Failure: Hyatt Regency Walkway Collapse
Location: Kansas City, MO
Year: 1981
Type: Connection failure
Deaths: 114

The Hyatt Regency walkway collapse was the deadliest structural collapse in the United States prior to the collapse of the World Trade Center in 2001. The failure occurred during a dance competition with approximately 1600 attendants, present both on the ground floor and the 2nd, 3rd, and 4th walkways. In the original, design three pairs of steel tie rods suspended from the ceiling supported the concrete walkways from box girders built up with two channel sections at the 2nd floor and 4th floor. The manufacturer supplying connections found that the proposed design called for complicated fabrication that may have created damage to the threads at the 4th floor. Instead he created an alternative design that included 6 pairs of steel rods, 3 connecting the 4th floor to the ceiling, the other 3 connecting the 2nd floor to the 4th floor walkway. This would require the 4th floor girder to support not only the weight of its own walkway, but also the weight of the 2nd floor walkway, which it was not designed for. The structural engineer failed to identify the problem after the drawings were returned and submitted for construction. The capacity sufficed for the dead load in the walkways, but the large live load of viewers on July 17th caused failure.The failure occurred in the welded joint connecting the channels. [1]

Connection Detail
Haag Engineering Investigation
NBC News Report 30 Years Later