Experimental and finite element study on seismic performance of the LCFST-D columns

In this paper, special-shaped columns composed of concrete-filled steel tube mono-columns connected by double vertical steel plates (LCFST-D) are proposed. Five specimens were tested under a constant axial force and cyclic lateral loading. The variables studied in the experiments include the axial compression ratio, sectional dimensions of the mono-column, and the width and thickness of the vertical steel plates. The specimens behaved in a ductile manner and experienced stable hysteresis behaviour before failing in a sequence involving local buckling at the base of the side mono-column, compressive crushing of concrete at the base of the side mono-column, and fracture propagation at the boundary between the side and central mono-column. The seismic behaviour of the specimens was evaluated in terms of strength, stiffness, deformation, ductility, energy dissipation capacity, and strain distribution. Based on the experiments conducted on these LCFST-D columns under cyclic loading, 3-D nonlinear element models were used to analyse the mechanical properties and seismic behaviour of LCFST-D columns. The results of this finite element analysis showed good agreement with the experiment results. Overall, the seismic behaviour of the LCFST-D column was significantly better than the behaviour of L-shaped columns composed of concrete-filled steel tube mono-columns connected by a single vertical steel plate (LCFST-S). Additionally, it was found that the mono-columns worked more cooperatively in the LCFST-D column arrangement. The research presented in this paper provides a basis for the application of LCFST-D column structural systems in high-rise steel buildings.