Development of improved welded moment connections for earthquake-resistant design

A comprehensive research program was conducted at Lehigh University to investigate the causes of brittle failures observed in numerous welded connections during the 1994 Northridge earthquake and ways to improve their ductility. In this program, tests on pre-Northridge connection details demonstrate that several weak links in the connection design and fabrication resulted in their premature failures. To develop improved details for welded unreinforced connections the effects of weld metal, weld access hole geometry, beam web attachment, continuity plates, and panel zone strength on cyclic ductility were investigated using non-linear finite element models and full-scale connection tests. The results from these studies are presented, along with recommendations to insure ductile connection performance.