Characterization of connections in the seismic assessment of steel moment resisting frames

Abstract

The response of steel Moment Resisting Frames (MRF) under seismic excitations is largely governed by the characteristics of beam-to-column connections. The seismic design of steel structures require that the “dissipative zones” intended to dissipate the input seismic energy are correctly identified based on the type of connections envisaged during engineering phase. Though extensive studies are reported in literature regarding response of beam-to-column connections under various types of loadings, it is strongly felt that a systematic joint characterization procedure required for seismic assessment of steel structures is still missing. Such a procedure will be eventually beneficial to the design engineers and researchers to ensure that the global seismic analysis is compatible with the assumed connection characteristics. The paper presents a detailed procedure for the characterization of beam-to-column joints necessary for seismic assessment of steel MRF structures. Extended end plate beam-to-column connections namely haunched, unstiffened and stiffened each of them representing full-strength, partial-strength and equal-strength design objectives are considered in the study. The characterization proceeds with development of moment-rotation curves using both the component method of Eurocode-3 and the Component Based Finite Element Method (CBFEM). The capacity design verifications of the connections for the assumed overstrength are then performed using CBFEM. Finally, the hysteresis behaviour of the connections under cyclic loads, where required, is predicted using the modified Richard - Abbott model.