Experimental Study on Reinforcement Ratio of RCFT Columns under Axial Compression

It is clear from the former researches on reinforced concrete filled tubular steel (RCFT) structures that RCFT structures have better performance than concrete filled tubular steel (CFT) structures, in other words, because of the existence of reinforcement, the performance of RCFT differed from that of CFT. Therefore, to clarify the effect of axial reinforcement on mechanical properties of RCFT, compression tests of RCFT columns with different ratio of axial reinforcement were carried out, meanwhile, corresponding tests of CFT, reinforced concrete (RC), pure concrete, and steel tube columns were done to compare with RCFT. By a series of comparison and analysis, effect of axial reinforcement on RCFT columns were discussed, and following conclusions were drawn: reinforcement ratio has direct effect on performance of RCFT. Over arranged reinforcement will cause pre-failure of concrete without exerting strength of reinforcement, and not only may cause brittle-failure or lower performance of the structure, but also cause the increase of construction cost. On the contrary, proper ratio of reinforcement can make the RCFT possess better confined effect, improve overall performance of the RCFT structure; furthermore, whatever the ratio of reinforcement, RCFT has better performance than both CFT and RC, especially possesses more brittle-failure resistance than CFT.