Abstract：Substitution of steel reinforcements with glass fiber-reinforced polymer (GFRP) bars shows great promise to solve the problem of durability in reinforced concrete (RC) structures. Due to the linear elastic mechanical properties of GFRP bars, the brittle failure (tensile failure and compressive failure) is unavoidable in GFRP-RC beams under flexure. Thus, the design provisions developed for concrete structures with steel bars are not necessarily applicable to those with GFRP bars. In this paper, a reliability based design approach for GFRP-RC beams under flexure is presented. Firstly, statistics of random variables in load and resistance model are obtained from literature. Then, a design space of 3432 GFRP-RC beams covering a wide range of design scenarios are considered to conduct stochastic simulation with respect to the ultimate flexural strength. The simulating results show that the reliability index (β=4.08~4.50) obtained from current Chinese Code is higher than the target reliability index (βT=3.7) for tension controlled sections. However, the reliability index (β=3.08~3.39) obtained is far lower than the target reliability index for compression controlled sections. Finally, to achieve the reliability index (βT=3.7) for all possible flexural failure modes, the GFRP partial material factor is suggested as 1.3 based on the reliability analysis, and a new equation of ultimate stress of GFRP bars in compression controlled sections is revised.
