Seismic Behavior of Hybrid Frame Joints between Composite Columns and Steel Beams

Abstract

This study presents experimental and numerical study on cyclic behavior of SRC composite columns-steel beam joints. The pseudostatic experiments were carried out on four samples with different axial loads. X-shaped shear reinforcement was added in the sample no. 4 in order to investigate its effect on the crack resistance in the joint core area. Low-frequency cyclic load was applied at beam ends to simulate the earthquake action. The failure characteristics, hysteretic behavior, stiffness degradation, shear resistance, and displacement ductility were investigated. Experimental results indicated that the failure mode of the joints was mainly shear failure, and the composite joints showed excellent seismic behavior with higher capacity and good ductility and energy dissipation ability. X-shaped shear reinforcement performed well to increase the concrete crack resistance. Shear forces from both experimental test and theoretical analysis were compared, and suggestions were given on modification of theoretical formulas. Simulation using the ABAQUS model showed good results that agreed well with the test results. Steel stress distribution and damage development were analyzed in the model. More parameters of web thickness, stiffener thickness, concrete strength, and stirrups and their influence on shear resistance were studied.