The document develops reliability-based design provisions for flexural strength of prestressed concrete bridge girders with bonded fiber-reinforced polymer (FRP) tendons. It focuses on strength reduction factors and the transition region between tension-controlled and compression-controlled sections.
Initially, a total of 48 bridge girders covering a range of design scenarios are considered to conduct stochastic simulation.
ACI says: “The statistical parameters of resistance are evaluated based on Monte-Carlo simulation. Then, the first-order second-moment method is applied to calibrate strength reduction factors to meet a uniform target reliability level,.”
A probabilistic analysis of flexural failure modes is then conducted to determine a transition region in terms of ratio provided-to-balanced reinforcement instead of the traditional net tensile strain limits in ACI 440.4R-04.
“As a result, this study recommends strength reduction factors of 0.80 for tension-controlled sections, 0.85 for compression-controlled sections, and a linear variation in the transition region,” ACI adds.
This paper was written by Fei Peng and Weichen Xue. More information is available on the website.