Cyclic behaviour of laterally skewed special moment frame connections having composite concrete slabs

This study presents a numerical investigation into the cyclic performance of skewed special moment frame (SMF) connections that include composite concrete slabs. The study uses advanced finite element simulations to investigate the behaviour of shallow (W14×), medium (W24×) and deep (W33×) steel column sections with three levels of beam skew (10, 20 and 30 degrees) for both bare-steel and composite (steel-concrete) construction. To account for complex torsional boundary conditions that may affect the skewed connection response, prequalification-type analyses were conducted considering the middle storey of a three-storey, two-way moment frame configuration. In the analyses, all skewed configurations achieved at least 0.04 rad of connection rotation during the cyclic loading protocol prior to a 20 % reduction in moment capacity. When a composite concrete slab was added, column twisting and column flange yielding increased at large skew angles (30 degrees) during positive moment cycles.