Study On Interface Bond Behavior Between Steel And High Strength Concrete After High Temperature

In order to study the bond-slip behavior between steel and high strength concrete after high temperature, a total of 51 specimens were designed for static push-out test after high temperature, considering three parameters of concrete strength, constant temperature and bond length. The mechanical failure process and forms were observed, and the load-slip curves with the characteristic point parameters on them were obtained, the bond strain distribution were learned, and computational formulas of ultimate strength and residual bond strength were gained by regression. The influence of change factors on the slip behavior of specimens were analyzed, and interface bonding failure mechanism after high temperature was discussed in detail. The possibilities of using existing specifications to calculate the ultimate bearing capacity of steel tube speciemens introducing material strength reduction factor were discussed.The results show that the load-slip curves mainly include three stages, the straight line rose stage, the curve descending stage and the subdued stage. The loading ends slip earlier than the free ends. When the constant temperature was under 600?, the bond strength of steel tube specimens increased with the increase of constant temperature, while the bond strength decreased when the constant temperature beyond 600?; The ultimate bond strength and residual bond strength of SRHC decreased first and then recovered partly with the constant temperature increasing. The bond strength was proportional to the concrete strength, While the average bond strength decreases with the increased of anchoring length. The interface elastic shear stiffness improved to a certain extent with the increasing of constant temperature, and with the increase of constant temperature, the bond damage process was postponed and slowed down; The bearing capacity of the steel tube specimens dropped rapidly when the temperature surpassed 400?,When the temperature raised from room temperature to 200?,400?,600?,800?, the bearing capacity of HSST was 101%,105%,76%,54%; the bearing capacity of HCST was 99%,94%,74%,55%.Some relative research results in the paper aboult bond-slip performance of interface between steel and high strength concrete after high temperature have certain reference significance for reinforcement and restoration of strength concrete composite structures.