Experiments of four-legged concrete filled steel tubular laced columns subjected to axial loads

Seven four-legged concrete-filled steel tubular(CFST) laced columns were tested with axial loads in a 5 MN pressure tester using an IMP data acquisition system to investigate the deformation and load behavior.The load-deflection curves,deformation,and ultimate load carrying capacities were analyzed with the slenderness ratio as the test parameter.The results show that the deformability of the laced columns becomes more like full-web columns as the slenderness ratio increases.All the CFST legs bore minor eccentric compression,and all models had good deformation capacity.The steel tubes yielded before the ultimate load;thus,the ultimate bearing capacities decrease with increasing slenderness ratio.Initial imperfection also affects the bearing capacity.