Impact of Loading Protocol on the Performance of the Steel Moment Frame Connections

Abstract

Today, for the moment frame structures, seismic provisions of the structural engineering design codes depend on the inelastic deformation as well as inelastic capacity of the connections. A cyclic loading protocol is normally exercised for measuring such capability. This paper investigates the deformation capacity of steel moment resisting frame’s connections subjected to different loading protocols. To evaluate the performance of the connections subjected to various cyclic loads, behavior of three types of connections is studied. Behavior and capacity of each connection are assessed subjected to different loading protocols; namely ATC, FEMA and SAC. The results from this research indicate that the ATC and FEMA loading make greater demands on the connections; while SAC basic loading shows a better agreement with the target values of the loading protocol. A loading protocol has been developed taking some criteria into account in order to match the target values presented in SAC study for steel moment connection’s bam to column sub-assemblies. Then the connections were subjected once again to the proposed loading protocol and results compared to those of other loading protocols. The results reveal that the connections subjected to the proposed loading protocol provide greater deformation and strength capacity. Also, lower equivalent plastic strain and lower dissipated energy were observed when the connection is subjected to the proposed loading protocol.