Research on shear strength of CFSST column and H-section with beam composite joint of unequal depth

Abstract

Four concrete-filled square steel tube (CFSST) columns and H-sections with beam composite joints of unequal depth were designed based on existing specifications and manufactured at ⅓ scale. A failure test of the specimens was carried out under lateral cyclic loading. Different height ratios between the left and right beam, ζ, (ζ = 0.52, 0.39, 0.26, 0.13) were tested to analyze the failure mode, hysteresis characteristics, ductility, strain, and deformation of the specimens and the damage characteristics of the structure. An equation was established to determine the shear bearing capacity of the CFSST column and H-section. The results show that shear failure in the joint core area is the dominant failure mode of the specimen. The greater the beam ratio, the smaller the yield displacement of the specimen is, and the earlier the joint core area reaches the yield strain. The damage value obtained from Chen's model is in good agreement with that obtained from the test and accurately describes the damage evolution and damage limit of the specimen from “basically intact” to “completely damaged”. The shear resistance of the joint core area is primarily borne by the steel tube web, the main concrete compression strut in the core area, and the restrained compression strut. The theoretical values and the experimental values of the shear bearing capacity of the CFSST column and H-section are in good agreement, demonstrating the accuracy of the proposed theoretical equation.