Built in 1920, the original capacity of the University of Washington's Football Stadium was only a mere 30,000, (CBS interactive, 1). Throughout the years Husky Stadium has undergone several renovations to increase the seating capacity. The total expansion to seating 72,500 resulted from four different expansions. This article is mainly concerned with the 13,000 additional bleacher seats added in 1987. Two successful sections, out of nine total, of the expansion were nearing completion. On February 25, 40 construction workers were diligently on the job when one noticed a buckle in a steel tube that supported the overhanging roof. All workers were able to escape but the 250 tons of steel all came crashing to the ground. This case study will take a detailed look at this near fatal stadium seating collapse.
Key Words
Guy Wires, Buckling
Events Leading Up to Collapse
Husky Stadium was originally constructed to hold a capacity of 30,000 people. In 1936, 10,000 above-grade seats were added around the rim of the structure. In 1950, 15,000 additional seats were added. These seats were roof covered stands added to the south side of the stadium. In 1968, 3,000 seats were added to the north rim and portable bleachers were installed beyond the east end zone. In 1987, 13,000 additional seats were added to the North Stands of the Stadium. This is the addition where the collapse occurred. Only two of nine sections were nearing completion. Construction was on time at this point. Lydig Construction of Spokane was the construction company working on the job. The primary structure being added was structural steel frames spaced approximately 50 feet on center along the width of the stadium. The frames consist of the cantilevered roof structure, extending the full width of the addition. They will support the additional seats to be added.
Causes of the Failure
On February 25, the collapse of the first two sections of the addition occurred. At 8:30 a.m. there was a crew of about 40 men working on the structure. Approximately 30 minutes later an ironworker spotted a buckle in a 28 inch diameter tube that supported the overhanging roof. In the usual steel tubular beam analysis, the cross section of the tubes is assumed to remain the same, however at large deformations significant local buckling or distortion of the cross section may occur, (Chen and Sohal, 2). All workers were then informed to evacuate the site. As the final iron worker was exiting, the entire structure began shaking and they all ran as the 140 ft high structure violently came crashing to the ground. Investigations were performed to determine the cause of the collapse. All pointed to the same triggering mechanism, removal of guy wires. Guy wires are tension cables designed to add stability to structures and are usually anchored at equal distances to allow similar tension in each wire, (Guy-wire, 1). There were 9 guy wires that were used to support the structure during the construction. Six of the guy wires were removed too early which resulted in the structure being unable to resist against lateral forces put on the members, (Lange, 1). This is what unanimously caused the collapse of the 1987 addition to the University of Washington Football Stadium. The iron workers that removed the guy wires objected saying that it was unsafe to do so but in the end did the task, (Sanger, 1).
John Stamet was on the scene the day of the collapse and was actually able to capture the collapse with photographs. Stamets was taking a picture of a crack in the steel framework and overheard workers talking about the structure and decided to stay and within minutes was able to photograph the event. He stated, "I was totally psyched. I just started shooting. Then it started to go. I thought, 'Oh my God, it's happening right now.' I had been standing there for only 10 minutes," (Griffin, 1). The amazing pictures help people visualize the destruction. These documented photographs can be viewed at the following site: http://uwnews.org/images/newsreleases/2008/February/20080221_pid39937_aid39936_stadium_w600.jpg.
Prevention
The collapse could have been prevented if the guy wires were removed at the proper time. Lydig Construction removed the guy wires too early. If the engineer had stated when it would have been appropriate to remove the wires the collapse could have been prevented. There was no indication in the code however stating the engineer had to do so. Therefore, the collapse was just a result of a loop hole in communication and the code.
The collapse also could have been prevented if the contractor would have listened to the iron workers who suggested that the removal was unsafe. This happens a lot in our industry when people dont listen to suggestions because they don't like to be underminded. This also happens because most of the time, the people making the decisions are working on several projects and fail to think things completely through not taking into account the consequences. This is a reminder that no matter who suggests a claim it should always be taken seriously.
Industry Lessons Learned
The industry seems as though not much was learned from this collapse. After doing research, several other construction failures similar to this one occurred because of the same reasoning. They were not as big scale as the washington stadium collapse but still influencial on the job, one such project was a 2000 ft. tall guyed television transmission tower which collaped in 1988, (Feld and Carper, 484). This was only a year after the husky stadium collapse. Three construction workers were replacing the steel structure's crossbracing. It also collapsed when bracing was removed to early. All three workers were killed. The major lesson that seems like it hasn't been learned is, If there is any doubt on whether or not bracing can be removed ask the proper person before going through with it.
Conclusion
The addition was able to be completed by the start of the football season that year. Today it is still having construction issues being one of the oldest college football stadiums in the nation. Bowed seating, rusted flooring, exposed rebar, and water runoff are all problems that need to be dealt with the continuing use of the stadium, (Raley, 1). It will be interesting to see how these problems and new problems will be handled in the near future.
⁷ Raley, Dan. (September 27, 2007). "Husky Stadium Aging Not So Gracefully." Seattle P-I, Seattle.
⁸ Sanger, S. L. (March 14, 1987). "Stadium Firm's Findings Cause of Collapse: Crews Removed Supports Too Soon." Seattle P-I, Seattle. News Section Page A-1.
University of Washington Football Stadium Addition Collapse (1987)
Table of Contents
Abstract
Built in 1920, the original capacity of the University of Washington's Football Stadium was only a mere 30,000, (CBS interactive, 1). Throughout the years Husky Stadium has undergone several renovations to increase the seating capacity. The total expansion to seating 72,500 resulted from four different expansions. This article is mainly concerned with the 13,000 additional bleacher seats added in 1987. Two successful sections, out of nine total, of the expansion were nearing completion. On February 25, 40 construction workers were diligently on the job when one noticed a buckle in a steel tube that supported the overhanging roof. All workers were able to escape but the 250 tons of steel all came crashing to the ground. This case study will take a detailed look at this near fatal stadium seating collapse.
Key Words
Guy Wires, BucklingEvents Leading Up to Collapse
Husky Stadium was originally constructed to hold a capacity of 30,000 people. In 1936, 10,000 above-grade seats were added around the rim of the structure. In 1950, 15,000 additional seats were added. These seats were roof covered stands added to the south side of the stadium. In 1968, 3,000 seats were added to the north rim and portable bleachers were installed beyond the east end zone. In 1987, 13,000 additional seats were added to the North Stands of the Stadium. This is the addition where the collapse occurred. Only two of nine sections were nearing completion. Construction was on time at this point. Lydig Construction of Spokane was the construction company working on the job. The primary structure being added was structural steel frames spaced approximately 50 feet on center along the width of the stadium. The frames consist of the cantilevered roof structure, extending the full width of the addition. They will support the additional seats to be added.Causes of the Failure
On February 25, the collapse of the first two sections of the addition occurred. At 8:30 a.m. there was a crew of about 40 men working on the structure. Approximately 30 minutes later an ironworker spotted a buckle in a 28 inch diameter tube that supported the overhanging roof. In the usual steel tubular beam analysis, the cross section of the tubes is assumed to remain the same, however at large deformations significant local buckling or distortion of the cross section may occur, (Chen and Sohal, 2). All workers were then informed to evacuate the site. As the final iron worker was exiting, the entire structure began shaking and they all ran as the 140 ft high structure violently came crashing to the ground. Investigations were performed to determine the cause of the collapse. All pointed to the same triggering mechanism, removal of guy wires. Guy wires are tension cables designed to add stability to structures and are usually anchored at equal distances to allow similar tension in each wire, (Guy-wire, 1). There were 9 guy wires that were used to support the structure during the construction. Six of the guy wires were removed too early which resulted in the structure being unable to resist against lateral forces put on the members, (Lange, 1). This is what unanimously caused the collapse of the 1987 addition to the University of Washington Football Stadium. The iron workers that removed the guy wires objected saying that it was unsafe to do so but in the end did the task, (Sanger, 1).John Stamet was on the scene the day of the collapse and was actually able to capture the collapse with photographs. Stamets was taking a picture of a crack in the steel framework and overheard workers talking about the structure and decided to stay and within minutes was able to photograph the event. He stated, "I was totally psyched. I just started shooting. Then it started to go. I thought, 'Oh my God, it's happening right now.' I had been standing there for only 10 minutes," (Griffin, 1). The amazing pictures help people visualize the destruction. These documented photographs can be viewed at the following site: http://uwnews.org/images/newsreleases/2008/February/20080221_pid39937_aid39936_stadium_w600.jpg.
Prevention
The collapse could have been prevented if the guy wires were removed at the proper time. Lydig Construction removed the guy wires too early. If the engineer had stated when it would have been appropriate to remove the wires the collapse could have been prevented. There was no indication in the code however stating the engineer had to do so. Therefore, the collapse was just a result of a loop hole in communication and the code.The collapse also could have been prevented if the contractor would have listened to the iron workers who suggested that the removal was unsafe. This happens a lot in our industry when people dont listen to suggestions because they don't like to be underminded. This also happens because most of the time, the people making the decisions are working on several projects and fail to think things completely through not taking into account the consequences. This is a reminder that no matter who suggests a claim it should always be taken seriously.
Industry Lessons Learned
The industry seems as though not much was learned from this collapse. After doing research, several other construction failures similar to this one occurred because of the same reasoning. They were not as big scale as the washington stadium collapse but still influencial on the job, one such project was a 2000 ft. tall guyed television transmission tower which collaped in 1988, (Feld and Carper, 484). This was only a year after the husky stadium collapse. Three construction workers were replacing the steel structure's crossbracing. It also collapsed when bracing was removed to early. All three workers were killed. The major lesson that seems like it hasn't been learned is, If there is any doubt on whether or not bracing can be removed ask the proper person before going through with it.Conclusion
The addition was able to be completed by the start of the football season that year. Today it is still having construction issues being one of the oldest college football stadiums in the nation. Bowed seating, rusted flooring, exposed rebar, and water runoff are all problems that need to be dealt with the continuing use of the stadium, (Raley, 1). It will be interesting to see how these problems and new problems will be handled in the near future.Bibliography
¹ (2009). "Guy-Wire." <http://en.wikipedia.org/wiki/Guy-wire>. (Sept. 20, 2009)² CBS Interactive. (2009). "Huskie Stadium." <http://www.gohuskies.com/facilities/husky-stadium.html>. (September 20, 2009).
³ Chen, Wai-Fah and Sohal, Iqbal S. (1987). "Local Buckling and Sectional Behavior of Fabricated Tubes." ASCE.
⁴ Feld, Jacob and Carper, Kenneth L. (December, 1996). "Construction Failure." Wiley, John and Sons Incorporated. 434(3).
⁵Griffin, Tom. "The Crash of 87'." Columns at the University of Washington Back Pages. WA. Page12/96.
⁶ Lange, Grer. (January 18, 2001). "Husky Stadium Collapses on February 25, 1987." Historylink.org. <http://www.historylink.org/index.cfm?DisplayPage=output.cfm&File_Id=2947>.
⁷ Raley, Dan. (September 27, 2007). "Husky Stadium Aging Not So Gracefully." Seattle P-I, Seattle.
⁸ Sanger, S. L. (March 14, 1987). "Stadium Firm's Findings Cause of Collapse: Crews Removed Supports Too Soon." Seattle P-I, Seattle. News Section Page A-1.