STRUCTURE magazine | October 2014 by structuremag

October 2014 Bridges

A Joint Publication of NCSEA | CASE | SEI

STRUCTURE ®

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Features Tappan Zee Hudson River Crossing

CONTENTS October 2014

By Michael D. LaViolette, P.E.

The Tappan Zee Hudson River Crossing includes two parallel, 3.1 mile-long bridges crossing the Hudson River north of New York City. Each of the two bridges consists of a 1,200-foot cable-stayed navigation span, along with a series of 350-foot continuous steel girder spans supported on seismic isolation bearings.

Building the First Movable Bridge in Malaysia

To facilitate economic and tourism growth, a bridge is planned to connect the North and South districts of Kuala Terengganu on the eastern side of the Malay Peninsula. This bridge will be 2200 feet long with a movable span crossing the navigation channel.

In 2009, the New Jersey Turnpike Authority began work on a 35 mile widening project. As part of the reconstruction of Interchange 8, the new Ramp TW/WT needed to cross Route 33. The erection of the proposed bridge, thought to be the longest single span curved steel bridge east of the Mississippi, presented several engineering and construction challenges

Departments

43 InSights A Structural Perspective on Sustainability

44 Professional Issues Diversity in the Structural Engineering Profession By Abbie B. Liel

Car Float and Transfer Bridges

The 130th Street and Torrence Avenue Railroad Truss Roll-In

By Diane Campione, P.E., S.E.

58 Structural Forum By Emily Guglielmo, S.E.

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.

Erratum

STRUCTURE® magazine, September 2014 Editorial by Randall Bernhardt, P.E., S.E. Jerry Carter, NCEES CEO, pointed out that NCEES withdrew from ANSI last year, which means that any standards developed by NCEES as ANSI standards were immediately withdrawn. NCEES still has the MLSE designation; just not as an ANSI standard. Originally intended to promote licensure in large industries that are not generally supporters of licensure, the length of time to see any impact metrics, coupled with staff time for procedural changes and audits, resulted in a cost/benefit analysis that did not support continued ANSI membership. www.ncees.org

STRUCTURE magazine

12 Historic Structures James River Bridge at Richmond, Virginia

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

16 Structural Design

21 Structural Licensure Florida’s Move Toward Structural Licensure

By Scott D. Martin, P.E.

23 Technology Fabricator’s Inside Perspective on Standardized Steel Bridge Design

36 Building Blocks

A Young Engineer’s Case for Structural Licensure

By Robert D. Richardson, P.E., P.Eng

10 Outside the Box

By Dennis Gonano, P.E.

51 Spotlight

By Thangam (Sam) Rangaswamy, Ph.D., P.E., S.E., SECB, Geoff Cooper, E.I.T. and Anthony Ehlers, P.E.

By Andrew Rauch, P.E., S.E.

By Steven J. Bongiorno. P.E., S.E.

By Michael H. Marks, P.E.

Pitfalls of Design-Build

Driver’s Education and Quality Assurance?

Designing with High Performance Concrete Reinforcing

Overcoming Challenges

40 Lessons Learned

7 Editorial

By Peter Davis

Columns

October 2014

The ABC’s of Traditional and Engineered Wood Products

By Michelle Kam-Biron, P.E., S.E., SECB and Lori Koch, E.I.T.

In every Issue 8 Advertiser Index 48 Resource Guide (Seismic) 52 NCSEA News 54 SEI Structural Columns 56 CASE in Point

on the Cover Rendering of the Tappan Zee Hudson River Crossing, perhaps the largest and most challenging bridge project currently under construction in the United States. See more about this project on page 27. Photo courtesy New York State Thruway Authority.

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Editorial

Driver’s new trends, newEducation techniques and current and industry Quality issues Assurance? By Andrew Rauch, P.E., S.E., LEED AP, CASE Chair

t is the last weekend of summer and there is a thunderstorm brewing while I am writing this article. (No, this is not another article about how climate change might affect engineers.) My youngest daughter completed her driver’s education classroom work this summer and earned her learning permit. For those of you who have not been through this, you don’t know terror like the first time your teen gets behind the wheel of your car. Her instructor also provided a DVD for parents and teens with 12 steps for teaching them how to drive. It was quite helpful and I wish I had it available when my first two were learning. (It is available for purchase online, and I am happy to share that information with you if you email me.) It is always helpful to have a how-to guide to assist you when doing something with which you are not familiar. Just as that DVD provides a guide for teaching a teen to drive, CASE’s Ten Foundations of Risk Management provide a guide for setting up a risk management program for your firm. In a previous article, I talked about the first foundation, Firm Culture, with ideas to think about for developing a culture of risk management within your firm. I would like to talk about another foundation in this article: Producing Quality Construction Documents, specifically the Quality Assurance Plan. If your firm has not developed a quality assurance plan, I urge you to strongly consider doing so. The quality assurance plan, along with ideas such as project “ownership” by all members of the design team, continual staff education, and firm standards forms a good platform for providing quality services to our clients. CASE Tool 9-2 provides a helpful outline for setting up your firm’s quality assurance plan. That document presents three parts to the plan: quality reviews, firm standards, and construction quality assurance. The quality reviews should include design reviews, engineering reviews, and construction document reviews and should occur at all project stages. Schematic and concept phase reviews are good for keeping the project from going down the wrong path. Design reviews verify that the chosen system makes sense, engineering reviews target critical portions of the analysis, and construction document reviews verify that the design is properly presented. Firm-wide standards greatly help with project consistency. They include such things as standard details, design standards, standard notes and construction administration standards. These standards provide the added benefit of reducing engineering and drafting efforts, adding directly to the bottom line. Construction quality assurSTRUCTURAL ance means developing standard ENGINEERING methods for dealing with the INSTITUTE normal parts of the process such as pre-construction meetings, a member benefit

structurE

submittal reviews, information requests, etc. Having standard procedures in place for construction observations helps to keep track of those items that require observation and minimizes the chance of expanding our scope simply by looking at things that were not originally part of our scope of services. Finally, it provides an opportunity for implementation of an early warning system to allow you to get out in front of issues before the spiral out of control. Since we are a multi-discipline firm, our plan was set up using an early ACEC document on quality assurance as a template. Since it is intended for use on a multi-discipline project, it sometimes feels unwieldy when using for only a single discipline. We also sometimes struggle with the appropriate project size for which it should be implemented. All projects need some sort of quality assurance, but does a simple site investigation report require the same level as a multi-story building. That is an obvious choice, but how about a residential garage, or maybe the small warehouse building. There has to be a line somewhere, but where should it be drawn? I have also heard a negative aspect of a quality assurance plan. If it is written down, it can be used as fodder in any lawsuits against you, especially if you did not follow it to the letter. Some firms skirt that issue by always having the plan as a draft, thinking if it is not completed it gives you some protection. In my opinion, not having a plan represents significantly greater risk than having your plan used against you. If the plan is set up as a set of guidelines rather than rigid rules, it can be flexible enough to work with projects of various sizes and still be a useful tool. So, if you have not already done so, take advantage of the resources available to you and set up a quality assurance plan for your firm. It will take some time. Implementing it and following through will always be a challenge, but in the end, you and your bottom line will be glad that you did.▪

STRUCTURE magazine

Andrew Rauch, P.E., S.E., LEED AP, is a principal with BKBM Engineers in Minneapolis, MN. He is the current chair of the CASE Executive Committee. He can be reached at arauch@bkbm.com.

October 2014

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STRUCTURE® (Volume 21, Number 10). ISSN 1536-4283. Publications Agreement No. 40675118. Owned by the National Council of Structural Engineers Associations and published in cooperation with CASE and SEI monthly by C3 Ink. The publication is distributed free of charge to members of NCSEA, CASE and SEI; the non-member subscription rate is $75/yr domestic; $40/yr student; $90/yr Canada; $60/yr Canadian student; $135/yr foreign; $90/yr foreign student. For change of address or duplicate copies, contact your member organization(s).Any opinions expressed in STRUCTURE magazine are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C3 Ink, or the STRUCTURE Editorial Board. STRUCTURE® is a registered trademark of National Council of Structural Engineers Associations (NCSEA). Articles may not be

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Outside the BOx highlighting the out-of-theordinary within the realm of structural engineering

YNJ Rail is the last remaining car float operation in the metropolitan New York area. This shortline railroad operates between Jersey City, NJ and Brooklyn, NY moving freight across New York Harbor, and is one of four remaining car float operations in the United States. The transfer bridge concept originated in the mid 1800s with a ferry between Havre de Grace and Perryville, MD for the Camden & Amboy Railroad and the Philadelphia, Wilmington and Baltimore Railroad. Rail cars were transported across the river by moving them from land to a barge by means of a transfer bridge. The rail cars are then unloaded at a similar facility across the waterway. In the late 1800s, New York City was a major manufacturing and industrial center requiring massive transfer of raw materials and finished goods. The base of the industry was on Manhattan Island, requiring materials to be moved by water between New York and New Jersey, or through the only land route across the Spuyten Duyvil (northern tip of NYC), which was controlled by Cornelius Vanderbilt’s New York Central Railroad. All other railroads terminated along the New Jersey side of the Hudson River, and goods were moved either by lighter (small barge) or car float. At the pinnacle of this period, over 6000 freight cars per day were transported across the river by car float. Super Storm Sandy caused severe damage to both the Jersey City and Brooklyn transfer bridge facilities. A temporary pontoon structure was constructed in Jersey City while a new permanent bridge is designed.

Car Float and Transfer Bridges By Peter Davis

Peter Davis, a licensed mechanical engineer, has 39 years of experience in the inspection, design and construction of heavy infrastructure including locks, dams and movable bridges. He can be reached at pete.davis@hdrinc.com.

Figure 1. NY Harbor Circa 1928.

car float. This mooring connection can impose significant loads onto the bridge structure, even though fender systems and mooring dolphins may be used. These loads include the propulsion from the tug boat as well as wind loads, causing a moment at the end of the bridge. In Figure 2, a typical arrangement between the car float and the transfer bridge, along with the capacity for elevation adjustments, is shown for a mechanically driven structure. This structure uses hydraulic cylinders suspended from a gantry to raise and lower both the bridge and the apron. In older designs, the bridge and apron utilized counterweights to balance the dead load of the structure. The reality of these structures is that the dead load represents approximately 20% of the total load on the structure. For this new transfer bridge, the cost of the counterweight system was not justified compared to increasing the hydraulic cylinder size. Another design utilizes a pontoon (floating structure) to support the bridge. This system

Transfer Bridges The structure that allowed rail cars to be loaded onto car floats is the float or transfer bridge. The transfer bridge is unique in that it must function as a movable bridge for the purpose of allowing adjustment between the top of rail elevation on land and on the car float. In New York Harbor, the typical tidal fluctuation is up to10 feet. As this relative elevation change is due to tide and car float freeboard changes, the bridge must adjust to provide the connection between car float and land. This elevation adjustment typically occurs over the 30 minute load/unload cycle. While both rail and highway movable bridges are opened to allow marine traffic to pass, they do not operate under live loads as do transfer bridges. Transfer bridge live loads include locomotives and rail cars that vary in weight due to their changing cargo. Today rail car loads can be in excess of 286 kips. In addition to operating under live load, these bridges provide a mooring connection to the

10 October 2014

Figure 2. Transfer bridge arrangement.

Are you measuring tension forces at

dizzying heights?

Figure 5. Heel bearing.

relies on the pontoon to adjust the bridge elevation based upon tidal variation, but does not compensate for the car float freeboard (loaded/unloaded). The size of the pontoon is based upon the dead load of the bridge and the expected change in freeboard of the car float. A simple calculation is used to determine the volume of water that must be displaced to compensate for the changes in car float loads. The volume of the pontoon is then sized appropriately. The railroad operator must adjust the elevation between the car float and bridge by loading the bridge (usually with a locomotive) such that the toggle bars can be engaged. This approach requires substantial operator skill and can limit the speed of loading and unloading operations. Based upon the range of tidal variation, the length of the bridge and apron are adjusted such that the maximum angular change between the land, bridge, apron and car float do not exceed the allowable for the rail cars (prevent bottoming). Most freight cars do not pose a limitation compared with hopper cars which dump the cargo through the bottom. The length of the bridge and apron determines the maximum positive and negative angles that will occur over the operating range of the bridge and car float. Transfer bridges generally range from 80 to 150 feet in length. In order to compensate for the angular changes of the rail during tidal extremes, the bridge shown is articulated. The articulated design allows the apron to make a hard connection with the car float utilizing a toggle bar arrangement (Figure 3). The toggle bars are critical to maintain top of rail alignment between the bridge and car float. These toggle bars resist large loads, as the car float tends to

rotate as the freight cars are moved on and oﬀ. It is common for the operators to develop a loading/unloading sequence that accounts for the shifting load conditions. A key feature of these bridges is that components of all loads are transmitted to the substructure through the hinge pin arrangement (Figure 4 ). The hinge pin is a critical element of the entire system. These loads include: live load, dead load, traction/braking loads, mooring loads (tug boat loads and moments from wind load on the car float), as well as seismic loads. Due to the operation of these structures, the seismic loads tend to govern. It is not uncommon for hinge pins to see loads ranging from 300 to 700 kips in the longitudinal direction, 180 to 800 kips in the vertical direction, and up to 230 kips transversely. The original design was a simple pin and clevis arrangement. For the loads of today’s freight cars, the hinge pin assembly becomes extremely large. In order to resolve the loads in compliance with AREMA design standards, a diﬀerent approach was taken. A saddle design (heel bearing) was developed, both simplifying the construction and improving the reliability of the hinge over time (Figure 5). The transverse loads are resolved using a mechanical device which is a movable key located in the center of the pier. An added design challenge includes regular submergence of the hinge pin arrangement. The selection of materials for this component is critical to provide the capacity, but also to provide reliable operation over an extended period (30 years). These “workhorse” bridges truly provide a unique challenge for engineers to showcase their skills.▪

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Figure 3. Toggle bars connecting the car float to the transfer bridge.

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Figure 4. Hinge pin arrangement connecting the transfer bridge to the abutment.

STRUCTURE magazine

October 2014

Historic structures significant structures of the past

t was early in railroad development in this country when the Richmond & Petersburg Railroad was proposed and chartered in 1836. It ran from just north of Petersburg on the north side of the Appomattox River to just south of Richmond on the James River. The charter stated the line could be extended into both Richmond and Petersburg upon the approval of the Common Council of each city. The line as proposed was only 22 miles long. The B&O Railroad had just reached the Potomac River across from Harper’s Ferry, and the railroad and Lewis Wernwag built a wooden deck bridge across the Monocacy River. The Mohawk and Hudson Railroad opened in New York State, connecting Albany and Schenectady, in 1831. The Allegheny Portage Railroad was 36-miles in length, connecting the Hollidaysburg Canal Basin with the basin at Johnstown on the Little Juniata River. It was designed by Moncure Robinson and opened March 18, 1834. Robinson was also working during this time on the construction of the Petersburg and Roanoke Railroad. That line was 59 miles long and ran from Petersburg to Blakely on the Roanoke River. It opened in 1833 and has also been called the first railroad in Virginia. It was no surprise that Robinson was also selected to design the railroad and the high level bridge connecting it with downtown Richmond. He is another of the early giants in civil engineering of the 19th century that is little known in the present day. At the age of thirteen, he entered William and Mary College graduating with an A.M. degree in 1818. Being interested in Civil engineering, he was a member of a party sent out by the board of public works of Virginia to run a line of levels across the entire state from Richmond to the Ohio

James River Bridge at Richmond, Virginia Mighty Colossus, Bestriding the Ancient Powhatan By Frank Griggs, Jr., Dist. M. ASCE, D. Eng., P.E., P.L.S.

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

Town Lattice Truss, Philadelphia and Reading Railroad Bridge, by Moncure Robinson from David Stevenson.

12 October 2014

River for the James River and Kanawha Canal. In 1822, he visited the Erie Canal, which was under construction, and became convinced that railroads in most cases were, as John Stevens said in 1812, superior to canals. He was one of the first Americans to Moncure Robinson. visit France to study civil engineering and survey the public works of Europe. He arrived in Paris in April 1825 and studied civil engineering at the Sorbonne, founded in 1257. While it primarily stressed the Arts, it was strong in math and science education and was offered free to American students. Why he did not attend the nearby École Polytechnique or the École des Ponts et Chaussées, the finest engineering schools in the world, is not known. Between 1825 and 1827, he also spent a great deal of his time in England meeting George Stephenson, who had just finished the Stockton & Darlington Railway and was beginning work on the Liverpool & Manchester Railway while improving on his steam locomotives. Returning to the United States in the latter part of 1827, Robinson soon became one of the leading railroad engineers in the country. He was first retained by the Canal Commissioners of Pennsylvania to make the survey for a railroad connecting Northumberland on the Susquehanna River with Pottsville on the Schuylkill River, later called the Danville-Pottsville Railway. It was a means to haul anthracite coal from the coal fields to Philadelphia via the Schuylkill Navigation. He also designed the Winchester and Potomac Railroad that ran from Winchester, Virginia along the west bank of the Shenandoah River to Harper’s Ferry. It was completed in 1836. It was connected with the Baltimore & Ohio Railroad by a railroad bridge built in 1837 by Wernwag across the Potomac River at Harper’s Ferry. In 1834, Moncure began work on what many called the greatest work of his career, the Philadelphia and Reading Railroad. This line was built on the west bank of the river parallel to the Schuylkill Navigation, which reached Reading in 1825. It was a twin track line built originally to carry coal from the anthracite fields north of Reading to Philadelphia. His design included three tunnels (Black Rock, Flat Rock and Pulpit Rock) and nine bridges across the river. The wooden bridges he built were all Town Lattice Truss bridges. Town had patented his truss in 1820 and updated it in 1835. It was commonly built for roadways, but Robinson was one of the first to use it for railroad purposes even though the Rensselaer & Saratoga Railroad built several across the Hudson and Mohawk Rivers near Troy, New York. Wernwag’s B&O Bridge across the Monocacy relied on a trussed arch, and his bridge across the Potomac

at Harpers Ferry (STRUCTURE, July 2014), designed with Benjamin Latrobe, was a variation of a Grubenmann design from the later 18th Century. The laying out of the railroad was straight forward, but the bridge across the James River was not. The James River carved out a deep channel over time, and the City of Richmond was about 60 feet above the river, with a similar difference of elevation on the south side. The river channel was of rock and was tidal up to the falls at Richmond. A portion of the James River & Kanawha Canal was built by Charles Ellet, Jr. and ran along the north side of the river. A low level wooden wagon bridge had crossed the river for some time, but the railroad needed a high level bridge. Robinson patterned his bridge on the ten span bridge he built on the Philadelphia and Reading Railroad. David Stevenson in his Sketch of the Civil Engineering of North America gave plans of this bridge, showing not only the truss pattern but the deck framing. Stevenson noted that he observed this bridge, with total length of 1,100 feet, during and after construction. The structure Robinson designed “was 2,844 feet in length, 60 feet above the water, and composed of nineteen spans, varying from 140 to 153 feet in the clear.” The

The Richmond Whig in an article entitled The Railroad Bridge Across James River wrote in the flowery language of the time,

James River Bridge looking towards Richmond.

superstructure was lattice, chiefly composed of two-inch pine plank, and contained only 1,500 pounds of iron. Its cost was $117,200, or $41 per foot lineal, including masonry – a limit Mr. Robinson found to be necessary to suit the means of the company. The low cost of such a structure for railroad use was commented on by foreign engineers, to whom it was little short of an enigma. It was Mr. Robinson’s forte to “cut his coat according to his cloth,” and he acquired an enviable reputation for his ability to adapt his expenditures to the means at his command…Had the Richmond & Petersburg Company been able to supply their engineer with means to build this bridge of iron, it would be doing duty today.” (Illustrated American, December 5, 1891) ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

STRUCTURE magazine

October 2014

What is there yet to be done upon the face of the earth that cannot be effected by the powers of the human mind, connected with the ingenuity of the human hand? The great elementary principles of nature have long ago been mastered by the skill of man, and rendered subservient to his wants and happiness. The bowels of the earth and the fathomless ocean, have alike been made to pour forth their treasures at his bidding. He has navigated the sea and the air, and made the inanimate objects of nature perform the labor that would have otherwise devolved upon his own hands. He has even, by his inventions, condemned the drudgery of personal locomotion, and caused himself to be carried, from point to point, upon the face of the earth and the waters, by inanimate agents, ‘with the rapidity of the wind; while he, luxuriously reclining, as though quiescent, drinks in new draughts of knowledge from the great fountain’ and all nature, as though daily more sensible of the conquest, is progressively making less and less resistance to his dominion. continue on next page

The great bridge across James River at Richmond, for the accommodation of the Richmond and Petersburg Railroad, may justly be considered as one of the greatest works of its kind in this country, or perhaps in the world. There are longer bridges of less altitude, and higher bridges of shorter span; but when the altitude and length of span of this bridge are taken collectively, there is, perhaps, not its equal in the world. For the gratification of the universal interest that at this time pervades the country, on the subject of Internal Improvements, I design to give

the public a short, but imperfect account of this gigantic, and in every point of view, interesting and splendid structure. The location of the bridge is across the falls of the James River, a few hundred yards above tide water, where the velocity of the current is exceedingly great. It is constructed of substantial lattices, upon lofty granite piers, with a floor upon the summit of the lattice frame. The stoutness of the flooring corresponds with the general strength of the decision, and it is rendered water and fire proof, by a strong coat of pitch and sand.

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The floor, upon which the traverse rails lie, rises five inches from each side to the centre, in order that the rain water may freely pass off. Guard rails are laid parallel to the traverse rails on each track, to prevent the possibility of either engine or cars running off. In addition to the precaution of covering the floor with a coat of pitch and sand, a gallery or walk is constructed throughout the whole length of the bridge, underneath the main floor, having a hand railing, upon which numerous buckets of water are to be kept hanging, ready for extinguishing fire, in case such an accident should call for their use…The frame work is preserved by a painted weather coating. The whole structure was designed with a view to as much economy as was thought consistent with a just regard to strength and durability…The work itself stands like a mighty Colossus, bestriding the ancient Powhatan, destined to hand down to posterity both itself and its authors; and those piers of imperishable granite will remain as proud monuments, to remote generations of the present State of Virginia, and her sons, as connected with the Sciences and the Mechanic Arts.

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The entire length of the span of the bridge is 2,900 feet, and the span between the piers 160 feet. The entire width of the floor is 22½ feet, (wide enough for a double railroad track,) being wider than, and projecting over the lattice frame, 2½ feet on each side; the frame work is, therefore 17 feet wide, on the top of the piers. The piers are 18 in number, founded in the rapids, upon the solid bed of granite rock that lies beneath. The elevation of the piers above common water is 40 feet, and their dimensions 4 by 18 feet at the top increasing one foot in width and one foot in thickness, for every 12 feet in the descending scale…The entire elevation of the wooden superstructure above the piers is 20 feet; so that the floor, which is on top, is 60 feet above the surface of the water…

October 2014

During the Civil War it served as the main supply line between Richmond and Petersburg that was under siege for nine months by General Grant and the Northern Armies. The bridge lasted until April 1865 when it was burned when the CSA evacuated Richmond after the fall of Petersburg. It was rebuilt and opened again on May 25, 1866. A steel bridge was erected on the stone piers when sparks from a passing locomotive caused the rebuilt bridge deck to burn in 1882. In the early 1900s, a fourth bridge was built on the smaller concrete pilings beside the original stone piers.▪

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Structural DeSign design issues for structural engineers

ecent advances in concrete reinforcement technology have led to the availability of high strength (as high as 100 ksi) and large diameter (as large as 3.5 inch diameter) reinforcing bars for concrete structures. These bars are available with thread-like deformation patterns that permit the use of complimentary connection and anchoring hardware, and facilitate prefabrication of large reinforcing cages. These advances in material and manufacturing technologies can be combined to create High Performance Concrete Reinforcing (HPCR) systems that can be used to significantly reduce the quantity of reinforcing and associated material and labor costs, and create potential schedule savings for concrete building structures. However, the implementation of these new reinforcing materials into the design of concrete structures can pose some significant challenges, as current design practices and prescriptive code procedures do not always address some of the unique performance characteristics of these materials. In an attempt to address some of these challenges, design recommendations for using high strength reinforcement have been presented in a few publications, most notably ACI Committee Report ACI-IGT-6R-10 and the National Cooperative Highway Research Program Report-679. As the availability of these materials becomes more prevalent, it is important that engineers understand the primary challenges and limitations associated with utilizing HPCR systems. Engineers should become familiar with effective optimization techniques using these advanced reinforcing systems in order to exploit their full benefits, which can result in more efficient and sustainable/cost effective structural designs.

Designing with High Performance Concrete Reinforcing By Steven J. Bongiorno. P.E., S.E.

Steven J. Bongiorno, P.E., S.E., is a consulting structural engineer who provides structural value engineering services to developers, engineers and contractors. He can be reached at Stevenbongiorno@ stevenbongiorno.com.

“Trouble with the Curve” High strength reinforcing materials are generally considered those with a yield stress in excess of 80 ksi. Such materials have been in existence for quite some time and are used regularly in Japan and Europe. Figure 1 shows the stress strain curves for two such high strength reinforcing materials that are commercially available in the U.S., along with that of conventional A615 Grade 60 reinforcing. One of the common characteristics of most high strength reinforcing materials is their lack of a well-defined yield point, exhibiting more of a roundhouse transition above the proportional limit. However, it is also readily apparent that although the two higher strength materials utilize a similar design yield stress of approximately 100 ksi, the stress strain curves are quite different. The Grade 97 material, while more similar in

16 October 2014

Figure 1. Comparison of two commercially available high strength reinforcing materials and conventional ASTM A615.

performance to conventional A615 and perhaps even closer to A706, within the low to moderate strain range, does not exhibit nearly the same degree of strain hardening in the higher strain ranges. Alternatively, the Grade 100 material exhibits a rapid and significant strength gain even at very small strains, but then little to no strain hardening beyond approximately 0.04 strain. The ACI 318 prescriptive design provisions are based on an idealized bi-linear elastic-perfectly plastic stress strain relationship. This is a reasonable assumption for conventional A615 and A706 materials because they do not deviate significantly from the bi-linear idealization until the higher strains that would be associated more with high seismic applications. For those conditions, ACI limits the allowable deviation from the bi-linear relationship, in addition to accounting for the actual material strength rather than an assumed strength (the “overstrength” concept). However, when the actual stress-strain behavior deviates significantly from the idealized bi-linear relationship at low to moderate strain levels, special consideration is necessary to ensure ductile behavior under normal loading condition, in order to account for the “overstrength at low strain” issues associated with some of these materials. For these reasons, it is often more prudent to consider the full non-linear stress strain relationship of high strength reinforcing materials for design, rather than a simplified bi-linear relationship. In some cases, the ACI-318 prescriptive procedures are simply not applicable to high-strength reinforcing material and require performance-based design methods.

Threaded Bar Reinforcement Systems Threaded bar reinforcement has been used for many years in foundation and post-tensioning applications, and occasionally as reinforcement for building structures. A number of large-scale building projects in New York and New Jersey recently utilized the HPCR systems as the primary longitudinal reinforcement in columns and shear walls.

(a)

(b) Figure 2. Typical features of threaded reinforcing bars. Continuous thread-like deformations are either (a) hot rolled or (b) cold rolled or cut into bar.

Threaded reinforcing bars are characterized by their continuous thread-like deformations, which provide equal or better bond than conventional rebar deformations. The thread-like deformation also provides a threading mechanism to facilitate the use of complimentary threaded accessories, such as couplings and anchors, at any location along their length (Figure 2). Threaded reinforcing bars can be cut anywhere along their length with no additional machining required. These features allow for full tension couplers to be used economically and efficiently because a full tension threaded bar coupler is often less expensive than the material cost of the required lap splice length. Additionally, using couplers on the full range of available threaded bar sizes eliminates the need to try to limit bar sizes to #11, which is the current limit beyond which conventional couplers are required. Similarly, anchorage hardware is easily installed onto the ends of threaded bars, eliminating the need for hooks, or machine threaded, or welded, headed anchors.

Benefits of HPCR

Code Considerations ACI 318-11 does not explicitly address the use of high strength reinforcing materials. Section 3.5.3.2 currently limits the yield stress to the stress corresponding to a strain of 0.35%. This limitation is partly to ensure that the assumption of an elasto-plastic stress strain relationship for materials that lack a well-defined yield point will not lead to unconservative calculations of member strength. The limitation is also intended to provide some measure of control for service level cracking. Section 9.4 further limits the value of the design yield stress to 80 ksi, to be compatible with the maximum usable compressive strain limit of 0.003 (Section 10.2.3). The maximum compressive strain of 0.003 assumes rapid loading conditions without considering actual loading sequence or long-term effects. The use of a higher compression yield stress can be justified by considering the long term redistribution of creep and shrinkage strains from the concrete to the reinforcement. Although ACI 318-11 does not address this phenomenon, Section 9.5.2.5 acknowledges it indirectly by allowing for a reduction in the long term component of deflections based upon the redistribution of creep and shrinkage strains to compression reinforcement. For vertical elements subjected to load reversals, such as shear walls, consideration of such strain/stress redistribution must account for any strain recovery that occurs during unloading and tension loading phases.

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October 2014

(a)

(b)

Figure 3. Comparison of alternate design of high rise core walls reinforced with (a) conventional #11 Grade 75 bars and (b) #24 Grade 100 threaded bars.

ACI 318-11 enforces minimum ductility requirements for flexural members in Sections 10.3 and 9.3 by ensuring that there is sufficient straining of the steel between service loading and nominal strength. However, the tension and compression control limits specified in these sections were developed for conventional A615 reinforcing material, and thus must be modified for high strength reinforcing materials to achieve similar ductility levels.

Strength Design Considerations Regardless of the level of sophistication used for the design of concrete members with HPCR, any design must still respect the basic tenants of the ACI 318 design philosophy. Foremost among them is the assurance of ductile failure modes for flexural and tension members. Equally important is the assurance that such ductile failure modes are not prevented or otherwise limited by a less ductile supporting mechanism. For example, if the “actual” capacity of a reinforcing material at a specified strain level is 50% greater than the assumed value, then the development, splicing, anchorage, etc. of the reinforcement at that strain level must be capable of developing or supporting similar actual strengths. This is of critical importance in reinforced concrete design because the

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Combining the large size, high strength and thread-like deformations of HPCR systems significantly reduces concrete reinforcing quantities. The first source of quantity reduction is due to the higher strength of the HPCR materials. The second source is the elimination of required lap splice lengths. As a simple example, one #24 (100ksi) threaded reinforcing bar can replace seven #11 (60ksi) conventional rebar, yielding a 37% decrease in material weight. Further reductions are realized with the elimination of lap splice lengths for the seven #11 bars, which may be as much as 65%. Even after accounting for the cost of the full tension coupler for one #24 – 100ksi threaded reinforcing bar, the material cost savings is significant. Other constructability and logistical benefits include less congestion, less pieces to fabricate

transport and install, less labor and less tie reinforcing, when present. The drawback of a #24 bar being too heavy for hand-installation is readily offset by the advantage of threaded features of the bars, grouping multiple bars into cages, or modules for off-site pre-fabrication. The cages can then be delivered when needed and erected relatively easily with the use of a crane (Figure 4, page 18). Figure 3 illustrates a realistic example of how the features of HPCR systems replace, and oftentimes increase, the capacity of shear walls in tall building structures. HPCR systems can consolidate the capacity of large quantities of conventional reinforcing into a few optimally placed clusters of HPCR. The reinforcement between these clusters can be significantly minimized to ideally be only the required minimum reinforcement. Additionally, the clusters can be fabricated into two-story high cages, saving erection costs on alternate floors. Alternately, staggering the two-story cages would require only half of the cages to be installed on any one floor.

P - M NOIMINAL INTERACTION DIAGARAM 300000 H.P.C.R. (100KSI) A615 (75KSI)

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Figure 5. Representative floor plan and coupled shear wall arrangement for a high rise building.

limit states design philosophy of ACI 318 is strain-based, not stress based. The strength design methods used for HPCR can typically employ the same code-based procedures and formulae used for conventional reinforcing, as modified in the design guides and recommendations of ACI (ACI-IGT-6R-10) and the National Cooperative Highway Research Program (Report-679). Engineers must exercise greater care in determining the appropriateness of any such design procedures and formulae due to some of the unique challenges and limitations of HPCR systems, as previously described; however, the engineer has the option of using non-prescriptive performance-based design procedures. Figure 6 illustrates a standard P-M interaction diagram for the shear walls shown in Figure 3. The diagrams use nominal strength

Figure 6. Comparison of the P-M nominal interaction diagrams for the lower shear wall in Figure 5 with the reinforcement distributions shown in Figure 3.

because the transition zone for the applicable phi-factors between tension-controlled and compression-controlled limits is different in conventional reinforcing materials and high strength materials. The HPCR design (Figure 3a) requires 30% less reinforcement area than the wall reinforced with conventional Grade 75 bars (Figure 3b). Redistributing the HPCR to their most effective locations achieves an equal or greater wall stiffness with an overall lesser reinforcement quantity, while also increasing the moment capacity for the same axial capacity (Figure 6). The use of HPCR in the superstructure may also result in special design considerations for the foundation elements. The effective use of HPCR in shear walls can result in large localized concentrations of high strength reinforcement at wall ends (Figure 3). This may impose higher than usual foundation anchorage and pull-out, or shear, demands on foundation mats and footings. The use of shear reinforcement or distribution elements (subgrade walls, grade beams, etc.) can be used to distribute the force concentrations over a longer length of the foundation.

Stiffness Design Considerations

Figure 4. Example of a prefabricated shear wall cage of HPCR.

High strength reinforcing materials generally exhibit larger tensile strains at service level loading than conventional reinforcing materials, which will result in larger deflections and wider crack widths. Because one of the primary benefits of utilizing HPCR is to decrease the total reinforcement quantity, the effects of any such reductions in reinforcement quantity

STRUCTURE magazine

October 2014

on the stiffness of the structural elements may become an important consideration. The relevancy depends on to what degree, if any, the engineer considers the reinforcement in his or her stiffness calculations. Many engineers still utilize effective stiffness modifiers (i.e. Ieff = 0.5Ig, etc), so it may not be necessary to use a more detailed approach for HPCR. However, in cases where the structural elements are stiffness-controlled, or where HPCR is being proposed as a value engineering alternate, it may become necessary to verify that stiffness of the elements reinforced with HPCR is not less than that of conventional reinforcement. Non-linear moment-curvature analysis is an effective way to compare the stiffness of sections reinforced with conventional versus high strength reinforcing and incorporates the actual stress-strain behavior of the materials, as well as the spatial distribution of the reinforcement. If there is significant axial force due to gravity or lateral loading, such as the case with coupled or linked shear walls in figure 5, then the moment curvature analysis can incorporate those axial forces in the analysis. Since curvature (Ø) = M/EI, the secant slope of the moment-curvature diagram up to the service moment, can be used as the effective stiffness EIeff. As Figure 7 shows, the stiffness of the shear wall with HPCR is greater than that of the conventional reinforcement, even with 30% less reinforcement, because of the more efficient location of the reinforcement toward the extreme fibers.

Summary Features of HPCR systems help significantly reduce the total reinforcement quantities for

(b) M - Ø DIAGARAM WITH NET TENSION LOAD

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Figure 7. Comparison of the moment-curvature diagrams for the walls in Figure 3 with (a) no net tension load and (b) high net tension load.

concrete structures because of their high strength, large size and the ability to couple and anchor the bars efficiently and economically. Additionally, their use permits higher concentrations of HPCR to be placed at optimal locations to further increase their effectiveness. As is often the case, proposing

HPCR systems as a value-engineering alternate only provides a simplified direct substitution which often fails to exploit the full advantages of HPCR systems. A direct substitution almost invariably results in a decrease in section stiffness because the area of reinforcing is being decreased, without any compensation

that may be achieved by concentrating the reinforcing at a more efficient location. However, when integrating HPCR into the original design, the engineer can incorporate the HPCR features and maximize the advantages using appropriate design procedures and recommendations for strength and stiffness.▪

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October 2014

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he move toward structural licensure is well underway in the state of Florida. The Florida Structural Engineers Association (FSEA) will be proposing legislation to the Florida Senate and House of Representatives in 2015 to establish the SE license. Many articles have appeared in various publications making the case for structural licensure. Arguments have been offered for this additional level of accreditation due to the complexity of current building codes compared to decades past, decreasing redundancies and safety factors, the reduction in educational degree requirements in a field that has become more specialized, and the potential for loss of human life should a structure fail. Readers of this magazine mostly understand this. ASCE, CASE, NCSEA, and NCEES have all agreed that an enhanced 16-hour exam focused on structures is the best path forward. However, in arguing for change in statewide engineering licensing laws, there are other engineering groups that need to be brought into the discussion. The Florida Engineering Society (FES), an affiliate of the National Society of Professional Engineers (NSPE), is the largest group of engineers in the state, comprising all engineering disciplines. FSEA first approached FES in 2010 to educate its board of directors regarding the issue of SE licensure and the plan that FSEA had at that time for amending state law. The FES Professional Concerns Committee explored the issue further and presented a position paper to the FES board of directors in favor of SE licensure. The official FES position statement adopted by its board in 2011 identified the “need for an additional structural engineering license for the practice of structural engineering for the design of buildings that exceed the [Florida] threshold limit.” The Florida Institute of Consulting Engineers (FICE) is an affiliate of the American Council of Engineering Companies (ACEC), and its members include the largest engineering firms operating in the state. FSEA approached the FICE board of directors in 2012, but by this time ill-informed rumors had begun circulating that structural engineers were looking to create their own license. Understandably, the FICE board was reluctant to express a position without further information. The FICE Structural Committee was tasked to explore the issue and develop a position paper. Simultaneously, FSEA worked to publish educational articles in two state periodicals that reach out to all engineering disciplines – the FES Journal and the FBPE Connection. In February 2014, the FICE board of directors approved its Structural Committee’s position paper, which supported “a structural engineering (SE) license in Florida for engineers practicing structural engineering for structures above a certain threshold.” With the recent publications in statewide journals, NSPE became more aware of the growing initiative

in Florida and publically renewed its opposition to SE licensure. A letter published in the FES Journal reiterated the national organization’s long-held position that the PE license should be “the defining qualification for practice” as an engineer, and that “a PE who is not fully competent to perform structural engineering is already ethically obligated not to do so.” Some engineering groups within FES and FICE still question the need for a discipline-specific license, but to date FES and FICE have not reversed their position statements in favor of SE licensure. The Florida Board of Professional Engineers (FBPE) is the public agency that regulates engineering in the state of Florida. When FSEA approached FBPE in 2013 about establishing the SE license, FBPE created an ad-hoc committee that was “tasked with the mission of investigating, evaluating and making recommendations regarding separate licensure and/or certification of structural engineers within the state of Florida.” The committee was made up of five FBPE board members plus representatives of FSEA, ASCE-SEI, and FES/FICE. After multiple meetings and discussions, the committee came to the conclusions that the SE “license” would be needed – i.e., “certification” would not be sufficient – and that changes to the law would indeed be required. All members of the committee had input on the proposed statute language, and in June 2014 the entire FBPE endorsed the following approach. In 2015, FSEA will attempt to have the Florida Statutes amended to establish the SE license, which would be obtained after licensure as a PE. Under the FSEA proposal, the applicant for the SE license would need to have passed the 16-hour NCEES Structural exam and show four years of active structural engineering experience. The 16-hour exam would also qualify as the exam for PE licensure, which could be applied for simultaneously. However, before the 2017 PE renewal period, Florida PEs who sign an affidavit attesting that they have been practicing structural engineering for at least four years would not need to pass the 16-hour exam to apply. All buildings over a certain threshold, to be defined by FBPE, would need to be designed by a licensed SE. All structures below that threshold could be designed by a licensed PE as currently required by Florida law. At the beginning of this process, none of the board members of FSEA fully grasped what the proper path forward was to enacting SE licensure, or for that matter any legislation that would affect so many that had not been directly involved in crafting the discussion. Only by actively working with all of the stakeholders, as well as fully educating any others who may be even remotely affected by such a change, has it been possible to move forward confidently with making SE licensure a reality in Florida.▪

STRUCTURE magazine

Structural licenSure issues related to the regulation of structural engineering practice

Florida’s Move Toward Structural Licensure

By Scott D. Martin, P.E., LEED AP BD+C

Scott D. Martin, P.E., LEED AP BD+C (SMartin@walterpmoore.com), is a Past President of the Florida Structural Engineers Association (FSEA) and a member of the FICE Structural Committee. He also served on the FBPE SE Licensure Committee. For more information regarding SE licensure in Florida, visit www.flsea.com/se-licensure/ or contact FSEA at fseadirector@flsea.com.

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n late 2013, Iowa’s Buchanan County engineers teamed with academia and industry to launch the V65 Jesup South Bridge Demonstration Project with the goal of illustrating the advantages of the eSPAN140 short span steel bridge design tool to accelerate steel bridge design and construction. At the heart of the design tool, developed by the Short Span Steel Bridge Alliance’s (SSSBA), the steel industry and Steel Market Development Institute (SMDI), is the use of standard steel beams and other elements that are readily available from the steel industry. The success of the tool strongly depends on the ability of steel fabricators to turn around the conceptual designs produced by the tool with minimal work. U.S. Bridge teamed with other industry partners to complete the demonstration project and assess the value of the tool to speed the delivery of bridge elements to the jobsite.

Bridge Basics The old Jesup South Bridge is located on one of the busiest roads in Buchanan County. Originally built in 1947, the deteriorating structure had a sufficiency rating of 49, making it a prime candidate for replacement. The bridge was narrow and not built for the loads required to support today’s traffic. County engineers sought to replace the existing 22-foot-wide bridge with a modern 40-foot-wide bridge using galvanized steel rolled beams and galvanized rebar. Around the same time, Buchanan County’s County Engineer Brian P. Keierleber, P.E., heard about the development of the eSPAN140 tool and the interest by the researchers at West Virginia University, the University of Wyoming and the SSSBA in documenting the benefits of the tool. Keierleber volunteered the Jesup South Bridge as a candidate for the SSSBA’s proposed demonstration project because the demonstration project presented a unique opportunity to see how the eSPAN140 tool could streamline the steel bridge design and construction process and open the door to alternative bridge replacement options. While the project was mostly driven by Buchanan County, SSSBA sought volunteers from the bridge design and construction community to facilitate the project (see Jesup South Bridge Demonstration Project Team sidebar). As an SSSBA member, U.S. Bridge knew about the development of the eSPAN140 tool. The demonstration project provided a perfect opportunity to translate the eSPAN140 data to design and fabrication in a practical setting. All the project participants visited the site to gain a full picture of the project and discuss expectations. For U.S. Bridge, the biggest concern at the time was to clarify responsibilities for the volunteer team, since the process would be a little different than a conventional project delivery.

Technology New Jesup South Bridge designed with standardized steel beams with eSPAN140 tool.

information and updates on the impact of technology on structural engineering

Concept to Construction In September 2013, Keierleber logged into the eSPAN140 site to design the new Jesup County Bridge. He input bridge length, width and number of lanes. He wanted a bridge with a 63-foot span and two striped traffic lanes, supported by five standard girders. The eSPAN140 tool is coded to use the AASHTO LRFD bridge code and corresponding HL-93 Vehicular Loading design codes. Within minutes, he received a customized steel bridge design as a PDF file that echoed his inputs and organized the information in a commonly depicted format (a format normally found in a set of contract documents). The eSPAN140 plans indicated composite beam sections from a W40x149 (the deepest/lightest beam) to a W24x192 (the shallowest/heaviest beam) for a bay spacing of 10 feet 6 inches. These results, called a “Steel Bridge Solutions” file from eSPAN140, also included typical bridge cross-sections and roadway widths, travel lanes and shoulders, and more, as well as the design and fabrication details for standardized rolled beams with slab thickness, girder spacing, bearing elevations and stiffener positions shown. It’s worth noting here that eSPAN140 does leave off at a certain point. For instance, if the bridge engineer doesn’t select the shallowest depth or lightest weight options that eSPAN140 offers for the optimal spacing, the engineer or fabricator will need to complete a final analysis and some design tasks to calculate accurate deflection values (for camber) and any updates to the shear stud spacing. Buchanan County’s County Engineer especially liked the user-friendly appeal of the eSPAN140 tool, which facilitated price comparisons of different bridge concepts to find the most economical solution. With plans in hand for the new Jesup South Bridge, Keierleber prepared contract drawings and coordinated the design with U.S. Bridge, who would model, detail and fabricate the short span steel bridge elements. continued on next page

STRUCTURE magazine

Fabricator’s Inside Perspective on Standardized Steel Bridge Design

eSPAN140 Facilitates Speedy Concept - to - Completion By Dennis Gonano, P.E.

Dennis Gonano, P.E., is the Director of Engineering at U.S. Bridge. He can be reached at dgonano@usbridge.com.

Jesup South Bridge Demonstration Project Team

U.S. Bridge modeled, detailed and fabricated the short span steel bridge elements based on initial design details from eSPAN140.

The 3D model was used to prepare drawings and as a basis for the CNC programming.

The County’s design plans reiterated the use of composite beam/deck construction, jointless integral abutment details and steel channel members as diaphragms – all consistent with Iowa DOT standards and the details given by eSPAN140. For the bridge railing, the County proposed a new crash tested steel post and w-beam rail called the MGS Bridge Rail System. The County’s selected framing layout consisted of five lines of W36x135 spaced at 8 feet 8½ inches and a slab overhang of 2 feet 7 inches. The diaphragm channels were MC18x 42.7 and were located at each bearing and at approximately one-third points along the span. Once the designer’s criteria was fully specified, eSPAN140 provided the level of detail that U.S. Bridge needed to move immediately to the next stage – and it was pretty easy to do. The steel bridge solution details outlined in the eSPAN140 results file provided enough information to drive the finer detailing requirements and fabrication processes. In addition to the erection plans and shop drawings, the U.S. Bridge team added some construction plans including a stay-in-place (SIP) formwork layout and railing installation plan, and supplemented the construction documents with some Iowa Department of Transportation standards because they were referenced by the county engineer.

then welded with 5/16-inch fillet welds to the beams with a tight fit to the top and bottom flanges. Welding was performed using a semiautomatic procedure with E71T-1 flux core (FCAW) wire. About one month after receiving the plans from eSPAN140, U.S. Bridge was able to begin shipping elements to the galvanizer for conditioning. After an internal quality control inspection, the beams were hot-dip galvanized according to ASTM 123 and checked again for coating thickness and any camber loss. The beams were delivered to the bridge construction site and set on October 2, 2013 where it was constructed by local crews. The Jesup South Bridge opened to traffic on November 19, 2013 – just three months after Buchanan County first entered the details into eSPAN140.

High-Gear Fabrication Plans for erecting the steel framing and installing the railing were submitted in concert with the steel shop drawings. These plans were reviewed by Buchanan County and, once approved, allowed the fabricator to move into high gear, releasing the shop drawings for fabrication and bringing the steel into the fab shops. The beams were drilled via a CNC controlled drill line, saw cut to exact length and cambered for dead load in preparation for stiffener fit up and welding. Bearing stiffeners ¾-inch thick and intermediate connection stiffeners ½-inch thick were plasma cut and drilled, again via CNC equipment, and

Lessons Learned From a time perspective, eSPAN140 is a handy tool that bridge engineers can utilize to get quick answers and evaluate alternatives directly, zeroing in on feasible options from a wide range of steel superstructure types. From a fabricator’s perspective, eSPAN140 is a helpful program that facilitates good dialogue with a client early on about steel sections, depths of structure, lifting weights, standard details, fabricating processes, corrosions protection, etc. – all the things that make steel a great bridge building material. The detailed design provides a good foundation for a fabricator to know, more or less, how a steel bridge option is going to solve a problem and what the owner can expect in terms of fabricated and installed costs. If it’s a ‘GO’, then U.S. Bridge is quickly on the way to producing bridge members for construction. The Jesup Bridge project is yet another example of the innovativeness of local infrastructure managers across the country. Undaunted by challenges of cost or material, they continue to seek out ways to plan, design and build modern and safe improvements, making the most of limited resources and their own workforce.

STRUCTURE magazine

October 2014

Donating Companies • U.S. Bridge: Bridge Superstructure Fabrication, Railing Materials and Fabrication, Steel Detailing • Nucor-Yamato Steel: Rolled Beams/ Girders • Skyline Steel: H-Piles for the Integral Abutment System • AZZ Galvanizing: Galvanizing • Nucor Fastener/Ziegler Bolt & Part Co.: Superstructure and Rail Fasteners • St. Louis Screw and Bolt: Shear Studs • BlueArc Stud Welding: Stud Welding • D-Mac Industries: Stay-in-Place Forms • Gerdau: Memphis Reinforcing Steel: Rebar • Buchanan County, Iowa: Installation/Demolition University Partners • West Virginia University: eSPAN140 Development, Design Coordination and Research • University of Wyoming: eSPAN140 Development, Design Coordination and Research • Iowa State University: Research The goal of the eSPAN140, according to SMDI, is to provide bridge engineers with another tool in their toolbox to develop costeffective solutions for their bridge repair and replacement challenges. While the materials for the Jesup South Bridge were donated, case studies for similar short span bridges have documented a 25% cost advantage when compared to concrete alternatives. Please see www.shortspansteelbridges.org for more information. View a time-lapsed video of the Jesup South Bridge construction process on the Short Span Steel Bridge Alliance website at http:// blog.shortspansteelbridges.org/2013/09/06/ demonstration-bridge-live-webcam/.▪ About the Short Span Steel Bridge Alliance The Short Span Steel Bridge Alliance (SSSBA) is a group of leaders in the bridge and buried soil steel structure industry who have joined together to provide educational information and design tools for the costeffective design and construction of short span steel bridges in installations up to 140 feet in length. For more information, visit www.shortspansteelbridges.org.

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Tappan Zee Hudson River Crossing The New NY Bridge Project By Michael D. LaViolette, P.E.

Figure 1. New NY Bridge rendering.

he Tappan Zee Hudson River Crossing (or “New NY Bridge”) is perhaps the largest and most challenging bridge project currently under construction in the US. The project includes two parallel, 3.1 mile-long bridges crossing the Hudson River between Rockland and Westchester Counties, approximately 25 miles north of New York City. Each of the two bridges consists of a 1,200-foot cable-stayed navigation span with common foundations and diverging towers, along with a series of 350-foot continuous, steel girder spans supported on seismic isolation bearings. Construction of the bridges is currently ongoing and is scheduled for completion in 2018 by Tappan Zee Constructors, a design-build LLC composed of Fluor Enterprises, American Bridge Company, Granite Construction Northeast and Traylor Bros. HDR is serving as the lead designer for the project, with significant contributions from Buckland & Taylor, URS, GZA and a diverse array of nearly 40 sub-consultants. The bridge is owned by the New York State Thruway Authority and represents their first design-build project. The project requirements dictated that the primary structural components of the crossing be designed and constructed to provide a 100-year service life before major maintenance will be required. These components include the foundations, substructures, superstructures and bridge decks. The design of bridge systems and components using materials with proven long-term performance characteristics was critical in meeting this requirement. A sophisticated probabilistic approach to the service life was implemented in the design phase to assure a reasonable certainty of satisfying the desired service life criteria. In addition to the demanding design and construction challenges – poor foundation soils, large variation in geotechnical design parameters, moderate seismicity, and ice loading – the bridge is designed to support a future third parallel bridge to carry dual-track railway traffic. The future construction of a commuter or light rail bridge in the narrow gap between the two highway bridges, and without the need for additional foundation construction in the water, required that all foundations and the main span towers be analyzed, and conceptual details developed, to ensure the feasibility of this future load condition. Significant ongoing challenges STRUCTURE magazine

facing the design-build team include the very aggressive schedule and the need to maintain the full traffic capacity of the existing bridge throughout the project. The iconic main span structure forms the centerpiece of the new crossing, comprising twin cable-stayed bridges, with 1,200-foot main spans and 515-foot side spans. Each deck will carry four traffic lanes and have wide inner and outer shoulders that provide operational redundancy and flexibility. The main span decks are carried by a semi-fan, parallel-strand, stay cable system anchored to distinctive, outward leaning, V-shaped reinforced concrete towers. The inclined legs of each tower are straight, open box sections connected by single, below-deck cross beams. The future rail transit deck will be supported by a future cable anchorage unit and cross beam that will connect the inner legs of the two towers. The bridge foundations are designed to carry the future rail structure without modification. Each superstructure consists of stiffened steel edge girders and transverse floor beams supporting high performance precast concrete deck panels made composite with the steel using cast-in-place infill joints. To minimize deck width and weight, the stay cables are eccentrically anchored outside of the edge girders.

Substructure Highly variable foundation conditions at the site represented one of the largest risks to the design-build team. Approximately onethird of the piers on the crossing are underlain by alluvial deposits of normally consolidated organic clay up to 180 feet deep, above lightly over-consolidated glacial lake deposits of varved silt and clay that extend up to 750 feet deep. Due to the extreme depth of these deposits, end-bearing piles were seen as impractical and, consequently, friction foundations consisting of 48-inch diameter, open-end pipe piles extending to 330 feet below the Hudson River were selected. A cast-in-place concrete plug is used to transfer foundation loads to the piles and provide an additional measure of redundant corrosion protection. continued on next page

October 2014

Figure 2. Precast pile tub buckling analysis model (deformations exaggerated).

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The remaining foundations, from Pier 19 to the Westchester abutment, are supported primarily on a combination of 48-inch and 72-inch piles driven to end bearing, with a limited use of 36-inch piles and drilled shafts near the shoreline. Piles are currently being preassembled into 160- and 180-foot subassemblies and driven with both vibratory and hydraulic hammers in order to minimize noise and environmental impacts to surrounding property owners and endangered aquatic species. While the main span tower foundation utilized a precast concrete soffit system, the approach span foundations consist primarily of precast concrete tub-style footings that will be filled with cast-in-place concrete once the tub is placed over the driven piles. The heavily reinforced precast tubs are made composite with the infill concrete through an extensive network of embedded reinforcing and roughened interior surfaces. Extensive threedimensional finite element analyses using SAP and Xtract were performed to investigate lifting and shipping stresses, temporary support conditions, buoyancy and wave action, staged concrete placement and time dependent effects including differential shrinkage. An exaggerated buckling model of the precast pile tub footing is shown in Figure 2.

Figure 3. Solid model of precast pier capbeam tub.

Precast concrete capbeam shells – up to 92 feet long, 10.5 feet wide, and 13 feet deep and weighing 280 tons each – are used for 59 of the approach piers. These tub-shaped precast elements minimize over-water formwork and provide a safe work space for tying of reinforcement (Figure 3). The design features of the capbeam shells were chosen to minimize pick weights, standardize details and to provide fully-composite behavior with the infill concrete. A detailed time-dependent analysis of the staged construction sequence was performed to evaluate the effects of differential creep, shrinkage and locked-in stresses between the precast shell and the cast-in-place infill concrete. Prestressing was provided in the precast pier cap shells to eliminate concrete tension during the second stage cast-in-place infill concrete placement, and to minimize cracking due to long-term differential shrinkage.

Superstructure A girder-substringer framing system was chosen for the nominal 350-foot approach spans, most of which are arranged in five-span continuous units. This type of system typically provides an estimated cost savings of 10 to 20 percent compared to a multi-girder system for spans in this range. In addition, this relatively light structural system reduces loads on the foundations, a criteria that was particularly important for the western approach spans which are supported on long friction piles. The use of large-scale prefabrication is a critical part of the bridge construction. The Left Coast Lifter, one of the largest floating cranes in North America, with an 1,800 ton lifting capacity, will be used to install pre-assembled two or three girder groups, one full span at a time, which eliminates nearly all temporary falsework in the river, improves worker safety, and saves time and construction costs for operations on the water. Hybrid girders, with girder flange plates consisting of a mixture of Grade 50W and

STRUCTURE magazine

October 2014

HPS 70W steel, are used to reduce girder weight and maintain high fracture toughness in support of the 100-year service life objective, with due consideration of the limited availability of this material. All thickness changes for the top flange plates are accomplished by varying the web depth and recessing the flange plate changes into the web to accommodate the use of precast deck panels. Girder web depths are transitioned only at the bolted field splice locations. Precast concrete deck panels, approximately 12 feet long and varying from 42 feet–3 inches to 46 feet–9 inches in width, utilize a single longitudinal closure pour between panels. The panels consist of high-performance concrete with 5 ksi compressive strength and mild reinforcement (no post-tensioning). In order to eliminate the need for form stripping, the transverse joints feature a permanent, integral bottom form ledge. The joint utilizes overlapping hairpin reinforcement projecting from each adjacent panel and a number of transverse reinforcing bars that are inserted through the hairpins to provide a continuous mechanical connection between panels. To validate the reinforcement-only option for the cast-in-place deck joints, a SAP2000 finite element model was used to evaluate the service-level stress condition of the bridge deck for a fully continuous superstructure. The SAP2000 analysis included staged construction, time-dependent effects and non-linear post-cracking behavior of the reinforced concrete deck and joints.

Structural Additions In consideration of the extensive public involvement and visual quality processes for the New NY Bridge, the project requirements included the incorporation of a shared use path (SUP) for pedestrians and bicycles as part of the permanent westbound bridge configuration. In addition, one of the intermediate construction stages includes a period

of time when westbound vehicular traffic is allowed to utilize the future SUP portion of the cross-section as a travel lane. Additional special structure details include: Belvederes – the westbound bridge incorporates six 12- x 60-foot belvedere structures cantilevered from the north face of the exterior girders. The belvedere structures are supported through a cantilever connection from the exterior girder web and rigidly braced to the interior girder to eliminate torsional girder deformations. Permanent Crossovers – will be provided between the eastbound and westbound structures at three locations along the crossing to facilitate public evacuation and turnaround capabilities in the event of an extended delay from a traffic obstruction. These simple-span structures are supported on brackets attached to the interior girders of the opposing bridges.

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Perhaps the greatest benefit of the designbuild method is that it allowed the engineers to interact directly with the contractor throughout the design phase. The innovations resulting from this collaboration not only met all the project requirements and design criteria, but did so by incorporating the contractors’ means and methods to generate cost-savings and provide the greatest schedule benefit. The New NY Bridge project is an outstanding example of using the design-build contracting method to deliver an innovative and cost-effective project. The Tappan Zee Constructors team worked together during the design phase to validate and compare various structural systems, ultimately developing a cost-effective design solution that is quickly being realized as a new, iconic bridge for the New York area.▪ All photos courtesy New York State Thruway Authority. Michael D. LaViolette, P.E., is a Principal Project Manager with HDR Engineering in Omaha, NE. He recently served as the Deputy Design Manager for all structures design on the Tappan Zee Bridge. In addition, he currently serves as Chairman of TRB Committee AFH40 – Construction of Bridges and Structures. For further information on the project, Michael can be contacted at mike.laviolette@hdrinc.com.

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October 2014

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Conclusion

Building the First Movable Bridge in Malaysia By Peter Davis

Figure 1. Rendering of the final bridge design concept.

alaysia is a country which became independent from the British is 1957 and has been developing its economy and infrastructure ever since. Malaysia is the 3rd largest economy in Southeast Asia and 29th worldwide based upon exports of natural and agricultural resources and petroleum. It has a large manufacturing sector; however, one of the economic goals is to increase tourism. Kuala Terengganu is a city on the eastern side of the Malay Peninsula approximately 500 kilometers (311 miles) Northeast of Kuala Lumpur. This side of the peninsula is less developed and presents opportunity for tourism based upon the beaches and interior habitat. This city of 400,000 is at the mouth of the Terengganu river delta. In order to facilitate economic and tourism growth in the area, a bridge is planned to connect the North and South districts of the city. This bridge will be 672 meters (2200 feet) long with a movable span crossing the navigation channel. The proposed bridge has pre-stressed concrete approach spans and a twin leaf bascule span over the 50 meter (164-foot) navigation channel. While bridges in the United States are used strictly for

transportation, this structure will provide mobility across the river and will also serve as a tourist attraction, allowing viewing of the Monsoon Cup races held locally as a major sporting event. The structure is to serve as an icon of the area and will fit the context of the local architecture.

The Bridge This 672 meter (2200 foot) long bridge carries 4 travel lanes, sidewalks and a median barrier for a width of 23 meters (75.5 feet) (Figure 2). The design speed is 60 KPH (35 MPH) and has a maximum 5% grade. The bridge will have 9 spans plus embankment approaches. Spans 1 and 9 (Figure 3) are designed using concrete beams to provide a minimum under-clearance of 2.2 meters (87 inches) to allow cars to be parked. This parking area will be utilized by the public to both enjoy the waterway as well as access to the amenities at the bridge. Spans 2 thru 4 are pre-stressed concrete box sections of 53 meters (173.9 feet) and 50.5 meters (165.7 feet) in length. These box sections are supported on drilled shafts and cast-in-place piers (Figure 4). For this structure, there is a high degree of consideration for the aesthetic characteristic to provide a modern image, as well as retain local architectural characteristics. Movable Span The movable span provides a 50 meter (164-foot) navigation channel with infinite vertical clearance. The clearance under the bridge when closed is 12 meters (39.4 feet). Contractors in Southeast Asia do not have experience with movable bridge construction. For this reason, it was important to simplify the construction as much as possible while maintaining the required functionality. The bascule leaves will be constructed from steel with a concrete roadway surface. The leaf design utilizes a three girder system for redundancy. Each leaf is 44.9 meters (147 feet) long and is supported by 6 trunnion bearings. The leaves weigh approximately 1600 tonnes each. The

Figure 2. Typical span cross section.

STRUCTURE magazine

October 2014

Figure 3. Approach span configuration.

trunnions are supported on towers within the enclosed bascule piers. These piers are supported by thirty 1830 mm (72-inch) diameter drilled shafts. Since the alignment of the leaves and machinery is very critical, a decision was made to use hydraulic cylinders to operate the spans. The alignment requirement for these cylinders is more forgiving than for traditional mechanical gearing. Three cylinders per leaf are used allowing for redundancy such that, if a cylinder fails, the bridge will remain operational. Each cylinder has a bore of 458 mm (18 inches) and a stroke of 3390 mm (133.5 inches). When the two leaves are closed, they are locked together with four “lock bars”. These lock bars are high strength steel 254 mm wide and 382 mm high (10- x 15-inch). The bars are driven and pulled using linear actuators. The bridge is controlled by a conventional relay-based system with a computer operator interface. This approach was taken so that a qualified electrician can repair the control system to maintain operation even if the computer-based system fails. The computer system provides both the operator interface as well as a monitoring system for the hydraulic power supplies and the control

system function. A programmable decorative lighting system will be installed to highlight both the fixed and movable spans. Towers The signature features of the bridge are the towers and the public space created by the connecting structure (Sky Bridge). The towers are 72.5 meters (238 feet) tall not including a 16.6 meters (54.5-foot) antennae. The towers replicate the minarets of mosques and provide a Malaysian version of the Tower Bridge in London. The Sky Bridge public space is 1118 square meters (12,000 square feet) between each pair of towers. Elevators are provided to access the Sky Bridge space as well as stairs for emergency evacuation. The Sky Bridge spaces are two stories, allowing food preparation and HVAC equipment to be located below the public space. Both the North and South approach span roadways have been widened to provide a drop off and loading lane for visitors to the bridge.

Construction The construction contract for the bridge was awarded in August 2014, with expected completion in 2017. Since the local contractors do not have a history of movable construction, the design team prepared shop drawing level design documents as well as a detailed construction sequencing. The construction sequence will include working sessions with the contractor such that they become aware of the specific challenges of installing, aligning and balancing the bascule leaves. In order for the bascule leaves to be properly aligned, key checks will be performed during their erection. These checks include monitoring deck and counterweight concrete weight, and making adjustments during pouring. In addition, the pouring of the approach span deck will be one of the last items to be constructed so that a smooth transition between the spans is achieved. It is a rare opportunity to participate in such an elegant project.▪ Peter Davis (pete.davis@hdrinc.com), a licensed mechanical engineer, has 39 years of experience in the inspection, design and construction of heavy infrastructure including locks, dams and movable bridges.

Figure 4. Box sections supported by drilled shafts and cast-in-place piers.

STRUCTURE magazine

October 2014

Overcoming Challenges Erecting a Long Single Span Curved Steel Girder Bridge By Michael H. Marks, P.E.

Figure 1. Completed structure.

n 2009, the New Jersey Turnpike Authority began work on a 35 mile widening from Exit 8A to Exit 6 consisting of extending the dualization of the roadway for car and truck lanes. The finished roadway will consist of six (6) lanes in each direction. Five (5) interchanges were reconstructed and/or reconfigured, along with the replacement or widening of all bridges along the route. A total of 23 contracts were let for the project with an approximate cost of $2.5 billion.

• Due to the large span length, radius and depth of girder, the stability of the girders both during the pick and at each stage of the erection had to be carefully analyzed and maintained. • The bridge was constructed above a heavily traveled and active roadway, resulting in very short work windows and lane closure times.

Bridge Description As part of the reconstruction of Interchange 8 in East Windsor, Mercer County, New Jersey, the new Ramp TW/WT needed to cross Route 33. To accomplish this, a new single span bridge was required. The bridge consists of a simple span superstructure with a cross section of eleven (11) curved steel welded girders spaced at 8 feet 3 inches, supporting a cast in place 8.75-inch deck. Each girder has a web thickness of ⅞-inch and depth of 129 inches. Flange size varies from 26 x 1½ inches to 28 x 3 inches. The span length of the structure is approximately 257 feet 8 inches along its baseline between Girders 5 and 6. The out-to-out width of the bridge deck is 87 feet 10 inches, consisting of an approximate 36-foot wide roadway for eastbound traffic and a 47-foot 6-inch wide roadway for the westbound lanes. The horizontal radii of the girders vary from approximately 1763 feet to 1845 feet, with the abutment bearing lines being radial. Girders 9 through 11 on the outside of the curve have significantly larger flanges than Girders 1 through 8 to accommodate the increased load due to the curvature. Between the girders, cross frames composed of steel angles are spaced at approximately 24 feet (Figures 1 and 3).

Steel Erection Issues EIC Group LLC (EIC), Fairfield, NJ, was retained by the steel erector subcontractor, Archer Steel Construction (Archer), Manalapan, NJ, to develop the erection plans and procedures for the installation of the steel girders. The erection of this bridge, thought to be the longest single span curved steel bridge east of the Mississippi, presented several engineering and construction challenges: • The curved girders had to be field spliced requiring the webs to be as plumb as possible for field fit. This necessitated the need for very exact center of gravity calculations and pick point determination. STRUCTURE magazine

Figure 2. Erecting Girder Pair A/B.

October 2014

Initial Erection Plan The steel girders were composed of three (3) segments (A, B and C) spliced together to make up the overall girder length (Figure 3). This long length made the erection of the completely assembled beam as a single lift, either alone or in pairs, not feasible both from a weight and stability point of view. Therefore, the structure had to be constructed by erecting individual segments. Based on engineering and construction issues over the roadway, it was decided to erect the structure by first erecting one end segment and supporting it on the abutment and towers. Next, the other segments would be assembled on the ground and erected as a unit. This unit would then be spliced in the air to the first erected segment and released. Figure 3. Framing plan and jack post locations. The southern segment (segment C), approximately 80 feet long, was the only portion of the structure not directly above the Typically, for a curved steel girder bridge, it is desirable to erect from active roadway. Therefore, a tower bent was proposed at the location the outside of the curve towards the center. As the curved girder is of the B/C splice and then the C segments erected and supported erected, it tends to rotate towards the outside. The result of this rotaby the South Abutment and the tower bent. It was planned that all tion is that the web will be slightly out of plumb, but leaning away eleven (11) towers would be set up, one for each girder line, followed from the center of curvature and next inner girder to be erected. This by the erection of all C segments. To satisfy stability requirements, outward lean makes it easier for the erector to connect to the cross the first 10 segments would be ground assembled and then erected frames of the next inner girder because the web is facing “up”. After as pairs. The last segment would be lifted as a single and connected the inner girder is connected to the crossframes, it can then be lowered to the cross frames from the previously erected pair. into place. If the sequence were to go from inside to outside of the After the C segments were complete, the A/B segments would be radius, then the web would be facing “down” due to the girder roll, ground assembled and then erected as pairs. They would then be air and would make it more difficult and time consuming to connect to spliced to the C segments and lowered onto the North Abutment. the next girder. This is especially critical if there is a traffic shutdown Again, the final girder would be erected as a single. and time is of the essence. continued on next page ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

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Girders 1-4

Figure 4. Jack Post A beneath Girder Line 4 and tower for support of Girder Line 5.

However, for single span curved bridges, especially those as long as this structure, this sequence is difficult to achieve. The abutments at each end of the span are constructed radially, thus reducing the opening the erector has to work with when setting each successive girder towards the center. This “pinching” effect will hinder the erector’s ability to swing the girder into place. Because of this and assembly area limitations, Archer needed to erect outward and therefore the roll of the girders had to be precisely controlled. It was planned to set all eleven girders on the towers to control the outward roll so the cross frame connections could be made with minimal effort. Once all girders were erected and plumbed, then all towers would be lowered simultaneously and the structure allowed to assume its deflected position. The pieces to be lifted ranged in weight from 56,000 pounds for the single C segments to 380,000 pounds for the paired A/B segments. Manitowoc 999 and the American 2250 crawler cranes with capacities of over 200,000 pounds were to be used for the erection. The rigging consisted of a 60-foot segmented pipe spreader beam designed by EIC specifically for Archer Steel, 16-foot pipe spreader cross beams, and wire rope slings with conventional beam clamps. The towers, also specifically designed by EIC for Archer, are 4-legged prefabricated telescoping pipes with steel grillage beams on top. Jacks were specified for elevation control and height adjustment.

Erection Erection was started in December of 2012. The first four towers were set up beneath segment C for Girders 1 to 4 at their designated locations. Due to availability issues of the remaining towers, it was decided to erect the first four girders in their entirety (all segments) and when complete, the remaining towers would be set up and the last 7 girder lines would be constructed. STRUCTURE magazine

The C segments of Girders 1 and 2 were then lifted in a pair by the 2250 crane using a pipe spreader and cross beam rigging arrangement, and then walked into position on the south abutment and towers. This was repeated for Girders 3 and 4. Next, during a complete road closure, the corresponding A/B spliced pairs were lifted and walked using both crawler cranes from the assembly area into an intermediary position in the closed roadway. They were set down on temporary mats while the cranes rotated their tracks into a new position. Once aligned properly, the cranes picked the piece again and crawled forward, air spliced the piece to the C segments and set on the abutment (Figure 2, page 32). This was repeated for the remaining A/B pair. Archer plumbed the girder webs carefully and then connected all cross frames and fully tightened the bolts. At this point, many of the remaining towers were still unavailable and thus could not be set up as planned. Due to time restrictions, it was decided to lower the towers that were holding G1 to G4. It was expected that the girders would rotate and that there may be difficulty connecting the next outer girder, as now the web would be facing down. To prevent this problem, EIC developed a solution that would utilize supplemental jacking posts under the erected girders while the towers were moved into the new positions. The proposed solution was to determine the downward deflection that would occur due to the girder roll and then install jacking posts at appropriate locations to jack the 4-girder assembly back up into web vertical position. Then the next 4 girders would be installed and connected to the first 4 girders. The towers would then be lowered again and moved. However, with eight girders in place, it was anticipated that the roll would not be significant enough to affect the erection of the last 3 girders. EIC in conjunction with BSDI of Coopersburg, PA performed a 3D finite element analysis of the four and eight girder systems. It was determined that after the towers were removed, the outer girder would drop a maximum of approximately 8.4 inches at midspan with almost 9 inches of lateral outward movement of the top flange. To jack the beams to vertical and remove the deflection, it would have been desirable to place the jacking post at the midspan as this would have resulted in the minimum jacking force. However, due to the active roadway, this was not possible. As a result, EIC decided to utilize two posts, one at 63 feet from the South abutment (Location A) and the other at 95 feet from the South Abutment (Location B) under G4 only. Due to jack stroke limitations, the two posts would work together to allow one jack to be de-pressurized while the other jack was raised to continue jacking. EIC’s analysis revealed that a force of approximately 200 kips would be required at Location A in order to raise the four girders and achieve a plumb web position. For the jacking posts, Acrow Shoring Superprops were utilized supported on timber foundations (Figure 3). Upon completion of the analysis, the towers were lowered allowing the four girder system to deflect. Measurements revealed deflections and girder roll to be almost exactly as predicted by the 3D model. Next, the jack at Location A was pressurized to lift the girders back to a web plumb position. The load required was also very close to predicted, approximately 200 kips. Also, as predicted by the model, jacking brought the girders fully back to the pre-release position and completely eliminated the girder roll. While the jacking was occurring at the Superprop, towers were moved and set up under the remaining seven girder lines. An additional three towers became available, so no further intermediate lowering was required. After the remaining girders were erected in similar fashion to the first four, all towers and the Acrow Superprop were

October 2014

Figure 5. Erected Girder Lines 1-4 with jack posts in place.

lowered simultaneously to allow the fully assembled bridge to deflect downward into its steel dead load only position (Figures 3, 4 and 5).

Conclusion The erection of single span curved bridges, especially with spans as long as Ramp TW/WT, requires careful planning and analysis to accommodate the large deflections, girder roll, and erection geometry restrictions. However, as typical in most construction projects, sometimes site constraints or issues with material availability require fast, economical and innovative solutions during construction. By performing a rapid and detailed 3D analysis of the partially constructed structure, the Archer/EIC team was able to evaluate the bridge behavior and anticipate response in an unconventional supported position in order to accommodate the contractor’s material availability. The bridge erection was completed within the allotted timeframe with no impact on the overall project schedule.▪

Michael H. Marks, P.E., is founder and principal of EIC Group LLC, a specialty bridge engineering firm based in Northern New Jersey. He may be reached at mmarks@eicgroupllc.com.

Project Team Owner: The New Jersey Turnpike Authority Engineer of Record: Gannett Fleming Inc, Mount Laurel, NJ General Contractor: Ferreira/Crisdel Joint Venture, Branchburg, NJ Steel Erector: Archer Steel Construction, Manalapan, NJ Erection/Construction Engineer: EIC Group LLC, Fairfield, NJ Steel Fabricator: High Steel Structures, Lancaster, PA Jacking Post Supplier: Acrow Corporation of America, Parsippany, NJ

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Helical Piles stamped into true spiral shape; Penetrates loadbearing strata

Building Blocks updates and information on structural materials

ood frame construction utilizing traditional and engineered wood products is the predominant method of building homes and apartments in the United States. Increasingly, wood framing is also being used in commercial and industrial buildings due to its economy and architectural flexibility. Wood frame buildings are economical to build in a wide range of climate zones. Wood framing is readily available and adaptable to traditional, contemporary and the most futuristic building styles. History has demonstrated the inherent strength and durability of wood frame buildings. The purpose of this article is to summarize the various traditional and engineered wood products that are available throughout North America, and to provide information on how designers can use wood products to build structures that are both sustainable and efficient. It should be noted that, although the authors tried to provide practical information regarding typical structural sizes, designers should verify with local suppliers regarding availability. Solid Sawn Lumber is a manufactured product derived from a log through sawing and surfacing. Structural and framing lumber is readily available in rafters, joists and studs from 2x4 to 2x12 and sometimes 2x14 nominal. Heavy timbers for beams and columns of 4x, 6x, 8x and even up to 20x are available for Western species such as Douglas Fir. With Southern Pine, 2x size is typical and can be used to create built up beams of 2 to 3 members for headers, and beams with 6x6 size for columns. Standard lengths are 8 to 20 feet in two-foot increments, although some suppliers may have longer lengths. Engineered designs that compute the required sizes of members are based on the standard dressed sizes and not the nominal sizes. All solid sawn lumber used for load-bearing purposes, including end-jointed structural lumber, are identified by a grade mark of a lumber grading/inspection agency

accredited by the American Lumber Standards Committee according to the Softwood Lumber Standard PS20. Structural lumber is either visually or mechanically graded on the basis of its strength; each grade combination has an assigned design value. Mechanically graded lumber is typically used for pre-engineered framing systems such as roof and floor trusses. General classifications include: dimensional lumber (2x, 3x and 4x) grades and timber grades or classifications known as “Dimension,” “Beams and Stringers,” “Posts and Timbers,” and “Decking,” with design values assigned to each grade. Standard grades for each product class should be specified after considering all grades appropriate for the intended use and strength requirements. For structural applications, include the required reference design values along with the grade that represents those design values. Also, specify desired moisture content (percent) such as GREEN or DRY based on requirements for the product, grade and intended use.

The ABC’s of Traditional and Engineered Wood Products By Michelle Kam-Biron, P.E., S.E., SECB and Lori Koch, E.I.T.

Michelle Kam-Biron, P.E., S.E., SECB, is Director of the national education program for the American Wood Council, which provides building industry professionals with continuing educational resources on ICC codes and AWC standards. She is also President-Elect of the Structural Engineers Association of Southern California. She can be reached at MKamBiron@awc.org. Lori Koch, E.I.T., serves as a Project Engineer for the American Wood Council. Lori has presented on various topics ranging from use of general engineering properties of wood, Engineered Wood Products (EWPs), Cross-Laminated Timber (CLT), and green building codes. She can be reached at lkoch@awc.org.

Glulam beams used in roof system.

36 October 2014

Lumber grade stamps.

Glued Laminated Timber (glulam) is made up of wood laminations, or “lams,” that are bonded together with adhesives. The grain of all laminations runs parallel with the length of the member. Individual lams typically are 13/8 inches thick for Southern Pine and 1½ inches thick for Western species, although other thicknesses may also be used. Glulam is available in both stock and custom sizes. Stock beams are manufactured in commonly used dimensions and widths cut to length when the beam is ordered from a distributor or dealer. Typical stock beam widths used in residential construction include 31/8, 3½, 51/8, 5½ and 6¾ inches. For non-residential applications, where

Example of glulam with camber.

Unbalanced and balanced glulam layups.

Example of glulam grade stamp.

Glulams need to be manufactured and identified as required in ANSI/AITC A190.1 Structural Glued Laminated Timber and ASTM D 3737. Glulam beams will have a trademark that signifies it was manufactured in conformance with these provisions. The trademark may also include: structural use, mill number, structural grade designation, and appearance grade. Prefabricated Wood I-Joists are “I” shaped engineered wood structural members that are prefabricated using sawn or structural composite lumber flanges and OSB or plywood webs, bonded together with exterior type adhesives. Typical I-joists for residential use are available in 9½, 117/8, 14 and 16-inch depths. For I-joists over 22 inches in depth, the design should consider the possible requirement of sprinklers in concealed spaces. Most manufacturers supply I-joists to distributors in lengths up to 60 feet. These are frequently cut to lengths of 16 to 36 feet. Typical applications are as rafters or joists. Similar to lumber, these framing members can be cut to any length on the jobsite to meet various framing challenges. Assemblies using prefabricated wood I-joists need to meet the provisions of ASTM D5055 Standard Specification for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists, the governing building code, and any additional requirements as set forth in the manufacturer’s code evaluation report. I-joists need to be identified with the manufacturer’s name and the quality assurance agency’s name. Structural Composite Lumber is a family of engineered wood products created by layering dried and graded wood veneers or strands with moisture resistant adhesive into blocks of material known as billets, which are subsequently resawn into specified sizes. Common types of SCL include laminated veneer lumber (LVL) and parallel strand lumber (PSL). LVL is produced by bonding thin wood veneers, with the grain of the veneers parallel

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October 2014

to the long direction. LVLs are available in 1¾-inch widths x 5½- to 24-inch depths and up to 60-foot lengths. Up to 4 LVLs may be connected together to create a larger beam or header.

Parallel Strand Lumber (PSL) and Laminated Veneer Lumber (LVL).

PSL is manufactured from veneer clipped into long strands laid in a parallel formation and are typically used as beams, headers and columns. PSLs are available in 3½- to 7-inch widths x 9¼- to 18-inch depths, and up to 60 foot lengths. Custom depths, achieved through secondary lamination, are available up to 54 inches. Similar to LVL, 2 to 3 PSLs can be connected together to create a larger beam. Single members or assemblies using structural composite lumber (SCL) need to meet the provisions of ASTM D5456 Standard Specification for Evaluation of Structural Composite Lumber Products and any additional requirements as set forth by governing

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long spans, unusually heavy loads, or other circumstances control design, custom members are typically specified. Common custom shapes include straight beams, curved beams, pitched and curved beams, radial arches and tudor arches. Members can be manufactured to any length, but transportation constraints must be considered for longer members. Glulam may be manufactured as unbalanced or balanced layups. In unbalanced beams, the quality of lumber used on the tension side of the beam is higher than the lumber used on the corresponding compression side, allowing a more efficient use of timber resources. Balanced members are symmetrical in lumber quality about the mid-height of the beam. Glulam is available in a range of different appearances, but having the same structural characteristics for given strength grades. Glulam appearance classifications are: Framing, Industrial, Architectural (stock beams are often supplied with this appearance so they may be exposed to view in the finished structure) and Premium (available only as a custom order where finish appearance is of primary importance). Camber is a curvature built into a fabricated member which opposes the direction and magnitude of the calculated deflection that occurs under gravity loads. The glulam industry recommends the camber for roof beams be 1½ times the calculated dead load deflection and for floor beams 1.0 times the calculated dead load. Camber is specified as either “inches of camber” or as a radius of curvature. Stock beams are typically supplied with a relatively flat camber radius of 3500 feet or zero camber.

Table 1. Design references and product standards for various wood products.

Framing Member

Design Reference Product Standard

Sawn lumber

NDS

USDOC PS20

Structural Glued Laminated Timber

NDS

ANSI A190.1 & ASTM D3737

Prefabricated Wood I-Joists

NDS and ER

ASTM D5055

Structural Composite Lumber

NDS and ER

ASTM D5456

Wood Structural Panels

NDS and ER

USDOC PS1 & PS2

Cross Laminated Timber

ANSI/APA PRG 320

RINE ENG MA I

ETY OF NAV A CI O

RCHITECTS LA

• THE ERS S NE

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building codes. SCL needs to be identified with the manufacturer’s name and the quality assurance agency’s name. Wood Structural Panels are wood-based panel products bonded with a waterproof adhesive. Included under this designation are plywood and oriented strand board (OSB). Wall and roof sheathing are manufactured in 3/8, 7/16, 15/32, ½, 19/32, 5/8, 23/32, and ¾-inch thicknesses, and floor sheathing is typically 19/32, 5/8, 23/32, ¾, 1, and 11/8-inch thick. Plywood is a wood structural panel comprised of plies of wood veneer arranged in cross-aligned layers and bonded with an adhesive that cures on application of heat and pressure. Most plywood manufacturers produce 4- x 8-foot panels. A few western mills have lathes and presses that can produce panels of 4 x 10, 5 x 10, 4 x 12 and 5 x 12 feet and even fewer that produce 10- and 12-foot panels. Larger panels can be produced by joining two panels together with structural scarf or finger joints. Oriented strand board (OSB) is a wood structural panel comprised of thin rectangular wood strands arranged in cross-aligned layers with surface layers, normally arranged in the long panel direction, and bonded with waterproof adhesive. OSB panels are typically 4 x 8 feet in size. Because OSB is typically manufactured in large sizes, many manufacturers can custom-make panels in almost any size e rat bo nce a l l e co peri p ex velo de end att rn lea are sh eet m n joi

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by simply altering the cutting pattern. Most OSB manufacturers make oversized panels up to 8 x 24 feet, which are typically used for panelized roof systems or modular floors. Both panels are produced in two bond classifications – Exterior and Exposure 1. Exterior panels have bonds capable of withstanding repeated wetting and drying cycles or longterm exposure to weather or other conditions of similar severity. Exposure 1 panels are suitable for uses not involving long-term exposure to weather. Panels classified as Exposure 1 are intended to resist the effects of moisture due to construction delays, or other conditions of similar severity.

solid-sawn lumber or structural composite lumber where the adjacent layers are cross-oriented and bonded with structural adhesive to form a solid wood element. CLT is a flexible building system suitable for use in all assembly types (e.g., walls, floors and roofs). Panels are prefabricated based on the project design requirements and arrive at the job site with windows and doors pre-cut. Although size varies by manufacturer, they can be as large as 54.1 x 9.7 x 1.6 feet and include 3, 5, 7, or more layers. Cross-laminated timbers are manufactured and identified as required in ANSI/APA PRG 320-2011 including the manufacturer’s name and the quality assurance agency’s name. Table 1 shows which framing member types are covered in the National Design Specification® (NDS®) for Wood Construction in addition to those covered by national evaluation reports (NER) – also called evaluation service reports. Evaluation reports are developed for proprietary products and provide designers and code officials with the appropriate information to design the framing member per the NDS. Design values for sawn lumber and glulam can be found in the NDS Supplement: Design Values for Wood Construction. Design values for wood I-joists and SCL are provided by the product’s manufacturer. Wood structural panel design data is provided in the NDS, and capacities for shear walls and diaphragms using WSPs is provided in the Special Design Provisions for Wind and Seismic (SDPWS). Design capacities for CLT are provided by the manufacturer.

Environmental Product Declarations

Wood structural panel grade stamps.

The panels need to meet the provisions of U.S. Department of Commerce Voluntary Product Standard 1 (PS1) Structural Plywood, U.S. Department of Commerce Voluntary Product Standard 2 (PS2) Performance Standard for Wood-Based Structural-Use Panels, or applicable code evaluation reports. Each panel will need to be identified for grade, bond classification, and Performance Category by the trademarks of an approved testing and grading agency. Cross-laminated Timber (CLT) is a prefabricated engineered wood product consisting of at least three layers of

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October 2014

As sustainable construction continues to become more mainstream, wood is poised to help engineers design structures that are safe and sustainable. In 2013, American Wood Council (AWC) released a series of Environmental Product Declarations (EPDs) for multiple wood products. EPDs are considered a type of environmental label or “ecolabel” – a document that gives information regarding the environmental characteristics of a product. ISO has developed standards on ecolabels that place them into three broad categories: • Type I – governed by ISO standard 14024. Awarded by third party programs to products demonstrating good environmental attributes. • Type II – governed by ISO standard 14021. Based on self-declared claims

by manufacturers about some aspect of their product. An example is a manufacturer’s “green” label on their biodegradable product. • Type III – governed by ISO standard 14025. These ecolabels are commonly referred to as EPDs. The data reported in a typical EPD is collected using Life Cycle Assessment (LCA) techniques. LCA is a scientific, internationally-accepted technique for assessing potential environmental impacts associated with some or all stages of a product’s life. Results of LCA studies are sensitive to system boundaries; different boundaries can give different results for the same product. Generic EPDs for the following structural products have been developed: • Softwood Lumber • Softwood Plywood • OSB • Glulam • I-joists • LVL With the exception of redwood decking, all EPDs shown in Table 2 are “cradle-togate,” beginning with life-cycle assessment of the resource, tracking product flows through the manufacturing process, and ending at the manufacturer’s exit gate, ready

Table 2. Environmental product declarations for structural wood products.

EPD Product Name

Date of Issue

Scope1

Owner(s)2

Softwood Lumber

16 April 2013

B2B

AWC/CWC

Softwood Plywood

16 April 2013

B2B

AWC/CWC

Oriented Strand Board (OSB)

16 April 2013

B2B

AWC/CWC

Glued Laminated Timbers

16 April 2013

B2B

AWC/CWC

Laminated Veneer Lumber (LVL)

12 July 2013

B2B

AWC/CWC

Wood I-Joists

23 July 2013

B2B

AWC/CWC

17 September 2013

B2C

AWC/CRA

Redwood Decking

B2B = Business to Business (Cradle-to-Gate); B2C = Business to Consumer (Cradle-to-Grave) AWC = American Wood Council; CWC = Canadian Wood Council; CRA = California Redwood Association

1 2

for shipment. It is noted that this limits the ability to account for the benefit of carbon sequestration by offsetting the release of biogenic CO2. This accounting is an accepted practice in cradle-to-grave LCA reports, since it is not realized at the point of manufacturing, but rather occurs over the life cycle ADVERTISEMENT–For Advertiser Information, visit www.STRUCTUREmag.org

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of the product. These EPDs are compliant with ISO 14025 – Type III Environmental Product Declaration, and can be used to earn points in both the LEED and Green Globes building certification systems. For more information and to download the free EPDs: www.awc.org/greenbuilding/epd.php.▪

Lessons Learned

problems and solutions encountered by practicing structural engineers

Pitfalls of Design-Build The Devil is in the Details By Thangam (Sam) Rangaswamy, Ph.D., P.E., S.E., SECB, Geoff Cooper, E.I.T. and Anthony Ehlers, P.E.

he Design-Build concept is gaining increased acceptance, and there’s no doubt it’s a seductive option to a cost-conscious building owner. Who wouldn’t want to shave off the direct cost of professional design fees? After all, a building’s a building, isn’t it, and it’ll come with a warranty, won’t it? Hey, the contractor promised to deliver a total package and understands my needs. Not so fast. Is it reasonable to believe that all contractors have the owner’s interests at the top of the agenda? Profit is the driving force behind all commercial enterprises, and there’s nothing wrong with that. However, it can be a murky line that separates the very different interests of owners and contractors. For sure, some contractors will have in-house professionals capable of designing appropriate spaces, HVAC and structural systems, land use plans and an appealing aesthetic appearance, but there are many who do not. By the same token, some owners will have their own procurement specialists but many will not. It is this disparity in sophistication that’s often overlooked. Moreover, it’s not until after something nasty happens to a building in service that the insurance underwriter will start to ask searching questions. Many of us in the consulting field have been happy to provide design assistance to a design-build contractor but our scope is often limited, and the design parameters likewise. Total control of the selection of the building systems is held by the contractor, and multiple design packages are released to both design professionals and vendors alike. Owners will see this as cost-effective, and in many cases it is. However, on the flip-side, has the owner given the contractor a detailed account of anticipated day-to-day operations; and does the contractor have a full grasp? These two components, the contractor and the owner, generally have little in common. Their occupations, and day to day responsibilities, are quite different. By way of examples, consider the following personal experiences: A plastics injection molding company decided to expand its operation and, as a result, determined the need for a two story storage warehouse. For its construction, the

manufacturing company solicited the services of a pre-engineered building erector/ construction company that promoted itself as a design-build contractor. It appeared a good fit, the price was right and the contract signed. The project certainly appeared to be within the contractor’s scope of work and the design work proceeded. The upper floor was designed to withstand a combined dead plus uniform live load of 100 psf., and the resulting construction was a 2½-inch slab on 0.06-inch metal deck resting on bar joists at 24 inches on center which, in turn, were supported by conventional steel framing. Spread footings were installed as the foundation system. Clearly, none of this is untypical of pre-engineered buildings used for commercial purposes. However, this is a manufacturing facility and an important operational component was overlooked. Upon completion of the warehouse, the second floor storage area was serviced by hard-wheeled fork-lift trucks on a continual basis, and within a couple of years the slab was severely damaged. Potholes were developing everywhere and the slab was fully perforated in several locations. A desperate owner contacted my firm for help. Upon analysis, we determined a 4-inch thick slab was necessary, and that the supporting super-structure would have to be strengthened to support both the increased concrete slab load and the concentrated loads of the forklifts. In all, additional intermediate supports were installed to support the joist and beam framing, including additional columns and foundations, and the design-build contractor returned to undertake the work. Notwithstanding the owner’s increased production costs resulting from disruption to the manufacturing process, the direct cost of the remedial work was in excess of $250,000. The contractor assumed this expense, but not before the owner leveraged their cooperation with the promise of the award of an additional planned expansion. Ironically, we earned an engineering fee the owner had initially sought to circumnavigate by opting for design-build delivery. After much finger pointing, the question of which party’s action led to this situation will remain. Pre-engineered metal buildings are more suited for light, uniform service loads, and

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design-builder contractors favor the ease by which components can be selected from prescribed catalog information. There is an obvious comfort in this, and the repetition of delivering these structures becomes routine. However, we can see here a classic example of a pitfall of the design-build system, since certain projects require more than the selection of a one-size-fitsall pre-manufactured building and an eagerness to continue cookie-cutter delivery. In fact, this is not the only construction failure of this type, and of this type of building format, that require the retention of engineering firms to investigate. Another situation involved the expansion at an auto-parts plant, with the addition of a 120- x 360-foot manufacturing building. Approximately, the shop layout required two 60-foot spans, spaced at 20-foot intervals for a total of eighteen bays. Each span was to have two overhead, twenty metric ton capacity, bridge cranes. The owner, a German based company, had previous experience with designbuild procurement in Europe, and their typical contract was adjusted to accord with U.S. standard forms. One of their specific contractual requirements was the submittal of structural calculations by the design-build contractor for review by an owner-retained structural engineer, and this was to be done before the start of construction. Clearly a prudent step, and any firm would be pleased to be hired by this sophisticated owner to provide this service. Despite this safeguard, and anxious to minimize ‘general conditions’ costs, the design-build contractor jumped into the project, ordering steel and installing foundations and anchor bolts. Gotta move fast to maximize that profit, you know. Submittals are just a formality and the calculations can come later. We’re the designers and we’re the builders, and we know what we’re doing. We’ve built other buildings like this. Nothing to it. Once challenged to deliver the calculation package, a photocopy of the Portland Cement Association’s slab-on-grade design chart, highlighted to justify thickness selection, was submitted. Not an encouraging start to the review process. There followed a protracted two week period before a further submittal. Meanwhile, construction continued. The second submittal, this time an impressive looking 300 page computer print-out, documenting the frame analysis, appeared to suggest the contractor was getting the message and finally playing by the rules. However, upon review it was clear that restraint of lateral forces and moments at the column bases had not been addressed.

Thangam Rangaswamy, Ph.D., P.E., S.E., SECB, is principal engineer with Rangaswamy & Associates, Inc. at their main office in Louisville, Kentucky. He established the Structural Engineers Association of Kentucky (SEAOK) and served as director, Secretary and President. He can be reached at sam@rangaswamy.com. Geoff Cooper, E.I.T., is an associate and project manager with Rangaswamy & Associates, Inc. He is currently affiliated with the Louisville office and may be reached at geoffc@rangaswamy.com. Anthony Ehlers, P.E., is an associate and project engineer with Rangaswamy & Associates, Inc. He also directs structural engineers at their India office located in Coimbatore. He may be reached at anthony@rangaswamy.com.

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The footings and anchor bolts, as installed, were designed to withstand the calculated vertical loads but were inadequate to resist other reactions. Not surprisingly, there followed much haggling with the contractor’s EOR. All the while, construction continued, and on schedule. Resolving the impasse, the owner’s structural engineer concurred with the owner-retained structural engineering firm’s determination and arrived from Germany in time to stop the imminent installation of the cranes. A lateral bracing system was subsequently designed to restrain the tops of the columns and mitigate reactions at the bases. The cost of this stabilization added a further $200,000 to the bottom line and can be judged a pitfall, brought on by the ready-fire-aim philosophy often inherent with design-build projects. As can be seen from the cases described above, the devil is in the details. It is essential that both the contractor and the owner are on the same page. Unfortunately, there is no mandated mechanism to guarantee this empathy. Active participation by insurance underwriters during design development could provide the necessary oversight, but this is not customarily the case. Design-build delivery is not the same as Contract Manager delivery but, to unsuspecting owners, they can appear to be the same. Both appear to present the owner with a contractor eager and able to demonstrate alternatives that offer savings. Unlike competitive-bid projects, each of these systems is conducive to the development of a close, one-on-one, relationship between the contractor’s team and the owner, and this intimacy will give comfort to the owner. However, despite the advantages of flexibilities within the Contract Manager delivery system, the contractor is, nevertheless, bound by documents prepared by an independent, third-party, design team, who duly monitor the project to ensure satisfactory delivery. Nothing is ‘left off the table’. Also of concern is the prevalence of design-build contracts at local authority level. The majority of small municipalities have limited funds with which to build EMT, firehouse facilities and the like, and the design-build option presents a good fiscal option…and, what’s more, there’s often a brother-in-law with a construction company only too eager to ostensibly ‘give back’ to the town. The potential problem is, though, will the buildings withstand seismic or hurricane forces when needed, or will the emergency equipment be stuck in the rubble?▪

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InSIghtS

A Structural Perspective on Sustainability By Robert D. Richardson, P.E., P.Eng, ENV SP

hat makes a bridge (or any other structure) sustainable? The American Society of Civil Engineers (ASCE) defines sustainability as, “A set of environmental, economic and social conditions in which all of society has the capacity and opportunity to maintain and improve its quality of life indefinitely without degrading the quantity, quality or availability of natural, economic, and social resources.” Based on this definition, it is clear that the structural component is one piece of the much larger picture in terms of sustainability. The Envision™ sustainability rating system was developed through a partnership between the Zofnass Program for Sustainable Infrastructure and the Institute for Sustainable Infrastructure (ISI), a not-for-profit organization founded by ASCE, the Council of Engineering Companies (ACEC), and the American Public Works Association (APWA). The goal was to establish a comprehensive tool that provides a holistic, cost-effective framework for evaluating and rating the community, environmental and economic benefits of all types and sizes of infrastructure projects. Envision™ categorizes a project’s contribution to sustainability into two key areas: pathway contribution and performance contribution. Pathway contribution is used to assess the important question, “Are we doing the right project?” by considering how the project aligns with overarching community needs and quality of life, and supports responsible and sustainable development. Generally, these issues are beyond the scope of the structural engineer. However, knowing how they affect the overall sustainability of a project, structural engineers are positioned to provide valuable input on aspects of performance contribution. Performance contribution is the determination of the project’s efficiency and effectiveness, and attempts to answer the question, “Are we doing the project right?” The project team should explore all practical opportunities to improve sustainable performance in multiple areas including increased energy efficiency, decreased water consumption, and reduced materials consumption. What can structural engineers do to enhance a project’s sustainability?

• Design with sustainability in mind. Look for ways to incorporate sustainable practices to improve design and project performance. • Identify opportunities to re-use existing materials or make use of structural systems that are easily decommissioned and deconstructed in the future, perhaps for use elsewhere. • Consider how the project will be built. If built in an urban environment, consider methods of accelerating construction to minimize impacts to the community. If built in a “greenfield” environment, consider how the foundations will be built and how that work may impact the ecology of the site, both temporarily and longterm. Evaluate alternative foundation layouts that may reduce those impacts. • Stay informed of new technologies. Although limestone is an abundant resource, Portland cement production requires significant energy to process. Waste materials, such as fly ash and blast furnace slag, are being used to replace Portland cement in concrete mix designs. Reduced need for Portland cement production, and using materials that would otherwise go to a landfill, provide excellent benefits. But what is the next step? In the UK, research is underway to investigate the performance of low-carbon cements (LCC), such as supersulfated cements and calcium sulfoaluminate cements, in structural concrete. • Avoid “standards traps.” Many design standards were developed decades ago and do not take into account the pressing need for sustainable growth or the changing conditions current infrastructure will face in the future. Following established standards without accounting for these factors will not help achieve the necessary systemic change toward sustainability. Standards traps can present significant challenges for structural engineers because, even though the engineer may embrace the re-examination of long-standing proceedural approaches, the project owner may not agree. This provides

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October 2014

an opportunity for the engineer to partner with the owner to increase understanding and perhaps initiate changes to the standard practices that capture the positive benefits achieved by designing with sustainability in mind. • Perform detailed drawing and calculation reviews. Drawing and calculation errors can lead to construction re-work, which is a waste of both materials and energy and negatively impacts the project’s sustainability. Moreover, the structure may not achieve its full anticipated design life and may require early replacement, which will result in significant resource and quality of life impacts for the community down the road. Finding the time to perform proper checks has always been a challenge, and the required commitment will be even greater in the future with the pressures and unforgiving deadlines of the designbuild project delivery method. Upton Sinclair wrote, “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” Designing and building safe, reliable structures requires the consumption of energy and materials. Typically cautious, structural engineers may be hesitant to enthusiastically embrace change and consider new pathways in design that appear to focus on conservation. However, with the depletion of natural resources and resulting enhanced environmental regulations, coupled with an industry-wide drive toward sustainable building practices, sustainable design should not be thought of as a change, but as “career sustainability.”▪ Robert D. Richardson, P.E., P.Eng, ENV SP, is the Washington Bridge and Structures Manager, and Bridges and Structures Sustainability Program Leader at HDR, Inc. Robert can be reached at Rob.Richardson@HDRinc.com. Sinclair, Upton. I Candidate for Governor: And How I got Licked (1935). Reprinted University of California Press, 1994, p. 109. ISBN 0-520-08198-6.

Professional issues

issues affecting the structural engineering profession

Diversity in the Structural Engineering Profession Challenges and Opportunities By Abbie B. Liel, with the SEI Young Professionals Committee

here are many benefits to a diverse workforce of structural engineers. The representation of multiple perspectives and experiences in the workplace has shown to enhance innovation, creativity, knowledge, and productivity (NAS 2006). Even so, less than 15% of civil engineers are women and less than 20% are nonwhite. In contrast, women now make up over 30% of lawyers and physicians, and over 70% of psychologists (BLS 2012). Since no evidence exists that significant gender or racial differences in math or science ability exist (Valian 1998; NAS 2006), discrepancies in engagement and achievement in engineering have been attributed to a range of factors including a lack of preparation and encouragement, workplace and academic cultures, and the public image of engineering. As the structural engineering profession grows and advances in the 21st century, it is critical that it be able to recruit and retain the most talented individuals, regardless of gender or race. To this end, this article examines the current demographics of the structural engineering profession and investigates how the experiences of structural engineers vary with gender and race/ethnicity. A full report on the Young Professionals Committee’s study will be published as an SEI report.

President1

% of Men

Vice President2

% of Women

Associate4 Senior Engineer5 Project Engineer6 Engineer7 Structural Designer8 EIT9 Other Positions 10 0%

10% 15% 20% 25% 0% 5% 10% 15% 20% 25% 30%

Figure 1. Demographics of structural engineers at U.S. firms, by position. Values shown are percent of each gender or race/ethnic category holding the position titles listed. * URM = Underrepresented Minorities.

Current Demographic Statistics Statistics on gender and racial diversity in the structural engineering industry in the U.S. were gathered in 2012 and 2013 from four different sources: (1) firms employing structural engineers; (2) professional organizations; (3) state licensure boards; and (4) universities. Data from firms employing structural engineers were obtained through a short questionnaire distributed to offices across the

% Women 16.7

% Hispanic

% African American

% Native American

5.0

0.6

0.1

Professional Organizations ASCE

11.7

n/a

SEI

6.7

n/a

SEI Committee Chairs

8.9

n/a

Regional SEA

9.1

n/a

EERI

7.4

n/a

EIT

15.3

n/a

7.4

n/a

2.9

n/a

24.8 <24.3>

10.3 <14.9>

2.9 <1.8>

0.6 <0.7>

Graduate Students

29.2 <20.5>

4.3 <2.9>

2.0 <1.2>

0.2 <0.2>

Faculty

17.4 <18.7>

6.1 <2.2>

1.1 <1.5>

0.0 <0.0>

Engineering Licensure

Universities – Civil <Structural> Engineering Undergraduate Students

% of URM*

Principal3

Table 1. Structural engineering demographic data compiled from various sources.

Structural Engineering Firms

% of White

STRUCTURE magazine

October 2014

U.S. Results were collected from 45 firms (representing approximately 1,350 engineers). The study also collected demographic data from professional organizations: ASCE, SEI, regional chapters of the Structural Engineers Association (SEA), and the Earthquake Engineering Research Institute (EERI). The gender breakdown of registered engineers-intraining (EIT), professional engineers (PE), and structural engineers (SE) was obtained from inquiries directed to state licensing boards. University data describes the demographics of students and faculty in civil or architectural engineering at 50 universities; for a limited subset of institutions, information about structural engineering students and faculty could be identified separately. Table 1 summarizes the representation of women and underrepresented minorities among the selected groups of structural engineers. The firm data suggest that about 17% of structural engineers are women. Women appear to comprise a smaller fraction, approximately 9%, of membership in the industry’s professional organizations. Moreover, ASCE data reveal that, at 6.7%, SEI has the lowest representation of women among all of ASCE’s institutes. There is also a decline in the representation of women between EIT, PE and SE licensees, indicating a shift in demographics over various career stages. Indeed, the percentage of women among SE licensees did not exceed 4.5% in any of the nine states providing these data. The participation of underrepresented minority groups

Survey of Structural Engineering Professionals The Young Professionals Committee also distributed online surveys to structural engineering professionals and students. This article focuses on professionals’ responses to questions about current roles and responsibilities, compensation, and career satisfaction, and examines how much these experiences differ according to an engineer’s gender or race/ethnic background. A total of 676 individuals responded to the survey with complete gender and race/ethnicity information. The survey participants are 74% male and 26% female. The respondents identified as 86% White, 9% Asian American or Pacific Islander, 3.7% Hispanic, and 1.2% Black/African American; there were no responses from Native Americans. The average

Fewer than 12 months 1 - 4 years

CONSTRUCTION CEMENT

5 - 9 years

FA S T ER

10 - 14 years 15 - 20 years

% of Men % of URM

21 - 30 years More than 30 years 0%

10%

20%

% of % of Women White % of Other Minority Groups 30%

40%

Figure 2. Survey respondents’ reported number of years working as a structural engineer.

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ages of the male and female respondents are 37 and 32 years, respectively. The relative overrepresentation of women in the survey pool (as compared to the data presented above) is consistent with a number of studies suggesting that women are more likely to respond to surveys than men (Underwood et al. 2000).

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Roles and Responsibilities Survey respondents ranged from those who had just started their careers to those who have been practicing for over 30 years. The average male respondent had worked in the profession longer than the average female respondent (12 vs. 7 years). As shown in Figure 2, there is a substantial reduction in the representation of women among engineers with 15 or more years of experience. This trend coincides with a relative decrease in women older than 35. These differences may represent changing demographics over recent years, but this hypothesis is not supported by nationwide demographic data of science, technology and mathematics fields (NSF, 2012). The results instead seem to indicate difficulty retaining women. As with the data from engineering firms, the survey responses indicated lower representation of women holding more senior positions. Race/ ethnic minorities are also more likely to hold more junior positions, but these differences are not as stark as those based on gender. On average, the survey respondents reported working 40-50 hours per week, which did not vary significantly with gender or race/ethnicity. Answers to questions about the type of work and responsibilities yielded many similarities across different groups, although substantially more men (54%) than women (28%) reported that they are responsible for managing at least one person; women reported spending more time on design relative to men. Interestingly, underrepresented minorities were more likely than white engineers to indicate that they are responsible

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of Hispanics, African Americans and Native Americans was harder to obtain, but results suggest that Native Americans make up less than 0.5% of structural engineers, African Americans less than 2%, and Hispanics somewhere between 3 and 5%. The lower representation of women among the licensure and professional organization data as compared to the firm data implies that women are disproportionately absent from leadership positions. This implication is supported by Figure 1, which reports the demographics of firms by job title. As shown, women are more likely to hold the more junior positions, while men are more likely to hold management and executive positions. Similarly, engineers who are non-white are less likely than white engineers to be found in roles of senior engineer or above. Of the 45 firms for which responses were received, six have women or underrepresented minorities in president or vice president positions. These firms appear also to have a greater presence of women and minorities at other levels. According to the data in Table 1, undergraduate students have the highest representation of women and racial/ethnic minorities, but this diversity decreases through the pipeline of structural engineering careers, with the lowest representation among licensed SEs. This trend suggests that white men are more likely to persist through structural engineering career pathways. An alternative hypothesis is that more women and minorities are starting structural engineering careers now than in the past. However, nationwide data show that women and minority representation among students entering science and engineering disciplines have decreased slightly over the past 10 years (NSF, 2012), refuting this hypothesis.

(a)

(b)

$400,000

environment, while men more frequently selected reasons related to financial compensation. White engineers were also more likely than underrepresented minorities to cite financial compensation as a reason to switch companies or consider a different career. Underrepresented minorities and women were more likely to respond that they had thought about leaving the structural engineering field.

$350,000

Less than $45,000 Annual Salary

$300,000

$45,000 - $65,000

$250,000 $200,000 $150,000 $100,000

Annual Salary

$65,000 - $90,000

$50,000 $-

$90,000 - $125,000

(c)

20 30 Years of Experience

Perspectives on Diversity in Structural Engineering

$400,000 $350,000

Annual Salary

$125,000 to $200,000

More than $200,000

In the final section, the survey asked about respondents’ perceptions of equality in the workplace. Although most of those surveyed said they had not experienced discrimination, women and underrepresented minorities were much more likely to have experienced discrimination (Figure 4). Women and underrepresented minorities are also much less likely to believe that equal opportunities exist for all. A follow-up question asked respondents to identify reasons for a lack of equality. Of the reasons listed in the survey, the top reasons respondents identified were: lack of women (14%) or minority role models (9%) in the industry, family commitments (10%), and inequalities that exist in the profession (12%). Comments from the survey (a sample of which are provided in the online version of this article) showed that equality in the workplace was seen as highly coupled to workplace philosophy and attitudes of supervisors and coworkers.

$300,000 $250,000 $200,000 $150,000 $100,000

% of Men Men

0% 10% 20% 30% % of % of % of Women White UM Women White URM

40% 50% % of Other Others Minority Groups

$50,000 $-

15 20 25 Years of Experience

Figure 3. Survey respondents’ (a) salary, and salary as a function of years in the workforce by (b) gender and (c) race/ethnic background (salaries reported in 2012).

for managing at least one other person (63% compared to 47%). Anecdotal evidence has suggested that women may be more interested in certain aspects of structural engineering, such as green building and historic preservation. In the survey, however, these choices were no more likely to be selected by women than any other subset of respondents and all groups identified the same most interesting aspects (steel design, concrete design, and seismic design). Nevertheless, women were more likely to report having LEED certification from the U.S. Green Building Council (26% of female compared to 16% of male respondents). Compensation Figure 3a shows the annual salaries reported by survey participants (if provided). On average, the survey respondents reported salaries (excluding bonuses) of $86,100 per year (as of Fall, 2012). Average annual salaries were higher for men ($91,600) than women ($71,600). In Figure 3b, salary is plotted as function of the respondents’ years of experience. The data show that men earn slightly more than women, even when engineers with the same years of experience are compared. Although the data are limited for the underrepresented minorities (only 21 responses included salary information), the responses suggest that their salaries are approximately equal to or higher than white engineers. Career Satisfaction

they are “very satisfied” than women (22%) and underrepresented minorities (33%). Although relatively few respondents chose “dissatisfied,” this selection was more popular among women (9%) and other race/ethnic minorities (9%) than among men, whites, and underrepresented minorities (2-3% of these groups). When asked why they are dissatisfied, respondents most frequently responded that they felt that there are no opportunities for advancement in their company. As another measure of satisfaction, the survey inquired if respondents had considered leaving or had left a company, or considered leaving the profession entirely. The desire for more opportunities for career advancement was cited often as a reason for switching companies or considering quitting structural engineering. Women more frequently selected reasons of better work-life balance and better work (a) Have you been discriminated against or encountered an uncomfortable work environment as a structural engineer because of your race, gender or another reason?

This study shows that representation of women and minorities remains low in structural engineering, and is lower than civil engineering as a whole and other science and technology disciplines. The scarcity of women and race/ethnic minority engineers is apparent

(b) Do you believe some groups of people have fewer opportunities to succeed in structural engineering careers? Fewer opportunities for women

Yes, frequently

Fewer opportunities for minorities

Yes, sometimes

Fewer opportunities for both women and minorities Yes, rarely

Equal opportunities for everybody

No, never

The survey asked engineers about their level of satisfaction with their career progress and advancement. Men (43%) and whites (38%) were more likely than other groups to report that

Challenges

Not sure or Other believes beliefs 0%

25%

50%

75% 100% % of % of Men Women

% of White

% of URM

0% 20% 40% % of Other Minority Groups

60%

80%

Figure 4. Responses to survey questions about (a) workplace discrimination and (b) opportunities for success.

STRUCTURE magazine

October 2014

particularly among leadership positions both in individual companies and professional organizations. The lack of diversity in leadership positions appears to stem from challenges with retention, indicated in particular by a decrease in women in their mid-thirties, in addition to challenges associated with creating a more diverse student base from which to recruit future structural engineers. The survey data reported here indicate that there are a lot of similarities in terms of how engineers in different demographic groups experience structural engineering careers. Nevertheless, statistically significant differences exist in terms of pay and career satisfaction based on gender and race/ ethnic background, and almost 60% of women see fewer opportunities for women than men. Minority male engineers seem to experience somewhat less discrepancy in pay (relative to white men) than women, but their concerns about respect and promotion were similar to those expressed by women.

Opportunities

This study was funded by the Structural Engineering Institute (SEI) and the University of Colorado Office of Diversity, Equity and Community Engagement Implementation of Multicultural Perspectives and Approaches in Research and Teaching (IMPART) Faculty Fellowship award for Abbie Liel.▪

Abbie Liel is Assistant Professor in the Department of Civil, Environmental and Architectural Engineering, University of Colorado Boulder. She can be reached at abbie.liel@colorado.edu. The online version of this article contains detailed references and additional survey information. Please visit www.STRUCTUREmag.org.

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Despite these challenges, the study offers some insights into how we can help talented individuals of all backgrounds achieve success in structural engineering. Some recommendations for structural engineering leaders are as follows: 1) Promote mentoring and develop mentorship programs. Responses to both the professional and student survey indicate that engineers are more likely to feel and be successful if they have a mentor. Diverse mentors and diverse leaders seem to promote a more diverse workplace. 2) Develop procedures for regularly evaluating potential biases in hiring and promotion decisions. Pay and responsibility inequities persist, even when adjusted for experience. Unintentional biases in these processes can be reduced by a culture of awareness. 3) Be aware that workplace culture can have a large influence on whether employees feel valued. Many of the frustrations expressed with the structural engineering workplace had nothing to do engineering, but rather social and cultural attitudes. 4) Foster policies to ease pressures of work-life balance. Part time opportunities and more flexibility in work schedules could substantially improve retention.

Acknowledgments

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Spotlight

The 130 th Street and Torrence Avenue Railroad Truss Roll-In An Accelerated Bridge Construction Feat By Diane Campione, P.E., S.E. Alfred Benesch & Company was an Outstanding Award Winner for the 130 th Street and Torrence Avenue Railroad Truss Bridge project in the 2013 NCSEA Annual Excellence in Structural Engineering awards program (Category – New Bridges & Transportation Structures).

n August 25, 2012, a multilevel grade separation designed by Alfred Benesch & Company (Benesch) made history when a 394-foot-long, 4.75-million pound, steel railroad truss bridge was rolled into place. Accelerated Bridge Construction (ABC) techniques were utilized to assemble and transport the truss 800 feet from a staging area to its final location in four hours. What is believed to be the largest, steel railroad truss bridge span ever rolled into place at the time of its construction now makes a striking silhouette as construction continues around it at the project site. The new railroad truss replaced an existing Chicago, South Shore and South Bend (CSS&SB) Railroad bridge, which carries freight trains and the Northern Indiana Commuter Transportation District’s (NICTD) commuter rail line from South Bend, Indiana to downtown Chicago. Rolling in the new CSS&SB bridge was a key component of the 130th Street and Torrence Avenue intersection improvement project, an extremely complex, $101 million effort by the Chicago Department of Transportation (CDOT). The intersection serves approximately 38,000 vehicles a day, including traffic to and from the nearby Ford Motor Company Plant. More than 50 freight trains also cross near the intersection, daily, on two at-grade Norfolk Southern Railway (NS) tracks while the CSS&SB tracks are supported over the existing NS tracks at Torrence Avenue. Realigning and depressing 130th Street and Torrence Avenue below the existing NS tracks will relieve traffic congestion and improve rail service efficiency in this area. Construction of two new NS bridges were designed on offset alignments to minimize impacts to the railroad. The new alignments created a conflict with the existing elevated CSS&SB structure above. This conflict was resolved by replacing the existing CSS&SB bridge with a new structure on a new alignment. At the end of preliminary design, the proposed CSS&SB structure consisted of a 368-foot-long truss with abutments skewed

at 45 degrees for the shortest span possible. However, geometric and logistical constraints surfaced during final design. The design team was challenged to explore options to minimize impacts to vehicular and rail traffic during construction, and reduce the construction schedule. This led the project team to investigate the use of ABC techniques. Eliminating the skew and building the truss span in a nearby staging area, then transporting the structure using Self-Propelled Modular Transporters (SPMTs), was found to be a more feasible and cost-efficient option. The revised structure consists of a truss that spans 394 feet center-to-center, with the bearings and supports perpendicular to the structure. The project was advertised for bidding in September 2010. The contract was awarded to Walsh Construction Company (Walsh) who subcontracted with The Sarens Group to perform the roll-in. Benesch, in addition to being the designer for the preliminary and final design phases, also serves as the construction manager for the project. All teams involved were familiar with using SPMTs to roll in larger transportation structures. In May 2012, truss assembly began in the staging area. By mid-August 2012, the truss was assembled and painted a signature blue. Before transferring the truss onto the SPMTs, the truss was jacked onto temporary supports. Two operators controlled the hydraulic jacks and were in constant communication to lift all four points of the truss the same amount simultaneously. After the SPMTs were positioned under the truss, it was ready to make its 800-foot journey from the staging area to its final location. Walsh prepared a detailed schedule for the roll-in within the eight-hour window allowed by NS to interrupt train service, which was divided into 15 minute increments. Work also included dismantling the crossing gates and signals; laying a temporary crossing over the NS tracks for the SPMTs to traverse; and removing and reinstalling these items after the truss was moved into place. On the Friday night before the move, Torrence Avenue was closed to traffic and the

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October 2014

truss was moved 150 feet to the edge of the roadway to make sure the SPMTs were operating as planned. The truss was supported by four SPMT units, each consisting of 96 individually computer-controlled wheels capable of rotating 360 degrees. Combined, there were 384 wheels controlled by a single operator using a joystick, much like one used on a remote-controlled toy car. The SPMTs also lifted and lowered the truss, eliminating the need for cranes. Closure of the NS tracks began Saturday morning. The truss moved 450 feet east. Then the SPMTs pivoted north and traveled another 200 feet where it stood inches above its final support location. It took two hours to move the truss into place and another two hours to adjust the location of the bearings. The SPMTs were removed, and track signals and crossings were restored well within the eight hour shutdown window. Once the truss was in place, the contractor and railroad teams placed the ballast and ties on the truss, installed the catenary wires that power the NICTD trains and put the finishing touches on the truss. On October 25, 2012, the first NICTD train crossed the new truss bridge. With the new CSS&SB railroad bridge in full working order, and construction continuing underneath, commuters are already taking advantage of the numerous benefits and travel efficiencies this project brings to the community. This work proceeded alongside the existing CSS&SB bridge, allowing rail service to remain operational. The success of the move was a huge win for Chicago, the community and for the project team.▪ Diane Campione, P.E., S.E., is a Senior Project Manager at Alfred Benesch & Company. She served as Project Manager on the design of the 130 th Street and Torrence Avenue Intersection Improvement Project, which includes the new CSS&SB Railroad truss bridge.

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NCSEA News

News form the National Council of Structural Engineers Associations

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President’s Report Carrie Johnson, P.E., SECB

I am amazed that almost a year has passed since I became NCSEA’s president for 2014, representing our 44 Member Organizations (MO’s) and their over 10,000 individual members. It has truly been a great honor. Last year at our Annual Conference, I set a goal to encourage each of our committees to work together to focus on joint efforts. My hope was that we could accomplish even more by focusing on working together. I am pleased to be able to deliver a favorable report on the progress in this area. The committee chairs each did an outstanding job of looking at their goals, analyzing what tasks could be enhanced by input from other committees and asking for input. I hope we continue this trend. The NCSEA Young Member Support Group and Basic Education Committee have teamed together to do a Resource Survey aimed at helping young engineers. NCSEA’s Continuing Education Committee was also able to help in this effort, by providing a list of resources from the SE Exam Study Guide. Out of this, they have compiled a list of essential resources for structural engineers. They now have plans for a training guide that will help engineers on a wide variety of topics covering both soft skills and technical knowledge. The Code Advisory Committee has teamed with both the Advocacy Committee and the Publications Committee. They have served in the capacity of reviewing white papers and books that NCSEA intends to publish for code-related content. This is a critical component of making sure that our publications are accurate. The Structural Licensure Committee works with SECB, SEI and CASE on the Structural Engineering Licensure Coalition (SELC) so that the efforts of all of the organizations can be combined. This committee provides a single voice in the effort to promote structural licensure. I am hopeful that through these efforts and the efforts of local MO’s, we will have a new structural licensing act in several states over the next few years. Last year, we did a complete redesign of our web site. This year, we have been able to focus on adding resources to the web site. There are excellent resources from NCSEA committees that are categorized by the intended audience – Engineers, SE Licensure, Students and Teachers, Emergency Response, Careers, and NCSEA documents. A number of committees have provided new content. It is our intent to continue to add resources that will be of value to structural engineers and engineering students. Everyone can help in this effort by donating existing resources, volunteering to help write new ones, or even by contacting one of the committees and giving feedback on what information you’d like to see. Over the next few months, we will add a new feature on our web site that will allow users to log in under their own unique user name. With this new system, we can provide memberonly content and discounts, allow users to register online for webinars and conferences, review membership status, update address information, and provide a record of attendance at webinars and conferences. STRUCTURE magazine

All of NCSEA’s committees are composed of, and led by, dedicated volunteers. Without their commitment, NCSEA would not be able to continue to grow and serve the structural engineering profession. Each of NCSEA’s Member Organizations also rely on teams of volunteers to accomplish a wide variety of goals. All of these volunteers are the heart and soul of our joint efforts to improve our profession. Without them, we could not move forward. I would like to thank all of these individuals for their continued support of their MO’s and of NCSEA. For those of you who do not currently serve, I encourage you to get involved, give back to the profession, and make a difference. There are opportunities available at the local, state, and national level to get involved on a wide variety of issues that are critical to the future of our profession. Getting involved can make a huge difference and can give you an opportunity to grow as a leader, learn from others, and meet interesting people. It can be as rewarding for you as it is for those you are helping.

Valuable programs and projects have been instituted, including our new NCSEA Grants Program and a resource sheet of essential books for structural engineers. Another item I am pleased to announce is NCSEA’s new Grant Program. This program will allow us to provide grants to member organizations to assist in funding new programs. The requirements are minimal and state only that the program must be consistent with NCSEA’s Mission to advance the practice of structural engineering and, as the autonomous national voice for practicing structural engineers, protect the public’s right to safe, sustainable and cost effective buildings, bridges, and other structures. We hope it will encourage a wide variety of new initiatives throughout the country. Any member of an MO is eligible to submit an application through the MO. The NCSEA Executive Committee will review the proposals. Grants will be issued to as many applicants as are deemed worthy, up to the maximum dollar amount available for the given year. In October, we will meet in Charleston, SC to discuss our strategic planning for the next five years. We have invited all of the NCSEA Past Presidents, the current Committee Chairs, and the current board of directors. I am excited about the prospect of discussing the future of NCSEA with this esteemed group. We would love to get input from as many MO members as possible. If you have any ideas regarding what NCSEA should be focusing on for the next five, ten, or even fifty years, please feel free to discuss it with any NCSEA Board member, committee chair or past president. October 2014

2015 Winter Leadership Forum Hyatt Regency Coral Gables, Florida

Developing Strategies for Growth & Success

NCSEA has instituted a new Grants Program for projects that further the mission of the association. The Grants Program was unveiled at the NCSEA Annual Conference last month, and the first grants will be awarded in March of 2015. In subsequent years, applications will be due in August and will be awarded at NCSEA’s Structural Engineering Summit in the fall. Any NCSEA Member Organization or member(s) of a Member Organization are eligible to submit an application. Applications of individuals must be submitted to the local Member Organization, reviewed and approved by the Member Organization, and then forwarded to NCSEA for consideration. Requests may be submitted for any program that is consistent with NCSEA’s mission. Requests will not be accepted, however, for political contributions or for reimbursement of lobbying expenses. Applications must clearly define who or what group is to receive the funds, when it will be spent, how it advances the NCSEA Mission Statement, and how it can be leveraged with other funding. Matching contributions from a Member Organization are encouraged, but not required. For more information on the Program and the application, visit www.ncsea. com/resources/documents.

New name for NCSEA Conference

• Should you grow organically or through acquisition? • Case Study: Purchase or Pass? NCSEA’s 2014 Winter Leadership Forum will feature roundtable discussions, presentations from firm principals and professionals in banking and finance, and a debate between structural engineering leaders on “How to Grow.”

NCSEA Webinars October 16, 2014

Overview of Codes Affecting Midrise Construction & Special Design Considerations Michelle Kam-Biron, P.E., S.E., SECB, M.ASCE, Director of Education, American Wood Council This course provides an overview of the latest and future changes to the International Building Code (IBC), AWC’s National Design Specification (NDS) for Wood Construction and Special Design Provisions for Wind and Seismic (SDPWS).

October 23, 2014

A Crash Course in Structural Glass Andrea Hektor, P.E., S.E., Associate, KPFF, Portland, OR This seminar will help familiarize engineers with the underlying concepts of glass as a structural material and the basics of glass design.

November 6, 2014

Connection Solutions for Wood-Frame Structures Michelle Kam-Biron, P.E., S.E., SECB, M.ASCE, Director of Education, American Wood Council This course will feature wood connection design philosophy, behavior, serviceability issues, and connection design techniques with an overview of common fastener types.

November 20, 2014

Tilt-up Eats Hurricanes for Breakfast - Five Things Every Engineer Should Know When Designing Tilt-Up Panels Jeff Griffin, Ph.D., P.E., P.M.P., Structural Engineer, LJB Inc.,

Based on the ACI 551 Tilt-Up Design Guide, this webinar will explore how engineers can capitalize on the advantages of tilt-upconstruction to provide safe, durable structures.

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These courses will award 1.5 hours of continuing education. Approved for CE credit in all 50 States through the NCSEA Diamond Review Program. Time: 10:00 AM Pacific, 11:00 AM Mountain, 12:00 PM Central, 1:00 PM Eastern. NCSEA offers three options for NCSEA webinar registration: Ala Carte, Flex-Plan, and Yearly Subscription. Visit www.ncsea.com for more information or call 312-649-4600.

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President & CEO Severud Associates Consulting Engineers

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NCSEA’s Annual Conference is getting a new name! The event, to be held next September 30 through October 3 at the Red Rock Resort in Las Vegas, will be known as the NCSEA Structural Engineering Summit. This annual event draws structural engineers, those interested in structural engineering, students and the companies providing structural engineering products and services for education, networking, and the NCSEA Trade Show.

Ed DePaola, P.E., SECB

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New Grants Program available for NCSEA members

“I enjoyed the interactive format and the lively discussions from diverse perspectives. Well worth my time.”

News from the National Council of Structural Engineers Associations

How do you provide additional value to your clients? What are the buyers of your services thinking, and what are they looking for? When do you compete on prices? How do you train your staff to constantly be selling your services? What is your banker thinking, and how does a bank value an engineering firm? These questions and more will be addressed at NCSEA’s third Winter Leadership Forum, January 29-30 at the Hyatt Regency Coral Gables, Florida. Structural engineering leaders and firm principals will gather to discuss the issues confronting engineering firms in today’s environment. The topics for this year’s Forum will focus not only on ways to grow your firm and provide additional value, but also on issues relating to acquisition and finance, including: • When is it time to expand? • Is your goal to become better or busier?

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NCSEA News

NCSEA

National Council of Structural Engineers Associations

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Geotechnical & Structural Engineering Congress 2016 February 14–17, 2016, Phoenix, AZ

Structural Columns

The Newsletter of the Structural Engineering Institute of ASCE

Call for abstract and session proposals opens October 22 We are seeking dynamic sessions and presentations on topics addressing both Geotechnical and Structural Engineering issues. Final papers are optional and will not be peer reviewed. Consider submitting either session proposals or single abstracts related to the topics and subtopics of interest to both professions. Topics include: Codes and Standards Collaboration for Design of Specialized Structures and Their Foundations Curricula and Continuing Education Earth Retaining Structures Extreme Loads Geotechnical & Structural Elements of Foundation Design Performance-Based Design Mega Projects Performance of Constructed Facilities Professional Practice Issues Reliability/Risk Assessment Resiliency and Sustainability Seismic Hazard Analysis-Geotechnical & Structural Implications Sizing of Foundations (LRFD vs ASD) Soil Structure Interaction Blast and Impact Loading and Response of Structures

Apply for Young Professional (age 35 and younger) Scholarship to Structures Congress April 23–25, 2015 in Portland, Oregon Applications due December 12 SEI is committed to the future of structural engineering and offers a scholarship for Young Professionals to participate and get involved at Structures Congress. Many find Structures Congress to be a career-changing and energizing experience, opening up networking opportunities and expanding horizons to new and emerging trends. The scholarship includes complimentary registration sponsored by the SEI Futures Fund. Enter by visiting the SEI website at: www.asce.org/sei/Content.aspx?id=23622324305.

Enter the 2015 SEI Student Structural Design Competition Gain valuable professional and networking experience, compete for cash prizes, and raise visibility for your team and university. Awards include complimentary registration, sponsored by the SEI Futures Fund, to participate and present finalist projects at Structures Congress April 23-25, 2015 in Portland, Oregon. Learn more and enter at www.asce.org/sei/Content.aspx?id=23622325036 by January 5, 2015. STRUCTURE magazine

Bridge and Transportation Structures Buildings Embankments/Dams/Slopes Geoenvironmental Grouting Hydraulic Fracturing (Fracking) Non Building Structures & Non Structural Components Pavements Properties of Geo-materials and Modeling Scour and Erosion Site Characterization Structural Research Underground Construction Unsaturated Soils The 2016 congress will feature a total of 15 concurrent tracks: 5 tracks will be on traditional GI topics, 5 tracks on traditional SEI topics, and 5 tracks on joint topics. In addition, we will be offering interactive poster presentations within these tracks. Key Dates: Open call for abstracts and sessions – October 22, 2014 Close call for abstracts and session – April 7, 2015 (no extensions) Visit the joint conference website at www.asce.org/geoseicongress for more information

2015 Ammann Fellowship Call for Nominations The O. H. Ammann Research Fellowship in Structural Engineering is awarded annually to a member or members of ASCE or SEI for the purpose of encouraging the creation of new knowledge in the field of structural design and construction. All members or applicants for membership are eligible. Applicants will submit a description of their research, an essay about why they chose to become a structural engineer, and their academic transcripts. This fellowship award is at least $5,000 and can be up to $10,000. The deadline for 2015 Ammann applications is November 1, 2014. For more information and to fill out the on-line application visit the SEI website at: www.asce.org/SEI.

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

October 2014

Students are invited to apply for valuable Society Scholarships and Society Fellowships for Fall 2015. Two scholarships uniquely serving structural engineering students are: Eugene C. Figg, Jr. Civil Engineering Scholarship and Y.C. Yang Civil Engineering Scholarship. Other opportunities for consideration are: Lawrence W. and Francis W. Cox Scholarship, John Lenard Civil Engineering Scholarship, Robert B. B. and Josephine N. Moorman Scholarship, and Samuel Fletcher Tapman ASCE Student Chapter Scholarship. Graduate students may apply for: Trent R. Dames and William W. Moore Fellowship, Freeman Fellowship, J. Waldo Smith Hydraulic Fellowship, and Arthur S. Tuttle Fellowship. Complete applications, including current transcripts, are due February 10, 2015. See the ASCE website at www.asce.org/Student-Organizations/Scholarships-andFellowships/Scholarships---Fellowships/ for more information, or contact awards@asce.org.

The ASCE Florida West Coast Branch is helping to advance the profession of Civil Engineering in Florida. SEI Florida West Coast Chapter chair David Konz, P.E., S.E., M.ASCE, represents ASCE on the Florida Board of Professional Engineers Structural Engineering Licensure Committee. The mission is investigating, evaluating and making recommendations regarding separate licensure and/or certification of structural engineers within the state of Florida. Several organizations are working together to come to a consensus, including: ASCE-SEI, FICE, FSEA, FES and FBPE. Each committee member reviewed the documents, statues, and administrative code with respect to the mission before submittal to Florida legislators. The committee coordinates through conference calls and recently advanced their consensus on the proposed modifications. If you have questions regarding the status of the legislation, feel free to contact the FBPE Executive Assistant Rebecca Sammons at RSammons@fbpe.org.

received programs for their members. The first program was a tour of the I-275 widening project that goes from east of SR60 to Downtown Tampa. Members enjoyed a site visit of the project and the opportunity to ask questions of the project team. The second activity was a lunch and learn webinar hosted at ATKINS North America. Participants earned 1 PDH for the presentation Aging Infrastructure, Risks, and Making Hard Decisions. See the SEI website at www.asce.org/SEI for more details.

Get Involved – SEI Local Activities Join your local SEI Chapter, Graduate Student Chapter, or Structural Technical Groups (STG) to connect with colleagues, take advantage of local opportunities for lifelong learning, and advance structural engineering in your area. If there is not an SEI Chapter or STG in your area, talk with your ASCE Section/Branch leaders about the simple steps to form an SEI Chapter. Visit the SEI website at www.asce.org/SEI and look for LAD Committees.

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

Help ASCE Recognize Outstanding Structural Engineers Second ATC-SEI Conference Call for 2015 SEI/ASCE Award Nominations

Improving the Seismic Performance of Existing Buildings and Other Structures

Nominations are being sought for the 2015 SEI and ASCE Structural Awards. The objective of the Awards program is to advance the engineering profession by emphasizing exceptionally meritorious achievement, so this is an opportunity to recognize colleagues who are worthy of this honor. Nomination deadlines begin October 1, 2014 with most deadlines falling on November 1, 2014. Visit the ASCE Awards and Honors page at www.asce.org/ leadership-and-management/awards/ for more information and nomination procedures.

December 10-12, 2015 Hyatt Regency San Francisco Call for abstracts and session proposals will open in October 2014. Organized by the Applied Technology Council (ATC) and the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE), this conference will be dedicated to improving the seismic performance of existing buildings and other structures. See the conference website at www.atc-sei.org/ for more information.

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October 2014

The Newsletter of the Structural Engineering Institute of ASCE

SEI West Coast Florida Chapter Call for Speakers on Technical The West Coast Florida Chapter has recently held two well- Topics for SEI Local Group Events

Structural Columns

ASCE Scholarships for Licensure in Florida Structural Engineering Students

CASE in Point

The Newsletter of the Council of American Structural Engineers

CASE Contracts – Now Available! #10: An Agreement Between Structural Engineer of Record and Geotechnical Engineer of Record The Structural Engineer of Record may be required to include geotechnical engineering services as a part of its agreement. If a geotechnical engineer & laboratory must be subcontracted for this service, CASE #10 may be used. It can also be altered for use between an Owner and the Geotechnical Engineer of Record. #11: An Agreement Between Structural Engineer of Record (SER) and Contractor for Transfer of Computer Aided Drafting (CAD) files on Electronic Media Fabricators and suppliers are requesting CAD or BIM files from the designer. By providing CAD or BIM files, changes may be made to the files by others that would not be distinguishable without a critical review. CASE #11 is used so that both the Structural Engineer of Record and recipient of the CAD or BIM files understand the limitations and extent to which the files may be used. This is an agreement to allow for the transfer of CAD or BIM files to others. #12: An Agreement Between Client and Structural Engineer for Forensic Engineering (Expert) Services This is a sample agreement when the engineer is engaged as a forensic expert. It is designed primarily for when the Structural Engineer is engaged as an expert in the resolution of construction disputes, but can be adapted to other circumstances where the Structural Engineer is a qualified expert.

ACEC Business Insights

#14A: Supplemental Form A, Additional Services Form A one-page Additional Services form to be signed by both the Structural Engineer and the Client. These publications, along with other CASE documents, are available for purchase at www.booksforengineers.com.

CASE Risk Management Convocation in Portland, OR

Win More Work: How to Write Winning A/E/C Proposals Also available in MOBI (Amazon Kindle) and EPUB (B&N Nook, Sony Reader, IPhone/IPad/IPod, Android, and other e-readers/apps). Over the past decade, A/E/C firms have seen a spike in the number of competitors vying for the same work. The crowded field makes it difficult to get noticed, remembered, and selected by decision-makers. Win More Work: How to Write Winning A/E/C Proposals offers an experienced look at how to write memorable proposals. Being memorable is the key to success. This book will help architects, engineers, construction executives, and their marketing professionals understand how to write proposals that can double their win rate – thereby freeing them up to provide better service to customers, reduce marketing costs from bad pursuits, or simply spend more time with family and fewer Saturdays at the office. This book is for the novice proposal writer as well as those with decades of experience. Read this book to understand how to create memorable proposals that win more work. This publication, along with others, are available for purchase at www.booksforengineers.com.

Follow ACEC Coalitions on Twitter – @ACECCoalitions. STRUCTURE magazine

#13: Prime Contract, An Agreement Between Owner and Structural Engineer for Professional Services This agreement is intended for the Structural Engineer to serve as the Prime Design Professional. It addresses projects which may require other engineering disciplines and architectural services which are more than incidental. Examples are parking garages, warehouses, light industrial buildings, sports facilities and structural renovations. It should be distinguished from CASE #2 which is to be used when the Structural Engineer of Record has an agreement with the Owner but does not serve as the Prime Design Professional. This document is written to be compatible with CASE #3 which can be used by the Structural Engineer as Prime Design Professional to contract with consultants on the same project in conjunction with this agreement

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

October 2014

CASE in Point

CASE Risk Management Convocation Strong Lineup of Risk Management Sessions at ACEC Fall Conference You will not want to miss these additional important risk management sessions: Climate-Smart Engineering Approaches to Disaster Risk Stephen Long, The Nature Conservancy Case Study – Infrastructure Funding and Other Innovations in Asset Management Mike Baker, David Evans and Associates, Inc. Engineer-Led Design-Build – Simple, Safe & Profitable Mark Friedlander, Schiff Hardin

The Conference also features: • General Session addresses by business strategist Erik Wahl, political analyst Charlie Cook and FERC Commissioner Tony Clark • Member Firm CEO panels on the nation’s booming energy markets and the 2015 business outlook

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CEO roundtables Exclusive CFO and CIO tracks Numerous ACEC coalition, council, and forum events Earn up to 21.75PDHs

For more information and to register, http://conf.acec.org/conferences/fall2014/index.cfm.

WANTED

Engineers to Lead, Direct, and Get Involved with CASE Committees! If you’re looking for ways to expand and strengthen your business skill set, look no further than serving on one (or more!) CASE Committees. Join us to sharpen your leadership skills – promote your talent and expertise – to help guide CASE programs, services, and publications. We have two committees ready for your service: • Contracts Committee: Responsible for developing and maintaining contracts to assist practicing engineers with risk management. • Toolkit Committee: Develops and maintains documents such as business practices manuals and policies for engineers under CASE’s Ten Foundations for Risk Management.

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

October 2014

CASE is a part of the American Council of Engineering Companies

The CASE Convocation offers a full day of sessions on Thursday, October 23 dedicated to best-practice structural engineering: 6:30 am Addressing the Hidden Risks in Today’s Design Contracts Brian Stewart, Collins, Collins, Muir & Stewart; James Schwartz, Beazley; Rob Hughes, Ames & Gough 10:30 am The Five Commandments of A&E Risk Dan Buelow, Willis A/E 2:30 pm Managing the Emerging and Enduring Risks of Professional Practice Karen Erger, Lockton Cos. 5:30 pm ACEC / Coalition Meet and Greet

Structural Forum

opinions on topics of current importance to structural engineers

A Young Engineer’s Case for Structural Licensure By Emily Guglielmo, S.E.

uring my first NCSEA conference in 2011, I was inspired by the passion for the structural engineering profession displayed by my more senior peers. Throughout the conference, a major discussion topic was the need for structural licensure in addition to generic professional engineering licensure. As I listened to the arguments, I did not fully understand the reasoning either for or against structural licensure. Years later, I can now state with full confidence that I strongly support efforts toward structural licensure, and I ask all of my young professional peers to stand with me. Why did you choose to be a structural engineer? Perhaps you loved to innovate, build, and create. Mathematics and science might have been your passion, and engineering was a pragmatic direction. Raised in the San Francisco Bay area, I developed a lifelong fascination with earthquakes. I vividly remember the 1989 Loma Prieta event. Midway through gymnastics practice, the building lights swayed back and forth, the balance beams shook, and the doors and windows rattled loudly. I was fortunate to be inside a safely designed building with adequate bracing and structural support. From that day forward, I was fascinated with the idea of creating structures that could withstand these extreme forces of nature and protect their occupants. Fast forward through a college and graduate education, and many years of practical engineering experience, and I was thrilled to be eligible to obtain my license. As I recall sitting for the Principles and Practice of Engineering (PE) examination, my memories are of wastewater, fluid dynamics, and environmental remediation. Successfully passing the exam, I concluded that I could recall my civil engineering college curriculum, address generic engineering topics, and research reference material during an examination. However, I was required to demonstrate little competency in the design of a structure that could withstand wind, snow, seismic, or even gravity forces. Several years later, I successfully passed the 16-hour NCEES Structural Engineering (SE) exam. That experience stands out in stark contrast to the PE exam. I was challenged by questions involving various structural

materials and the appropriate utilization of building codes. The exam required an ability to solve real-world structural engineering problems, complete with detailing and sketches. The rigor and associated knowledge required to pass the SE exam was a far superior measure of competency when compared to the PE examination. As structural engineers, we have a public duty to design safe structures. Presuming that engineers who pass a generic civil exam have the ability to do so is dangerous. Some opponents of structural licensure argue that we should give individuals the professional discretion to judge their own ability to design a given project. However, an engineer is often blissfully unaware of the amount of knowledge, detailing requirements, and standards that are required in structural engineering. As an analogy, in the past, most medical care was performed by general practice physicians. While the quality of the care was usually good, the medical field evolved with the development of specialists. It is clear that a physician with years of surgical training is better equipped to remove a gallbladder than a general practitioner. Similarly, a cardiologist is better suited to manage difficult arrhythmias than a generalist. Likewise, specialization makes good sense for engineers, since we are uniquely trained and practiced in a particular field of expertise. Structural licensure would ensure demonstrated competency in our specialty. Some opponents of structural licensure argue that there is no evidence of major building failures due to incompetent engineering, thus proving the adequacy of the current system. However, as structural engineers, we should be proactive about public safety and critical with respect to who is permitted to design our community’s infrastructure. It would be short-sighted and irresponsible to wait for a catastrophic event before lobbying for structural licensure. Structural engineers often complain about reduced fees and the profession’s lack of prestige. However, we should look in the mirror and question ourselves about the significance we place on our work. If we honestly think that structural engineering is vitally important to the design community and the public at large,

then we should stand behind that statement and require all structural engineers to prove their competency through structural licensure. Other young engineers ask me, “Why should I take the SE exam if my state does not offer structural licensure?” In addition to the moral and professional mandate outlined above, passing the SE exam offers a prestige increasingly important to structural engineers. Even if your state does not currently offer structural licensure, it likely will require one during your professional career. The most convenient time to take the SE exam is early, when you are the most proficient at design and familiar with codes and standards. As a bonus, the NCEES SE exam creates a nationwide platform to apply for comity in most states, resulting in additional professional distinction and opportunity. As tomorrow’s leaders, I strongly urge you to become an advocate for structural licensure in your state. Most jurisdictions already have local licensure committees who would greatly benefit from a passionate young structural engineer promoting structural licensure. Furthermore, you can serve as an example to your peers by taking the SE exam. Many NCSEA Young Member Groups offer technical training and team study approaches to help engineers prepare for the exam. Structural engineering is at a critical crossroads. Visionary leadership from young professionals is vitally needed to address many significant challenges. While they may appear daunting, they also can be viewed as an opportunity for young engineers to shape the future of the profession and protect their communities. I strongly urge you to advocate for structural licensure in your state, take the SE exam, and help advance our practice while improving public safety.▪ Emily Guglielmo, S.E., is an Associate with Martin/Martin structural engineers in the San Francisco Bay Area. She serves on both the NCSEA Young Member Group Support Committee and the SEI Young Professionals Committee. She can be reached at EGuglielmo@martinmartin.com.

Structural Forum is intended to stimulate thoughtful dialogue and debate among structural engineers and other participants in the design and construction process. Any opinions expressed in Structural Forum are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C 3 Ink, or the STRUCTURE® magazine Editorial Board. STRUCTURE magazine

October 2014

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STRUCTURE magazine | October 2014

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