Eccentric compression behavior of reinforced recycled aggregate concrete columns after exposure to elevated temperatures: Experimental and numerical study

Abstract

As the thermal performance of recycled aggregate concrete (RAC) is different from that of natural aggregate concrete (NAC), the mechanical properties of reinforced recycled aggregate concrete (RRAC) members after exposure to elevated temperature have been attracted great interest. However, there are little literatures about the eccentric compression behavior of the RRAC column after exposure to elevated temperature. This paper presents experimental and numerical studies on the eccentric compression behavior of RRAC columns after exposure to elevated temperatures. In this research, nine specimens were tested to study the effects of the recycled coarse aggregate (RCA) replacement percentage, elevated temperature and eccentricity ratio on eccentric compression behavior. The results showed that the temperature was the primary factor influencing the eccentric compression behavior, followed by eccentricity ratio, while RCA replacement percentage had the least effect. As temperature increased or eccentricity ratio decreased, the failure mode of eccentric columns changed from tension-controlled to compression-controlled, while the RCA replacement percentage had a little influence on it. The eccentric load bearing capacity decreased as the temperature and eccentricity ratio increased or RCA replacement percentage decreased. The parametric analysis of finite element (FE) model indicated that there was a coupling effect between design parameters of slenderness ratio, eccentricity ratio and longitudinal reinforcement ratio with temperature on the eccentric load bearing capacity. Based on the ABAQUS, the cross-sectional thermal field of RRAC columns was simulated. An equivalent model for the residual bearing capacity of RRAC columns was presented and agreed well with the results of experiment and simulation.