Performance of lightweight concrete filled steel tube columns

This thesis explores the performance of lightweight concrete filled steel tube columns under axial load. The experimental study was conducted using two mixes design of M30 for LWC and SCC that filled into different dimensions of steel tubes to accomplishing 16 specimens, involved 8 of LWCFST and 8 of SCCFST specimens. The main parameters that considered in this study are concrete compressive strength, diameter to tube thickness ratio and length to diameter of tube ratio, which had an effect on the axial load capacity of LWCFST column. Test results confirmed the confinement effect. And increasing of diameter to steel tube thickness ratio leads to significantly decrease the axial load capacity of the LWCFST columns. In addition, if length to diameter of tube ratio has to decrease, it causes to increasing the axial load capacity of the LWCFST columns. Furthermore, occurrence local buckling in the failure mode of the short columns (length to diameter of tube ratio = 2), whereas, for longer columns (length to diameter of tube ratio = 5, 7.5 and 10.5), and overall buckling had observed. Finally, the prediction and comparison methods illustrate that AISC 360-10 provides good values which are close to the experimental results more than of EC4 1-1, 1994 with the most conservative in the prediction of axial load capacity of LWCFST columns under axial load.