Behavior of Square Hollow Section Steel Tubes Filled with Concrete under Different Loading Conditions

In this paper, the behavior of composite stub columns under different loading conditions is studied using the finite element method. The accuracy of the theoretical method is validated by comparing with the experimental results. The behavior of specimen under different loading conditions is analyzed. Then, based on the finite element method, the comparison of mechanical behavior under three typical loading conditions is studied. The results show that the difference on bearing capacity will become larger with the increase of steel area to concrete area ratio. For the core concrete loaded specimen with lower steel area-to-concrete area ratio, whose bearing capacity is the lowest, but its ductility is very good. With the increase of the steel yield strength, the bearing capacity will increase evidently for specimen loaded simultaneously. While for the specimen with only core concrete loaded, the steel yield strength has little influence except increase of ductility.