Reliability Analysis of Concrete Beams Internally Reinforced with Fiber-Reinforced Polymer Bars

By employing the concept of reliability index, an interim index of "comparative reliability" is proposed that bypasses the loading variables and weighs the resistances of two structural elements with the same ultimate limit state directly against each other. The comparative reliability index is then related to the conventional target reliability to allow a simple calculation method of the strength reduction factor for elements whose safety factor is yet to be calibrated. This is achieved by comparing a pair of elements that experience the same failure mode and yet only one holds a validated level of safety (that is, strength reduction factor and reliability index). This concept is put into practice by calculating flexural and shear-strength reduction factors for fiber-reinforced polymer (FRP) reinforced concrete (RC) members by comparison with conventional steel-reinforced concrete beams possessing the same ultimate capacity. As a result, a revised set of strength reduction factors and deign provisions are proposed for use in FRP design guidelines for shear and flexure.