Performance Assessment of Bolted Extended End-Plate Moment Connections Constructed from Grade St-37 Steel Subjected to Fatigue

Abstract

Most studies on the bolted extended end-plate (BEEP) moment connection have focused on the rotation capacity of the connection before the yielding of the connection members takes place, and effects of seismic low-cycle fatigue (LCF) and ultralow-cycle fatigue (ULCF) in this type of connection have received little attention. This study focused on the effects of LCF and ULCF in BEEP-moment connections in steel moment frames. In this regard, four steel moment-frame structures of 3, 7, 12, and 15 stories with BEEP connections were selected for this study. All four structures, constructed from Grade St-37 steel material, were subjected to 11 earthquake records for investigation. Also, the effects of ULCF were evaluated by ABAQUS Finite Element Software using a cyclic-void growth model (CVGM). The results revealed that the effect of LCF in BEEP connections was more notable in beams than in columns. The results also showed that in high-rise structures, higher modes of vibration play an important role in increasing the damage due to LCF. Also, in BEEP connections under ULCF, the maximum rotation capacity of the connection was achieved by preventing both the yielding of the end-plate and the failure of the bolts.