Mechanical behavior and its variability analysis of fiber reinforced polymer rebars after high temperatures

Abstract

This study investigated the influence of high temperatures on the mechanical properties of glass and basalt fiber reinforced polymer (GFRP and BFRP) rebars. These rebars with a wide range of diameter from 10 to 25 mm were heated up to 400 ℃ and tested under shear and compression. Based on the data from the extensive experiments, the variability of shear and compressive strength was assessed. Results indicate that the reduction of both shear and compressive strength with high temperatures did not show notable dependence on the rebar diameter and type. High temperatures, especially 350 and 400 ℃, would induce more reduction of compressive strength than that of shear strength. Using the combined probability test and the Bayesian information criterion (BIC) test, this study proposed an approach to establishing appropriate probabilistic strength models for FPR rebars after high temperatures. The Gamma distribution outstood all chosen models for capturing the variability of residual shear strength of FRP rebars, while both Gamma and Weibull distributions were needed for compressive strength. Results herein can facilitate a better understanding of high-temperature induced change in properties of GFRP and BFRP rebars, and provide useful probabilistic strength models for probability-based evaluation of FRP rebars reinforced concrete structures after a fire.