Shear behavior of steel reinforced recycled aggregate concrete beams after exposure to elevated temperatures

Abstract

This paper experimentally investigates the shear behavior of steel reinforced recycled aggregate concrete (SRRAC) beams after exposure to elevated temperatures. A total of seventeen specimens, including thirteen SRRAC beams exposed to elevated temperatures (i.e., 200 °C, 400 °C and 600 °C) and four SRRAC beams at room temperature as reference, were fabricated with different recycled coarse aggregate (RCA) replacement ratios of 0, 30%, 70% and 100%, respectively. The influence of different parameters (i.e., temperature, RCA replacement ratio and compressive strength of concrete) on the shear behavior of SRRAC beams was investigated intensively. The experimental results indicate that the concrete colour changes from light grey to grayish-reddish with increasing temperature. Increasing temperature and RCA replacement ratio can increase the weight loss of SRRAC beams. The failure patterns of SRRAC beams are similar to those of steel reinforced natural aggregate concrete (SRNAC) beams after exposure to the same elevated temperatures, and the bearing capacity and initial stiffness of beams will reduce as the temperature increases. Increasing the RCA replacement ratio can reduce the initial stiffness of beams. In addition, five design codes including YB 9082, JGJ 138, Europe 4, AISC 360, and AIJ-SRC were employed to evaluate the residual shear capacity of SRRAC beams. Based on the experimental data, a grey correlation analysis was conducted to evaluate the parametric sensitivity of the shear behavior of SRRAC beams. The evaluation results indicate that the selected codes for SRNAC structures are feasible to evaluate the residual shear capacity of SRRAC beams when the exposure temperature is below 600 °C.