Cyclic-Loading Performance of Welded Flange-Bolted Web Connections

Cyclic-loading tests were conducted on eight large-scale welded flange-bolted web steel moment connections. The objective was to investigate the need for supplemental welds on the beam web connection, for beam sections where the web accounts for a substantial portion of the beam's fluxural strength. Such supplemental web welds are currently required by model seismic codes in the United States. Results of the testing program showed highly variable performance among the eight specimens. Plastic rotations developed by the beams prior to connection failure were judged to be poor to marginal for severe seismic applications. All connections failed by fracture at or near the beam-flange groove welds. Variability in the performance of the beam flange groove welds appears to have dominated the response of the specimens. This paper summarizes the test program and compares results to those of previous U.S. test programs. Concerns are expressed about the welded flange-bolted web moment connection detail for severe seismic applications.