STUDY ON BOND-SLIP BEHAVIOR BETWEEN SPAPED STEEL AND CONCRETE IN SRC STRUCTURES AFTER EXPOSED TO HIGH TEMPERATURE

The bond-slip behavior between shaped steel and concrete after exposed to high temperature has a remarkable influence on the mechanical performance of steel reinforced concrete (SRC) structures experienced high temperature. In order to study the bond strength and slip behavior of SRC members after exposed to high temperature, the statically push-out tests for eighteen SRC short columns after exposed to high temperatures and three other comparative short columns at normal room temperatures were carried out. Test results show that the typical load-slip curves of SRC short columns after exposed to high temperatures are almost the same as that at normal room temperatures. But ultimate bond strength and residua bond strength between shaped steel and concrete both descend with the elevation of the highest temperature and the increase of duration of the highest temperature ever experienced. The slip corresponding to ultimate bond strength decreases in some extent with the elevation of the highest temperature and the increase of duration of the highest temperature ever experienced, while the slip corresponding to residual bond strength increases on the contrary. Based on the test results, a bond-slip constitutive model for SRC members after exposed to high temperature is proposed, and the calculating methods to ultimate bond strength, residual bond strength and their corresponding slip in this model are also put forwarded. The proposed bond-slip constitutive relation can be employed for the finite element analysis of SRC members after exposed to high temperature.