2016

Definitions (Wikipedia, February 2016) Design-Build (DB) is a project delivery system used in the construction industry. It is a method to deliver a project in which the design and construction services are contracted by a single entity known as the design-builder or design-build contractor. Integrated Project Delivery (IPD) is a collaborative alliance of people, systems, business structures and practices into a process that harnesses the talents and insights of all participants to optimize project results, increase value to the owner, reduce waste, and maximize efficiency through all phases of design, fabrication, and construction. Evidence-Based Design (EBD) is a field of study emphasizing credible evidence to influence design. This approach has become popular in healthcare to improve patient and staff well-being, patient healing, stress reduction and safety. Evidence-based design is a relatively new field, borrowing terminology and ideas from disciplines such as environmental psychology, architecture, neuroscience and behavioral economics. Despite common beliefs to the contrary, the “low” price is not always the “best” price. Knowledgeable owners request best value pricing from their master builders, rather than low bids, whenever possible. The structural engineer should be an integral part of the team developing a best value bid package. Some of the most important items that drive the scoring of best value pricing are the logistics of building in confined spaces and finding a cost effective method to keep materials flowing into the site without double handling. As part of the process, the structural engineer will be asked to quickly evaluate and comment on traditional means-and-methods issues. These can include the permissible loads on decks for material storage, the locations of construction joints, the time until delay strips can be cast and so on, to validate the bidders approach as they move closer to the best value bid submission. Therefore, during the preparation and

trusting the contractors to meet the intent of the drawings, and the contractors trusting the structural engineer to respond to RFI’s and field issues in an expeditious manner. From project pursuit to programming, through design and on-boarding, and throughout construction, the structural engineer can be an invaluable member of the team. If the engineer communicates clearly, is professional and open in dealing with team members, and brings expertise and a can-do attitude to the team, he will stay within the circle of trust. Bottom line, spend the time

to build a circle of trust with your other team members. Believe in the other members, and they will believe in you.▪ Joseph Rietman is President and CEO of vScenario, a full service Construction Management Firm. He is currently President of the American Institute of Constructors, a Member of the Building Commissioning Association and on the Board of Governors for the Constructor Certification Commission. Joseph can be reached at jrietman@vscenario.com.

WHEN THERE’S A SOFT-STORY PROBLEM THERE’S A FAST AND SIMPLE HARDY FRAME® SOLUTION.

STRUCTURE magazine

When space is at a premium, The Hardy Frame Special Moment Frame turn-key system offers more flexible solutions for soft-story applications than any other moment frame on the market. It’s no wonder it’s the preferred solution for soft-story retrofit projects in San Francisco and Los Angeles. • Pre-assembled: no field welding • AISC 358 Pre-qualified • No lateral bracing at beam required • Code compliant • Custom designs available Hardy Frame from MiTek, the retrofit experts. Contact us today and learn how easy soft-story retrofit can be. 800.754.3030. www.hardyframe.com/softstory ©2016 MiTek, All Rights Reserved

May 2016

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

evaluation of the best value written proposals, and oral presentations, the structural engineer has an important seat at the table as the owner scores all written and oral responses that ultimately end in an award. You see, not only are the schedule, manpower, material, and equipment procurement important aspects of the project, none of these are as important as having a high performing team that has the ability to communicate freely with each other with full confidence and trust. Pulling the best value structural sub-contractors into the circle of trust is a must next step, called on-boarding. The teaming of the structural engineer and the subcontractors only grows as the design is completed and the project team is able to reap the rewards of the early decision making, optimization, and budget stabilization. The team is also at a critical stage of the project development, allowing for the last true opportunity to influence cost savings through value engineering or alternate means and methods. During this on-boarding stage, the team relies equally on the structural engineer and the structural sub-contractors. The structural sub-contractor is asked to assist the structural engineer in the development of the project documents by providing detailed constructability reviews of the DDs and CDs, taking into account quantity and quality of materials to ensure an efficient design application. Through this method, the subcontractor initiates design decisions by providing information, estimates, schemes, and recommendations regarding construction materials, methods, systems, phasing, and costs that provide the highest quality building within the budget and schedule. The structural engineer really ought to embrace this aspect of the process, as a “good” design can be transformed into a “great” design using the input and experiences of qualified and trusted partners. What engineer wouldn’t like to eliminate most of the construction phase RFIs at this point in the project? The project is not out of the woods yet… it has been moving fast and the design-build leader may have great controls, but the team needs to be prepared for the things that fell through the cracks due to speed-to-market. For that reason, the structural engineer should expect to be engaged on the project site to perform structural observations at key milestones, and whenever needed to address “hot” and “urgent” items. Again, the circle of trust that has been established to this point is crucial to the structural engineer

Noteworthy

news and information

Changing Faces on the STRUCTURE Editorial Board Mark W. Holmberg, P.E., Vice President and Civil Manager for Heath & Lineback Engineers, Inc. in Marietta, Georgia is stepping down as a member of the STRUCTURE® magazine Editorial Board. Mark joined the Board in November 2006 as a CASE representative. His structural engineering experience includes building and bridge projects. Mark has designed commercial, industrial, institutional low to mid-rise structures, and pre-stressed concrete girder, post-tensioned concrete box girder, and steel girder bridges for stream crossings, highway grade separations, and interchanges. Barry Arnold, P.E., S.E., SECB, Chair of the STRUCTURE magazine Editorial Board, had this to say about Mark’s departure: “Mark has served faithfully on the Editorial Board for nearly 10 years. Even though Mark announced he would step down from the Board in November, he has

continued to support the magazine and to work with authors on developing articles. Mark’s dedication and commitment to the magazine and the profession are commendable, and he will be missed.” Regarding his tenure on the Board, Mark commented, “As a member of the STRUCTURE magazine Editorial Board since 2006, I have worked with a number of outstanding authors whose contributions make the magazine a wonderful resource for structural engineers. It has been an honor to serve on the Board as the ACEC CASE representative, and it has been a pleasure working with all of the talented Editorial Board members and Copper Creek’s publishing team. However, it is time for me to step aside from my Editorial Board duties. I look forward to continuing to receive my monthly copy of STRUCTURE magazine and reading all of the great articles.” Jeremy L. Achter, S.E., LEED AP, will replace Mr. Holmberg as a CASE representative. Jeremy is an Associate Principal with ARW

Engineers of Ogden, Utah. He is a Past Board Member of the Structural Engineers Association of Utah (SEAU), a Member of the Cold Formed Steel Engineers Institute (CFSEI) and a member of the Structural Advisory Committee to the Utah Uniform Building Code Commission (UBCC). Barry Arnold said this about Mr. Jeremy Achter’s appointment: “I am pleased to welcome Jeremy Achter to the Editorial Board. In addition to having plenty of experience writing and editing, he is also passionate about supporting and improving the profession. Jeremy came highly recommended by his colleagues, and I have no doubt that he will be a great addition to the team.” Please join STRUCTURE magazine in congratulating Mark Holmberg on his many years of service to the magazine and welcoming Jeremy Achter to the team.▪

ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

RFEM 5

BIM Integration

Structural Analysis and Design Software

Non-linear Analysis

Powerful, Intuitive and Easy Finite Element Analysis

DOWNLOAD FREE TRIAL www.dlubal.com

Dlubal Software, Inc.

Join us: SEAoK May 12-13, 2016 Lexington, KY SEAoP June 8, 2016 Villanova, PA

Philadelphia, PA (267) 702-2815 info-us@dlubal.com www.dlubal.com

STRUCTURE magazine

May 2016

STEEL/COLD-FORMED STEEL PRODUCTS GUIDE a definitive listing of steel/cold-formed steel product manufacturers/distributors and their product lines Aegis Metal Framing

Halfen USA, Inc.

SidePlate Systems, Inc.

Phone: 314-851-2231 Email: sdetter@aegismetalframing.com Web: www.aegismetalframing.com Product: Ultra-Span® Description: The Aegis network of fabricators supply Ultra-Span trusses and wall panels throughout the United States supported by Aegis’s BIM compatible, building modeling and truss design software, professional engineering service and expert field support.

Phone: 800-423-9140 Email: info@halfenusa.com Web: www.halfenusa.com Product: HM/HZM Mounting Channels Description: Modular alternatives to site-welding for steel to steel connections where adjustability is desired. HZM toothed channels provide mechanical load transfer in 3 planes. Hot Rolled HM Mounting Channels provide dynamic load resistance in tension and shear, while coldrolled channels support static loads.

Phone: 330-952-2605 Email: jhoover@sideplate.com Web: www.sideplate.com Product: SidePlate Steel Frame Designs Description: SidePlate Systems is an engineering partner that works to reduce construction costs on steel-framed projects. Our connection technologies reduce steel frame tonnage, eliminate field welding, and shorten construction schedules on projects in any design criteria...all at no cost to the design team.

Albina Co., Inc.

IES, Inc.

Simpson Strong-Tie®

Phone: 866-252-4628 Email: info@albinaco.com Web: www.albinaco.com Product: Curved and Rolled Steel Description: Produce virtually any metal component that needs to bend or curve. Impeccable reputation in the steel bending and fabrication industry for producing difficult and unusual parts. Pipe, tube, structural steel, pate and specialty bending and rolling for structural, architectural, industrial, manufacturing, ornamental and recreational applications.

Phone: 800-707-0816 Email: info@iesweb.com Web: www.iesweb.com Product: VisualAnalysis Description: Hot or cold, big or small, our friendly tools can do it all: model steel and more (with joy) when VisualAnalysis you deploy!

Phone: 800-925-5099 Email: web@strongtie.com Web: www.strongtie.com Product: SCHA Slide-Clip Connector Description: Ideal for panelized or stick-frame construction where cold-formed steel bypass framing anchors to the top of a floor slab or the bottom flange of a steel beam. It features a wider support leg to decrease eccentricity on anchors and provide a variety of anchorage options.

ASDIP Structural Software Phone: 407-284-9202 Email: support@asdipsoft.com Web: www.asdipsoft.com Product: ASDIP Steel Description: A suite of modules specifically dedicated to the design of structural steel members, based on the latest AISC specifications (AISC 360) and ACI 318 Appendix D. Design steel base plates, anchor rods, shear lugs, steel columns, and steel/ composite beams with ease.

Bentley Systems, Inc. Phone: 800-BENTLEY Email: Samantha.Langdeau@bentley.com Web: www.bentley.com Product: STAAD.Pro Description: Design any structure and share your synchronized model data with confidence using STAAD.Pro. Ensure on time and on budget completion of your steel, concrete, timber, aluminum, and coldformed steel projects, regardless of complexity. You can confidently design structures anywhere in the world using over 80 international codes.

Dlubal Software, Inc. Phone: 267-702-2815 Email: info-us@dlubal.com Web: www.dlubal.com Product: RFEM Description: Finite element software is complete with LRFD and ASD design of hot-rolled steel according to AISC and other international standards. Features include critical load factor determination, tapered and curved beams, and automatic cross-section optimization. In addition, direct interfaces with Tekla and Revit allow for seamless and bi-directional data exchange.

MiTek Builder Products Phone: 800-754-3030 Email: dlopp@mii.com Web: www.hardyframe.com Product: Hardy Frame Shear Wall System Description: Includes c-fs panels and structural steel special moment frames that lead the industry in strength, stiffness and ductility to resist lateral loads. The panel shape permits recessed fixtures and the ability to insulate. Installations include back-to-back for double capacity and reinforced anchorage solutions.

RISA Technologies Phone: 800-332-RISA Email: info@risa.com Web: www.risa.com Product: RISAFloor Description: Get the most out of your steel designs with RISAFloor and RISA-3D. The ability to use multiple materials in one FEA model makes these programs your first choice for both hot rolled and cold formed steel. With 16 steel databases and 21 steel codes RISA has all your bases covered.

S-FRAME Software Phone: 604-273-7737 Email: info@s-frame.com Web: www.s-frame.com Product: S-STEEL Description: Design and optimize steel buildings with S-STEEL, an S-FRAME integrated steel design solution. Code-check and auto design for both strength and serviceability to multiple design codes. Supports composite beam design, staged construction, and numerous optimization criteria and constraints. Comprehensive design reports include equations, clause references and interactive graphics.

Technical Glass Products Phone: 800-426-0279 Email: sales@fireglass.com Web: www.tgpamerica.com Product: SteelBuilt Curtainwall Infinity™ System Description: Strong and slender, can use almost any structural member as a back mullion, allowing openings with larger glazed areas, smaller frames and greater free spans. Compatible with back mullions of virtually any profile, it can satisfy a nearly limitless range of design and performance requirements.

Trimble Phone: 770-426-5105 Email: kristine.plemmons@trimble.com Web: www.tekla.com Product: Tekla Structures Description: Models created with Tekla software carry the accurate, reliable and detailed information needed for successful Building Information Modeling and construction execution. Tekla works with all materials and the most complex structures – you set the limits.

USG Structural Solutions Phone: 312-436-4260 Email: jmestrada@usg.com Web: www.usg.com/structural Product: USG Structural Panels Description: Meets stringent performance requirements, offer exceptional features and deliver superior strength. All so you can rest easy that your design will always be covered by the best. USG Structural Panels are the only noncombustible structural panels certified by UL when tested in accordance with ASTM E136.

All Resource Guide forms for the 2016 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

May 2016

introDucing the

HoW/2

Design ConneCtions with SDS/2

SerieS by SDS/2

true connection DeSign, not SimpLy connection veriFicAtion SDS/2 is the only system that provides true connection design — for individual members, as well as all interacting members in a structural joint.

compLete connection DeSign reportS

FuLL Joint AnALySiS Instead of choosing a connection from a library, SDS/2 designs the connection for you, based on parameters that you establish at the beginning of a project. All connections SDS/2 automatically designs will comply with the connection design code standards the user chooses.

learn more Want to see how simple it really is to design connections in SDS/2? Scan the QR code to watch SDS/2’s connection design in action.

SDS/2 provides long-hand calculations of all designed connections, which simplifies the verification process. Scan the QR code to view an example of SDS/2’s automatically generated calculation design reports.

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.

800.443.0782 sds2.com | info@sds2.com

award winners and outstanding projects

Spotlight

Did You Say, “Build it with Mushrooms”? By Shaina Saporta, P.E. and Matt Clark, C.Eng., P.E. Arup was an Outstanding Award Winner for the Hy-Fi project in the 2015 NCSEA Annual Excellence in Structural Engineering awards program (Category – Other Structures).

n January 2014, David Benjamin of The Living approached us to ask if Arup would be interested in supporting their entry into the MoMA Young Architects Program competition. The only information? They had an “unusual” idea. Each summer, MoMA PS1 in Queens, New York, selects the centerpiece installation of the summer concert series from their Young Architects Program, an annual competition for innovative and promising new architects. And The Living’s idea for the 2014 season was indeed unusual – to build the installation out of mushroom bricks. These bricks are grown by Ecovative out of Mushroom Material. Ecovative’s innovative process mixes mycelium, the root structure of a fungus, with agricultural waste like corn husks in various shaped molds. As the mycelium continues to grow it binds with the agricultural waste, creating a rigid material similar to synthetic packing products. Ecovative’s goal is to replace these and eventually other, synthetic commodities with their sustainable, biodegradable product. At the time, the Mushroom Material was only being used for packaging, so there was no data on the bricks’ structural properties to support Arup’s design work. Testing would be essential to making this project a reality. So they started with the basics. The first test consisted of an engineer standing on a brick to determine an approximate allowable compressive stress. From there, Arup started defining the height of the installation. They also immediately began a rudimentary creep test. With the short design time – from initial meeting to on-site in five months – gathering as much data as quickly as possible would be key in delivering the project. Over the following months, Arup worked with Ecovative, The Living, and Columbia University’s Carleton Strength of Materials Laboratory to test iterations of bricks. Compression tests were performed from initial testing through delivery of materials to the site, all to ensure the final product was consistent with design assumptions. Shear tests were done on various mortar types,

including testing organic mortars such as a wheat paste. Cyclic compression testing was done to understand if any of the compression deformation was elastic. An assembly test of a small section of wall was used to validate design assumptions. Testing was extensive and carried on through the entire process of design, informing the work and providing opportunities to revisit assumptions. Initial compression tests indicated the bricks were very soft but did not demonstrate any loss of stiffness or spalling at very large strains. Stiffness increased at large strains as the material compressed, removing void volume. The stiffness at low strains, however, was very low. Different material mixes and grow methods were tested to improve the material performance. The design modulus of elasticity for the final mushroom mix was 140psi. With the low elastic modulus, the structure was governed by serviceability and stability concerns. BMT Fluid Mechanics helped by looking at a risk-based approach to wind loads, allowing for reduced design wind pressures in conjunction with a storm-action plan. Even with reduced design wind pressures, a mushroom structure of this size, nearly 41 feet in height, was too flexible under wind load. A timber frame structure was introduced to stiffen the structure under lateral loads. The frame was made of built-up sections of salvaged scaffolding planks and tied together at the tops with a steel perimeter plate which acted as the diaphragm. Foundations at the base of each frame consisted of ground screws. With 5 weeks on-site, construction had to be both quick and efficient. The crew, led by Art Domantay, consisted of both architecture

STRUCTURE magazine

May 2016

students, recent graduates and experienced professional masons and builders. Working together, the team mixed old and new construction methods with the traditional lime mortar and new mushroom bricks. Dubbed the most ‘Instagram-able’ spot of the summer by the director of MoMA PS1 (#hyfi), the installation captured the imagination of the public. At the weekly summer parties, people would engage with the structure. Not content just to look, the innovative material had visitors touching the structure, even climbing it! Information and displays nearby told the story of the compostable structure, allowing the curious to explore the science behind the mushroom brick. And at the end of the summer, the tower disappeared. The scaffolding frame was dismantled to be used by others, the ground screws were removed, and the mushroom bricks composted back into the earth. So often as structural engineers, our success is in the permanence of our work. The success of this project was in its ability to physically disappear while hopefully making a lasting impact on our industry. Mushroom bricks won’t replace steel or concrete, but they will challenge us to think about new materials. What other materials can we build with?▪ Shaina Saporta is a Senior Engineer in the Buildings group of Arup’s New York office. She can be reached at shaina.saporta@arup.com. Matt Clark is an Associate in the Buildings group of Arup’s New York office. He can be reached at matthew.clark@arup.com.

GINEERS

NCSEA Webinars May 10, 2016 Introduction to Building Structural Dynamics for Seismic Design Structural Engineers

Geoff Bomba, P.E., S.E., Senior Associate, Forell Elsesser Structural Engineers

June 7, 2016 Construction of Post-Tensioned Structures

Pawan R. Gupta, Ph.D., P.E., S.E. LEEP AP, Principal & Managing Director, Diagnostics June 21, 2016 Introduction to Structural Fire Engineering

David Barber, P.E., Principal, ARUP, and Darlene Rini, P.E., Fire Engineer, ARUP

May 24, 2016 Designing with Post-Tensioned Concrete

More detailed information on the webinars and a registration link can be found at www.ncsea.com. Subscriptions are available! 1.5 hours of continuing education. Approved for CE credit in all 50 states through the NCSEA Diamond Review Program. www.ncsea.com. AL

CT UR

RU ST

NCSEA

TIN

UIN

RS EE

Pawan R. Gupta, Ph.D., P.E., S.E. LEEP AP, Principal & Managing Director, Diagnostics

360 Engineering Group, PLLC ARW Engineers Barter & Associates BBFM Engineers BHB Consulting Engineers, PC Bob Rude Structure Butz Dunn & DeSantis C.A. Pretzer Associates, Inc. DCI Engineers Inc. FGPP&R, PC Gilsanz Murray Steficek LLP The Haskell Company HGA Architects and Engineers Howard I. Shapiro & Assoc. IBI Group KPFF Consulting Engineers Inc Martin/Martin, Inc. O’Donnell & Naccarato Prairie Smoke Engineering Reaveley Engineers & Associates SidePlate Systems, Inc. Simpson Gumpertz & Heger Sound Structures, Inc. Stantec Thornton Tomasetti VAK Engineering Wallace Engineering

Engineers from the following firms were represented at the 2016 Winter Leadership Forum:

At this year’s NCSEA 2016 Winter Leadership Forum, leaders from the engineering profession and dedicated entrepreneurs gathered for two days of deep, thoughtprovoking discussion. Topics discussed included ways to strengthen and protect businesses against the ever changing and always risky business of consulting engineering. Leading industry experts in the fields of employee law, risk management, and architecture discussed important topics such as protecting your firm when using alternative delivery systems, employee rights and handling disputes, and fundamentals of risk management. These interactive and stimulating sessions culminated in a lively discussion of case studies presented by structural engineers. Because the gathering is intentionally limited in quantity, each participant also enjoyed ample opportunities to engage their peers and the presenters in lively discussions during meals, breaks, and social gatherings, resulting in a learning experience that was both unequalled and of the highest quality. One attendee noted that “The conversation and learning never stopped. I felt like I was among friends who cared about my success and wanted to hear about and learn from my experiences and opinions.” In addition to enjoying the beautiful setting and delightful weather on Coronado Island, participants expressed delight in the format of the WLF and the openness and honesty with which the ideas, principles, and lessons learned were presented. – Barry Arnold, NCSEA Past President

GIN EN

NCSEA News

News form the National Council of Structural Engineers Associations

COUNCI L

N CO

O NS

STRUCTU

OCIATI

NATIONAL

Leaders and Principals Gather for Lively Discussion and Networking on Coronado Island

ED UC AT

ASS

RAL

Diamond Reviewed

STRUCTURE magazine

May 2016

Keynote: Structural Engineering for Walt Disney Theme Parks Kent Estes, Ph.D., S.E., Walt Disney Imagineering ASCE 7-16 Wind: How it Affects the Practicing Engineer Don Scott, P.E., S.E., F.SEI, F.ASCE, Vice President/Director of Engineering, PCS Structural Solutions.

New ACI Standards and the Repair of Existing Concrete Structures Gene Stevens, S.E., P.E., J.R. Harris & Co., and Chuck Larosche, P.E., WJE SEAOC Structural / Seismic Design Manual Ryan Kersting, S.E., Buehler & Buehler Structural Engineers, Doug Thompson, SECB, STB Structural Engineers, and members of the Structural Engineering Association of California Seismic Committee

Florida SE Licensure: How the Bill was Created and almost became Law Tom Grogan, P.E., S.E., Florida Structural Engineers Association

Becoming a Trusted Advisor: Communication and Selling Skills for Structural Engineers Annie Kao, P.E., Senior Field Engineer, Simpson Strong-Tie

Upcoming Changes to AISC 341 – Seismic Provisions for Structural Steel Buildings Jim Malley, S.E., Senior Principal, Degenkolb Engineers

2015 IBC, ASCE 7-10 and SDPWS Seismic Provisions for Wood Construction Michelle Kam Biron, P.E., S.E., SECB, Director of Education, American Wood Council

Top 10 Useful Lessons for Structural Engineers Lawrence Novak, S.E., F.ACI, F.SEI, LEED AP, Director of Structural Engineering, Portland Cement Assoc.

Has THIS Ever Happened to You? NCSEA Young Member Group Support Committee, moderated by Jera Schlotthauer, EIT, chair

Detailed information on each session and speaker can be found at www.ncsea.com.

So you Want to Delegate Connection Design – How to Do It Right Kirk Harman, P.E., S.E., SECB, President, The Harman Group

GINEERS

May 2016

O NS

STRUCTURE magazine

OCIATI

NATIONAL

ASS

RAL

Presenting TMS 402-13, The Masonry Design Standard Edwin Huston, P.E., S.E., Principal, Smith & Huston, Inc., Consulting Engineers

Great (and Horrible) Masonry Design Practice Donald Harvey, P.E., Associate Vice President, Atkinson-Noland & Associates

Registration for the 2016 NCSEA Structural Engineering Summit is now open online at www.ncsea.com. The Summit will be held at Disney’s Contemporary Resort, which is just a short monorail ride, water-launch trip or walk to the Magic Kingdom Park. Hotel reservations are now open as well, accessible through a link online at NCSEA’s website. Register now for the best discounts and secure your hotel room, as we expect a sell-out.

STRUCTU

Wind Loads on Non-Building Structures for the Practicing Engineer Emily Guglielmo, P.E., S.E., F.SEI, Principal, Martin/Martin, Inc.

Strut and Tie Design: What They Didn’t Teach You in School Thomas Mendez, S.E., Engineer, WSP | Parsons Brinckerhoff

News from the National Council of Structural Engineers Associations

The slate of educational sessions for the NCSEA Structural Engineering Summit, September 14-17, has been set and features two tracks of sessions on both technical and non-technical subjects specific to structural engineers. The Summit will feature keynote speaker Kent Estes, Ph.D., S.E., of Walt Disney Imagineering. The Summit draws together the best in the structural engineering field and features technical and nontechnical educational sessions, social and networking events, the NCSEA Excellence in Structural Engineering Awards, and the trade show. Sessions include:

Registration & Hotel Reservations Open

NCSEA News

Summit Educational Slate Set

COUNCI L

The Newsletter of the Structural Engineering Institute of ASCE

Structural Columns

Call for Proposals Open until June 2 Now accepting individual paper and complete session proposals for consideration. Structures Congress 2017 is the premier event for structural engineering. Be part of the technical program; submit a proposal today for a complete session or an individual abstract. SEI encourages submissions from practitioners, educators, researchers, structural engineers, bridge and building designers, firm owners, codes and standards developers, and others. Abstract and Session Proposals should focus on topics and subtopics consistent with the list to the right. A complete list of sub-topics is available at www.structurescongress.org. The due date for abstract and session proposals is June 2, 2016. Visit the congress website, www.structurescongress.org, to submit your proposals. The conference website will have detailed information and step by step power points to assist you.

Major Topics Blast and Impact Loading and Response of Structures Bridges and Transportation Structures Buildings Business and Professional Practice Education Forensics Natural Disasters Nonbuilding and Special Structures Nonstructural Systems and Components Research Sharing Claim Experiences Questions? Contact Debbie Smith at dsmith@asce.org or 703-295-6095.

Opportunity to Join a Bridge Committee

New Faces of Civil Engineering

The SEI Technical Activities Division has established a wide range of bridge committees, working on issues and subject matter affecting bridges in the US and around the world. Several committees focus on the specific materials of timber, steel, and concrete. In addition, there are committees that examine bridge management and bridge and tunnel security. Joining a bridge committee is a great opportunity for younger members. Learn more at www.asce.org/structural-engineering/ sei-technical-activities-division.

Each year, ASCE names 10 New Faces of Civil Engineering Professionals. This multidisciplinary program includes representatives from the civil, mechanical, electrical, chemical, industrial and manufacturing engineering professions, amongst a host of others. In addition, each year ASCE recognizes the tremendous strides that civil engineering students are making to improve the quality of life for all with its annual New Faces of Civil Engineering – College Edition recognition program. Learn more about the 10 New Faces of Civil Engineering and their accomplishments at www.asce.org/new-faces-professional.

SEI Futures Fund Call for Proposals Due June 1 The SEI Futures Fund (SEIFF) invites proposals for new initiatives in line with SEIFF strategic areas that benefit Futures Fund Investing in the Future of Our Profession the structural engineering profession and/or SEI as a whole, and would not otherwise be funded out of SEI Division or operating funds. Strategic areas: • Promote student interest in structural engineering • Support younger member involvement in SEI activities • Enhance opportunities for professional development • Invest in the Future of the Profession

STRUCTURE magazine

Guidelines: • Proposed activities must benefit the structural engineering profession and/or SEI as a whole, and would not otherwise be funded out of SEI division or operating funds. • Proposed activities must be completed in the year funded, & may not include standing committee operating expenses. • It is recommended that proposals be vetted through the Committee or Chapter’s Executive Committee as appropriate. For more information and a detailed proposal format, please contact Suzanne Fisher at sfisher@asce.org. Proposals are due June 1, 2016. Visit www.asce.org/structural-engineering/sei-futures-fund to donate. May 2016

International Workshop on Disaster Resilience

The first ASCE Innovation Contest drew entries from around the world, with practitioners, project managers, educators, researchers, and students attracted to the challenge of developing and submitting their most creative and innovative ideas for reshaping infrastructure. From dozens of submissions, a judge’s panel of 22 experts from across the civil engineering industry named 15 winners. Learn more about the winners at blogs.asce.org/asceinnovation-contest-selects-15-winners-with-greatest-potential.

The SEI Disaster Resilience of Structures, Infrastructures, and Communities Committee is participating in organizing the 1st International Workshop on Disaster Resilience, September 20 – 22, 2016 in Torino, Italy. The program includes two days of sessions at the magnificent Hall of Honor in 16th century Valentino’s Castle. An additional day of sessions and visits will be held in the Joint Research Centre in Ispra, which includes the Elsa Lab and Crisis Management Center. Learn more on the workshop website at www.workshop-torino2016.resiltronics.org.

SEI Welcomes New Sustaining SEI Member Dan Frangopol Awarded OPAL for Education Organization Member Geopier Foundations Long-time SEI volunteer and

contributor, Dan Frangopol, Sc.D., P.E., F.SEI, F.EMI, Dist.M.ASCE, has been honored by ASCE with the 2016 Outstanding Projects and Leaders award for education. The OPAL awards honor outstanding leaders whose lifetime accomplishments have contributed to civil engineering in one of five categories – construction, design, education, government, or management. Dan has made numerous contributions to SEI since the founding of the institute. He is presently the chair of the Technical Council on Life-cycle Performance. The 2016 honorees were recognized at the OPAL Awards Gala, March 17, 2016, in Arlington, VA. Learn more about this year’s OPAL awards and watch a video of Dan’s accomplishments at http://blogs.asce.org/life-cycle-engineeringpioneer-receives-2016-opal-for-education.

2016 Joint Congress Student Contest Winners The 2016 G-I/SEI Challenge was a series of four geo-structural student competitions. The G-I/SEI Challenge organizers wish to thank and acknowledge competition sponsorship by AGSCO Corporation, ELE, Geosyntec Consultants, Golder Associates, The Reinforced Earth Company, and Tensar International Corporation. G-I/SEI Wall Competition: teams designed and constructed a three-dimensional model retain wall that was then externally loaded using a segmental hardwood load frame. • 1st prize – Rensselaer Polytechnic Institute • 2nd prize – University of Arkansas • 3rd prize – University of Illinois

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

7th Annual GeoPrediction Competition: the competing teams estimated the lateral deflection profile of a shored wall with tieback anchors supporting a deep excavation, as measured from inclinometer data. • 1st prize – Oregon State University • 2nd prize – Arizona State University • 3rd prize – Middle East Technical University, Turkey G-I/SEI Student Video Competition: On the theme “Soil/ Structure Interaction,” students created short videos that effectively explained how geotechnical and structural engineering are intertwined. The top six videos will be available on the Geo-Institute’s YouTube channel. • 1st prize – Oregon State University • 2nd prize – Arizona State University • 3rd prize – University of Texas The winning design in the GeoStructures T-Shirt Competition was submitted by Arizona State University.

May 2016

The Newsletter of the Structural Engineering Institute of ASCE

Geopier Foundations, Inc., is SEI’s newest Sustaining Organization Member. We hope you will join them, Hayward Baker, International Code Council, and Simpson Strong-Tie in support of SEI. Being a Sustaining Organization Member will raise recognition for your organization with decision makers in the structural engineering community year-round, and show your leadership and support for SEI in their goal to advance and serve the structural engineering profession. Demonstrate your commitment and increase your organization’s visibility with more than 25,000 SEI members and at SEI conferences through www.asce.org/SEI, the monthly SEI Update e-newsletter, and STRUCTURE magazine. Learn more at www.asce.org/SEI-Sustaining-Org-Membership. Questions? Contact Suzanne Fisher sfisher@asce.org.

Structural Columns

ASCE Innovation Contest Winners

WANTED

CASE in Point

The Newsletter of the Council of American Structural Engineers

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. 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!

Expectations and Requirements To apply, you should • be a current member of the Council of American Structural Engineers (CASE) • be able to attend the groups’ two face-to-face meetings per year: August, February (hotel, travel reimbursable) • be available to engage with the working group via email and conference call • have some specific experience and/or expertise to contribute to the group

CASE Risk Management Tools Available Foundation 5 Education – Educate all of the Players in the Process Tool 5-1 A Guide to the Practice of Structural Engineering Intended to teach structural engineers the business of being a consulting structural engineer and things they may not have learned in college. While the target audience for this tool is the young engineer with 0-3 years of experience, it also serves as a useful reminder for engineers of any age or experience. The Guide also contains a test at the end of the document to measure how much was learned and retained. Other sections deal with getting and starting projects, schematic design, design development, construction documents, third party review, contractor selection/project pricing/delivery methods, construction administration, project accounting and billing, and professional ethics. Tool 5-2 Milestone Checklist for Young Engineers The tool will help your engineers understand what engineering and leadership skills are required to become a competent engineer. It will also provide managers a tool to evaluate engineering staff.

Follow ACEC Coalitions on Twitter – @ACECCoalitions.

STRUCTURE magazine

Tool 5-3 Managing the Use of Computers and Software in the Structural Engineering Office Computers and engineering software are used in every structural engineering office. It is often a struggle to manage and supervise these tools. Software availability is in constant flux, software packages are continually updated and revised, and few software packages fully meet the needs of any office. This tool is intended to assist the structural engineering office in the task of managing computers and software. Tool 5-4 Negotiation Talking Points This tool provides an outline of items for your consideration when you are in a situation in which you are pressured to agree to lower fees. The text is subdivided into situations that are commonly experienced in our profession. This document is purely advisory and designed to assist you in your individual negotiations and business practices.

Foundation 6 Scope – Develop and Manage a Clearly Defined Scope of Services Tool 6-2 Scope of Work for Engaging Sub-Consultants This tool should be used when a structural engineer is asked by the prime consultant or owner to provide input on subconsultant selection and scope of work, or when the structural engineer is required to retain the sub-consultant directly. You can purchase all CASE products at www.booksforengineers.com.

May 2016

August 3 – 4, 2016; Chicago, IL

CASE Member Firms Win Engineering Excellence Grand, Honor Awards

The CASE Summer Planning Meeting will again be scheduled for August 3 – 4 in Chicago, IL. A popular feature of the planning meeting is a roundtable discussion on topics relating to the business of Structural Engineering, facilitated by the CASE Executive Committee members. Topics have included the Business of BIM, using social media within your firm, Peer Review and Special Inspections. Attendees to this session will earn 2.0 PDHs. Please contact CASE Executive Director Heather Talbert (htalbert@acec.org) if you are interested in attending this roundtable or have any suggested topics for the roundtable.

Congratulations go out to CASE Member firms Walter P Moore of Houston, TX and Weidlinger Associates (now part of Thornton Tomasetti) for each winning a Grand Award. Walter P Moore’s highlighted project, SFO Air Traffic Control Tower & Integrated Facility in San Francisco, CA and Weidlinger Associates’ highlighted project, Manhattan Bridge Rehabilitation of Cables and Suspenders, New York City were finalists for the Grand Conceptor Award awarded at the recent Engineering Excellence Awards Gala held during the ACEC Annual Convention last month. CASE Member Firm KL&A won an Honor Award for their project, Aspen Art Museum, Aspen, CO.

CASE in Point

CASE Summer Planning Meeting

CASE Risk Management Seminar This summer, for the first time in 9 years, CASE will put on the industry’s only seminar dedicated solely to improving your firm’s business practices and risk management strategies. Come and join us and learn to Manage Risk for High Stakes Success in Chicago on August 4–5 for training and collaboration with industry leaders and project managers from firms of all sizes, intended to improve your structural engineering practice. Immerse yourself in topics designed to help engineers learn better ways of reducing areas of risk and liability on projects, while learning about tools that are available to implement better practices immediately in your firm. This new CASE Convocation Seminar is geared towards Owners, Principals, Project Managers, and Risk Managers. If you are concerned with risk management, new trends, and profitability, you cannot afford to miss this event! Join us August 4 – 5 in Chicago for the updated CASE Risk Management Convocation! To register for this event, go to www.acec.org/coalitions.

A/E Industry’s Premier Leadership-Building Institute Filling Fast for September Class Since its inception in 1995, the American Council of Engineering Companies’ prestigious Senior Executives Institute (SEI) has attracted public and private sector engineers and architects from firms of all sizes, locations and practice specialties. Executives – and up-and-coming executives – continue to be attracted by the Institute’s intense, highly interactive, energetic, exploratory, and challenging learning opportunities. In the course of five separate five-day sessions over an 18-month timeframe, participants acquire new high-level skills and insights that facilitate adaptability and foster innovative systems thinking to meet the challenges of a changed A/E/C business environment. The next SEI Class 22 meets in Washington, D.C. in September 2016 for its first session. Registration for remaining slots is available. STRUCTURE magazine

Executives with at least five years’ experience managing professional design programs, departments, or firms are invited to register for this unique leadership-building opportunity. As always, course size is limited, allowing faculty to give personal attention, feedback, and coaching to every participant about their skills in management, communications, and leadership. SEI graduates say that a major benefit of the SEI experience is the relationships they build with each other during the program. Participants learn that they are not alone in the challenges they face both personally and professionally, and every SEI class has graduated to an ongoing alumni group that meets to continue the lifelong learning process and provide support. For more information, visit http://sei.acec.org or contact Deirdre McKenna, 202-682-4328, or dmckenna@acec.org.

May 2016

CASE is a part of the American Council of Engineering Companies

August 4 – 5, 2016; Chicago, IL

Structural Forum

opinions on topics of current importance to structural engineers

Public Perception of Structural Engineers By Dilip Khatri, Ph.D., S.E.

ho are we to the Public? Do they know or care about what we do? Sadly, the public doesn’t know who we are or what we do. Structural engineers have allowed our clients (architects) to define the meaning of “buildings” and thus have grabbed credit for our work for the past 100 years. An architect represents every project, with no space/room for the technical accomplishments that make those projects happen. This is not to say that we should be angry with architects. By no means does this article imply or suggest that we should direct any criticism towards our partners in the creative design world. The focus of this article is on us, on our profession, because we are the cause of our own problem. Let’s start with two examples of structural engineering accomplishments with zero public recognition. The Empire State Building, New York City’s symbol and America’s icon of the “Empire State” and a nation on the rise, was designed by the architects Shreve, Lamb, Harmon. Mr. William Lamb has received accolades of credit for this building, which was cited as the 8th Wonder of the World. Where is the name of Homer Gage Balcom? He was the genius structural engineer that created the structural system to pioneer this first, tallest building of its kind. No one remembers H.G. Balcom. More recently, the Disney Concert Hall, lauded as an artistic masterpiece, was designed by Frank Gehry. Not a mention of the extensive computer modeling and seismic analysis that went into this curvilinear steel membrane nightmare that made no sense to anyone, until a structural engineer could translate it from Frank Gehry’s sketches into working drawings. The Disney Concert Hall was a “pipe dream” that would have never happened without the hard work of John A. Martin & Associates transforming a design plan from a “doodle sketch.” Yet, there is not a mention of them by the Honorable Frank Gehry in any of his speeches or public recognition. I could go on for pages and pages, but let’s focus on the solution.

Structural engineers have three prominent character traits (among others) that prevent them from gaining recognition: 1) Lack of Image Recognition: Our professional culture does not demand “Image Recognition”. We regard ourselves as “above” all that nonsense, and we don’t seem to care whether our name goes on the plaque in front of the building or is mentioned in a press release. We are, by nature, a very humble profession considering our accomplishments. 2) Too Busy to be Bothered: We are so busy with taking care of our workload and meeting deadlines, the idea of public participation seems ludicrous and impossible. We don’t participate in public events in a leadership role, so consequently the public doesn’t get to know us. 3) We do not engage the Press: The Press loves to interview architects, and they love the attention. We don’t invite the Press to any of our events and are scared of anything in the media with our name on it due to fear of consequences or a bad photo. Our culture starts with our college experience. When we were students, we were among the hardest working on campus – engineering is tough. I’ll be the first one to admit that I hated my humanities courses and general education. Political science and psychology were low points in my college experience. Now, after 33 years in the business, I wish I had paid attention to these subjects earlier in my life, as I find they dictate my success now with as much (or more) value than my engineering skills. I’ve never had a client walk away from me because I couldn’t design a beam or column, but they will walk away if they can’t get along or communicate with you. Recognition and public awareness have to be built over years of participation in the public arena. We are a long way off. The media doesn’t know we exist. Watch the news after a major hurricane or earthquake; they seldom interview a structural engineer to ask his/her opinion. They will talk with a firefighter, a

paramedic, or a priest, but don’t have a clue who we are. So what do we do? First, the younger generation needs to stay in the profession. The average professional tenure in civil engineering is only around 14 years, according to the U.S. Department of Labor. We need to attract and keep our best and brightest engineers for the long haul. We need to collectively change our attitude when it comes to public recognition. We need to seek it, demand it, and eventually create a public relations channel so that every great project allows our industry to be recognized. I have many ideas on this topic. Others will as well. Now is a good time to spark the conversation and raise awareness on this important issue. Think about real estate brokers. They have a professional license but minimal education compared to engineers. They demand a set commission and have no problem taking full recognition for their work. They sell the buildings that we design! They only sell them! They don’t design them! Yet, everyone knows who a real estate broker is and has a public image of what a broker wears, drives, and looks like. As a reward, brokers and agents can demand higher commissions for their work. I’m not advocating that we become like brokers. But a little salesmanship will help us. We need to partner with our architect clients to share in the recognition. One day, everyone will know who the structural engineer was that designed the White House, the Burj Khalifa, the Empire State Building, the Hoover Dam, the Golden Gate Bridge, and all of the other countless monuments and icons that dot the world because of our efforts.▪ Dilip Khatri is the Principal of Khatri International Inc, Civil and Structural Engineers, based in Las Vegas, NV, and Pasadena, CA. He was a Professor of Civil Engineering at Cal Poly Pomona for 10 years. He serves a member of the STRUCTURE Editorial Board and may be reached at dkhatri@aol.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

May 2016

STRUCTURE magazine | May 2016

Articles inside

CODE UPDATES

STRUCTURAL ECONOMICS

BUILDING BLOCKS

STRUCTURAL FORUM

TECHNOLOGY

LESSONS LEARNED

INFOCUS