The siouxland veterans memorial bridge, mm from sioux city, nebraska, to sioux city, iowa, was opened to traffic in january 1981. In may 1982 iowa department of transportation personnel discovered a fracture across the full width of the top flange on the down stream tie gemirder. The investigation into the cause of the fracture included chemical and physical testing and fractographic and metallographic examinations. results of the latter examinations showed that the fracture originated at a gas-flame-cut edge of the 2 3/4-in.-thick a588 flange plate. It arrested at least once at a depth of 0.37 in. And possibly earlier at a depth of about 0.05 in. Before propagating in a brittle mode across the flange. The fracture surface was heavimly corroded, indicating that the fracture had occurred long before its discovery. The physical tests indicated that the plate in which the fracture occurred did not meet the specified toughness requirements. Additional tests on samples of material extracted from other parts of the girders revealed highly variable toughness properties, some of which did not meet the requirements of the specifications either. thispaper appears in transportation research record mno. 1180, bridge design and testing.
Samenvatting