Behavior of Steel Shear Connections under Column-Removal Demands

Abstract

An understanding of the behavior of shear connections in steel gravity frames under the unique combinations of moment, shear, and axial force relevant to extreme loading conditions is necessary to assess the vulnerability of a structure to disproportionate collapse. However, such an understanding is currently limited by a deficiency of physical test data. To investigate the inherent robustness of commonly used steel shear connections, an experimental program consisting of 35 full-scale physical tests was completed. Specimens included shear-tab, welded-bolted single-angle, bolted-bolted single-angle, and bolted-bolted double-angle connections. A testing procedure was developed that imposed on a connection the force and deformation demands that would be expected in the bays immediately adjacent to a compromised column in a symmetrical multibay frame. Various geometric arrangements of each connection type were tested, and each arrangement was subjected to a range of loading histories representing different column-removal scenarios. The test results characterize the load-development history, deformation mechanisms, and expected failure modes following column removal for each type of connection. Connection strength and ductility limits under the effects of this unique type of combined loading are quantified.