INTERFACE BOND BEHAVIOR BETWEEN CIRCLE STEEL TUBE AND HIGH STRENGTH CONCRETE AFTER HIGH TEMPERATURES

In order to reveal the interface bond behavior between a circle steel tube and high strength concrete (HCST) after high temperatures, a total of 17 circle steel tubes filled high strength concrete specimens were designed for a push-out test after high temperatures, by considering three parameters such as high strength concrete grade, max high temperature and of bond length. The load-slip curves, bond strain distribution and parameters of feature points were obtained. After that, the computational formulas for residual bond strength were gained by regression. The influence of change factors on the slip behavior of HCST specimens was analyzed, and the bond slip constitutive formula was put forward. The results show that:the bond strength decreases with the increase of temperature, the effect of bond strength increases with the strengthen of concrete subsided after temperature; the bond damage process was postponed with the increase of temperature; the energy dissipation capacity of the bonding interface increased with the rise of concrete strength grade and temperature.