On April 23, 1987, the L'Ambiance Plaza building under construction in Bridgeport, Connecticut, collapsed killing 28 construction workers. This was the largest loss of life in a U.S. construction accident since 51 workmen were killed in the collapse of a reinforced concrete cooling tower under construction at Willow Island, West Virginia, in 1978. On April 24, 1987, the Occupational Safety and Health Administration (OSHA), Department of Labor, requested that the National Bureau of Standards (NBS) carry out an investigation of the failure to determine the most probable cause of the collapse. Data were collected and assessments made of the nature of the failure of various elements of the structure during and subsequent to the rescue efforts. In addition to observations from the on-site inspection, the NBS team in carrying out its investigation used:
- information on the collapse obtained from interviews of survivors and eyewitnesses;
- project documentation including design specifications, plans, shop drawings, construction records, testing laboratory reports and project correspondence;
- laboratory tests of samples removed from the collapsed structure;
- data obtained from a subsurface investigation at the site after the collapse, and;
- analytical studies, including computer analyses.
It was concluded that the most probable cause of the collapse was due to loss of support at a lifting jack in the west tower during placement of an upper level package of three floor slabs.
For more information and details of the investigation, see the NIST report "Investigation of L'Ambiance Plaza Building Collapse in Bridgeport, Connecticut (NBS IR 87-3640)."