Experimental and Numerical Studies of Failure Modes and Load-Carrying Capacity of Through-Diaphragm Connections

Abstract

Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular (CFST) columns and steel beams. To investigate the behavior of this type of connection in both modes, two through-diaphragm connections were tested under cyclic and monotonic loadings and the load-carrying capacity, ductility, and strength of degradation of connections were discussed. Using ABAQUS software, we developed nonlinear finite-element models (FEMs) to simulate the load-carrying capacity and failure modes of the connections under monotonic loading. The finite-element (FE) analysis and test results showed reasonable agreement for the through-diaphragm connections, which confirms the accuracy of FEMs in predicting the load-carrying capacity and failure modes of connections. Based on the validated FEM, a parametric study was then conducted to investigate the influence of the thicknesses of the tube and diaphragm on the load-carrying capacity and failure modes of these connections. The results indicate that the strength, stiffness, and load-carrying capacity are influenced less by the thickness of the diaphragm, and more by the thickness of the steel tube. According to the FE analysis results, it can be found that the critical condition between the two failure modes is determined by the shear resistance and bending resistance.