David L. Lawrence Convention Center



Wiki Group 14: Sally Ostendorf, Blake Gifford, Jessie Hunter

Keywords
Truss, bolt, support, nut, communication, construction error



Abstract


Beginning in 1990, Pittsburgh, PA begin the process of expanding their convention center in order to stay competitive in the region. In 1999, after
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Figure 1: Outer View of the DLCC; Courtesy of the Pittsburgh Tribune - Review
a $750,000 international competition, the design proposed by Rafael Vinoly Architects was chosen from a pool of 25 ideas. A year later, ground was broken for the new David L. Lawrence Convention Center (DLCC). By 2003, the building officially opened even though it had already been used for a few convention events. At its opening, the DLCC was given the Gold LEED certification, making it the first "green" convention center in the world.

The convention center has about 1.5 million square feet of space. That means 1.5 million square feet of room for problems and errors. Multiple collapses occured early in the building's life, with a truss collapse in 2002 and a lightly-loaded truck falling through the loading deck floor in 2007. Communication errors, lack of organization, and failure to check connections all led to these issues.



Summary of Events


On February 12, 2002, a truss on the eastern end of the David L. Lawrence Convention Center collapsed, killing one worker and injuring two others. The truss was the 13th in the set of 15 north-south supports of Phase 3 of the convention center. Phase 1 was set to open February 23, 2002. The collapse killed 38-year-old ironworker Paul Corsi Jr., who was wearing a safety harness hooked to the truss. Though 2" nuts were intended to be used on each 90 foot truss, 1" nuts were used instead, becoming a major contributing factor to the collapse. The incident did not affect the opening of Phase 1, though another later structural failure occurred in February 2007 when a lightly-loaded truck fell through the floor of the loading deck.


Causes of the Failure


The principal north-south support (from Penn Avenue to the Allegheny River) for the convention center is comprised of 15 steel trusses.
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Figure 2: Plan of DLCC

During construction, plans were changed for how these trusses were to be supported. The change was to go from using a compression strut to using a tension strut. After this change was made, no clear instructions were put in to the shop drawings to accommodate this change. Because of this, no one on the construction site really knew how to install the trusses.

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Figure 3: One of the Truss 13 bolts; Courtesy of the Pittsburgh Tribune - Review
The Williams Form Engineering Corp. supplied fasteners and joinery for the $354 million construction of the convention center. In addition to the nearly 200 bolts that were provided to connect the steel trusses, Williams supplied two different types of nuts. The heat treated, hardened steel anchoring nuts, which were 2” thick, were colored black and designed to fasten the truss bolts into place. The smaller, weaker locking nuts (of which there were two types), which were either ½” or 1” thick, were silver in color and designed to lock the black anchor nuts into place, nothing more.

On the 13th truss (also called line 13), the locking nuts, in contradiction to their design
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Figure 4: View of the collapsed truss; Courtesy of the Pittsburgh Tribune - Review
capabilities, were used to fasten the truss bolts instead of the anchoring nuts due to the lack of clear instructions and direction for which nuts to use, see Figure 3. Furthermore, there was insufficient inspection of the nut-and-bolt assemblies. The only inspection of the assembly was the crew foreman Rogers who inspected them by simply doing a hand check to make sure that the bolts were in securely. He did not check to see if the right nuts and bolts were used.

On February 12, 2002, the misused locking nuts finally gave in to the weight of the structure and came off causing the truss to fall to the ground killing
ironworker Paul Corsi Jr. and injuring two others, see Figures 4 and 5.








Prevention


Construction workers used silver, weaker 1" nuts that had been placed onsite instead of the stronger, black 2" nuts; the nuts were not similar in size or color. After the collapse, no one could say why those nuts had even been onsite where Truss 13 was located. Lack of communication between the workers, Dick Corp. management, and Solar Testing Lab was the overarching cause of this failure.

All parties involved claimed that checking the nuts were not their job. Officials from Dick Corp. claimed that inspecting the nuts was the job of Solar Testing Lab, which was hired by Sports & Exhibition Authority (SEA) to monitor the construction project. Even the crew's foreman said that Solar Testing Lab was supposed to test the nuts and bolts, saying, "I'm not a bolt inspector," (Law Office of Michael C. George, "Collapse Theory Gains Support"). However, when a material tes
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Figure 5: Onlookers by Truss 13; Courtesy of the Pittsburgh Tribune - Review
ter for Solar Testing Lab, Patrick McKelvey, was interviewed he claimed that no one had told him which nut was correct for the trusses and that he "probably wouldn't have noticed whether the proper nut was used," (Barnes, Tom. (June 26, 2002). "Fasteners Blamed in Collapse Convention Center Supplier Says Wrong Nuts Were Used." Pittsburgh Post-Gazette.).

If there had simply been more communication between the many different workers and companies, this failure could have easily been prevented. The workers would have known exactly what nuts to use and the companies would have known when to deliever what parts. This includes the architects and engineers providing the right documents and the companies distributing these documents so all stages and parts of the process are clear for all parties involved. "Proper and clear erection notes and procedures should have been provided in order to direct the erector on all stages of erection. However, these were clearly missing from shop drawings," (Lavon, Benjamin. Goodrich, Andrew. (November 11, 2009). "Convention Center Steel Truss Collapse." American Society of Civil Engineers Publications.)

Even if communication had stayed the same, someone knowledgeable inspecting the nuts would have caught the blaring mistake. The nuts that were supposed to be used were 2" black nuts as opposed to the nuts that caused the failure, which were smaller, 1" silver nuts. If one of the managers had come through with construction documents to check the truss who knew which nuts were correct, it would have been easy to see the wrong nuts and get them replaced before the collapse ever occured.

Construction sites are complex. There are many different people, parts, and things on one site working to complete one job. The companies and workers involved need to stay informed and communicate with each other in order for the project to be completed efficiently and without mistakes. If policies, laws, and practices are put into place to force everyone to stay connected and informed as to the materials used on each part, failures like this can easily be prevented.



Lessons Learned From the Failure


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Figure 6: Workers by the collapsed truss; Courtesy of the Pittsburgh Tribune - Review
Communication between officers and companies involved in the construction of the DLCC was the overarching cause of the 2002 truss failure. During the investigations many officials realized that nobody had been charged with the job of inspecting the connections. The officials of Solar Testing Labs didn't want to contradict the professionals at Dick Corp. while the officials at Dick Corp. assumed that Solar Testing Labs was doing all the inspections as their crews worked.

Solar Testing Labs, the company hired by SEA to oversee and monitor the project, claimed that it was not their policy to inspect every individual ground connection. In addition, they didn't inspect the connections until months after assembly; they only issued a final "all-clear." Because of the failure and the ensuing investigation, Solar Testing Labs now inspects every connection before issuing the final approval (Franken, Stephanie. (June 26, 2002). "Incorrect use of nuts blamed for collapse." Pittsburgh Tribune-Review.).


No goverment action was taken after this failure to ensure companies on construction sites communicate better. However, Solar Testing Lab's policy change is a step in the right direction. In order to prevent more of these types of failures from occuring, companies must take the initiative to communicate with their peers and within their own company. However, the public will not know if this occuring or not until another failure occurs from lack of communication.

On the construction side, better bracing of the truss would have helped take the load off the incorrect nuts. This would have given the workers more time to notice their mistake. This could have involved crane hoist lines, guy wires, or other bracing. Also, those erecting the structure must be properly trained. According to Benjamin Lavon and Andrew Goodrich, this training should make sure erectors know how to avoid : "lack of, or confusing erection procedure, unbalanced loads (created) during erection, erection violations of OSHA provissions, lack of porper training of its employees, lack of proper supervision of its employees, lack of proper inspections of its work, use of improper inspections of its work, use of improper hardware for critical connections, lack of proper engineering review, and design or fabrication changes that impact erection procedure," (Lavon, Benjamin. Goodrich, Andrew. (November 11, 2009). "Convention Center Steel Truss Collapse." American Society of Civil Engineers Publications.)





Bibliography


Barnes, Jonathan (September 02, 2002). "Inquest Calls For Homicide Charge." Engineering News-Record.
This article talks about the Pittsburgh coroner's decision to recommend that the death of Paul Corsi Jr. during the truss collapse be changed from accidental to homicide. It further details the charges, to be held againt Dick Corporation, the David L. Lawrence Convention Center's steel erection subcontractor, and the rebuttle by Dick Corp.

Barnes, Jonathan (July 08, 2002). "Inspector Says Contractor Responsible For Checking Nuts." Engineering News-Record.

This article details testimony during the investigation into the truss collapse at the David L. Lawrence Convention Center. It also deals with who was responsible for putting the smaller nuts on the truss and who was responsible for not checking those nuts.

Barnes, Jonathan. (July 29, 2002). "Steel Collapse Causes Cited." Engineering News-Record.
This article details causes of the collapse, including the wrong size nuts and weaker anchor bolts used. It also talks about problems with inspections and installation of the materials.

Barnes, Tom. (February 16, 2002). "Authority director tries to calm public's fears after convention center fatality." Pittsburgh Post-Gazette. <http://www.Post-Gazette.com/regionstate/20020216center3.asp> (February 10, 2009).

This newspaper article talks about authority figures trying to calm the public after a truss failure in the new David L. Lawrence Convention Center. The convention center was set to open two weeks after the truss fell, killing one and injuring two others. The article reveals the truss collapse was in a seperate phase than the already completed space set to open in a couple weeks. It also reassures the public that the truss failure was not caused by workers being rushed to complete the building.

Barnes, Tom. (June 07, 2002). "Collapse theory gains support." Pittsburgh Post-Gazette. <http://www.post-gazette.com/localnews/20020607inquest4.asp> (February 10, 2009).
This newspaper article states that the theory about wrong-sized nuts being the cause of the David L. Lawrence truss collapse is gaining popularity as more information comes out. It details unanswered questions and whether or not charges will be filed in relation to a worker's death.

Barnes, Tom. (June 26, 2002). "Fasteners Blamed in Collapse Convention Center Supplier Says Wrong Nuts Were Used." Pittsburgh Post-Gazette. <http://proquest.umi.com/pqdweb?index=6&did=128846471&SrchMode=1&sid=3&Fmt=3&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1265916420&clientId=9874&cfc=1> (February 12, 2010).
This newspaper article explains that silver colored nuts that were either 1/2" or 1" were used to install the 15 trusses. The nuts that were supposed to be used were black colored and were 2". The choice should have been made based on plans but no one is really sure as to who should be blamed for the mistake and no one takes responsibility for being in charge.

Barnes, Tom. (June 06, 2002). "Use of wrong nuts tied to truss collapse." Pittsburgh Post-Gazette. <http://www.post-gazette.com/localnews/20020606inquest0606p3.asp> (February 11, 2010).
This article from the Pittsburgh-Post Gazette marks a decisive point in the investigation of the truss collapse, going into further detail about the main cause. The article also covers the questioning of Robert Elmendorf and Matthew Abate, a metallurgist and ironworker, on the collapse as well as the legal issues presented by the death of Paul Corsi Jr.

"Building Floor Plans." The David L. Lawrence Convention Center. Web. 12 Feb. 2010. <http://www.pittsburghcc.com/cc/floorplans.html>
This site contains detailed specifications and floor plans of the David L. Lawrence Convention Center.

Franken, Stephanie. (June 26, 2002). "Incorrect use of nuts blamed for collapse." Pittsburgh Tribune-Review. <**http://www.pittsburghlive.com/x/pittsburghtrib/news/cityregion/s_78245.html**> (March 20, 2010.)
This article talks about the use of the incorrect "jam" nuts and includes interviews with officials from the two main companies involved, Dick Corp. and Solar Testing Labs.


Korman, Richard. (February 25, 2002). "Fatal Pittsburgh Steel Collapse Defies Quick Analysis of Cause." Engineering News-Record.
This article talks about the lack of answers found to explain the fatal truss collapse only a few weeks earlier. It summarizes the events and states that the accident will not delay the opening of the separate Phase One section of the Convention Center.

Lavon, Benjamin. Goodrich, Andrew. (November 11, 2009). "Convention Center Steel Truss Collapse." American Society of Civil Engineers Publications.
This document presented at the 5th ASCE Forensic Engineering Congress in Washington, D.C. in November of 2009, summarizes the incident itself rather than what caused it, more of a play-by-play of what occurred at the exact moment of structural failure.

Post, Nadine M. (February 18, 2002). "Fatal Collapse at Pittsburgh Center." Engineering News-Record.
This article is an overview of the failure, starting with information about the new building, continuing with information about the trusses and the accident.

Staff Writer. (February 16, 2002). "Cause of collapse unknown, official says." Pittsburgh Tribune-Review. <http://www.PittsburghLive.com/x/pittsburghtrib/s_17782.html> (February 10, 2009).
This article reveals that faulty anchor bolts might have caused the truss collapse in the David L. Lawrence Convention Center. It also details some aspects of the U.S. Occupational Safety & Health Administration's investigation, such as the fact they have six months to complete the investigation and that they may require authorities to test trusses in other areas of the convention center.

Unkown Author. (2002). "Collapse Theory Gains Support." The Law Office of Michael C. George Attorneys. <http://www.mikegeorgelaw.com/CM/In-The-News/Collapse-theory-gains-support.asp> (March 21, 2010).
This report details an investigation into the death of Paul Corsi and who is reponsible for not checking the bolts and nuts on Truss 13.

Unkown Author. (August 12, 2002). "Two Firms Fined $19,000 Each in Fatal Pittsburgh Collapse." Engineering News-Record.
This article focuses on the U.S. Occupational Safety and Health Administration's decision to fine both Dick Corporation and ADF International Incorporated because of the fatal truss collapse in February 2002. The article details reasons for the fine and what happened during the inquest.

Unkown Author. (September 09, 2002). "OSHA Agrees to Reduce Charges Against Dick Corp. in Collapse." Engineering News-Record.
This article, following the one on August 12, 2002, talks about the U.S. Occupational Safety and Health Administration's lowering of Dick Corporation's fine. The fine was lowered from $12,000 to $19,000 because of insignificant evidence that one of the three safety violations occurred.