Experimental research on the behavior of concrete-filled SHS steel tubes under different loading conditions

A total of six concrete-filled square hollow section (SHS) steel tubes were tested. The main research is to study the behavior of specimens under different loading conditions, which include steel tube and core concrete simultaneously loaded, only core concrete loaded, only core concrete loaded together with grease between steel tube and core concrete. In the experiment, the load-strain relationship curve and the load-longitudinal deformation action curve were obtained and analyzed. The result showed that the bearing capacity and elastic rigidity of the specimen with core concrete loaded were lower than those of the specimen whose core concrete and steel tube were loaded simultaneously, but the ductility of the former is better than that of the later. The bearing capacity of specimen under different loading conditions is over the summation of the load bearing capacity of steel tube and core concrete. The cohesion between steel tube and core concrete had no evident influence on the bearing capacity of the specimen loaded on the core concrete.