Inelastic Cyclic Testing of Welded Unreinforced Moment Connections

Abstract

The results of an experimental study of the seismic performance of improved, welded unreinforced beam-to-column moment connections are presented. The study involved the inelastic cyclic testing of 11 full-scale connection specimens to evaluate the effects of weld access hole geometry, beam web attachment detail, panel zone strength, continuity plates, and composite slab on connection performance. With a high toughness weld metal and modified detailing, it is demonstrated that a welded unreinforced flange moment connection can reliably achieve an inelastic rotation of 0.03 rad or more prior to failure. The modified details include the use of a weld access hole with a modified geometry and a welded beam web. The test results indicate that a strong panel zone enhances inelastic connection performance. Based on the results of the study recommendations are given for the seismic-resistant design of improved welded unreinforced connections for steel moment-resisting frames.