Investigation on buckling behavior of T-shaped box-T section columns under axial load

Abstract

Special-shaped columns (i.e., L-shaped, T-shaped, and cross-shaped) present the main advantages of avoiding column protrusion and enlarging the indoor space, and they also have large stiffness and strength in the direction of their longer sections. However, there is a lack of systematic research of the buckling performance of T-shaped column. In this paper, T-shaped box-T section columns, composed of one cold-formed box section and several T-sections, were concerned. The elastic buckling analysis of T-shaped box-T section columns was firstly conducted, and it is recommended to set stiffeners to restrain the distortional buckling of the first order buckling modes of the columns. Based on the elastic buckling analysis, 10 T-shaped box-T section columns with one stiffener were tested under axial load. The measured material properties, geometries, initial imperfections, failure modes, ultimate capacities, and loading histories of the specimens were reported and employed to validate the finite element (FE) models. The plane section assumption was confirmed for T-shaped box-T section columns based on the records of the strain gauges and the FE results. FE analysis was carried out to investigate the effects of initial geometric imperfections, residual stress, and stiffeners on the buckling performances of T-shaped box-T section columns. Totally 880 FE results of the pin-ended columns were employed to evaluate the design curves of the current specifications GB 50017-2017, EN 1993-1-1, and ANSI/AISC 360-16, and new design curves were also proposed.