On July 17, 1981, two suspended walkways within the atrium area of the Hyatt Regency Hotel in Kansas City, Missouri cllapsed leaving 113 people dead and 186 injured. The National Bureau of Standards (NBS) was asked to determine the most probable cause of the collapse. NBS researchers first arrived in Kansas City on July 21, 1981.
Based on the results of the NBS investigation, it was concluded that the most probable cause of failure was insufficient load capacity of the box beam-hanger rod connections. Observed distortions of structrual components strongly suggest that the failure of the walkway system initiated in the box beam-hander rod connection on the east end of the fourth floor walkway's middle box beam.
Details of the investigation are included in the report, "Investigation of the Kansas City Hyatt Regency Walkways Collapse (NBS BSS 143)."