Fractures in seismically loaded bridges

This paper reviews the currently perceived causes of the damage to civil engineering structures, especially the fracture of steel bridge members, during the Hanshin-Awaji earthquake near Kobe, Japan, in January 1995. The following types of damage to bridge structures are discussed: (1) collapse of reinforced concrete bridge piers; (2) collapse of rigid frame railway viaducts; (3) local buckling of panels at the pier shaft in steel bridges; (4) failures of corner welds of steel bridge piers; (5) lantern buckling of cylindrical steel bridge piers; (6) brittle fracture at the pier corner of rigid frame steel piers; and (7) failure occurring in centrifugal cast steel pipe columns. Specifications for seismic design methods for bridges in Japan are reviewed. After the earthquake, the Guide Specifications for reconstruction and repair of highway bridges were issued as an emergency measure. The Design Specifications for Highway Bridges were revised in October 1996. A tentative design guide for railway bridges was issued in March 1996, and revision of the Specifications for these bridges is in progress. Improvements are needed especially for the seismic strengthening of reinforced concrete columns and steel bridge piers. Much has been learned from the earthquake, but much more research is needed.