Impact of aggregate content and tube thickness on semi-lightweight aggregate concrete filled steel tube subjected to uniaxial compression

Artificial lightweight aggregates (LWA) generally can be more deformable in lateral expansion than that of natural crushed stone. Therefore, concrete made of LWA can exhibit a higher Poisson effect, and this characteristic could be advantageously used in the confined elements. In the present study, experimental research on behaviors of semi-lightweight aggregate concrete filled steel tube (LWACFT) under axial compression is performed, in which the key parameters such as the volume content of LWA and the thickness of steel tube are involved. The results showed that the bearing capacity of LWACFT columns is influenced by the compressive strength and Poisson effect of LWAC in dual-facets. With a rational LWA volume fraction, the bearing capacity of LWACFT columns is not less than that of traditional CFT. Furthermore, the experimental results of bearing capacity are compared with the results by current design codes. With the volume content of LWA and the steel thickness as the variable, the modified and simplified models have been proposed to predict the axial load versus strain curves and the bearing capacity of LWACFT columns. The research results have demonstrated that the predicted results by the model proposed in this study agree well with the experimental ones.