Wind-induced cable vibrations caused steel diaphragm plates to fracture and fail on a 2,200-ft cable-stayed suspension bridge in Minneapolis, according to a preliminary report prepared by Northbrook, Ill.-based engineer Wiss, Janney, Elstner Associates, the firm the city hired to investigate the cause of the failure.
According to the report, "stay cable vibrations (wind induced) were not included in original design calculations package," prepared by San Francisco-based URS Corp., designer of the five-year-old Martin Olav Sabo pedestrian and bicycle bridge.