Bond behavior of recycled aggregate concrete-filled steel tube after elevated temperatures

This paper experimentally investigated the interfacial bond behavior of recycled aggregate concrete-filled steel tubes (RACFST) after different temperatures (i.e., 20 ?C, 200 C, 400 C, 600 C). A total of 40 specimens (twenty circular columns and twenty square columns) were tested by means of push-out to study the effect of the following parameters: (a) experienced temperature (T), (b) mass replacement percentage of recycled coarse aggregate (gamma) and (c) cross-section shape. The influences and mechanism of above parameters on bond behavior were discussed. The test results indicate that T and gamma had different influences on bond behavior and interfacial damage resistance. The interfacial failure process of the square specimen was non-uniform compared with that of the circular specimen and its overall failure process was more brittle. The bond behavior and interfacial damage resistance of the circular specimen were generally stronger than those of the square specimen. Besides, applicability of several existing prediction formulas for bond strength was evaluated. Lastly, more accurate prediction formulas for bond strength and analytical models for bond stress-slip relationships were proposed.

Automated summary

This paper experimentally investigated the interfacial bond behavior of recycled aggregate concrete-filled steel tubes after different temperatures and discussed the influences and mechanism of temperature, mass replacement percentage of recycled coarse aggregate, and cross-section shape on bond behavior. More accurate prediction formulas for bond strength and analytical models for bond stress-slip relationships were proposed.