Strength resistance factors calibration for shear in FRP-reinforced concrete beams

The reduction factors currently used in fiber-reinforced polymer (FRP) reinforced concrete design codes are largely derived from those developed for steel-reinforced concrete, leading to inconsistent safety levels across different material systems. To address this issue, specifically for FRP-reinforced concrete (FRP-RC) beams subjected to shear, this study compiles a comprehensive database of 122 experimental results from FRP-RC beams that failed in shear. A reliability analysis was conducted to evaluate the safety performance of two widely used design standards: ACI 440.1R-15 and CAN/CSA S806-12. The goal is to assess the adequacy of their current reduction factors and propose revised values that achieve a consistent target reliability level across both codes. The analysis shows that the reduction factor specified in ACI 440.1R-15 (0.75) yields a reliability index of 3.5, which aligns with the target level recommended by ASCE 7-22. In contrast, the CAN/CSA S806-12 design equation, which uses a reduction factor of 0.65 for concrete, slightly underperforms in terms of reliability. A more conservative reduction factor of 0.60 is therefore proposed to bring its safety level in line with that of ACI 440.1R-15, ensuring consistency between the two codes. Unlike prior studies that relied on approximate methods (FORM/FOSM) or focused on modified equations, this work employs Monte Carlo Simulation with 1 × 107 iterations on the unmodified code provisions across multiple load combinations (dead, live, wind, and snow), providing a more comprehensive and robust reliability assessment framework.