Test of post-fire bearing capacity of ceramsite concrete filled steel columns after exposure to fire

The experimental investigation of post-fire mechanical behavior of a set of unprotected short columns of ceramsite concrete filled steel tubes (CCFST) are conducted, variation of residual bearing capacity of the short columns of CCFST after exposure to fire are discussed. Based on the test results, effect of the factors, such as dimension of cross section of the specimen, concrete mix proportion on the post-fire bearing capacity were especially investigated. It is shown that the CCFST short columns after exposure to fire have higher post-fire bearing capacity and better ductility, and there was no descent segment in load displacement curves of the most specimens. It was concluded that effect law of the maximum value of response temperatures on bearing capacity of CCFST short columns after exposure to fire is related to some key parameters of the specimen which are mix proportion, dimension of cross section of the specimens. It is shown that the post-fire bearing capacity of the CCFST short columns decreases with increment of water cement ratio of the concrete of the specimens subjected to fire load.