The effect of FRP prestressing on the fatigue performance of strengthened RC beams

Abstract

AbstractAlthough Fiber Reinforced Polymer (FRP) prestressing is widely recognized for enhancing the serviceability conditions of strengthened structural elements, there are no available fatigue prediction models encompassing the specificities and advantages of FRP prestressing. In this context, this paper addresses the effect of FRP prestressing on the fatigue performance of strengthened reinforced concrete (RC) beams through the assessment of experimental data, constant life diagrams, and the adjustment of specific stress versus number of cycle (S‐N) curves for RC strengthened with prestressed FRP. First, data obtained through the development of an experimental program give an insight into the long‐term behavior of full‐scale beams subjected to in‐service and severe fatigue loading conditions. Fatigue life prediction models based on the adjustment of S‐N curves are developed using an extensive database of failure data and runouts of fatigue tests. Finally, data of fatigue tests plotted in a constant life diagram evidence the combined effects of stress range, mean stress, R ratio, and reinforcing steel properties on the fatigue life of RC beams strengthened with prestressed FRP. Results highlight the positive effects of FRP prestressing by the improvement of serviceability condition under static loading and the increasing of endurance limit under cyclic loading.