Reliability based assessment of FRP rehabilitation of reinforced concrete girders

The use of prefabricated fiber reinforced polymer (FRP) strips to rehabilitate concrete structures has increased in popularity over the past few years. As such, many design codes and guidelines have been developed to enable designers to use the FRP materials with confidence in their performance. In this work, FRP durability test results are used with a widely known degradation prediction model to determine the value of FRP material properties used in rehabilitation and strengthening of concrete over time. Equations are presented based on the test data to predict the tensile strength, tensile modulus, short beam shear strength, and flexural strength over time of FRP prefabricated strips from three manufacturers. Corresponding degradation data is presented for the adhesive recommended be each manufacturer for use. The degradation model is used on example girders used in previous research for illustration of differences in the codes and guidelines design property values and those possessed by FRP materials over time. A reliability anaylsis is conducted in each example case to compare the results. A proposed shift in design philosophy is presented to enable inclusion of material degradation over time and thereby make concrete rehabilitation with FRP strips more efficient and cost effective.