You have probably just read the Knoxville News-Sentinel's account of the failure of the three-span State Route 69 Bridge over the Tennessee River. During construction, the two erected spans of the steel superstructure suddenly collapsed and fell into the Tennessee River.Ý Of the three ironworkers working on the steel superstructure at the time of the collapse, two were recovered uninjured. The third man drowned; his body was recovered five days later.
Bridges are important structures and have been constructed and used safely for many years. Although a structure may be very stable and capable of transferring design loads to the foundation when it is completed, during construction it may behave differently. If all of the primary members or secondary members are not positioned and secured, the structure may respond to loading differently than the completed structure. Construction loads often are different from the design loading of the completed structure. On the morning of May 16, 1995, an unexpected loading of the incomplete bridge superstructure caused the Route 69 bridge to catastrophically fail--with tragic results.
Immediately after the accident, the engineering consulting firm Wiss, Janney, Elstner Associates, Inc. [WJE] of Northbrook, IL, was contracted by the State of Tennessee Attorney General's office to investigate the collapse and report the cause. During the case study, you will have controlled access to data accumulated by WJE. To begin your research, you should read the first two chapters of WJE Report No. 951078 (see next page) . You will also have access to a large gallery of photographs taken of the accident scene and a set of engineering drawings for the bridge.
During this case study, you will be directed to break into small groups; each group will then research the circumstances surrounding the accident, determine the primary cause of the accident, and report their findings to the class. Each group will then develop, build, test, and present a laboratory model to demonstrate a potential failure scenario. You will be working individually, in teams, and as a class.
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