To investigate the influences of high temperature on mechanical behaviors of steel tube reinforced concrete column, the central compressive test on steel tube (ST) reinforced recycled aggregate concrete (RAC) column after exposed to 500C and 700C with/without carbon fiber reinforced polymer (CFRP) reinforcement were conducted. The failure modes, ultimate load carrying capacities and displacements, together with the strain response of the ST reinforced RAC columns were studied. The results showed that the high temperature have great influences on the failure modes and ultimate load carrying capacities. For the specimens with CFRP reinforcement, a great increase on load carrying capacity and displacement, however, the failure mode was changed from ductile to brittle failure. Moreover, the highest increase on load carrying capacity was found on the specimens with 50% RAC and CFRP reinforcement when compared to the ones with 0% and 100% RAC. The displacement and strain development curves were calculated by using an ABAQUS code, and the results were in good agreement with the experimental results. For the specimens with CFRP reinforcement, the deformations of steel tube, RAC and CFRP under compressive loading were investigated, and the strengthened mechanism was found.
