Experimental investigation on hysteretic behavior of thin-walled circular steel tubes under constant compression and biaxial bending

Abstract

This paper presents a comprehensive experimental and numerical investigation on hysteretic behavior of thin-walled circular steel tubes as loaded members in reticulated shells. The experimental setup available for constant compression and biaxial bending loading was designed to examine the failure process, failure modes, load bearing capacity, ductility, stiffness degradation and energy dissipation capacity of sixteen thin-walled circular steel tubes. Also, the effects of the loading condition, axial load ratio, slenderness and steel strength on hysteretic behavior of specimens were investigated. The study showed that test results of specimen loaded in two directions might overestimate hysteretic characteristic of this member. Premature local buckling may be caused by the high axial load ratio and the recommended axial load ratio may be n ≤ 0.2 to ensure the load bearing capacity, deformation capacity and ductility of circular steel tubes and to prevent the premature local buckling occurring in engineering practice. Slenderness affects the load bearing capacity, ductility, and energy dissipation capacity of specimens, and with an increasing slenderness, the stiffness degraded considerably and quickly. Specimens with high strength steel exhibited higher load bearing capacity and better stiffness but lower energy dissipation capacity than those made by low strength steel. Furthermore, the nonlinear finite element analysis was performed to simulate hysteretic behavior of test specimens, and the results got a satisfactory agreement with those of test.