Kansas City Hyatt walkway collapse
On July 17, 1981, two interior atrium walkways collapsed during a dance party at the Hyatt Hotel in Kansas City, Missouri. One hundred fourteen people were killed and more than 200 were injured.
The walkways crossed the multistory atrium at the 2nd and 4th floors, and were suspended from the roof by steel rods. The engineer intended the rods to be continuous, with the upper walkway held in place by nuts and the rods continuing to the walkway below.
During construction, the fabricator recognized the difficulty of installing 4 story–long threaded rods, and of rotating the nuts two stories into place. A proposal for two sets of shorter rods was put forth. One set would hang the 4th floor walkway from the roof, and a second set would hang the 2nd floor walkway from the 4th floor walkway. The engineer approved the design change without performing a structural analysis.
Post-accident analysis revealed that the revision had doubled the load on the 4th floor steel beams. Further, each beam specified by the engineer was not a single member, but two parallel members welded together. Under full loading, the welds failed, causing the upper walkway to “pancake” onto the lower walkway.
