University

On Sunday, May 18, 1997, just prior to the graduation commencement, approximately one-third of the balcony collapsed, injuring several visitors, one of whom later died. On May 19, 1997, WDP was requested to conduct an independent engineering investigation to determine the cause of the collapse. The design was traced back to the early 1800's. An expert report summarizing the investigation was issued in August 1997.

As part of the investigation, WDP visited the site to make visual observations of the debris, take measurements, gather material samples, and determine the existing conditions of the structure. Laboratory investigations and testing were conducted on two of four hanger rods and on portions of the face beam. Eyewitness accounts of the collapse and conditions prior to the collapse were studied. Analytical studies of the structural system and individual structural elements were conducted.

The most probable precipitant of the partial collapse at the northern end of the balcony was the tensile failure of one of four primary hanger rods used to support the cantilevered edge of the balcony. Laboratory testing revealed that the hanger rods are of late 18th century to mid-19th century construction and are most likely the original rods used to construct the balcony during the 1820's. The failed hanger rod had experienced a 96% reduction in effective area due to the long-term corrosion of the rod within the balcony face beam.