STRUCTURE magazine | February 2012 by structuremag

February 2012 Steel

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE ®

SEISMIC ACTIVITY IS NOT JUST A WEST COAST PHENOMENON

Don’t Take A Risk With Mother Nature Natural disasters have been in the news lately. Both here in the U.S., and abroad, Mother Nature has been reminding us that earthquakes are not just a “ring of fire” occurrence but can happen anywhere, anytime. That’s why in the United States our building codes have been updated to take into account earthquakes, hurricanes, tornados and other seismic activity. Powers is committed to providing products that meet the latest building code requirements and helping designers and engineers understand the importance of specifying code compliant anchors. To help assist the engineering community, Powers Register today for FREE has developed real-time anchor PDA2 software download at: www.powersdesignassist.com software which is now available in a FREE download ® and our 6th Edition Technical Manual, available through your local Powers representative

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News

Clarity for Specifiers and Buyers

indapter USA has announced the roll out of a new international distributor network, providing engineers and buyers with a regional sales and technical support service. Lindapter USA would like to remove any potential confusion and confirm that LNA Solutions are not an authorized Lindapter distributor and are not supported or accredited in any manner by Lindapter. “LNA” Solutions is not an acronym of “Lindapter North America” and LNA Solutions are not licensed to use the Lindapter trademark to represent their organization.

Original Lindapter products are readily available across the USA from authorized distributors including: UCCSC (NJ & FL) Strut & Supply (IL) All Pro Fasteners (TX) Edge Construction Supply (WA) Clement Support Services (CA) Lindapter USA has significantly enhanced its distribution network throughout North America to supply inventory from multiple locations, offering buyers greater product availability and faster delivery at lower costs.

Authorized distributors are trained and supported by Lindapter’s R&D and Technical Support Department, with seven engineers providing a rapid response to technical inquiries, a free connection design service, CAD drawings and installation guidance. Lindapter has launched a new catalog for North America demonstrating the latest technical innovation in steel connections. Ensure your approved vendor list includes your nearest authorized Lindapter distributor, all of whom are listed at www.lindapterusa.com

Features 26

Cold-Formed Steel Wall Panels Key Component in Casino Makeover By Victor Carsello, S.E., P.E.

Rising from the ashes of a devastating fire is the new 53,000 square foot state-of-the-art Empress Casino with an old Hollywood feel. The new pavilion consists of a one-story steel frame structure built over the basement of the original structure. Adjacent to the new pavilion is a new four-story precast parking deck. In order to create an early Hollywood art-deco look, designers used strong vertical elements consisting of two or three projecting ‘fins’ grouped into pilasters.

Contract Plans to Erection Drawings

By Carrie Johnson, P.E., SECB

By Kevin Jacques

11 Structural Forensics

21 Codes and Standards

Vernon Avenue Bridge

2012 IBC Changes for Wood Design – Part 2

By Leonard Dzengelewski, P.E.

By John “Buddy” Showalter, P.E. and John R. Henry, P.E.

14 Structural Performance Seismic Design of Structural Steel Pipe Racks

25 Just the FAQs

By Richard M. Drake, P.E., S.E., SECB and Robert J. Walter, P.E., S.E.

Departments 30 Business Practices Strategic Management of Human Capital By Eric K. Rodriguez, P.E.

34 Great Achievements General Edward W. Serrell

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

38 Legal Perspectives By David J. Hatem, Donna Hunt, and Sue E. Yoakum

18 Construction Issues

Responding to Forces of Nature

February 2012

Professional Liability Insurance Concerns for Structural Engineers

Columns 9 Editorial

CONTENTS

Changing Masonry Standards Masonry Infills

41 Lessons Learned Trimbloid X

By Keith Bouchard, E.I.T.

43 Spotlight Arena Stage at the Mead Center for American Theater

By Gerald Epp, M.Eng, P.Eng, Struct.Eng, P.E.

50 Structural Forum What is Structural Engineering Exactly?

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE

By Erik Nelson, P.E., S.E.

February 2012 Steel

the

Cover

Rising from the ashes of a fire is a new 53,000 square foot state of the art casino with an old Hollywood feel. Expanded dining, entertainment and shopping, including a steakhouse, 200 seat buffet, sports bar, Rodeo Drive themed gift shop, and lush interior finishes were incorporated into the new facility with the hopes of luring back old patrons that had not yet returned after the fire, as well new ones that would be attracted to the upgraded facilities. Pictured is a corner feature of the parking structure ready for sheathing and finish. See more about this project in the feature article on page 26.

Publication of any article, image, or advertisement in STRUCTURE® magazine does not constitute endorsement by NCSEA, CASE, SEI, C 3 Ink, or the Editorial Board. Authors, contributors, and advertisers retain sole responsibility for the content of their submissions.

STRUCTURE magazine

February 2012

In every Issue 6 Advertiser Index 37 Resource Guide (Bridge) 44 NCSEA News 46 SEI Structural Columns 48 CASE in Point

Advertiser index

PleAse suPPort these Advertisers

Bentley Systems, Inc. ............................. 40 Computers & Structures, Inc. ............... 52 CTS Cement Manufacturing Corp........ 19 Design Data .......................................... 33 ESAB Welding and Cutting Products .... 17 Fyfe ....................................................... 23 GT STRUDL........................................ 28 The IAPMO Group............................... 35

ICC....................................................... 20 Integrated Engineering Software, Inc..... 31 JMC Steel Group .................................. 29 KPFF Consulting Engineers .................. 36 Lindapter ................................................ 4 Nucor Vulcraft Group ........................... 10 Powers Fasteners, Inc. .............................. 2 RISA Technologies ................................ 51

editorial Board Chair

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

Craig E. Barnes, P.E., SECB

Brian W. Miller

Richard Hess, S.E., SECB

Mike C. Mota, Ph.D., P.E.

Mark W. Holmberg, P.E.

Evans Mountzouris, P.E.

Hess Engineering Inc., Los Alamitos, CA

CRSI, Williamstown, NJ

The DiSalvo Ericson Group, Ridgefield, CT

Roger A. LaBoube, Ph.D., P.E.

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

KPFF Consulting Engineers, Seattle, WA

Brian J. Leshko, P.E.

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

John A. Mercer, P.E.

John “Buddy” Showalter, P.E.

HDR Engineering, Inc., Pittsburgh, PA

Mercer Engineering, PC, Minot, ND

BergerABAM, Vancouver, WA

American Wood Council, Leesburg, VA

Faculty Position in Structural Engineering

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Advertising Account MAnAger Interactive Sales Associates

Jon A. Schmidt, P.E., SECB

CBI Consulting, Inc., Boston, MA

SidePlate Systems, Inc. ............................ 7 Simpson Strong-Tie........................... 8, 24 StrucSoft Solutions, Ltd. ......................... 3 Struware, Inc. ........................................ 15 University of Notre Dame ....................... 6 Valmont Tubing .................................... 13 Wheeling Corrugating........................... 42

The Department of Civil Engineering and Geological Sciences at the University of Notre Dame (cegeos.nd.edu) invites applications for a full-time tenure-track or tenured position in structural engineering to complement the existing faculty. Qualified candidates at all levels (assistant, associate, or full professor) will be considered, with hiring rank and tenure status commensurate with academic accomplishments. The successful candidate must hold a doctoral degree in an appropriate field and must demonstrate potential for high quality research and teaching. The existing faculty has significant strength in natural hazard risk mitigation and sustainable civil infrastructure. In accordance with these strength areas, the department is seeking an outstanding faculty member with a research focus on, but not limited to: infrastructure systems, high-performance and sustainable civil structures, reliability and performance of structures under extreme loading, innovative materials, computational mechanics, and foundation-structure interaction. Candidates for the position should be qualified to teach civil engineering courses, with a strong commitment to teaching excellence at both the undergraduate and graduate levels. The successful faculty candidate is expected to develop and sustain an externally funded research program and publish in leading scholarly journals. Applications should be submitted online at struct.nd.edu as a single PDF with cover letter, detailed CV, statements of research and teaching, and names and contact information for three references. Review of applications will start immediately and continue until the position is filled. The University of Notre Dame is committed to diversity in education and employment, and women and members of underrepresented minority groups are strongly encouraged to apply. The University also supports the needs of dual career couples and has a Dual Career Assistance Program in place to assist relocating spouses and significant others with their job search.

Inquiries related to this search can be directed to Dr. Yahya Kurama at struct@nd.edu.

STRUCTURE magazine

February 2012

editoriAL stAFF Executive Editor Jeanne Vogelzang, JD, CAE

execdir@ncsea.com

Editor

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STRUCTURE® (Volume 19, Number 2). 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 $65/yr domestic; $35/yr student; $90/yr Canada; $125/yr foreign. For change of address or duplicate copies, contact your member organization(s). Any opinions expressed in STRUCTURE magazine are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C3 Ink, or the STRUCTURE Editorial Board. STRUCTURE® is a registered trademark of National Council of Structural Engineers Associations (NCSEA). Articles may not be

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editorial

Responding new trends, new techniques to and Forces current industry of Nature issues By Carrie Johnson, P.E., SECB, Secretary, NCSEA

designed for the current code, with the current drifting requirements, could make a significant impact on answering questions about the need for further code changes. This year, there are certainly parts of the country where structures sustained major tornado damage, but the probability that any individual building will be subjected to a tornado is actually very small, on the order of 1/100,000. This means that, even in the most tornado prone region of the country, a building would be expected to experience tornado effects only one time every one hundred thousand years. As a result, the building codes do not currently require design of buildings for tornado resistance. The design wind speeds experienced in the Joplin, Missouri, tornado this year were in excess of 250 mph, which corresponds to a wind pressure nearly eight times the current design requirements. In this case, it may not be practical to require designing the entire building for the worst case. Other solutions, such as safe rooms, should be considered as options. If enforcement of the current code design and construction requirements would have eliminated the damage, should we be working on code changes or code enforcement? If upgrading existing buildings to the current requirements would have eliminated the damage, should we be working more actively to help communities understand why upgrades are a good idea? The International Existing Building Code has requirements for remodeled structures. Those for additional parking, additional restrooms, etc., are enforced to a much greater degree than the structural requirements. Perhaps we would also have a greater effect on public safety if we spent more time lobbying jurisdictions to enforce the special requirements already present in the current codes. In parts of the country, these requirements are either ignored or largely misunderstood by local jurisdictions. In other cases, they are only enforced on buildings over a certain size or complexity. We also do ourselves a disservice if we add requirements in the code that are overly difficult or impractical to calculate. You just have to look at the trial design problem results to see that we may already be at that point. At last year’s NCSEA Annual Conference in Oklahoma City, Ron Hamburger gave a very interesting presentation on the code update process. During the presentation, he took time to ask the audience to vote on several ideas for future codes. One that I believed was very thought provoking was an idea that perhaps the main code should cover 90% of the buildings and the remaining 10% would require specialty codes. An idea like this may allow us to simplify design concepts where we can and still ensure that the designs for complex buildings or complex areas aren’t left out. There are a lot of things we can do to have a positive effect; and they all require time and effort. We need to get involved, at the local, state, and national levels, with all jurisdictions that control how structures are designed and built. The main idea here is to get involved. It requires time, effort, and thoughtful work. The more people who decide to get involved, the more we can do!▪

a member benefit

structure

arthquakes, tornados, heavy snowstorms and other forces of nature have been in the news a lot this year, and in parts of the country we haven’t normally expected them. We even had a 5.6 magnitude earthquake in Oklahoma. It was surreal, feeling the earthquake and then turning on the news to find that we were under a tornado watch on the same night. While I’ve kidded with fellow engineers from Texas about not being in an earthquakeprone region like Oklahoma, I still had to stop and think about the code requirements. The natural tendency after any major event is a call to strengthen the codes; but what we really need to do is look at this thoughtfully and carefully, and take each type of event and the corresponding probability into account. As structural engineers, we should be helping the public find a balance between continually updating codes and enforcing the ones we have. On the one hand, we will lose the public’s trust if we do not make updates based on what we have learned from past events. On the other hand, we are doing ourselves a disservice if we allow design requirements to be revised to the extent that they limit the individual engineer’s ability to design efficiently, or they increase the overall cost of construction to the extent that structures aren’t built. We need to study in-depth the buildings that sustain damage under any given event, asking the following series of questions: Was the event in excess of the current code? Did the original drawings meet the code in effect at the time it was constructed? Was the structure constructed in conformance with those drawings? Were the failures due to the need for stronger codes or from lack of enforcement of the existing codes? Although I may not have expected an earthquake in Oklahoma, the code does require engineers in Oklahoma and throughout the country to design for earthquakes. Historically, I think some of these requirements have been ignored. After each significant earthquake event, we need to look at the structures that did sustain damage and analyze whether or not that damage is in excess of what should have been expected. If so, the codes do need to change; but if not, we should work more on enforcement of existing requirements. Over the last twenty years, there are areas of the country where the loads have been increased to account for snowfalls in excess of the code; but not all buildings have been brought up to the new standard. The practice of analyzing the code snow loads for adequacy needs to occur on a continual basis; but we also need to look deeper than the ground snow load when we are analyzing STRUCTURAL the situation. When a problem ENGINEERING INSTITUTE occurs, knowing whether or not the structure in question was

STRUCTURE magazine

February 2012

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Structural ForenSicS investigating structures and their components

The Vernon Avenue Bridge in Barre, Mass., was one of the first “work horse” bridge projects in the U.S. to involve implementing a structural health monitoring system.

unique project in Barre, Mass., is helping to transform the way bridges are designed, constructed, and managed. With support from the National Science Foundation, the construction process for the Vernon Avenue Bridge involved implementing a structural health monitoring (SHM) system, making it one of the first “work horse” bridge projects in the country to do so. Some larger “signature bridges” have SHM systems, but the Vernon Avenue Bridge is not a signature bridge. As a smaller bridge spanning a river, it may not draw national attention, but its continued operation is vital to the community it serves. The Vernon Avenue Bridge, which spans the Ware River, is a three-span, continuous, steel girder bridge with a composite reinforced concrete deck. The bridge measures 47 meters long (154 feet) with a 23.5-meter center span (77foot) and two 11.75-meter secondary spans (38.5-foot). There are six main girders, evenly spaced at 2.25 meters (7.4 feet) apart, which run the length of the bridge.

The research project’s roots go back to January of 2008, when the National Science FoundationPartnership for Innovations (NSF-PFI) selected a team of researchers from Fay Spofford & Thorndike (FST), Tufts University, the University of New Hampshire, and Geocomp Corporation to participate in a collaborative partnership titled, Whatever Happened to Long Term Bridge Design? The partnership sought to evaluate bridge design procedures to facilitate long-term monitoring, as well as develop protocol for a structural health monitoring system. As part of the work, the partnership designed and installed an instrumentation system. The bridge’s system of more than 200 sensors provides the partnership’s researchers with a great opportunity to observe many different types of bridge behavior. In support of the NSF project, the Central Massachusetts town of Barre, in coordination with the Massachusetts Department of Transportation, granted the research team access

Vernon Avenue Bridge

The bridge construction crew conducts the pour.

STRUCTURE magazine

By Leonard Dzengelewski, P.E.

Leonard Dzengelewski, P.E. is Deputy Manager of Fay, Spofford & Thorndike’s Structural Division. He may be reached at ldzengelewski@fstinc.com.

A strain gauge is installed on a prepared surface.

Three of the steel girders at the steel fabrication plant in Lancaster, Penn.

to the construction of the Vernon Avenue Bridge. The research team’s involvement centered on developing structural baseline analytical models of the bridge, an instrumentation plan, and protocol to help compare measured with predicted behavior.

How It Works

uniaxial accelerometers at 13 stations along the length of the bridge. Data from these sensors are continuously collected using iSite™ data acquisition boxes provided by Geocomp Corporation. • Strain sensors and thermistors distributed along the length of each girder on both sides of the web, with the exception of the exterior girders which only have instrumentation on the interior face. Each girder was fabricated in two parts with a splice located just off the north pier. All iSite™ data acquisition boxes were placed on the south end of the girders for ease of access to a power supply and communication source. • Two pressure plates were installed on the approach span to capture the vehicle weights of the ambient traffic.

instrumentation was completed during the construction phase. The strain gauges and thermistors were installed at the steel fabrication yard of High Steel, Inc., in Lancaster, Pennsylvania. The installation was done after steel fabrication was complete and prior to delivery to the construction site. Wires were wrapped for transportation; each gauge was environmentally protected. Meanwhile, concrete thermistors were tied to reinforcing bars prior to the deck pour. Tiltmeters and accelerometers were installed at the bridge site after girder erection and deck casting, but prior to commissioning. Data was collected throughout the construction process, including the concrete deck pour and during the load test, which took place after completion of the bridge. This element of Vernon Avenue Bridge project allowed the research and construction teams to work together closely. Instrumentation and data acquisition never impeded on the construction schedule. Also, project costs were not adversely impacted. Overall, the construction and research teams’ cooperation and commitment was paramount to making this unique project a success.

Prior to SHM instrumentation, the research team created two structural models (fine and course) with SAP 2000©. The fine model used solid and shell elements; the coarse model utilized Bridge Modeler with shell and frame elements. Using these models, an instrumentation plan was designed that featured more than 200 sensors, including strain gauges, tiltmeters, accelerometers, and temperature gauges. This particular aspect of SHM instrumentation features its own set of challenges. SHM is based on the concept that a bridge can provide data regarding its own strains and stresses under various loading condiWhat Made The Bridge Load Rating Using tions. This is accomplished by determining Project Unique? Nondestructive Test Data specific locations for the various types of sensors and monitors used. Also, place- The most unique aspect of the Vernon Some bridges in the U.S. interstate highway ment of the sensors and monitors must be Avenue Bridge project was how SHM system are load posted due to structural defibalanced with the desired inforciencies. However, these bridges mation sought in order to make may have additional load carrying the best use of the data collected. capacity that is not accounted for Too many or too few monitors in the traditional load rating analor sensors can provide an overysis approach, which is based on load or an insufficient amount elemental as opposed to 3D system of information, rendering data behavior. The American Association hard to decipher. of State Highway Transportation The research team’s instrumentaOfficials (AASHTO) allows for the tion plan featured: use of nondestructive test data for • One-hundred strain gauges, capturing the three-dimensional 36 steel thermistors, 30 system behavior of the bridge, concrete thermistors, 16 which may lead to determination The Vernon Avenue Bridge project serves as an example of how to successfully bi-axial tiltmeters, and 16 of a higher load carrying capacity. instrument a structural health monitoring system during the construction process.

STRUCTURE magazine

February 2012

Three-dimensional computer models of the Vernon Avenue Bridge were calibrated using the nondestructive static and dynamic test data. Calculations from the calibrated models showed some additional load carrying capacity in comparison to the traditional analysis approach.

Studying the Effects of Temperature on Bridge Response

Acknowledgements The project was supported by a grant from the National Science Foundation-Partnership for Innovations Program (Number 0650258) with assistance from the National Science Foundation CAREER Program (Number 0644683). The Town of Barre, owner of the bridge, provided access and ongoing help with coordination for all phases of the project. Likewise, the Massachusetts Department of Transportation provided coordination and assistance. The bridge constructor, E.T. & L. Corporation, and their steel fabricator, High Steel, Inc., provided access, assistance, and coordination during bridge construction.

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A Smart Decision The Vernon Avenue Bridge, which opened to traffic in September of 2009, is now serving residents and visitors of Barre. Just as important is that the project will serve as an example of how to successfully instrument a structural health monitoring system during the construction process for use in short-term and long-term bridge structural health monitoring. During a time of aging bridge infrastructure and limited funds for improvements, this type of SHM instrumentation can be a smart decision. Installation during construction may reduce overall costs of SHM systems and improves feasibility of their use. In the long run, successful leveraging instrumentation, monitoring, and modeling technologies will allow for more accurate and cost-effective bridge management both today and in the future.▪

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The Research Team Professor Masoud Sanayei of Tufts University served as Principal Investigator (PI).

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A controlled load test is the ideal way to obtain a known response for a monitored bridge. However, if temperature loadings cause a similar response to that of a load test, the natural cyclic temperature loadings on a bridge may be used instead of a load test, or to supplement it, for model calibration and successful performance of an SHM system. Since load tests can be expensive and disruptive, successful application of temperature effects in this way would greatly improve the feasibility and use of SHM to assist bridge monitoring and maintenance. In 2011, the research team has focused on calibrating structural models by temperature response. To date, this approach has been more challenging than the static and dynamic response from the controlled load tests. Weights and positions of trucks can be accurately determined. However, measuring and analyzing temperature response of a structure is more difficult.

Associate Professor Erin Santini Bell of the University of New Hampshire served as the Co-PI. Brian Brenner, a Vice President at Fay Spofford and Thorndike and a Professor of the Practice at Tufts, also contributed as a Co-PI for the project. Dr. Allen Marr of Geocomp Corporation served as the main partner for instrumentation and data acquisition. Graduate students at Tufts University and the University of New Hampshire played a major role in the instrumentation, data acquisition, and analysis of the Vernon Avenue Bridge using the measured nondestructive test data.

Structural Performance performance issues relative to extreme events

tructural steel pipe racks typically support pipes, power cables and instrument cable trays in petrochemical, chemical and power plants. Occasionally, pipe racks may also support mechanical equipment, vessels and valve access platforms. Main pipe racks generally transfer material between equipment and storage or utility areas. Storage racks found in warehouses are not pipe racks, even if they store lengths of piping. To allow maintenance access under the pipe rack, transverse bents are typically moment-resisting frames (Figure 1). Although the bent is shown with fixed-base columns, it can also be constructed with pinned bases if the supported piping can tolerate the resulting lateral displacement. The transverse bents are typically connected with longitudinal struts. If bracing is added in the vertical plane, then the struts and bracing act together to resist lateral loads longitudinal to the pipe rack (Figure 2). If the transverse frames are not connected with longitudinal struts, the pipe rack is considered “unstrutted.” The frame columns must act as cantilevers to resist lateral loads longitudinal to the pipe rack.

Seismic Design of Structural Steel Pipe Racks By Richard M. Drake, P.E., S.E., SECB and Robert J. Walter, P.E., S.E.

Richard M. Drake, P.E., S.E., SECB is a Senior Fellow/Structural Engineering at Fluor in Aliso Viejo, California. He can be contacted at Rick.Drake@fluor.com. Robert J. Walter, P.E., S.E. is a Principal Civil/Structural Engineer at CB&I in Plainfield, Illinois. He can be contacted at walter@cbi.com.

This article is condensed from a paper published by the authors in the Engineering Journal (AISC), 4th Quarter, 2011, and is reprinted with permission. The online version of this article contains detailed references. Please visit www.STRUCTUREmag.org.

Design Criteria In most of the United States, the governing code is the International Building Code (IBC), which applies to buildings and other structures. IBC prescribes structural design criteria in Chapters 16 through 23, and adopts by reference many industry standards and specifications that have been created in accordance with rigorous American National Standards Institute (ANSI) procedures. For the most part, design loads are prescribed in ASCE 7, structural steel material references are prescribed in AISC 360, and structural steel seismic requirements are prescribed in AISC 341 and AISC 358. The edition of each standard that is used should be based on the edition of the governing building code or as otherwise approved by the authority having jurisdiction. Design criteria for nonbuilding structures are usually provided by industry guidelines that interpret and supplement the building code and its referenced documents. In the case of pipe racks, additional design criteria are provided by Process Industry Practices, PIP STC01015, and the ASCE Guidelines for Seismic Evaluation and Design of Petrochemical Facilities. In this article, the IBC requirements govern; the PIP practices and ASCE guidelines may be used for pipe racks, as they supplement the IBC and the referenced industry standards and specifications, but they are not code-referenced documents themselves.

14 February 2012

Figure 1: Typical transverse bent.

Earthquake Loads Earthquake loads are prescribed in IBC section 1613, which references ASCE 7. Seismic detailing of materials as prescribed in ASCE 7 Chapter 14 is specifically excluded; instead, seismic detailing of structural steel materials is prescribed in IBC Chapter 22. PIP STC01015 recommends that earthquake loads for pipe racks be determined in accordance with ASCE 7 and the following: • Evaluate drift limits in accordance with ASCE 7 Chapter 12. • Consider pipe racks to be nonbuilding structures in accordance with ASCE 7 Chapter 15. • Consider the recommendations of the ASCE guidelines. • Use Occupancy Category III and an importance factor (I) of 1.25, unless specified otherwise by client criteria. • Consider an operating earthquake load (Eo) that includes the operating dead load (Do) as part of the seismic effective weight. • Consider an empty earthquake load (Ee) that includes only the empty dead load (De) as part of the seismic effective weight.

Seismic Design Considerations ASCE 7 Chapter 11 defines a nonbuilding structure similar to a building as: “A nonbuilding structure that is designed and constructed in a manner similar to buildings, will respond to strong ground motion in a fashion similar to buildings, and has a basic lateral and vertical seismic forceresisting system conforming to one of the types indicated.” Examples include pipe racks. As a nonbuilding structure, consideration of seismic effects on pipe racks should be in accordance with ASCE 7 Chapter 15, which refers to other chapters as applicable.

Seismic System Selection

Figure 2: Typical 4-level pipe rack consisting of nine transverse frames connected by longitudinal struts.

Period Calculations The fundamental period determined from ASCE 7 Chapter 12 equations is not applicable for nonbuilding structures, including pipe racks, because they do not have the same mass and stiffness distributions assumed for buildings. It is acceptable to use any analysis approach that accurately includes the mass and stiffness of the structure, including finite element models and the Rayleigh method. The determination of the pipe rack period can be affected by the stiffness of the piping leaving the pipe rack. When this stiffness is not accounted for in the period calculation, it is recommended that the calculated period be reduced by 10%. Analysis Procedure Selection Static or dynamic analysis methods can be used. Static procedures are allowed only under certain conditions of regularity, occupancy, and height. ASCE 7 Chapter 12 specifies when a dynamic analysis is required. The philosophy underlying this section is that dynamic analysis is always acceptable for design. A dynamic analysis procedure is required for a pipe rack if it is assigned to SDC D, E, or F and it either: • has T ≥ 3.5Ts; • exhibits horizontal irregularity type 1a or 1b; or • exhibits vertical irregularity type 1a, 1b, 2, or 3. The most common dynamic procedure used for pipe racks is modal response spectrum analysis. The equivalent lateral force (ELF) procedure is allowed for a pipe rack structure if a dynamic analysis procedure is not required. The simplified alternative structural design criteria for

STRUCTURE magazine

February 2012

simple bearing wall or building frame systems are not appropriate and should not be used for pipe racks. Equivalent Lateral Force Procedure The ELF procedure involves calculating the effective earthquake loads in terms of a static base shear that is dependent on the imposed ground acceleration and the structure’s mass (effective seismic weight), dynamic characteristics, ductility and importance. The base shear is then applied to the structure as an equivalent lateral load vertically distributed to the various elevations using code-prescribed equations that are applicable to building structures. Using this vertical distribution of forces, seismic design loads in individual members and connections can be determined. ASCE 7 determines design earthquake forces on a strength basis, allowing direct comparison with the design strength of individual structural members. continued on next page

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Either ASCE 7 Table 12.2-1 or ASCE 7 Table 15.4-1 can be used to choose a seismic force-resisting system, which will provide the prescribed seismic detailing requirements, design parameters (R, Ωo, Cd), and height limitations. Table 15.4-1 permits select types of nonbuilding structures that have performed well in past earthquakes to be constructed with less restrictive height limitations in Seismic Design Categories (SDC) D, E, and F than those specified in Table 12.2-1. Note that Table 15.4-1 includes options where seismic detailing per AISC 341 is not required for SDC D, E, or F. For example, steel ordinary moment frames can be designed with R = 1 without seismic detailing. Seismic detailing requirements can also be avoided in SDC B and C for any structural steel system if R = 3 or less, excluding cantilevered column systems. The transverse bents are usually momentresisting frame systems. The choices are special moment frame (SMF), intermediate moment frame (IMF), or ordinary moment frame (OMF). In the longitudinal direction, when bracing is present, the choices are usually special concentrically braced frame or ordinary concentrically braced frame. Less common choices are eccentrically braced frame or buckling-restrained braced frame. If bracing is not present, the choices in the longitudinal direction are the cantilevered column systems. In both directions, the seismic system selected must be permitted for both the SDC and the pipe rack height. ASCE 7 Table 15.4-1 footnotes permit specific height limits for pipe racks detailed with specific seismic systems: • With R = 3.25, “Steel ordinary braced frames are permitted in pipe racks up to 65 feet (20 m).” • With R = 3.5, “Steel ordinary moment frames are permitted in pipe racks up to a height of 65 feet (20 m) where the moment joints of field connections are constructed of bolted end plates. Steel ordinary moment frames are permitted in pipe racks up to a height of 35 feet (11 m).” • With R = 4.5, “Steel intermediate moment frames are permitted in pipe racks up to a height of 65 feet (20 m) where the moment joints of field connections are constructed of bolted end plates. Steel intermediate moment frames are permitted in pipe racks up to a height of 35 feet (11 m).”

Figure 3: AISC 358 extended end plate connections.

Modal Response Spectrum Analysis MRSA is acceptable for the analysis of pipe racks, and may be required if certain plan and/ or vertical irregularities are identified. The basis of MRSA is that the pipe rack’s mass (effective seismic weight) and stiffness are carefully modeled, allowing the dynamic analysis of multiple vibration modes that result in an accurate distribution of the base shear forces throughout the structure. The MRSA must include a sufficient number of modes in order to achieve a minimum of 90% mass participation. Two MRSA runs are typically required for pipe racks. The first run includes the operating dead load (Do) as the seismic effective weight to determine the operating earthquake load (Eo). The second run includes the empty dead load (De) as the seismic effective weight to determine the empty earthquake load (Ee). The MRSA input ground motion parameters (SDS, SD1) are used to define the ASCE 7 elastic design response spectrum. To obtain “static force levels,” the MRSA force results must be divided by the quantity (R/I). ASCE 7 does not allow an engineer to scale down MRSA force levels to ELF force levels because the ELF procedure may result in an underprediction of response for structures with significant higher-mode participation. On the other hand, when the MRSA base shear is less than 85% of the ELF base shear, the MRSA results must be scaled up to no less than 85% of the ELF values. This lower limit on the design base shear is imposed to account for higher mode effects, and to ensure that the design forces are not underestimated through the use of a structural model that does not accurately represent the mass and stiffness characteristics of the pipe rack. Drift To obtain amplified seismic displacements, the displacement results calculated from the

elastic analysis must be multiplied by the quantity (Cd/Ie) to account for the expected inelastic deformations when checking against the drift limits of ASCE 7 Table 12.12-1. The displacement results must be multiplied by Cd for checking pipe flexibility and structure separation. It is important that the drift of pipe racks be compared to other adjacent structures where piping and cable trays run. The piping and cable trays must be flexible enough to accommodate the movements of the pipe rack relative to these structures. Seismic Detailing Requirements The selection of a seismic force-resisting system from ASCE 7 Table 12.2-1 dictates detailing requirements prescribed in ASCE 7 Chapter 14. Because this chapter is specifically excluded by the IBC, seismic detailing requirements for structural steel systems must be taken instead from IBC Chapter 22 and AISC 341. The selection of a seismic forceresisting system from ASCE 7 Table 15.4-1 directly dictates seismic detailing requirements prescribed in AISC 341. AISC 341 includes such requirements for each structural steel system listed in the two ASCE 7 tables. In general, there is a relationship between R values and seismic detailing requirements. Lower R values and higher earthquake design forces are accompanied by minimal seismic detailing requirements. Higher R values and lower earthquake design forces are accompanied by more restrictive seismic detailing requirements to provide greater ductility. AISC 341 prescribes that beams in OMF systems do not require lateral bracing beyond those requirements prescribed in AISC 360. However, beams in IMF and SMF systems have progressively more restrictive requirements for lateral bracing of beams that can only be met by the addition of a horizontal bracing system at each pipe level. For this

STRUCTURE magazine

February 2012

reason, it may be more economical to select an OMF system for the transverse bents. AISC 341 prescribes that beam-tocolumn connections for IMF and SMF systems be based on laboratory testing. OMF beam-to-column connections may be either calculated to match the expected plastic moment strength of the beam or based on laboratory testing. AISC 358 prescribes specific requirements for laboratory-tested systems appropriate for use in seismic moment frames. One of the systems included in AISC 358 is the bolted endplate moment connection, commonly used in pipe rack construction (Figure 3). These connections are popular in industrial plants because they involve no field welding. Redundancy in SDC A, B, or C In accordance with ASCE 7, for all structures, ρ = 1.0. Redundancy in SDC D, E, or F The typical pipe rack has no horizontal bracing system that serves as a diaphragm. If one individual bent fails, there is no load path for lateral force transfer to the adjacent frame. As a result, the pipe rack must be treated as a non-redundant structure. • For a transverse bent to qualify for ρ = 1.0, it must have four or more columns and three or more bays at each level. This ensures that the loss of moment resistance at both ends of a single beam does not result in more than a 33% loss of story strength. Otherwise, ρ = 1.3. • For an individual longitudinal braced frame to qualify for ρ = 1.0, it must have two or more bays of chevron or X bracing (or four individual braces) at each level on each frame line. This ensures that the loss of an individual brace or connection does not result in more than a 33% loss of story strength nor cause an extreme torsional irregularity (Type 1b). Otherwise, ρ = 1.3. If the pipe rack is provided with a horizontal bracing system that serves as a diaphragm and provides a load path for lateral transfer, it can be treated as a redundant structure. • For a pipe rack to qualify in the transverse direction for ρ = 1.0, it needs to have horizontal bracing between all transverse bents and a minimum of four transverse bents. Otherwise, ρ = 1.3. • For a pipe rack to qualify in the longitudinal direction for ρ = 1.0, there needs to be a minimum of four transverse bents, and each longitudinal frame line needs to have two or more individual braces at each level. Otherwise, ρ = 1.3.▪

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ConstruCtion issues discussion of construction issues and techniques

he journey from Contract Plans (CDs) to Erection Drawings (EDs) is a time consuming and tedious process. To best explain the process, one must understand a few concepts. First, how do they differ? CDs in general specify the standards with which to measure a project’s materials, tolerances and performance (AISC, ASTM, IBC, etc.). They also illustrate the “Designers intent”, plan dimensions, elevations and material sizes to name a few. The EDs are very similar to the CDs. They also show the plan view, etc. However, they differ in content by eliminating non-pertinent items to the job at hand. For example, rebar is not commonly detailed on a steel ED since the erector is only concerned with assembling the structural steel. They also differ by showing the material’s piece marks, greater detail in dimensions with respect to the steel and carefully noted field weld symbols. Where a CD will show shop welds, an ED will not. This weld is already in place on the material. Showing it now would be redundant and confusing. One other area that CDs and EDs may differ is in the depiction of the “Designer’s Intent”. It is this part of the detailer’s job that is often the most difficult and confusing. It is also the greatest area worthy of the designer’s review. This will become more apparent later in this article. It is also important to note that the ED is used for two very different purposes. First, it is used as a platform from which to make the shop details of the members. It has been said that a good set of shop drawings can only originate from a good set of plans. The other use is rather obvious, to give the erector a map as to where all of the material on site belongs and to which member it connects. Bear in mind that the erector’s job is more than a technical job, it is dangerous. A detailer scrutinizes the plans to make sure that the only thoughts the erector has while making the connection is safety. In some cases, for complex projects, the EDs may also specify an order of installation that may not be immediately obvious to the erector. When a crane is moving the correctly sequenced member into place at the correct time, crane time, safety and costly bottlenecks are reduced. One of the stumbling blocks to getting the EDs completed is the RFI. While they are a necessary part of the construction process, they cost money and time, and they create project delays. So, how does one reduce the number of RFIs? Quite often it falls under the detailers ability to interpret the “Designer’s Intent”. Below are some points that may reduce the number of RFI’s generated and thus save the designer time which may be to allocated to billable hours. Beam reactions not shown on the plans. This issue usually pertains to the shallow and short beams.

Contract Plans to Erection Drawings By Kevin Jacques

Kevin Jacques is the president of the Drafting Subcontractor, Inc. a Structural Steel, Miscellaneous Metals and Joist/ Deck detailing firm, president of the New England Steel Detailers Association, Director of the New England Chapter of the National Institute of Steel Detailing and the chairman of their Education Committee. He may be reached at kjacques@draftingsub.com.

18 February 2012

Figure 1: Moment connection detailed with no load provided.

A w8x10 spanning 3 feet can support 53.7kips (26.8 k end reaction). A very costly eight bolt connection can be detailed. But really, is that the designer’s intent? Specifying the end reactions be equal to ½ the maximum uniform load per the AISC is counter intuitive. A short beam may have more bolts than one twice its length. Moment connections that do not show a detail, don’t provide a load or the detail given does not fit the project are problematic. See Figure 1 for a moment connection detailed using a 3D modeling software. This connection (un-buildable) was using the maximum moment for the beam. Now see Figure 2. This moment connection is the result of having the actual design moment provided. A very clean, buildable and erectable connection that does exactly what the designer desired. Naturally, an RFI had to be generated to get the desired outcome. Hung lintels are of particular concern for the erector. Welds should be considered also, as they are usually related. All too often the detailer is given a detail that does not allow for the proper adjustment and safe installation that an erector requires. A designer should bear in mind that these details need to consider mill tolerances, material availability, fabrication tolerances and what the strike of a welder’s arc can do to steel. Both vertical and horizontal adjustment should be planned. And using slip critical connections

Figure 2: Moment connection detailed with the load provided.

Figure 3.

is supposed to do all of the thinking for the fabricator/erector whose job is to build the product. A detailer would also have a thorough knowledge of welding symbols and how to apply them (not necessarily able to weld). Probably the most significant skill to have as a detailer is exceptional drafting skills. Remember, a beam only has a 1/16-inch of tolerance for bolted connections. This is a relatively tight tolerance that requires a skilled draftsperson. One skill or qualification that was not mentioned is a degree in engineering. While detailers may understand and speak fluently in this area of knowledge, don’t rely on them to have the education, training or credentials of an engineer (although some are PE’s). However, one can rely on their experience and knowledge of making things buildable and erectable. One final point to reduce RFIs is this: get the steel detailers involved early in the project. After reviewing the list of a detailer’s qualifications, the almost sickening attention to detail (hence the job title) and their ability to make things buildable and erectable, it only seems natural to have them as part of the design team. It would all but eliminate the RFI process as the detailer would iron out all of the issues well before the bidding begins. It would also greatly reduce change orders and possibly the overall cost of the project. The fabricator would no longer guess during bidding; they would have everything in front of them. The software exists to tailor the connections to the fabricator’s shop and, in this economy, what business person would turn away a fast moving job due to some small nuances. At the very least, call upon the local detailers to get advice on the details that keep engineers up at night and answering RFIs. Clearly they have better things to do.▪

STRUCTURE magazine

February 2012

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may not be a viable option, as galvanizing does not meet the surface standards. Also, welding symbols that show a continuous weld rather than a stitch weld can create even more field problems. One last thought to entertain when specifying welds is one that would place the welder below the surfaces to be welded (called an overhead weld). This is not only unsafe for the welder but anyone working below. It also creates a weld quality issue as the welder, rightfully so, is more concerned with his/her safety than the welding operation being done properly. Roof/Floor frames are the Achilles heel to any project. If they are located and sized, Murphy’s Law dictates that they will change. More often than not, they are the last piece of the puzzle and must be placed from below the deck. This creates many time consuming hazards (see overhead weld). Considering the automation that has evolved in recent years, it may be more advantageous to use Wf beam sections with single clip angle connections (with the end reactions noted) rather than angles with saddles. If a frame has to move, new holes made with a Mag drill will make short work of the fix. And the weight difference is not too great (w8x10 vs. L4x4x5/16 @ 8.2 lbs./ft.). Acute angle framing is a tough connection to detail and greatly reduces the capacity of the beam. See Figure 3 for a suggested alternative. In this case, a picture is really worth a thousand words. While there are many more issues to cover, it is equally important to note the qualifications of a detailer. As mentioned, being able to interpret the designer’s intent is very important. They are also a translator of engineering jargon into pictorial details that are easily deciphered by the fabricator or erector on the fly. Remember, the detailer

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104.11 Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved.

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his article is the second of two that outlines changes for wood design in the 2012 International Building Code (IBC). The first article focused on the 2012 National Design Specification® (NDS®) for Wood Construction and appeared in the January 2012 issue of Structure magazine. Part 2 will outline other updated standards and code modifications.

2301.1.1.2 New HRA designation for EndJointed Lumber End-jointed (finger jointed) lumber may be used interchangeably with solid sawn lumber of the same species and grade. If used in a fire resistance rated assembly, finger-jointed lumber must have the heat resistant adhesive (HRA) designation on the grade stamp. 2305 General Design Requirements for Lateral Force-Resisting Systems

2012 IBC Changes Changes to the 2012 IBC are summarized in the Table (page 22) and covered in more detail as follows. 1609.1.1 Wind Loads and the use of ICC600 and WFCM A newly referenced standard ICC-600, Standard for Residential Construction in High-Wind Regions, is applicable for certain residential structures within its scope. ICC-600 fulfills in a more general way what AWC’s Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings does for wood construction. The WFCM is also an acceptable alternative standard referenced in this section for determining wind loads within the limits of 1609.1.1.1. ICC 600 requires compliance with the WFCM in Chapter 3 of the standard, and then gives all the prescriptive requirements for the rest of the building: foundations, roofing, windows, etc. This new standard can be used with the typical wind provisions of the 2012 IBC and ASCE 7-10 Minimum Design Loads for Buildings and Other Structures. A table in the standard provides building geometry limits based on material type for the framing, such as three stories and a certain roof pitch. It applies mostly to residential buildings in high wind areas, but certain commercial structures could be within its scope. 1905.1.9 ACI 318 Appendix D and NDS A new exception in the 2012 IBC to ACI 318 Appendix D permits up to 5/8-inch diameter anchor bolts installed in wood sill plates attached to concrete foundations to be designed in accordance with the NDS, with certain conditions. A problem developed in Appendix D of the concrete design standard, ACI 318, regarding design and sizing of anchor bolts. A code change to the 2012 IBC clarified that design in accordance with the NDS for determining anchor bolt lateral design values parallel to grain is permitted. 2301.2 New Log Structure Standard ICC-400 A new standard on Design and Construction of Log Structures, ICC-400 is referenced in the 2012 IBC. This will give code officials and log structure designers a reference standard. Previously, they were approved under the alternative design provisions of Section 104.11.

Provisions for lateral design of wood structures have been coordinated with the 2008 edition of AWC’s Special Design Provisions for Wind and Seismic (SDPWS-08). Design values for nailed diaphragms and shear walls were deleted from the 2009 IBC tables because the values are in the SDPWS-08 standard. Design and deflection values for stapled wood-frame diaphragms and shear walls remain in the code. Although the deflection of nailed wood-frame diaphragms and shear walls is determined in accordance with SDPWS, the deflection of stapled diaphragms and shear walls is not covered in the standard. Section 2305 provides the formulae and design parameters required to calculate deflection of blocked wood structural panel diaphragms and shear walls fastened with staples.

Codes and standards updates and discussions related to codes and standards

2012 IBC Changes for Wood Design

2306 Allowable Stress Design Section 2306 references the 2008 SDPWS for lateral design of wood structures using allowable stress design. The general term “wood frame” has been added as a clarification of the intent, so the code now refers to wood-frame diaphragms and wood-frame shear walls. Design values for nailed diaphragms and nailed shear walls have been deleted from the tables in Section 2306 because the values are in the SDPWS standard. Design values for stapled shear walls and diaphragms remain in tables in the code. Table footnotes have been revised to account for removal of allowable design values for nailed diaphragms and shear walls. Sections 2306.2 and 2306.3 have been revised to clarify that design and construction as well as limitations in the SDPWS are applicable to stapled diaphragms and shear walls. Specific sections referring to particleboard, fiberboard and lumber-sheathed shear walls have been deleted because they are covered under the general term of “wood-frame shear walls” and their design provisions are included in the SDPWS standard. A new national consensus standard, APA PRP210, has been added to address wood structural panel siding products that were formerly covered under several national standards such as APA PRP-108. Siding products manufactured

STRUCTURE magazine

Part 2 By John “Buddy” Showalter, P.E. and John R. Henry, P.E.

John “Buddy” Showalter, P.E., Vice President, Technology Transfer, American Wood Council and John R. Henry, P.E., Principal Staff Engineer, International Code Council. Contact Mr. Showalter (bshowalter@awc.org) with questions.

Summary of Changes to 2012 IBC.

IBC Section

Standard or topic

Modification

1609.1.1 Determination of wind loads

AWC 2012, Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings

Updated standard

ICC 600 Standard for Residential Construction Updated standard in High-Wind Regions 1905.1.9 ACI 318, Section D.3.3 2301.2 General design requirements

ACI 318-11 Appendix D

Permits NDS anchor bolt design

AWC WFCM 2012

Updated standard

ICC-400-12 Log Structure Standard

Updated standard

2301.1.1.2 End-jointed lumber

End-jointed lumber

New heat resistant adhesive designation

2303.1.4 Wood structural panels 2304.6.2 Interior paneling

DOC PS 1-09 and PS 2-10 for Plywood and Wood-based Structural-use Panels

Updated standards

2305 Lateral Force Resisting System

AWC 2008 Special Design Provisions for Wind and Seismic (SDPWS)

Removed code criteria duplicated in 2008 SDPWS

2306 Allowable stress design

AWC 2008 SDPWS

Removed code criteria duplicated in 2008 SDPWS

2306.1 Allowable stress design reference standards

AWC NDS-2012

Updated standard

AITC 113-10 Standard glulam dimensions

Updated standard

AITC 117-10 Softwood glulam

Updated standard

APA PRP-210 plywood siding

New standard

AWC Span Tables for Joists and Rafters 2012

Updated standard

2306.1.1 Joists and Rafters

2307 Load and resistance factor design AWC 2008 SDPWS

Removed code criteria duplicated in 2008 SDPWS

2307.1 Load and resistance factor design reference standards

AWC NDS-2012

Updated standard

2308.2.1 Nominal design wind speed greater than 100 mph (3-second gust)

AWC WFCM 2012

Updated standard

2308.12.4 Braced wall line sheathing

Braced wall line requirements for seismic design categories D and E

Table 2308.12.4 revised and new section 2308.12.4.1 added

to the ANSI/APA PRP-210 standard have been developed specifically for wall-covering/weatherproofing applications, carry an exterior exposure durability classification, and have equivalent shear performance on a thickness-by-thickness basis when fastened in accordance with shear wall Table 2306.3(1). The code permits panels complying with ANSI/APA PRP-210 to be designed using values for plywood siding in SDPWS. To clarify the intent, the figure that accompanies the diaphragm table has been modified in the 2012 IBC. The figure in previous editions of the code has been difficult to interpret because of improper placement of annotation lines. The new figure has a legend to better differentiate between blocking and framing members, and annotation lines are more accurately placed in the figure. The design engineer is concerned with a specific diaphragm sheathing layout pattern with two loading cases, one for each orthogonal direction. Instead of six separate diaphragm configurations, the new figure shows three diaphragm layout patterns and two load

cases for each diaphragm configuration. Although no technical changes were made to the figure, the new figure better illustrates the intent of the diaphragm design table. The reference to AWC’s Span Tables for Joists and Rafters in 2306.1.1 has been updated to the 2012 edition. The companion supplement, Design Values for Joists and Rafters, has been updated to the 2012 NDS Design Values Supplement. Changes include new design values for Coast Sitka Spruce and Yellow Cedar, and updates to Northern Species design values. 2307 Load and resistance factor design LRFD provisions are now coordinated with 2008 SDPWS. Requirements for 3X members at abutting panel joints in the 2009 IBC Section 2307.1.1 are no longer necessary because similar provisions are contained in Section 4.3.7.1 of SDPWS-08. SDPWS requires 3X framing at adjoining panel edges and staggered nailing where nail spacing is 2 inches on center or less at adjoining panel edges, or where 10d common nails having penetration into framing members

STRUCTURE magazine

February 2012

and blocking of more than 1½ inches are nailed at 3 inches on center or less at adjoining panel edges, or where required nominal unit shear capacity on either side of the shear wall exceeds 700 plf for buildings in Seismic Design Category D, E, or F. An exception permits two 2X framing members, provided they are fastened together in accordance with the NDS to transfer shear between members. When fasteners connecting the two framing members are spaced less than 4 inches on center, fasteners are required to be staggered. The reference to AWC’s NDS in 2307.1 has been updated to the 2012 edition. 2308 Conventional light-frame construction Three modifications were made to Section 2308.12.4 that clarify the intent of provisions regarding prescriptive wall bracing of buildings in Seismic Design Categories (SDC) D and E. Conventional wood frame buildings in SDC A, B, and C require braced wall panels spaced every 25 feet in accordance with Table 2308.9.3(1). Conventional wood frame

2303.1.1.2 New HRA designation for EndJointed Lumber End-jointed (finger jointed) lumber may be used interchangeably with solid sawn lumber of the same species and grade. If used in a fire resistance rated assembly, finger-jointed lumber must have the heat resistant adhesive (HRA) designation on the grade stamp. 2305 General Design Requirements for Lateral Force-Resisting Systems

Codes and Standards updates and discussions related to codes and standards

2012 IBC Changes for Wood Design

STRUCTURE magazine

Part 2 By John “Buddy” Showalter, P.E. and John R. Henry, P.E.

Provisions, which do not require overturning restraint and do not include alternate braced wall panels. According to the NEHRP Commentary, it appears that the primary concern that led to the aspect ratio requirement is aimed at minimizing overturning demand due to lack of overturning restraint at braced wall panels. The alternate braced wall panels address overturning directly by specifically requiring overturning restraint devices; thus, they should not be subject to the 2:1 h/w limit. To resolve this, footnote “a” was modified so that the 2:1 height-to-width ratio limitation does not apply to alternate braced wall panels.

STRUCTURE magazine

Conclusion The 2012 IBC represents the state-of-the-art for design and construction of buildings outside the scope of the International Residential Code (IRC). Enforcement has already begun in those jurisdictions adopting the latest building code. However, building officials are also apt to accept designs prepared in accordance with newer reference standards even if the latest building code has not been adopted in their jurisdiction. IBC 104.11 and IRC R104.11 for alternate materials and design provides the authority having jurisdiction with that leeway.▪

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buildings in SDC D and E are regulated by Table 2308.12.4 for determining required wall bracing. This table previously provided the minimum length of wall bracing per 25 feet of braced wall line length but did not give a minimum percentage. Because there was no percentage given, it was not clear how to properly apply table requirements. For example, for a building sited where SDS > 1.00g, the table required 12 feet of wall bracing for each 25 feet of wall. It was clear that a 25-foot-long wall required 12 feet of bracing, and a 50-foot-long wall required 24 feet of bracing, but it was not explicitly clear what amount of bracing would be required for a 40-foot-long wall. To resolve this, Section 2308.12.4 and Table 2308.12.4 were revised to specify a minimum percentage of wall bracing instead of a minimum length of bracing per 25 feet. For example, for a building sited where SDS > 1.00g, the table now requires 48 percent of wall bracing. Thus, a 40-footlong braced wall line requires 0.48 x 40 = 19 feet of wall bracing. Second, for buildings in SDC A, B, and C, Sections 2308.9.3.1 and 2308.9.3.2 are quite clear that alternate braced wall panels and alternate braced wall panels adjacent to a door or window opening can be substituted for wall bracing required by Section 2308.9.3. However, for buildings in SDC D and E, the code was not clear that these alternate braced wall panels could be substituted for wall bracing required by Table 2308.12.4. Although it was the intent of the code, it was difficult to conclude this by simply reading this section. To resolve this issue, a new Section 2308.12.4.1 has been added that clearly states that alternate braced wall panels constructed in accordance with Section 2308.9.3.1 or 2308.9.3.2 are permitted to be substituted for braced wall panels required by Table 2308.12.4. Third, footnote “a” of Table 2308.12.4 states that the height-to-width ratio for braced wall panels cannot exceed 2:1. For a typical 8-foot-high wall, this means the minimum length of the braced wall panel must be 4 feet. The alternate braced wall panel described in Section 2308.9.3.1 is 2 feet 8 inches in length, and the alternate braced wall panels adjacent to an opening in Section 2308.9.3.2 can be only 16 inches in length for a one-story building. It was not clear whether footnote “a” in effect meant that the alternate braced wall panels of Section 2308.9.3.1 and 2308.9.3.2 cannot be used in SDC D and E because of the restriction on height-to-width ratio. This table is derived from Section 12.4 and Table 12.4-2 of the 2003 NEHRP

February 2012

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Just the FAQs

Question The 2011 Building Code Requirements for Masonry Structures (TMS 402-11/ACI 530-11/ASCE 5-11) added Appendix B–Design of Masonry Infill. What is masonry infill and what are the limitations on its use in seismic regions?

questions we made up about ... Masonry

Answer As the name indicates, masonry infill completely fills in the portal space inside a bounding frame, usually made of steel or reinforced concrete (Figure 1). Masonry infills create a composite structural system composed of the bounding frame with the portal space masonry, which can be reinforced or unreinforced. Unreinforced masonry infills have been constructed worldwide for decades. They have been experimentally investigated since the 1950s and have just recently been added to the masonry standard for the United States. Experimental results, as well as field performance, indicate that infills provide significant strength and ductility for resisting various types of lateral loads – even after considerable cracking. The composite behavior results in higher ductility than the unreinforced masonry alone, as well as increases in both the strength and stiffness of the system when compared to the bare frame. Unreinforced masonry infills are easy and economical to construct; the construction process is relatively simple. The masonry panels must completely infill the frame; no openings are permitted. In most cases, the bounding frame is constructed first, allowing for the installation of floor or roof framing. After the bounding frames are constructed, the masonry infill is laid in the interior portal space. Masonry infills provide a strong, ductile system for resisting lateral loads, in-plane and out-of-plane. Several stages of in-plane loading response occur with a masonry infill system. Initially, the system acts as a monolithic cantilever wall whereby slight stress concentrations occur at the four corners, while the middle of the panel develops an approximately pure shear stress state.

Figure 2: Diagonal strut.

Figure 1: Clay masonry infill with concrete frame.

As loading continues, separation occurs at the interface of the masonry and the frame members at the off-diagonal corners. Once a gap is formed, the stresses at the tensile corners are relieved while those near the compressive corners are increased. As the loading continues, further separation between the masonry panel and the frame occurs, resulting in contact only near the loaded corners of the frame. This results in the composite system behaving as a braced frame, which leads to the concept of replacing the masonry infill with an equivalent diagonal strut (Figure 2). These conditions are addressed in the masonry standard. Masonry infills resist out-of-plane loads by an arching mechanism. As out-of-plane loads increase beyond the elastic limit, cracking occurs in the masonry panel. This cracking allows for arching action to resist the applied loads, provided the infill is constructed tight to the bounding frame and the infill is not too slender. The second part to the question addresses the limitations of masonry infill use in seismic regions. As indicated by the question, the 2011 Building Code Requirements for Masonry Structures added Appendix B to address the design of masonry infills. Masonry infill designs must comply with the requirement of Chapter 1, with the exception of Sections 1.12 – 1.15. However, infill masonry is not included in ASCE 7, Table 12.2-1; to use the system in seismic design requires that the system be treated as a special structure and then receive the approval of the building official. For use as a special structure, the Commentary of Section B.1.1 gives a recommendation that includes:

Changing Masonry Standards

“When participating infills are used to resist in-plane loads as part of a concrete or steel frame structure, a hybrid system is effectively created that may not otherwise be defined in Table 12.2-1 of ASCE 7 for seismic force-resistance. Until further research is completed, the Committee recommends using the smallest R and Cd value for the combination of the frame and masonry infill be used to design the system.” ▪ STRUCTURE magazine

Masonry Infills Answer provided by Charles J. Tucker, P.E., Ph.D., Associate Professor of Engineering at Freed-Hardeman University, Henderson, Tennessee. Dr. Tucker is the Chair of the Masonry Infill subcommittee of the Masonry Standards Joint Committee.

Cold-Formed Steel Wall Panels Key Component in

CASINO MAKEOVER By Victor Carsello, S.E., P.E.

n March, 2009, while undergoing a $50 million renovation, a massive fire broke out at the Empress Casino in Joliet, IL, located 40 miles southwest of the city of Chicago. The fire destroyed the main pavilion building, which housed entertainment, dining, shopping and administrative functions. The main casino operations, which are housed on a permanently docked barge on the bank of the Des Plaines River, suffered only minor damage. The Empress casino originally opened in 1992, with an Egyptian theme signified by two large Pharaohs flanking the main entrance and a pyramid feature on the roof. With the fire brought a new opportunity to rebuild and breathe new life in to the almost twenty year old facility. Penn National Gaming, Inc. made the decision to rebrand the casino as a Hollywood Casino, complete with a 1930s old Hollywood, art deco style motif. At the time of the fire, the casino barge was also undergoing a major renovation. The casino was forced to close while the pavilion debris was being removed and a temporary entrance constructed. This temporary closure also provided an opportunity to speed up the casino renovations. After three months, the casino was reopened to smaller crowds which were not aided by the faltering economy.

NEW PAVILION BUILDING Rising from the ashes of the fire is a new 53,000 square foot state of the art facility with an old Hollywood feel. Expanded dining, entertainment and shopping, including a steakhouse, 200 seat buffet, sports bar, Rodeo Drive themed gift shop, and lush interior finishes were incorporated into the new facility with the hopes of luring back

The new Hollywood Casino at Joliet, IL. Courtesy of National Prefab Systems, LLC.

old patrons that had not yet returned after the fire, as well new ones that would be attracted to the upgraded facilities. The new pavilion consists of a one-story steel frame structure built over the basement of the original structure. Adjacent to the new pavilion is a new four-story, 400,000 square-foot, 1,100 car precast parking deck. In order to create the art-deco look, Urban Design Group of Atlanta, GA (the architect) used strong vertical elements consisting of two or three projecting ‘fins’ grouped into pilasters. These pilaster features were located intermittently along the front façade of the building and at corners, and grew progressively taller towards the main entrance.

SPEED

STRUCTURE magazine

KEY

Because of the importance of the pavilion building in attracting people to the casino, getting the new facility up and running was critical. An aggressive 18 month design and construction timeline was established. One early decision which helped meet the demanding schedule was to use prefinished cold-formed steel wall panels. Using the wall panels contributed in several ways to meeting the construction schedule. Fabrication of the wall panels could take place at the same time as the structural frame was erected. Scaffolding was not required for the installation of the exterior insulation finishing system (EIFS), to the benefit of a congested and very busy construction site. The unpredictable Chicagoland weather was taken out of the equation by reducing the possibility of weather related delays to only the short window of time that the panels were being erected. The building was enclosed significantly quickly, allowing interior finishes to start earlier.

PANEL DESIGN

Figure 1: 45-foot tall wall panel being hoisted into place. Courtesy of Salamone Builders.

AND

FABRICATION

The typical wall panel was 10 feet wide and varied in height from 25 to nearly 45 feet tall. The panels were designed to the 2003 International Building Code (IBC) to resist out-of-plane wind loads, which governed over the low seismic forces that develop in the lightweight panels. LgBeamer software by Devco was used to design the cold-formed steel studs. The structural steel frame, designed by Structural Engineer of Record, Gregory P. Luth and Associates, Santa Clara, CA, provided HSS girts which limited the stud spans to typically no more than 25 feet. Stud depths ranging from 6 to 8 inches were used, with thicknesses ranging from 71 mils to 45 mils (14 to 18 gauge). Wall panel fabrication began for the first sequence of panels at the facility of Chicago Panel and Truss (CPT), Aurora, IL during the height of a typical cold Midwestern winter. This first run of panels were located at the back side of the pavilion, in an area that linked the parking garage to the bridge that led to the casino barge. This served as a good starting point for the panel team as these panels were flat and windowless with simple horizontal and vertical reveals, unlike the highly ornamental front façade. They were also among the tallest

February 2012

Figure 4: Main entry of pavilion after completion of prefab wall panel installation. Courtesy of Chicago Panel and Truss.

panels on the job, so it was a good point to reference for the panel erector, framing contractor Salamone Builders, Aurora, IL. The panels were checked for erection stresses and deflections as the panels were hoisted from a horizontal to vertical position, and lift points were established to keep these within specified limits (Figure 1). After the panel team was able to work through the field connections and panel alignment with this first sequence of panels, attention was turned to the front façade, which contained more ornamentation and the pilaster features which helped define the art deco look. The pilasters consisted of projecting fins typically grouped together in twos or threes and running continuously up the building, reaching heights of over 50 feet tall. They projected horizontally up to 3 feet from the face of the main wall panels. The panel fabricator and framing contractor worked closely together to determine the best method for building these pilasters. Options included fabricating the pilasters separately from the main panels, field building them, or building the pilaster and wall panel as one monolithic piece. The latter was decided in order to limit the amount of field work and number of pieces, after it was determined that it was feasible to ship and erect a monolithic piece.

The pilasters were built and finished lying flat on a bed (Figure 2). The panels were then hoisted onto a flatbed for shipping. A typical pilaster took eight days from the time the panels were started until they were finished and ready for shipping to the job site. The corner pilasters panels, which were built with a 2-foot return (Figure 3), were finished and shipped on custom built racks. The tops of the pilasters were all finished with surface mounted light fixtures. Because access within the pilasters would not be possible after the EIFS finish was applied, conduit, electrical boxes and blocking for the fixture attachment were all installed prior to the application of the EIFS finish. Erection of the panels proceeded swiftly, aided by careful preplanning by the framing contractor, including ensuring that there was a level foundation to set the panels on. A generous offset of the face of the exterior wall from the structural grid allowed for ample space to make connections to the structure. The typical panel-to-steel connection consisted of deflection clips fastened to the structure with powder actuated fasteners and a 6-inch, 56 mil (16 gauge) outrigger piece to bridge the gap between the wall panel and clip. Because there was no access to make the connection from the front side of the panels or above the roof deck, the generous structure offset was appreciated by the erectors. continued on next page

Figure 2: Pilaster element during the finishing process. Courtesy of Chicago Panel and Truss.

Figure 3: Prefinished corner element on pavilion building. Courtesy of Salamone Builders.

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February 2012

Parking Structure The project also included the dressing up of the new parking structure, located adjacent to the pavilion and visible from the main entry. The garage is a four-story precast structure with exterior columns and spandrel beams. Pilaster features, very similar to the ones on the main pavilion, were located at the garage column locations. A canopy at the V.I.P. entry to the garage was constructed, along with a cold-formed steel wall panel with pilasters that increased in height towards the center of the entry. Wall panels were constructed in a similar manner as the main pavilion except that, because of the closer floor-to-floor spacing, smaller depth and thinner thickness studs could be used. The corner features on the garage showcased the versatility of coldformed steel. Because of the complex geometry, conventional C-shaped studs and connection techniques were not practical. The solution was to use a series of horizontal trusses spaced at 2 feet on center (Figure 4, page 27). Using the trusses simplified the creation of the required profiles, and the small changes in the geometry that occurred higher up the pilaster were handled with ease. The trusses were tied together with a continuous vertical spine of 6-inch depth studs. Fast, versatile, and lightweight, prefinished cold-formed steel wall panels were an important element in rebuilding the pavilion after a devastating fire. Cold-formed steel framing was able to meet the architect’s goal of creating a 1930s era art deco feel, while the prefabricated construction enabled the general contractor to meet a demanding schedule.▪

Corner feature of parking structure ready for sheathing and finish. Courtesy of Chicago Panel and Truss.

Victor Carsello, S.E., P.E. is President of Carsello Engineering Inc. in Naperville, IL. He may be reached at vcarsello@gmail.com.

Project Team Structural Engineer of Record: Gregory P. Luth & Associates, Santa Clara, CA Specialty Structural Engineer of Record for CFS Walls: Virgilio and Associates, Hawthorn Woods, IL Owner: Penn National Gaming, Wyomissing, PA Architect of Record: Urban Design Group, Atlanta, GA Construction Manager: W.E. O’Neil Construction Co., Chicago, IL Panel System Consultant: National Prefab Systems, LLC, Chicago, IL Wall Panel Fabricator: Chicago Panel and Truss, Inc., Aurora, IL CFS Framing Contractor: Salamone Builders, LLC, Aurora, IL

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STRUCTURE magazine

February 2012

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Business Practices

business issues

Strategic Management of Human Capital By Eric K. Rodriguez, P.E.

The Workforce Problem The retirement of the Baby Boom Generation (those born between 1946 and 1963) has prompted much thought and discussion about a potential gap in the American workforce. That discussion has definitely occurred within the engineering profession. However, the situation may not be as dire as some believe it to be. A quick look at birth statistics and the number of science and engineering (S&E) degrees awarded annually paint a more positive picture. Figure 1 shows the relationship between the two statistics. With the exception of a short spike in the birth rate in 1969 and 1970, the period from 1961 to 1973 saw a drastic decline in the number of births annually. It is this drastic decline in the number of births that is most likely the root of the fears associated with the mass retirement of the Baby Boomers. However, if you look at the period from 1983 to 1995, when most of those born between 1961 and 1973 earned their degrees, you will see that the number of S&E degrees awarded still increased modestly. At least for S&E professions, this trend contradicts the thinking that there simply aren’t enough people to replace the Baby Boomers once they are gone from the workforce. To further support the argument that the S&E workforce isn’t top heavy with aging Baby Boomers, Figure 2 shows a fairly

Figure 1: S&E degrees awarded have steadily trended upward despite drastic declines/inclines in the birth rate. Sources: Centers for Disease Control and Prevention. National Center for Health Statistics. VitalStats. www.cdc.gov.nchs/vitalstats.htm. December 2011 and National Science Foundation, Division of Science Resource Statistics. 2008. Science and Engineering Degrees: 1996-2006. Detailed Statistical Tables NSF 08-321. Arlington, VA. Available at www.nsf.gov/statistics/nsf08321/.

even age distribution among workers with S&E degrees. Of course, the S&E workforce is comprised of several professions and each of those professions will be impacted to varying degrees by an aging workforce. According to the National Science Board report, Science and Engineering Indicators 2010, 34% of the civil engineering profession workforce was age 50 or older in 2006. This suggests that by 2021 approximately one third of the 2006 civil

Figure 2: Ages of S&E workforce are evenly distributed at all degree levels (as of 2003). Source: National Science Board. 2010. Science and Engineering Indicators 2010. Arlington, VA: National Science Foundation (NSB 10-01)

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February 2012

engineering workforce will be gone. That is not the problem, however. The problem is twofold: first, companies must develop younger engineers so that they are prepared to assume the responsibilities left behind by those who have retired and, second, they must recruit the next generation of engineers into the profession. Accomplishing those two tasks may be easier said than done. Firms can’t just assume there will always be an abundant pool of engineering graduates to choose from. Going back to Figure 1, you can see another drop in the birth rate in the early 1990s. This drop in the birth rate, along with the growing popularity of non-S&E degrees, could signal a slower increase (or even worse, a decrease) in the number of new engineering graduates. And, engineering firms just aren’t competing with each other for top talent; they are also competing with outside industries who value the skills that engineers possess. Adding to the challenge, the other industries competing with engineering firms for talent are often able to offer higher compensation, more glamorous roles, quicker advancement, or a number of other perks, all of which might be just enough reason for one to leave the engineering industry or skip it altogether. Developing today’s professionals and recruiting tomorrow’s is nothing new. But,

the methods industries and companies must utilize to address these tasks are new. Those professions and companies that insist on using the tried and true methods of the past will find themselves struggling to hold on to their most valuable individuals and failing to attract the most promising young talent. To overcome these challenges, companies must effectively manage their human capital. For many companies, this responsibility falls on the human resources (HR) department; and, often times, it becomes a part of the basic day-to-day activities that are performed on an asneeded basis. Human capital management must be more than this. It must become a strategic initiative of the firm. And, firm managers, along with HR professionals, must be responsible for developing and implementing a strategic human capital plan.

Identify Challenges

Evaluate Progress

Human Capital Strategy

Deﬁne and Implement Action Plan

While there is no one-size-fits-all strategic human capital plan, Figure 3 shows a typical process a firm might follow in establishing and executing such a plan. Identify Challenges The first step in developing a strategic human capital plan is to identify the challenges facing the firm. Though this may seem blatantly obvious, it bears mentioning because of its importance. This is where the firm must take a critical look at itself and identify its own shortcomings. Common HR issues that most firms will face at one point will most likely come to mind, such as difficulties in

Clearly State Goals

Figure 3: Typical process for designing and implementing a strategic human capital plan.

hiring highly qualified individuals, retaining top performers, or developing specific skill sets in workers. Then there are issues like a non-diverse workforce, generational gaps, and succession planning that may not be as common or obvious; however, issues such as

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STRUCTURE magazine

Align Strategies

February 2012

these could leave large gaps or shortcomings in a firm’s human capital. The previous examples are all challenges that are directly related to human capital issues. But, there may be other challenges facing a firm that are indirectly related to human capital issues. For example, a firm that is experiencing increased revenues along with stagnant or decreased profits might have a staff that is top-heavy with senior leadership positions. Another example would be a firm that is struggling to meet tighter schedules and budgets might have a workforce that is not receiving the proper training to take advantage of new technologies. Align Strategies Before the firm can move on to addressing the challenges it identified previously, the firm must first address the second step in the strategic development process, which is ensuring that the human capital strategy is aligned with the overall business strategy. Again, what may seem like common sense becomes a very important component of developing a strategic human capital plan. This strategic plan must improve the management of human capital, as well as help meet the objectives of the overall business strategy. If the two strategies are not aligned with each other, they will eventually work against each other. In this case, one will eventually lose priority and fail; the other may be derailed to the point that it too will eventually fail. Clearly State Goals At this point in the process, after identifying the major challenges facing the firm and considering the overall strategic direction of the firm, the goals for the strategic human capital plan should start to become apparent. The goals should be clearly stated and measurable. It is not enough to have a stated goal to “Develop a highly skilled and trained workforce.” Such a goal is entirely subjective and does not allow the firm to determine whether it is being successful in its execution. If developing a highly skilled and trained workforce is a goal, then “highly skilled and trained” must be defined and a timeframe for meeting the goal must be established. A better way to state the same goal would be: “At the end of Year 1, all professional staff will be participating in a professional development/continuing education program that requires ten hours

of learning that is directly related to his/her everyday duties and five hours of learning that promotes professional growth.” The two goals state essentially the same concept. By providing clear measures and a deadline, however, the latter removes all subjectiveness from determining whether or not the firm has been successful in meeting the goal. This is crucial in allowing the firm to perform the final step in the process. Define and Implement Action Plan Now that the firm has a solid understanding of the direction it wants to head, it is time to set forth an action plan. At a minimum, the action plan should provide the following information: • Strategy Leader: The person responsible for the Human Capital Strategic Plan as a whole • Goal Leaders: The persons who will take ownership of specific goals • The tasks required to accomplish each stated goal • The resources available to designated goal leaders It is important that someone in the organization take ownership of the Human Capital Strategic Plan and be its champion. Otherwise, the strategic plan will likely be forgotten as others in the organization focus their efforts on shortsighted goals. The strategy leader will need to manage a team of goal leaders (from various groups/ departments of the company) that will each be responsible for meeting a specific goal stated in the strategic plan. Individual goal leaders should work with the human capital strategy leader in developing a process to meet each goal. And, the strategy and goal leaders (human capital strategy team) should be given the proper resources needed to attain each goal. After the human capital strategy team is in place, implementation of the strategic plan can begin. Naturally, this will be the most difficult stage of the entire process. Implementation can be difficult because it involves a diverse group of individuals. As noted earlier, the responsibility of executing this strategic initiative cannot fall on just the HR department; rather, firm managers must also play a key role in ensuring the strategic plan is executed successfully. This is where the difficulty lies. The person managing the strategic plan must guard against individuals sacrificing their human

STRUCTURE magazine

February 2012

capital strategy obligations in favor of their day-to-day obligations. Evaluate Progress Once the strategic plan is in motion, progress will need to be evaluated periodically. By doing this, the strategy leader can hold the goal leaders accountable. And, through these progress evaluations, the team will be able to identify which action plans are on track for success and which are in danger of failure. For those goals that are in danger of failure, the team should analyze why. Reasons for the potential failure could be anything from poor team execution to unrealistic expectations. However, just because a specific goal is off to an unsuccessful start, the goal shouldn’t be scratched. Rather, the team should address the reasons the progress isn’t where it should be and make the necessary modifications. This allows the entire process, from identifying challenges to evaluating progress, to be dynamic. This dynamic approach to the process will be key in the successful design and implementation of the human capital strategic plan. The team will learn what works well within the organization and what doesn’t. They should also look for new challenges facing the firm. When these new challenges are identified, they can be worked into the current strategic plan or into an entirely new plan.

Conclusion The personalities of workers are rapidly changing. The issues that matter most to the Baby Boomers often don’t matter to those workers from Generation Y. The way people from different generations learn, work, and communicate are different. Just as there is no one-size-fits-all human capital strategic plan, there is no one-size-fits-all way of managing people. Understanding your workforce, and understanding the challenges to building and maintaining a strong workforce, are crucial factors to your company’s success.▪ Eric Rodriguez, P.E. is a Management Consultant at Interface Consulting International, Inc. Mr. Rodriguez focuses on the A/E/C industry and can be reached at ekrodriguez@interface-consulting.com.

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Great achievements

notable structural engineers

General Edward W. Serrell By Frank Griggs, Jr., Ph.D., P.E., P.L.S.

n early proponent of wire cabled suspension bridges, Edward Serrell accomplished much as an engineer in both the pre- and post- Civil War era. In addition to his structural works, Serrell was a grand conceptor, envisioning exotic, for the times, notions on helicopterlike flying machines and alternative routes to the Panama Canal. Serrell was born November 5, 1826 in London, England, the tenth child of William and Ann Serrell. Since his parents were American citizens, he was a citizen of the United States. His family returned to the U.S. in 1831 and settled in New York City. He attended the local schools. At twelve years of age, he entered the Mechanic’s School. At fourteen he started working with his father and brothers, John and James, in the civil engineering field. After serving his apprenticeship, he became an assistant engineer on the Erie Railroad in 1845 and later worked on the Central Railroad of New Jersey. In 1846, at the age of 19, he was one of four engineers (Charles Ellet, John Roebling and Samuel Keefer) who responded to a request for proposals for a railroad suspension bridge across the Niagara River at the rapids. The contract was given to Ellet who built a temporary bridge across the gorge in 1849, followed by Roebling’s bridge in 1855. After working on the Atlantic Dock in Brooklyn, he moved to New Hampshire to work on the Northern Railroad. Then he went to New Jersey to work on the Somerville and Elizabethtown Railroad, followed by the extension of the Harlem Railroad in New York City. In 1848, he went to Panama with U.S. Topographical Engineers to conduct surveys upon which the general line of the Panama Railroad was constructed and various canal routes explored.

Lewiston-Queenston Bridge 1851.

In 1851, he built his first suspension bridge across the Niagara River between Lewiston, New York and Queenston, Canada. The bridge had a deck length of 841 feet with a cable length from tower to tower of 1,040 feet. The towers on both sides of the river were short, resulting in short back spans. A print, circa 1855, by William Beard called it “the largest in the world, built in 1850.” Construction started (1850) and the bridge opened on March 20, 1851. Charles Ellet and John A. Roebling bid on the bridge, but the Commissioners chose Serrell. He had wind guys dropping down for the deck to anchorages on the shore. In early 1864, the Commissioners were worried about ice jams and removed the wind guys, and when the danger was past, they neglected to restore them. Unfortunately, with the wind guys off, the deck fell into the river on February 2, 1864 in a windstorm. The bridge remained in that state until 1899 when it was rebuilt by Leffert and Richard S. Buck. After the success of his Lewiston/Queenston Bridge, he was called to review several sites and design a much longer railroad/roadway suspension bridge over the St. Lawrence River at Quebec. He proposed a bridge with a central span of 1,610 feet and side spans of 805 feet for the Grand Trunk Railway. His hollow masonry towers were 330 high and 52 by 137 feet at the base. Roebling had not yet started his 820-foot span railroad bridge over the Niagara, and Serrell was proposing a bridge over twice as long. The design provided a 32-foot wide deck with two 10½-foot roadways flanking an 11-foot space for a single railroad track, much like the original plans for the Niagara Bridge. In the cover letter of his report he stated, “I see no insurmountable engineering difficulties in the case; no reason for thinking that a substantial Bridge, suitable for railway and other travel, cannot be built here…” He recommended a site near the Chaudierre River and concluded, “Gentlemen of Quebec, you must either build a bridge or a new city.” To support his position, he wrote a 65 page treatise entitled Report on a Railway Bridge Proposed for crossing the St. Lawrence River at Quebec made to His Worship the Mayor and the City Council. It was a very complete report, giving the history of suspension bridge design including the works of the Europeans

STRUCTURE magazine

February 2012

St. John Bridge, Gleason’s 1853.

as well as Ellet and Roebling. Due to objections from the city of Montreal, the project was not funded and a bridge would not be built across the river at Quebec until 1917. In 1853, Serrell built a suspension bridge at St. John, New Brunswick, the site of the famous Reversing Falls. The span was 830 feet in length. The towers were built with heavy blocks of granite and were one hundred and sixty feet above the river. Many attempts were made previously to span the river but failed due to the strength of its currents. A portion of the deck at mid span failed in a windstorm in February 1858 and was replaced. It was rebuilt in 1887 and survived until 1915. Along with William Kennish, he prepared a report in 1855 to F. M. Kelley on the Atrato River canal route entitled, The Practicability and Importance of a ship canal to connect the Atlantic and Pacific Oceans with a History of the Enterprise. Serrell himself wrote the section entitled, “Confirmatory Report of E. W. Serrell, Esq., Consulting-Engineer” in which he also reviewed many other possible routes for a canal across Central America. He then worked on the Brooklyn waterworks plan, the water-works at Bridgeport, Conn., St. John, N. B., and the North Carolina Western Railroad, a railroad in Iowa, and a bridge over the Mississippi. In 1855 he turned his attention to the construction of the Hoosac Tunnel in Massachusetts for the Troy and Greenfield Railroad. In February 1856, he and Herman Haupt were awarded the contract to dig the tunnel. In July of the same year, the firm was dissolved and the contract transferred to H. Haupt & Co. Serrell was named a consulting engineer His next project, in 1857, was for a large bridge in England over the Avon River, near Bristol. A competition was held in the late 1820s and Isambard Kingdom Brunel’s design for a suspension bridge was selected, with a span of 703 feet. Construction started in 1831 but was stopped in 1843 after only the towers were completed. Proposals were solicited in 1857 to complete the bridge, possibly using new plans. Serrell’s plan was for a single span of 703 feet, with a clearance over the river of 245

feet. It would have been the longest span bridge in England. He was the first American engineer invited to make a proposal for a public work of this kind in England. The Civil Engineers and Architects Journal, December 1857, noted: “…The cables, although of wire, are composed of great numbers, and are bound together in solid masses: it is intended to have so many strands that, collectively they will carry seven times their own weight and the weight of the suspending-rods and roadway, and seven times as much weight upon the roadway as it would have upon it if filled quite full and crowded with people. The cables will be carried over the towers, and secured in anchor-pits on the rocks, in the usual manner...” His plan was not accepted. The final plan used wrought iron chains rather than Serrell’s wire cables and was opened in 1864. Serrell was a Major in the 8th Militia regiment of the State of New York before the Civil War. From his office at the Raritan and Delaware Bay Railroad, he wrote a letter to President Lincoln noting that he even though he had not supported him for President, “I feel bound so say to you in this hour of trial that my humble services, whatever they may be worth are at the disposal of your government.” He then raised the 1st New York Volunteer

Engineer Regiment and was, shortly after, elected its Colonel. The regiment was formed “to assist the regular U.S. Army’s small corps of engineers with a volunteer unit that would be largely topographical engineers along with a regiment of mechanics and artificers.” One of his most well known achievements in 1863 was the construction of the “Swamp Angel,” a heavy gun emplacement that had the range to reach Charleston from a peninsula at Hampton Roads. It was built in a marsh and required unique methods to stabilize the soil to receive the gun. He finished his army career in Benjamin Butler’s Army of Virginia and was sent by Butler to New York to work on a flying machine for which he claimed to have found “the method of navigating the air by means of elevating fans.” One set of fans was to raise the ship and the others, front and back, to propel it horizontally using high-pressure steam boilers to work the propellers. When General Ord replaced Butler, he wanted to know what Serrell was doing in New York. When asked, Serrell indicated he was on recruiting duty. The army tried to force him out, but he instead resigned to protect his image. He was mustered out the service in February 1865 and was brevetted brigadier general of volunteers in March of the same year. ADVERTISEMENT - For Advertiser Information, visit www.STRUCTUREmag.org

STRUCTURE magazine

February 2012

Lyman’s Viaduct, Serrell and Clarke.

Returning to New York City he set up an office at 78 Broadway, offering to design “RAILROADS, BRIDGES AND EXPLORATIONS, SERRELL’S PATENT WROUGHT IRON VIADUCTS.” His next major project was for a railroad/wagon bridge to cross the Hudson River at its narrowest point near the present day Bear Mountain Bridge. The bridge was chartered in 1868 as the Hudson Highland Suspension Bridge Company. Serrell was named its chief engineer, and he designed a double deck bridge with 1,665 feet between towers that was 155 feet above the river level. It had 20 cables, each 14 inches in diameter. It would have been much larger than any bridge built at the time and twice as long as Roebling’s Niagara span with two decks. Serrell’s bridge carried roadway (lower) and railway (upper) traffic. The project

Hudson Highland Bridge as proposed by Serrell 1868, Harper’s Weekly.

was not funded at the time, and it finally died when the Poughkeepsie Railroad Bridge was opened just upstream in 1889. He was appointed chief engineer of the New Haven, Middletown and Willimantic Railroad in 1870, on which the well known Rapallo and Lyman Viaducts were built. He apparently had trouble with the designs and approached Clarke and Reeves & Company, under T. C. Clarke, to submit a design for the wrought iron viaduct. The plans were completed in 1872. Serrell still did not trust the design and authorized traffic on only one track rather than the called for twin track line. After leaving the line, he wrote a letter to the governor of Connecticut

expressing his concern about safety of the bridge. James Laurie, former president of the American Society of Civil Engineers (ASCE), was then called in to report on the viaducts. He determined they were both well designed and able to carry the load specified by Clarke. In 1888, Serrell became president of the Washington County Railroad (now Vermont Rail System) running 56 miles from Greenwich, New York to Rutland, Vermont. He then returned to his interest in an isthmian canal. He talked with President McKinley in September 1901 about his project and wrote that McKinley seemed to be agreeable to his proposed route, but that McKinley stated, “this must be

harmonized, see if you can arrange a plan to harmonize.” McKinley was assassinated a few days later on September 6, 1901. In 1902, at the age of 76, Serrell was still promoting his Darien (San Blas) route for the isthmus canal and on January 18 made a presentation to the Isthmian Canal Commission for the American Isthmian Ship Canal Company. He sent a letter to the editor of the New York Times on the project on December 14, 1903, after a treaty was signed with Panama, and was critical of the Panama Route. In supporting his route he stated, “By it not only will the United States and the whole world get a canal adequate to do the business to be done, instead of, as at Panama, having a rain-water canal with locks, having less than one-tenth of the business ability of the Darien, but by the method provided by the Pugsley bill the Government will save the entire cost of construction of the canal, and expenditures variously estimated at from $180,000,000 to $250,000,000, and several years of time, because the Darien-Mandingo route can be built much quicker than any other.” His plan was for a sea level canal with a huge tunnel. In 1904, he wrote a 16 page pamphlet, The American Isthmian canals: The Darien Mandingo canal, in support of his proposal. His route was not accepted. He wrote again about his attempts at a flying machine during the Civil War in article entitled A Flying Machine in the Army on June 24, 1904 in Science. This was after the Wright Brothers first flight but before public flights in 1908. In it he described experiments with a helicopter-type machine made (unsuccessfully) by officers of the Northern Army during the Civil War. Serrell died on April 25, 1906, at Rossville, New York and is buried in St. Luke’s Cemetery. One source noted, “He is a young man who may be considered a good example of what patient, enduring, energetic, determined action will accomplish. Without fortune or family influences, he has, by his own unaided industry and natural talents, won his way to his present high position in an honorable and useful profession.” He, along with Charles Ellet and John A. Roebling, developed the use of the wire cable suspension bridge in the United States.▪ Dr. Griggs specializes in the restoration of historic bridges, having restored many 19 th Century cast and wrought iron bridges. He was formerly Director of Historic Bridge Programs for Clough, Harbour & Associates LLP in Albany, NY, and is now an independent Consulting Engineer. Dr. Griggs can be reached at fgriggs@nycap.rr.com.

STRUCTURE magazine

February 2012

a definitive listing of major bridge professionals and suppliers Top Firms Engineering & Construction Contech Construction Products Inc. Phone: 800-338-1122 Email: nollj@contech-cpi.com Web: www.contech-cpi.com Product: CONSPAN Bridge Systems Description: CON/SPAN’s innovative, economical design stands apart from any other system. Its distinctive arch action utilizes fast, set-in-place construction; and your design and installation is backed by extensive technical support.

Hayward Baker Inc. Phone: 800-456-6548 Email: info@HaywardBaker.com Web: www.HaywardBaker.com Product: Geotechnical Construction Description: Hayward Baker provides the complete range of geotechnical construction techniques for Design-Build solutions for new bridge construction and remediation of existing bridges, specializing in deep foundations, foundation rehabilitation, and ground improvement. Old and new bridges benefit from Hayward Baker’s decades of advancement of geotechnical construction techniques.

Software Vendors/Developers ADAPT Corporation Phone: 650-306-2400 Email: info@adaptsoft.com Web: www.adaptsoft.com Product: ADAPT-ABI 2012 Description: Easy-to-use, cost effective, and practical bridge design software for all of your concrete bridge types: balanced cantilever (cast-in-place or precast), incrementally launched, span-by-span, cable-stayed, precast-prestressed girders with field splicing and topping slab, box girder bridges and more. Handles geometry and stress control during construction and reports service load design values.

Georgia Tech – CASE Center Phone: 404-894-2260 Email: joan.incrocci@ce.gatech.edu Web: www.gtstrudl.gatech.edu Product: GT STRUDL Description: GT STRUDL Structural Design & Analysis software offers linear and nonlinear static and dynamic analysis features including response spectrum, transient and pushover analyses, plastic hinges, discrete dampers, base isolation, and nonlinear connections. Optional Multi-Processor Solver module enables the solution of static/dynamic models with over 300,000 DOF.

MIDASoft, Inc. Phone: 212-835-1666 Email: midasoft@MidasUser.com Web: www.MidasUser.com Product: midasCivil Description: Software for all bridge types – Curved steel girder, Prestressed and Post-tensioned Segmental, Cable stayed & Suspension bridges. Construction stages

Bridge resource guide

with time dependent material effects (creep, shrinkage, concrete modulus & tension losses in tendons). Nonlinear dynamic analyses covering dampers, isolators and soil-structure interaction. Live load analysis to AASHTO & CSA S6.

RISA Technologies Phone: 949-951-5815 Email: info@risatech.com Web: www.risa.com Product: RISA-3D Description: With RISA-3D’s versatile modeling environment and intuitive graphic interface you can model any structure from bridges to buildings in minutes. Get the most out of your model with advanced features such as moving loads, dynamic analysis, and over 40 design codes. Structural design has never been so thorough or easy!

S-FRAME Software Inc. Phone: 203-421-4800 Email: info@s-frame.com Web: www.s-frame.com Product: S-FRAME® Structural Office Description: S-FRAME Structural Office R10 is a structural modeling, analysis and design suite of tools for frames, trusses, bridges, office and residential high-rises, industrial buildings, plate/ shell structures, and cable structures for seismic analysis, staged construction, Direct Analysis Method, linear/nonlinear static and time-history analyses, moving load analysis, buckling load evaluation and more.

Strand7 Pty Ltd Phone: 252-504-2282 Email: anne@beaufort-analysis.com Web: www.strand7.com Product: Strand7 Description: Strand7 is an advanced, general purpose, FEA system used worldwide by engineers for a wide range of structural analysis applications. It comprises preprocessing, solvers (linear, non linear, dynamic and thermal) and post processing. Release 2.4 includes staged construction, a moving load module, a quasi-static solver for shrinkage and creep/relaxation problems.

Suppliers

Fyfe Co. LLC Phone: 858-642-0694 Email: michael@fyfeco.com Web: www.fyfeco.com Product: Tyfo® Fibrwrap® Systems Description: FYFE Company is the manufacturer of Tyfo FIBRWRAP Systems used for the strengthening, repair, and restoration of concrete, timber, steel and masonry structures. These externally-bonded carbon and glass fiber-reinforced polymer (FRP) systems can be applied to bridge structures for increased load ratings, seismic retrofit, corrosion rehabilitation, and service life extension.

GRL Engineers, Inc. Phone: 216-831-6131 Email: media@pile.com Web: www.GRLengineers.com Product: Services for QA,QC of Bridge Foundations Description: GRL Engineers, Inc. specializes in testing and analysis of deep foundations. Services include: Wave Equation Analysis, Dynamic Load Testing, Dynamic Pile Monitoring, Vibration Monitoring, Cross Hole Sonic Logging, Pulse Echo Integrity Testing, Evaluation of Existing Foundations, Hammer Performance Analysis of Driving, Becker Drill and SPT Hammers. Offices nationwide.

Western Wood Structures Phone: 800-547-5411 Email: bridges@westernwoodstructures.com Web: www.westernwoodstructures.com Product: Timber Bridge Design and Supply Description: Western Wood Structures is a sales and engineering company specializing in the design, fabrication, distribution, and installation of glulam timber bridges. We design and supply vehicular and pedestrian bridges, using the highest quality, pressure-treated glulam timber. Experience our enduring commitment to quality, achieved through 42 years of premium performance.

Wheeler Phone: 800-328-3986 Email: info@wheeler-con.com Web: www.wheeler-con.com Product: Panel-Lam Timber Vehicle Bridges Description: Treated timber bridge kits for low volume road applications. Designs for HS20 and HL93. Crash-tested railings available.

CTS Cement Manufacturing Corp.

Wheeling Corrugating

Phone: 800-929-3030 Email: jong@ctscement.com Web: www.ctscement.com Product: Rapid Set® Low-P™ Cement and Type-K Cement Shrinkage Description: Complete bridge deck overlays faster with Rapid Set Low-P cement. Get better quality, lasting performance and an in-place cost less than Portland cement concrete. Type-K Cement Shrinkage-Compensating Concrete has been used in over 800 bridge decks with reduced permeability, excellent durability, virtually no cracks and increased concrete life cycle.

Phone: 304-234-2326 Email: bensonmw@wheelingcorrugating.com Web: www.wheelingcorrugating.com Product: Stay-In-Place Steel Bridge Forms Description: Wheeling Bridge Form is a heavyduty steel decking system for forming bridge slabs quickly and permanently. High strength, galvanized Wheeling Bridge Deck is specially designed to sustain heavy loads and adapts to pre-stressed concrete, built-up girders, or steel beam bridges. Wheeling Bridge Deck also provides a safe, solid, working platform.

STRUCTURE magazine

February 2012

LegaL PersPectives

discussion of legal issues of interest to structural engineers

Professional Liability Insurance Concerns for Structural Engineers By David J. Hatem, P.C., Donna Hunt, Esq., AIA and Sue E. Yoakum, Esq., AIA

rofessional Liability Insurance is the fundamental strategy structural engineers utilize to transfer and mitigate their greatest risk. The primary insurance risk for structural engineers is their exposure to professional liability claims. Such claims typically fall under an engineer’s errors and omissions or “E&O” insurance coverage. Most professional liability claims against engineers allege negligence, but breach of contract claims are also common. Breach of contract and negligence claims are frequently deeply intertwined. A generic example would be a claim or suit for breach of contract for the failure of a structural element where the purported contractual breach is the engineer’s deficient load calculations. The liability analysis in such a circumstance would still predominantly be a negligence analysis. As a practical matter, lawsuits often raise both breach of contract and negligence in order to “cover all bases.” In legal-speak, negligence is a tort, or a civil wrong. Payment under a professional liability policy under a negligent performance theory against an engineer in the performance of professional service is thus linked to the legal elements of a tort. To prove negligence, a claimant or plaintiff must establish four elements: (1) the engineer had a duty to perform relevant professional services, (2) the engineer breached that duty, (3) the engineer’s breach is the cause of the claimed damages, and (4) the claimant suffered those damages. If a claimant fails to establish each of these four elements of negligence, the claim should ultimately fail. Weak or missing elements of negligence are factored into a defense attorney’s evaluation of a claim, and may dictate how a matter is defended. Claims and cases which have missing or questionable elements may still settle due to the high cost of litigating a matter, but it is generally the missing elements which permit them to be settled at a very low nuisance value level. Strong negligence cases, those containing credible proof of each element of negligence against an engineer, are more challenging to defend. This variety of cases can only be defended successfully when the engineer, his attorney,

and the engineer’s professional liability carrier work as a team in confronting the claim or litigation. Professional liability insurance policies typically define “professional services” as those services that the insured is legally qualified to perform for others in their licensed capacity as an architect, engineer, land surveyor, landscape architect, or construction manager. In some instances, additional, non-traditional services may be covered by a professional liability policy if the additional service is specifically included in a specialized endorsement (addition) to the insurance policy. Professional services are frequently defined in insurance policies and in statutory language as those services for which special training, education, or licensing is required. Selected examples of types of professional services include: design; preparation of reports and studies; observation of contractor’s performance and resident engineering services; review and evaluation of contractor’s shop drawings and other submittals, change order proposals, value engineering proposals; recommendations regarding rejection of contractor’s work and/or acceptance of work; and, forensic engineering/expert services. It is customary for owners to require engineers to carry a certain amount of professional liability insurance as a negotiated term of a project’s contract. An owner can require professional liability insurance in the form of coverage under the engineers’ general practice policy. This is the typical E&O policy which is maintained in the engineer’s ordinary course of business. In addition, depending on the scope and nature of the project, an owner may elect to purchase or require the purchase of a project specific professional liability insurance policy covering the design team involved in the particular project. In a rare example of the insurance industry being simple and direct, this type of professional liability insurance is frequently referred to as “a project policy.” The project policy concept has been around for decades, but is applicable to only a small percentage of construction. The most common way to insure a design

STRUCTURE magazine

February 2012

professional against negligence claims is the conventional E&O practice policy. The practice policy usually supplies coverage for all of the engineering firm’s projects. Most firms carry $1–$2 million in professional liability coverage. Some engineers who work on larger scale projects will carry larger limits. Engineers should review their level of coverage with their brokers frequently. The undertaking of new work should be discussed with the broker to make certain that adequate coverage is always available. Engineers should also seek value from their brokers in selecting a policy. In some instances, a professional liability carrier will provide its clientele with additional services, such as contract review and risk management advice, at no additional charge. Engineers should not hesitate to have their broker’s research carriers who provide this valuable assistance. An owner of a large project or megaproject will often require project specific professional liability insurance. This dedicated insurance for a particular project could provide coverage in the range of $10 to $50 million. Policies of this type often require a deductible or self insured retention (SIR), in a greater than usual amount. Amounts of $250,000 to $2 million are not uncommon, depending on the size of the given project. Some project policies serve as the primary professional coverage for the engineer for the project. The engineer’s own practice policy may sit in excess or on top of the project specific professional policy in an umbrella coverage capacity. The details of how this works depends on each engineering firm’s practice policy and the particular insurance company providing the practice policy. Projects which require a project policy require additional consultation on coverage with an engineering firm’s broker. Legal advice should also be sought on all contracts which require insurance coverage greater than a company’s typical practice policy. While project policies are an innovative and often necessary insurance product, they are not without their potential pitfalls. There are three common problems associated with project policies from an insured’s perspective. While these are not always unmanageable,

they can present challenges to an insured if it is not properly educated on the project policy’s terms, and the financial or other obligations imposed upon the insured as a condition of the project policy coverage. These typical problems are; 1) very high deductible or SIR obligations, 2) limited coverage for architect and engineer subconsultants on Design-Build Projects, and 3) professional protective insurance policies. As noted above, project policy deductibles and SIRs tend to be much higher than a practice policy deductible. This could be a trap for the unwary if an engineering firm is not mindful that it must contribute $250,000 or more in order to get to the point where the policy’s coverage “kicks in.” If an engineering firm is unable to meet this financial burden, the protective coverage of the project policy might not come into play. In situations where a project policy is purchased by an owner, higher deductibles and SIR obligations are often selected in order to reduce the owner’s cost of the project policy. Some project policies are written with a $5 Million or $10 Million per claim SIR. Cleary, such a policy with absurdly high SIR are of no comfort to the designer. Some project owners may attempt to mitigate the significant per claim SIR funding obligations of the engineer by agreeing to pay all or a significant portion of the SIR obligations. If that is the case, that specific obligation of the owner must be set forth clearly and concisely in the Project’s contract documents. Engineers should note that even if this term appears in a contract with a public entity, the term may be interpreted by a Court as a conflict of interest or be otherwise unenforceable. Such a term might also create accountability or ethics concerns for public owners. A public owner’s agreement to pay an insured’s SIR could also raise concerns with project overseers, regulators and grantors at both the state and federal levels. In projects where there is a higher than usual deductible or SIR, engineers need to be very careful in establishing their fee for services. Risk and expenses associated with a high per claim deductible or SIR must be factored into the project’s costs. Failure to consider this critical factor carefully or the failure to discuss the implications of a high deductible or SIR with the engineer’s broker and attorney could create a situation where an engineer’s insurance obligations on a project diminish or eliminate entirely the intended profit.

Another frequent concern with project policies arises in the Design-Build project context, and involves exclusion of coverage for claims by the Design-Builder against the Design-Builder’s engineering subconsultants. The exclusion of that coverage renders dysfunctional any joint defense between the Design-Builder and its engineer subconsultants. This scenario may require the sub-consultant to attempt to obtain professional liability insurance coverage from their practice policy even if there is a project policy. If that does not occur, the DesignBuilder may wind up being responsible for the negligent acts and omissions of its sub-consultants through vicarious liability. That is an unenviable position to be in on a project if you are a Design-Builder engineering firm, and there are owner based claims alleging errors and omissions of a sub-consultant engineer. There may be professional liability risk for an engineering sub-consultant under its practice policy in addressing claims from the Design-Builder if that the sub-consultant is not eligible for coverage under the project policy. Another problematic scenario is that the sub-consultant engineer may have a deductible and SIR obligations under both a project policy and its own practice policy before any coverage comes into play. To further complicate things, some practice policy professional liability insurers have exclusions under their practice policies for claims against the engineering insured on projects in which a project policy is in effect. Because of these various potential problems, sub-consultant engineers should review their practice policy, and any applicable project policy thoroughly with their broker and legal counsel before entering into a sub-consultant agreement where a project policy is believed to be in effect. Another issue involving practice policies has to do with the particular type of practice policy purchased. The procurement of an Owner Professional Protective Insurance Policy (OPPI) by the project owner, or Constructor Professional Protective Insurance (CPPI) by the contractor or Design-Builder, will have ramifications on coverage to an engineer working on the project. These policies initially provide coverage only to the procurer, either the project owner, constructor or DesignBuilder, but not the engineer. Although not specifically excess in nature, coverage under these policies is triggered once the

STRUCTURE magazine

February 2012

underlying practice coverage limits of the engineer (or a defined sub-limit thereof ) have been exhausted. The existence of these professional protective policies often is not disclosed to the engineer. The OPPI or CPPI insurer also may reserve rights to subrogate against the engineer.

Conclusion The simple fact that a project owner may be supplying a project policy does not necessarily eliminate an engineer’s professional liability insurance concerns on a project. In fact, as several situations discussed above illustrate, project policies can complicate an engineer’s intended insurance coverage. Project policies are frequently an ideal insurance product for a specific situation. However, engineers must know and understand the terms and obligations of a project policy in order to determine whether it supplies an actual benefit. A project policy with a deductible or SIR so high that the engineer can never pay it, is of no practical value and could easily jeopardize the viability of the engineering firm in the event of a large claim. When it comes to obtaining and evaluating professional liability insurance, whether it is a practice policy or a project policy, an engineer’s broker and his lawyer are his best resources. Engineers should seek the advice of these professionals, both before entering into contracts and immediately upon the presentation of a claim, in order to protect themselves and their businesses.▪ David J. Hatem, PC is the founding Partner of the multi-practice law firm Donovan Hatem LLP. He leads the firm’s Professional Practice Group. He can be reached at dhatem@donovanhatem.com. Donna Hunt, Esq., AIA is the Director of Claims/Risk Management Services at Lexington Insurance Company. In addition, Donna is responsible for the management of Lexington’s Professional Lines Risk Management Programs, and is a licensed architect. She may be reached at donna.hunt@chartisinsurance.com. Sue Yoakum, Esq., AIA is an attorney and a licensed architect at Donovan Hatem LLP. Ms. Yoakum focuses her practice assisting design professionals. She can be reached at syoakum@donovanhatem.com.

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problems and solutions encountered by practicing structural engineers

Lessons Learned

Trimbloid X

By Keith Bouchard, E.I.T.

f you have ever walked, run, biked, roller-bladed, or spent any time at all on Boston’s Charles River Esplanade, it’s likely you have come across the sculpture Trimbloid X. The sculpture, which was created by the late artist David Kibbey in the early 1970s, has had a prominent position in Boston’s signature park for a number of years. Trimbloid X is a three-dimensional X-shape standing 10 feet tall and fabricated from Cor-Ten Steel™ sheets that were bent and welded together. The sculpture’s three “legs” and three “arms” are all welded together at a horizontal plane of symmetry at mid-height of the object to create its unique geometry. As was common for sculptures at the time, the artist chose Cor-Ten Steel for its distinctive red patina and its corrosion resistant characteristic that would presumably allow the sculpture to be displayed outdoors for many years to come. However, as has become well understood in the years following the creation of Trimbloid X, Cor-Ten Steel and its weathering steel successors are not as resistant to corrosion as the industry initially claimed. It is true that, if exposed to intermittent wetting and drying cycles, Cor-Ten Steel will form a protective red patina that will prevent further corrosion of the underlying steel. Unfortunately, in cases of ponding water or constant moisture, the protective patina will not form and the steel will be susceptible to continuous oxidation until eventually the full section dissolves. There is no better example of this regrettable fact than Trimbloid X. The natural shape of Trimbloid X funnels water to the center of the sculpture, where no means are provided to whisk it away. The standing water eventually ate through the center of the object, allowing moisture and organic matter into the hollow “legs” and accelerating deterioration. Add years of delayed maintenance and the result is what you’ll see if you stroll down the Esplanade today – gaping holes in the side of the sculpture, trails of corrosion down the legs, and protective fencing to keep the public away from its sharp, rusty edges. This is the condition that CBI Consulting Inc. (CBI) found the sculpture in when engaged by the Massachusetts Department of Conservation and Recreation (DCR) to assess the condition of the sculpture and provide repair schemes and estimates. The Massachusetts DCR has a very limited budget for the repair of the object, so CBI explored a variety of different options to re-establish its structural integrity while respecting the original artistic intent. These include reinforcing the sculpture in the field, shop-repairing the object with new weathering steel and possibly painting with a weather-resistive coating, and “skinning” the object with new weathering steel sheets. Each of these options has pros and cons with regards to ease of construction and respect to the sculpture, as well as cost. Through consultation with steel fabricators and the Massachusetts DCR, CBI recommended that the object be disassembled and repaired in the shop with new weathering steel patches. Coating the sculpture with a patina-colored paint was not recommended, as there was concern that it would interfere too much with the “industrial” look of the original sculpture. The existing patina on salvaged parts of the sculpture to remain will need to be sand-blasted off to attempt to match the

STRUCTURE magazine

Above: Trimbloid X on Boston’s Esplanade. Right: Corroded Steel at the Center of the Sculpture.

new steel. The owner was warned that, even with this measure, there is no guarantee that the original steel will closely resemble the repair steel. As one steel supplier noted, different batches of weathering steel are like “trees in a forest: they all basically look the same but no two are alike.” However, with the severe level of deterioration present on the object and the limited budget, this is likely the best the owner can do short of completely re-sculpting the piece.▪ Keith Bouchard, E.I.T. is a Project Manager with CBI Consulting Inc. in Boston, MA. He can be reached at kbouchard@cbiconsultinginc.com. Historical research for Trimbloid X was provided by Barbara Mangum of Sculpture and Decorative Arts Conservation Services, Somerville, MA. This article was originally printed in the SEAMass Newsletter (July 2010) and is reprinted here with permission.

February 2012

DOING OUR PART

IN BUILDING CONNECTIONS

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award winners and outstanding projects

Spotlight

Arena Stage at the Mead Center for American Theater Excellence, Creativity and Innovation By Gerald Epp, M.Eng, P.Eng, Struct.Eng, P.E.

ngineers rose to the demand for an exuberant free-form expression with practical and elegant solutions to the project’s complex technical challenges (and shrinking budget). Two major elements enclose the existing theaters, isolating them from the noise of the busy capitol:

High Roof The initial fully-designed and peer-reviewed scheme had the roof cantilevering 180 feet, supported by harped steel cables anchored into a custom steel space truss. Post-9/11 funding shortfalls necessitated redesign. A 500-foot-long steel truss structure was introduced, retaining drama by bringing a support wall only part way along the back side, leaving an 85-foot cantilever which appears similar to the original. The large, complex roof that spans over the theaters – cantilevering toward the Washington monument – required close collaboration between engineer and erector. Every nine-foot-deep truss is unique, has one-of-a-kind support conditions, and spans up to 170 feet. A sharp edge was efficiently achieved with light steel framing. To accommodate the multiple orientations of the leaning support columns, a single 2½-inch diameter bolt connection was devised, speeding erection of the large trusses. A simple “bounce test” (one engineer, all alone) was used to test the stiffness of the cantilever tip, resulting in an instruction for minor stiffening in the secondary trusses.

Timber Façade The roof is supported by large engineered timber columns, which also serve as backup to a sinuous 650-foot long, up to 58-foot tall suspended glass façade; the acoustical and environmental barrier. The geometric complexity is exacerbated by a four degree tilt from vertical. For efficiency, two-thirds of the double-glazed facets were designed to be identical in size. The remaining bays unnoticeably take up the irregular geometry. The timber columns are set back, receiving tapered timber arms that reach out to laterally support timber muntins, to which

Courtesy of Bing Thom Architects. Fast + Epp was an Award Winner for the Arena Stage at the Mead Center for American Theater project in the 2011 NCSEA Annual Excellence in Structural Engineering Awards Program (Category – New Buildings over $100 Million)

the glazing units are clipped. All of the timber is engineered wood – parallel strand lumber (PSL). The 20-inch by 30-inch elliptical timber column is designed to carry axial forces (up to 400 kips) and out of plane near hurricane wind-forces while minimizing the amount of PSL used. Deflection actually controlled the design. The column cross-section was designed with a partially restrained relief joint through the neutral axis to manage the strong potential for movement and checking. The base connector for the columns visually references a lightly touching ballet slipper, heightened by “pencil-sharpened” tapering on the bottom nine feet of the timber. Non-linear 3D solids finite element analysis and full scale load testing were performed to minimize the weight of the ductile iron casting. The roughly 16- by 12-foot glazing units and shaped PSL muntins are suspended from 5/8-inch diameter stainless steel cables via fully adjustable connectors. In order to accommodate erection tolerances and ensure tension during the life of the building, a carefully calculated assembly of three plates as “leaf springs” was installed at the top of each cable. The entire façade is structurally complex; lateral deflections occur in both the span of the columns and in the slender spans of muntins between the columns, which gain their stiffness through a combination of bending and axial forces (catenary action). Analysis determined stiffness in the system was quite dependent on bending moments being carried through every PSL muntin-to-muntin joint, making the connection an important part of the overall design. Research and load testing was carried out on a tight-fitting multi-pin connector which would allow the connection to be virtually invisible, yet efficiently carry the high forces. It was further proved on a system basis when a full size

STRUCTURE magazine

February 2012

50- by 60-foot mock up was constructed and tested with full design wind forces. All the lateral forces from the roof and façade were focused into the petal-shaped architectural concrete walls of the new “Cradle” theater, eliminating the need for visually disturbing bracing along the length of the façade. This is believed to be the tallest free-span timber-backed glass façade in the world.

Complexity and Design Sustainability This was in every respect a complex structure to build. The general contractor and the entire team of consultants were highly engaged with the project, paying close attention to detail in planning, 3D-modeling and shop drawings. To ensure smooth execution of the timber façade, a related design-build company took on the contract for its design, testing, fabrication and installation. This project involves the unprecedented use of architecturally exposed engineered wood. Such wood is far and away the most sustainable structural material. Extensive use of efficient architecturally-exposed structural materials starkly contrasts with the heavily clad structures of Washington. Persistent “value engineering” eliminated superfluous finishes and put pressure on the structural engineer to provide an aesthetically satisfying structure. For example, the custom timber façade is not only structurally unique, but also uniquely serves as acoustical barrier and roof support, yet costs less than commercially available alternatives.▪ Gerald A. Epp, M.Eng, P.Eng, Struct.Eng, P.E. is a founding partner at Fast + Epp. He has been President of the design-build company, StructureCraft Builders Inc., since 1998.

Getting Motivated for SE Licensure

NCSEA News

News form the National Council of Structural Engineers Associations

By Thomas A. Grogan Jr., P.E., S.E., SECB

any states already have some form of structural engineering (SE) practice restriction, but if you live in a state without one, you might be asking yourself what it takes to start one. The Florida Structural Engineers Association (FSEA) decided just over two years ago that Florida should look into SE licensure, but only after some very healthy debate among our board members. We asked ourselves: Would our membership support this worthy cause? What would it take to get there? From whom could we elicit help? Though we had the backing of NCSEA, if our members were not in favor of SE licensure, then we would be dead in the water. We did several things to address this concern. First, we had two of our board members join the NCSEA Licensing Committee and spend some time learning what other Member Organizations around the country were doing in this area. Of particular interest were the recent successes in Washington and Utah. Those committee members also attended national licensing summits to learn which other professional organizations were for and against SE licensure. Second, we polled our membership and were pleased to learn that over 80% were in support of SE licensure. This provided the impetus to start the process in earnest. Third, we formed our own state SE licensure committee, which I currently chair, and it now has over a dozen members. At the first meeting of this committee, which was attended by over twenty engineers, we heard from two members of the NCSEA Licensing Committee: Susie Jorgensen, the chair, and Barry Arnold, the person behind the scenes who helped get the SE practice restriction in Utah. Susie shared with us the status of SE licensure and its importance in our profession’s over-arching mission to protect the safety, health and welfare of the public. This was followed by Barry’s passionate presentation on why he became involved and the work of his committee in Utah. Several of the FSEA committee members were not enthusiastic about SE licensure at first; but they ended up becoming vital contributors to our progress. They played devil’s advocate and challenged Susie, Barry and the other members, to the point where we were not sure that we had enough support from within our committee. Though initially quite frustrating, this became valuable over the next several months as we worked hard to convince these individuals that this was a worthy cause for which we needed not only their support, but also their help. That initial meeting unified the committee; and we voted to continue pursuit of SE licensure. We have continued to meet almost every month since. Using Utah as a model, we decided that we needed to write a white paper outlining why SE licensure was important for Florida. We gathered all of our facts, including information on several collapses in Florida over the past 20 years, attributed to poor design. We also learned that over 80% of the complaints filed with our Florida Board of Professional Engineers (FBPE) were structural issues. This was very enlightening and motivated the committee to take their work to the next level. From the white paper, we drafted and published a one-page document that explained very briefly why we were STRUCTURE magazine

pursuing this goal. In addition, we formed several subcommittees: legislation, advocacy, and marketing. Momentum was starting to build. When pursuing any legislation, it is important to know who will support you and who might be against you. The Florida Engineering Society (FES), an affiliate of the National Society of Professional Engineers (NSPE), is the predominant engineering organization in our state, with strong connections to the legislature and paid lobbyists. We realized that having their support would be critical to our success. Two of our licensure committee members are also members of FES, so they began the discussion of separate licensure at FES state meetings. The FES board believed that our request warranted their review and charged their Professional Concerns Committee with carrying it out. After careful assessment of our white paper and one-page document, the Professional Concerns Committee wrote a position paper indicating that they were in complete support of this initiative, as long as it applied only to Threshold Buildings as already defined by state law and would be a post-licensure credential. This was extremely good news, and several of us were invited to their next state board meeting to participate in a discussion, after which they voted on the issue. Although the discussion was heated and contentious, at the conclusion, the FES board passed a motion indicating they would support SE licensure and offered support to FSEA in working with the legislature. FSEA has reciprocated by offering to support FES on other initiatives that they are pursuing. Since that time, FSEA has written a revision to the state law that would recognize structural engineering as a specific discipline and give the FBPE the ability to define the types of structures to which practice restrictions would apply. However, at the moment we are in a holding pattern, as Governor Rick Scott has asked that no new legislation be initiated unless it immediately creates jobs. We intend to begin again in earnest toward the middle of 2012; but we will be contacting FES to determine what lobbying support they are willing to provide. Though we still have a ways to go, we believe that our committee is motivated and ready to address all the obstacles to obtaining SE licensure. It is this motivation that will be critical to our success in this endeavor.

NCSEA Continuing Education in February February 7 webinar: Design Considerations for Exterior Wall Interfaces in Steel-Framed Buildings by Patrick McManus February 10-11: NCSEA Winter Institute on Soft Soil – Water and Wind, Hotel Monteleone, New Orleans, LA

February 2012

NCSEA recognizes and thanks its Partnering Organizations and the following companies, organizations, and individual structural engineers, for their Associate, Affiliate, and Sustaining Memberships in 2011-2012.

Partnering Organizations CASE Washington, DC

SEI Reston, VA

Associate Members AISC Chicago, IL

International Code Council Birmingham, AL

Schuff Steel Company Phoenix, AZ

American Wood Council Leesburg, VA

ITW Red Head Addison, IL

Simpson Strong-Tie Pleasanton, CA

Bentley Systems, Inc Carlsbad, CA

Metal Building Manufacturers Association Cleveland, OH

USP Structural Connectors Burnsville, MN

Insurance Institute for Business & Home Safety Tampa, FL

Cast Connex Corporation Toronto, Ontario

DECON USA, Inc. Beaufort, SC

RISA Technologies Foothill Ranch, CA

CETCO Building Materials Group Hoffman Estates, IL

Dwyer Companies West Chester, OH

Rosboro Springfield, OR

Fibrwrap Construction, L.P. Ontario, CA

SE Solutions, LLC Holland, MI

Hardy Frames, Inc. Ventura, CA

SidePlate Systems, Inc. Laguna Hills, CA

Hilti, Inc. Tulsa, OK

Steel Joist Institute Florence, SC

Cold-Formed Steel Engineers Institute Washington, DC Construction Tie Products, Inc. Michigan City, IN CSC Inc. Chicago, IL

Powers Fasteners Brewster, NY

Sustaining Members Barrish, Pelham & Associates, Inc. Sacramento, CA Barter & Associates, Inc. Mobile, AL Burns & McDonnell Kansas City, MO Cartwright Engineers Logan, UT CBI Consulting, Inc. Boston, MA Construction Technology Laboratories Skokie, IL Cowen Associates Consulting Structural Engineers Natick, MA

Criser Troutman Tanner Consulting Engineers Wilmington, NC

Ruby & Associates, Inc. Farmington Hills, MI Simpson, Gumpertz & Heger, Inc. San Francisco, CA

Degenkolb Engineers San Francisco, CA

Structural Engineers Group, Inc. Jacksonville, FL

DiBlasi Associates, P.C. Monroe, CT

TGRWA, LLC Chicago, IL

Dominick R. Pilla Associates Nyack, NY

The Harman Group, Inc. King of Prussia, PA

Dunbar, Milby, Williams, Pittman & Vaughan Richmond, VA Gilsanz Murray Steficek, LLP New York, NY LBYD, Inc. Birmingham, AL

STRUCTURE magazine

Thornton Tomasetti Chicago, IL United Structural Systems Ltd., Inc. Lancaster, KY

February 2012

News from the National Council of Structural Engineers Associations

Affiliate Members

NCSEA News

2011–2012 NCSEA Membership

Structural Columns

The Newsletter of the Structural Engineering Institute of ASCE

2012 Structures Congress March 29-31, 2012 Chicago, Illinois Forge Connections in the Windy City Register early to take advantage of reduced rates – www.asce.org/SEI.

Pre- and Post Conference Seminars This year SEI is offering a wide variety of Pre- and Post Conference Seminars. This is an opportunity to explore current topics in structural engineering in an in-depth way. Visit the Structures Congress website at www.asce.org/SEI for complete information about these sessions.

Wednesday, March 28, 2012:

Saturday, March 31, 2012:

• Innovation in Design of Steel Structures: Research Needs for Global Competitiveness (Organized by AISC) • Advancing Structural BIM: Expanding your Role • Maintaining our Nation’s Bridge Inventory: A Short Course on Diagnostic Bridge Testing • Conflicts of Interest

• Enhancing Building Security at Reasonable Costs: Modern Concepts (Organized by AEI) • LRFR Bridges: Introduction to the LRFR Provisions of the AASHTO Manual for Bridge Evaluation • Wind Load Provisions of ASCE 7-10

Student Program

Young Professionals Program

New This Year!

As part of a strategic effort to welcome young professionals age 35 or younger, the Structures 2012 Congress includes two new, invitation-only, events designed exclusively for you. The Young Professionals Full Registration Package includes the following: • Meet the Leaders Breakfast • Opening Plenary Luncheon and Awards Program • Young Professionals Mixer • SEI and PCI Welcome Reception in Exhibit Hall • CASE Breakfast • Buffet Lunch in Exhibit Hall • CHICAGO! Mid America Club Reception • Closing Plenary Luncheon and Business meeting • More than 100 technical sessions • All networking breaks • Structures 2012 Congress Proceedings For more information about the Structures 2012 Congress, visit www.asce/SEI.

Students, you asked and we responded! The Structures 2012 Congress Full-Time Student Registration package will include four new, invitation-only, events designed exclusively for students and young professionals. Full-time Student Registration includes the following events: • Student Welcome and Walking Tour • Meet the Leaders Breakfast • Opening Plenary Luncheon and Awards Program • Student Design Competition Session • School-To-World 101 Session • Young Professionals Mixer • SEI and PCI Welcome Reception in Exhibit Hall • CASE Breakfast • Buffet Lunch in Exhibit Hall • Closing Plenary Luncheon and Business meeting • More than 100 technical sessions–click here to see the session matrix • All networking breaks

NDT/NDE for Highways and Bridges: Structural Materials Technology New York, New York – August 21-24, 2012 ASNT, ASCE (SEI. AEI and EMI), and NYSDOT, among others, are co-sponsoring SMT 2012 Conference: NDT/NDE for Highways and Bridges: Structural Materials Technology. This conference will be held in the New York LaGuardia Airport Marriott near New York City on August 21-24, 2012. The goal of this conference is to promote the exchange of information between national and international researchers, practitioners and infrastructure owners on the application of Nondestructive Evaluation (NDE) and Nondestructive Testing (NDT) technologies for the condition assessment of highway infrastructure. Through technical presentations and exhibits, infrastructure owners, transportation STRUCTURE magazine

officials, researchers, consultants, and contractors will be exposed to the state-of-the-practice in NDE methods. In addition, participants will have the opportunity to discuss urgent problems faced by civil infrastructure owners and the potential solutions utilizing available emerging NDE technologies. Plans are also underway to host a workshop “Use of Remote Sensing for Infrastructure Management” as part of the conference activities on August 24th. More information on the conference and exhibitor information, please visit the Conference website at www.asnt.org/events/conferences/smt12/smt12.htm. February 2012

Mark your calendars now for Engineers Week, February 19-25, 2012. This year’s theme of 7,000,000,000 People – Seven Billion Dreams highlights engineers’ vast reach, making dreams real all over the world. ASCE invites you to take part in the festivities whether as an individual, civil engineering organization or ASCE Section or Branch. To make planning easier ASCE has celebration ideas, tips for planning outreach events, low cost and free resources, and staff standing by to answer your Engineers Week questions. Take advantage of online information, available on the ASCE website at www.asce.org/Outreach/Engineers-Week-2012/. Order free Engineers Week posters at outreach@asce.org. Tips to get started: 1) Start by naming an Engineers Week contact for your Section or Branch. Name one contact to receive this year’s support information for Engineers Week. 2) Recogize a special volunteer at the ASCE Multi-Regional Leadership Conferences. Send the name and mailing address of one community volunteer from your Section/Branch who deserves special recognition to outreach@asce.org. Questions? Feel free to contact Leslie Payne, Senior Manager, Pre-college Outreach at ASCE. Call 703-295-6364 or email outreach@asce.org.

Wind Beam Trial Design Problem Call for Participation ASCE/SEI standards continue to provide information clearly. Send in your solution today and encourage your colleagues to participate as well. Visit the SEI website at www.asce.org/SEI for more information and to download the exercise. Submit your solution by March 1, 2012 to: Suzanne Fisher at sfisher@asce.org.

2012 Joint Conference of the Engineering Mechanics Institute & 11th ASCE Conference on Probabilistic Mechanics and Structural Reliability EMI/PMC 2012

South Bend, Indiana

June 17-20, 2012

The College of Engineering at the University of Notre Dame is proud to host the 2012 Joint Conference of the Engineering Mechanics Institute and 11th ASCE Joint Specialty Conference on Probabilistic Mechanics and Structural Reliability (EMI/PMC 2012) June 17-20, 2012. The joint conference provides a major

forum for the exchange of ideas and discussion of recent developments in all mechanics, materials, probabilistic-methods and structural reliability fields. Mark your calendars for June 17-20, 2012 and visit http://emipmc12.nd.edu/index.html to stay abreast of all the latest news on EMI/PMC 2012.

SAVE THE DATE

ASCE’s Annual 2012 Conference in Montreal, Quebec, Canada

ATC & SEI Advances in Hurricane Engineering Conference Miami, Florida October 24-26, 2012 www.atc-sei.org/

2012 Electrical Transmission and Substation Structures Conference Columbus, Ohio November 4-8, 2012 http://content.asce.org/conferences/ets2012/index.html

STRUCTURE magazine

Make your plans to attend ASCE’s 142nd Annual Civil Engineering Conference in Montreal, October 18-20, 2012. With a cutting edge conference theme of Civil Engineering in the New Global Economy and a world crossroads location of Montreal, there are certain to be sessions and events that spark ideas for new solutions to worldwide challenges and emerging markets. Or, hear topics and discussions on matters you will be facing in the future; stay ahead of the competition. Visit the ASCE Conference website at www.asce.org/conferences for more information about ASCE’s 142nd Annual Civil Engineering Conference.

February 2012

The Newsletter of the Structural Engineering Institute of ASCE

Submit a Trial Design Solution and be entered in a drawing to win a copy of ASCE/SEI 7-2010 Minimum Design Loads for Buildings and Other Structures. Trial Design problems are an investigation into how structural engineers interpret code provisions. The exercise is designed to take about an hour, and all solutions will be anonymous in the publication of results. Your participation will help ensure that

Structural Columns

ASCE provides resources to celebrate Engineers Week

The Newsletter of the Council of American Structural Engineers

CASE in Point

The Council of American Structural Engineers (CASE) is a national association of structural engineering firms. CASE provides a forum for action to improve the business of structural engineering through implementation of best practices, reduced professional liability exposure and increased profitability. Our mission is to improve the practice of structural engineering by providing business practice resources, improving quality, and enhancing management practices to reduce the frequency and severity of claims. Our vision is to be the leading provider of risk management and business practice education, and information for use in the structural engineering practice. Your membership gets you free access to contracts covering various situations, as well as access to guidance on AIA documents,

free national guidelines for the Structural Engineer of Record designed to help corporate and municipal clients understand the scope of services structural engineers do and do not provide, free access to tools which are designed to keep you up to date on how much risk your firm is taking on and how to reduce that risk, biannual CASE convocations dedicated to Best Practice structural engineering, bi-monthly Business Practice and Risk Management Newsletter, AND free downloads of all CASE documents 24/7. For more information go to www.acec.org/case or contact Heather Talbert at htalbert@acec.org. You must be an ACEC member to join CASE. You can follow ACEC Coalitions on Twitter – @ACECCoalitions.

CASE to Present at NASCC: The Steel Conference 2012 Shop Drawings and the SER: To Do or Not To Do? That is the Question. In today’s world of sophisticated structural analysis and design software, Building Information Modeling (BIM) and 3D steel detailing software, has the time come for the SER to prepare the shop drawings for the Fabricator? This process has been used routinely for many years for highway bridges, and is occasionally being used today for buildings. Should this practice become the standard? While this seems to answer the question of responsibility for connection design once and for all, it raises many new concerns. Are engineers properly trained and experienced in the preparation of shop and fabrication drawings? How does this affect the allocation of risk and responsibility on a project? What impact would this have on the business practices of both engineers and fabricators? Would this practice help or hinder the process?

Moderated by CASE Programs and Communications member Edward W. Pence, Jr., P.E., S.E., F. ASCE, the panel of experts consisting of a fabricator – Chet McPhatter, COO Banker Steel Company, an engineer – Darren R. Hartman, P.E., LEED AP, Vice President, Thornton Tomasetti, and a detailer – Tom Vossmeyer, P.E., President, International Design Services, Inc. will each present their particular experiences and ideas regarding this practice, and predict how this would affect them. This will be followed by a Q&A period from the audience. The results of this presentation and discussion will be presented as a “white paper” to the AISC Code of Standard Practice Committee. To learn more about the CASE session and the Steel Conference 2012, scheduled for April, go to www.aisc.org.

Donate to the CASE Scholarship Fund! The ACEC Council of American Structural Engineers (CASE) is currently seeking contributions to help make the structural engineering scholarship program a success. The CASE scholarship, administered by the ACEC College of Fellows, is awarded to a student seeking a Bachelor’s degree, at a minimum, in an ABET-accredited engineering program. We have all witnessed the stiff competition from other disciplines and professions eager to obtain the best and brightest young talent from a dwindling pool of engineering graduates. One way to enhance the ability of students in pursuing their dreams to become professional engineers is to offer incentives in educational support. STRUCTURE magazine

In addition, the CASE scholarship offers an excellent opportunity for your firm to recommend eligible candidates for our scholarship. If your firm already has a scholarship program, remember that potential candidates can also apply for the CASE Scholarship or any other ACEC scholarship currently available. Your monetary support is vital in helping CASE and ACEC increase scholarships to those students who are the future of our industry. All donations toward the program may be eligible for tax deduction and you don’t have to be an ACEC member to donate! Contact Heather Talbert at htalbert@acec.org to donate. February 2012

CASE in Point

CASE Updates its Risk Management Toolkit with Tool 2-3: Employee Evaluations

evaluations into a firm’s regular practice, as this should already be a firm policy. The goal is to present different options, new questions, new ideas and techniques that will make your firm’s evaluation procedure better. It is the third tool related to the Second Foundation for Risk Management, Prevention and Proactivity. Developed by the CASE Toolkit Committee, this tool is available at www.booksforengineers.com.

Act Now! Early Bird Rate for the ACEC Spring Convention 2012 ACEC’s Spring Convention 2012 will be held April 15-18, 2012 at the Grand Hyatt Hotel in Washington, DC. Speaking highlights for this year’s convention include Mississippi Governor Haley Barbour on the 2012 Election, Pennsylvania Governor Ed Rendell on Infrastructure Politics, a keynote address from Lee McIntire, CEO CH2M HILL, and a CEO Panel with Steven Blake, ARCADIS, Andrew Buckley, Cardno, and George Little, HDR. In between helping ACEC’s lobbying efforts on the Hill, you can participate in the Small/Large Firm Teaming Fair and Federal Markets Conference, earn PDHs at leading-edge business seminars, and network with players in key markets. The conference culminates with the Engineering Excellence Awards Gala. The “Academy Awards” of the engineering industry recognizes preeminent engineering achievements for 2011 from throughout the world, including the Grand Conceptor Award for the best overall engineering accomplishment. A distinguished panel of judges representing a variety of professions will select this year’s best engineering triumphs using criteria such as uniqueness and originality, complexity, and technical, economic and social value. These awards aﬃrm the vital role of ACEC member firms in enhancing the quality of life and security of America and the world. Take advantage of the early bird registration and save $100 if you register by March 7, 2012. For more information and to register, go to www.acec.org/conferences/annual-12/index.cfm.

STRUCTURE magazine

100 Years of Excellence

AnnuAl Convention   and   legislAtive summit April 15-18, 2012 Grand Hyatt Hotel Washington, D.C.

February 2012

CASE is a part of the American Council of Engineering Companies

It is understood that employee evaluations are common practice, and that the importance of a regular evaluation may not need to be explored. But perhaps your firm could benefit from viewing the evaluation process from a different perspective; instead of a once-a-year check-in where staff and management exchange thoughts on performance, use the employee evaluation as a form of risk management to proactively monitor performance, and to protect the business. CASE Tool 2-3: Employee Evaluations assists the structural engineering oﬃce in evaluating employee performance. The evaluations provide a method to assess employee performance and serve as an integral part of the company’s risk management program. The tool is set up as a document that can be selectively edited and customized by the user to best suit their engineering firm. It is understood that many, if not all, engineering oﬃces already implement some form of an evaluation procedure, whether it be a formal and regularly scheduled event or an informal, more impromptu meeting that is not regularly scheduled. In any case, the goal is not to advocate for the introduction of

Structural Forum

opinions on topics of current importance to structural engineers

What is Structural Engineering Exactly? By Erik Nelson, P.E., S.E.

his is the first in a series of articles that will lay out my thoughts about my profession. I start with some common definitions of structural engineering and then present my own perceptions. A popular but limited definition of structural engineering is “the art of molding materials we do not wholly understand into shapes we cannot precisely analyze, so as to withstand forces we cannot really assess, in such a way that the community at large has no reason to suspect the extent of our ignorance.” (For its history, see Jon Schmidt’s “InFocus” column in the January 2009 issue of STRUCTURE, “The Definition of Structural Engineering.”) This is clever and fun but only addresses uncertainty of forces and materials. What a limited understanding of what we do! Yes, we are experts in the ability to make decisions under great amounts of uncertainty, but that is only one aspect of our work. Stress and strain are necessary calculations but represent only a small fraction of all that we do; otherwise, we could be completely replaced by computers. Those of us who do genuine engineering are never concerned about this. Another flawed definition comes from the British Institution of Structural Engineers: “Structural engineering is the science and art of designing and making, with economy and elegance, buildings, bridges, frameworks and other similar structures so that they can safely resist the forces to which they may be subjected.” This sounds pretty good, right? Unfortunately, it fails completely in describing how one goes about designing. Like most other definitions, it puts too great an emphasis on force resistance. Yes, we proportion members based largely on forces, but that is only one of many design considerations – we also have to take construction practices, architectural constraints, client needs, and many other factors into account. As Hardy Cross famously put it, “Strength is essential, but otherwise unimportant.” The American Society of Civil Engineers unfortunately defines civil engineering thus: “The profession in which a knowledge of the mathematical and physical sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize economically, the materials and forces of nature for the progressive well-being of humanity in creating, improving and protecting the environment,

in providing facilities for community living, industry and transportation, and in providing structures for the use of humankind.” How could a definition of engineering omit the most important word – design! This one is lengthy and dull, and fails to describe what we do, instead focusing on the end product, what we make. Saying that a cook makes cake does not describe cooking very well. Here is more of the same from the National Society of Professional Engineers (NSPE): “Engineering is the creative application of scientific principles used to plan, build, direct, guide, manage, or work on systems to maintain and improve our daily lives.” This suggests that our creativity is not employed for artistry, self-expression, costs, or constructibility, but solely for science. That is just plain weird – and wrong. The applied science portion of what we do is actually the easiest and most straightforward. It is objective and has its own linear, step-wise methodology. That is why young engineers are doing the calculations and the modeling, while more experienced engineers are doing less. Yes, it needs to be right, so there is a lot of responsibility in this phase; but that does not necessarily make it difficult. The experienced ones are doing the other 90% of what we do, the more difficult tasks that require much more than calculations. Design is the other 90% of engineering that is only achieved after one graduates from being a mere applied scientist (or technician) to being a genuine engineer! It is a widespread misconception that engineers are applied scientists. Scientists are applied scientists. Most of our engineering educators are applied scientists. Scientists make sense of what exists in nature. They test and examine nature. Scientists discover. Engineers take nature and make what exists outside of it. Engineers invent and create. Engineers are makers. Engineers are designers. Alan Harris put it succinctly: “Engineering is no more applied science, than painting is applied chemistry.” Here is my own definition: “Structural engineering is the design of BIG things.” The know-how required to do this is immense and is only obtained via lifelong learning. Engineers are 1% to 10% of each of the following: • Scientists • Mathematicians • Computer Scientists • Information Seekers (State of the Art)

STRUCTURE magazine

February 2012

• Specialists in Systems • Experts in Construction • Citizens of a Locality of Construction Practices and Material Availability • Cost Estimators or Experts on Best Practices to Reduce Cost • Experts on Local Fabrication and Construction Technologies • Experts on Building Codes, Specifications, Standards, Guides, and Regulations • Risk Evaluators and Code Interpreters • Experts in Calculations • Experts in Three-Dimensional Representation in the Mind • Experts in Synthesizing Complex/ Unsolvable Things into Simple/ Solvable things. • Experts in Analysis Modeling Using Software • Skeptics of Engineering Software • Debaters of Efficiency, Economy, and Elegance • Artists, Philosophers, Poets, and Dreamers with Unconstrained Self-Expression • Drafters and/or BIM Specialists • Collaborators Working Within Design Teams • Listeners of the Vision and Needs of the Project/Client/Architect • Users of Rules of Thumb (Heuristics) • Experts in the Ability to Make Decisions Under Great Amounts of Uncertainty Structural (and civil) engineering is the design of big things. This definition may contribute to a positive “rebranding” of the profession which may improve the career appeal of our profession and hopefully help with the dismal 50% retention rate in our engineering schools. We have a marketing problem of clearly describing what we do. Engineering is so much more than completing calculation procedures!▪ Erik Anders Nelson, P.E., S.E. (ean@structuresworkshop.com), is owner of Structures Workshop, Inc. in Providence, RI. He teaches one class per semester at the Rhode Island School of Design and Massachusetts Institute of Technology. Please visit and comment on his blog at www.structuresworkshop.com/blog.

STRUCTURE magazine | February 2012

Articles inside

NCSEA News

Resource Guide (Bridge)

CASE in Point