Cohesive Model-Based Approach for Fatigue Life Prediction of Reinforced-Concrete Structures Strengthened with NSM FRP

This paper presents a fatigue-life prediction model of reinforced concrete beams strengthened with near-surface mounted (NSM) fiber-reinforced polymer (FRP) composite rods under flexure. This model is based on the fracture-mechanics approach using a cohesive model, and accounts for different bridging properties in steel and FRP reinforcement in strengthened concrete structures. It predicts the number of fatigue cycles to ultimate failure in the strengthened members, in which the failure is defined by unstable propagation of an effective crack in concrete. Several sets of experimental results in the literature are selected to verify the efficiency and precision of this model, in which the writers compare typical stress versus fatigue-life curves. This model is capable of predicting the fatigue life of NSM-strengthened concrete beams to a good precision and relates the fatigue life to the structural stress in an explicit manner.