Seismic performance of CFDST column to steel beam welded-bolted joint with slab

Abstract

To study the impact of RC slab on the seismic performance of CFDST column to steel beam welded-bolted joint, two CFDST column to steel beam welded-bolted joints with RC slab and two without RC slab were designed and fabricated. Low-cycle reciprocating load tests were conducted to analyze the effects of different configurations and the failure modes, hysteresis curves, skeleton curves, ductility, energy dissipation capacity, beam-end strain of the joint. The results showed that the hysteresis curves of all joints were relatively full and exhibited no pinching phenomenon. All joints experienced ductile failure, with failure modes characterized by tensile fracture at the connection between the steel beam upper flange and the upper ring plate, tensile tearing at the transition sections of the upper ring plate, wavy plastic deformation of the upper flange under compression, or crushing of the RC slab. The RC slab effectively improved the moment capacity, ductility, and energy dissipation capacity of the specimens, and also delayed the stiffness and strength degradation. The moment capacity, ductility, initial stiffness, and energy dissipation capacity of the specimens were reduced by decreasing the number of bolts in the lower ring plate. The nonlinear finite element method (FEM) models of the composite joints were established using Abaqus, and the failure modes and moment capacity obtained from the models were in good agreement with the experimental results. Based on the validated FEM models, some design parameters of the joints were explored.