Time-Dependent Reliability Analysis of FRP Rehabilitated Pipes

Abstract

The goal of this paper is to present work that demonstrates the application of probabilistic modeling to evaluate the long-term performance of fiber-reinforced polymer (FRP) rehabilitated piping components. The time-dependent reliability index is evaluated for a fully deteriorated piping component rehabilitated with FRP considering the demands of internal fluid pressure, external soil pressure, and traffic loading. Carbon FRP (CFRP) and glass FRP (GFRP) composites are compared and the influence of material deterioration, fiber volume fraction (FVF), and variation in thickness of the composite are assessed using a first order reliability method and compared to a steel pipe under similar loading. A CFRP rehabilitation scheme having a FVF greater than 40% would be needed to exceed the as-built reliability index of a steel pipe under time-dependent composite deterioration, while no practical GFRP FVF can achieve the performance of steel pipe in the presence of time-dependent composite deterioration. Variations in the coefficient of variation (COV) can adversely affect the safety of both FRP rehabilitation schemes where an increase in COV from 10 to 30% result in decreases in the reliability index by 39.4% for CFRP (40% FVF) and 39.7% for GFRP (40% FVF).