Experimental Study of Low-Cycle Fatigue Behavior of a Welded Flange-Bolted Web Connection in Steel Moment-Resisting Frames

This paper describes an experimental investigation of the low-cycle fatigue (LCF) behavior of welded flange-bolted web (WFBW) connections, which are commonly employed in high-rise steel moment-resisting frames (MRFs) in Japan. The main parameters investigated in this study were (1) bolt configuration of the web connection and (2) steel grade. According to test results, LCF capacity depends on the slip behavior of different bolt configurations, even at relatively minor inelastic rotations. Slip behavior effects can be evaluated by the yield strength of the shear plate or the slip-critical strength; for specimens whose shear plate yield strength was designed to be higher than the slip-critical strength, LCF capacity showed that the upper limit can neglect slip behavior. Furthermore, it was shown that LCF behavior can be evaluated by the same fatigue curve in the relationship of fatigue capacity and beam rotation amplitude, regardless of steel yield stress.