Stability of weld metal subjected to cyclic static and seismic loading

摘要

Brittle fracture of the welded connections was observed in the steel framed buildings in the vicinity of Northridge, California after the 17 January 1994 earthquake. Fractographic examination of numer- ous beam--column moment connections revealed that the fractures initiated from a notch--like defect formed when the backing bar was left in place. The backing bar notch was enlarged when poor work- manship resulted in adjacent lack-of--fusion and slag inclusions. The problem was further exacerbated when low notch toughness weld metal was deposited that was unable to prevent initiation of unstable crack extension or brittle fracture.