Calibration of Flexural Resistance Factors for Load and Resistance Factor Design of Concrete Bridge Girders Prestressed with Carbon Fiber–Reinforced Polymers

Abstract

In this research, the flexural resistance factors in the American Association of State Highway and Transportation Officials’ (AASHTO) load and resistance factor design (LRFD) format were calibrated for bridge girders that are prestressed with carbon fiber–reinforced polymers (CFRP). The underlying principle of LRFD is to achieve a uniform probability of failure (target reliability) for all possible design scenarios, which is realized through application of load and resistance factors. Calibration of resistance factors requires an extensive design space to be applicable to different design scenarios. For this purpose, 12 design cases with various girder span lengths, girder positions, girder spacing, roadway widths, and failure modes were considered. The load and resistance model random variables, their statistics, and flexural resistance model accuracy were obtained from material testing and literature. Existing load factors were used, and flexural resistance factors were derived using Monte Carlo simulation and a comparative reliability method for different target probabilities of failure for interior and exterior girders failing in tension and for interior girders failing in compression.