Indirect fatigue evaluation of CFRP-reinforced bridge deck slabs under variable amplitude cyclic loading

Abstract

Currently, bridge deck slabs reinforced with Fiber Reinforced Polymer (FRP) bars have been widely studied and applied to the bridge deck slabs in North America. However, there is still a lack of knowledge on the structural performance of the concrete bridge slabs reinforced using FRP bars, especially Carbon Fiber Reinforced Polymer (CFRP) bars. This aim of this study was to investigate the fatigue performance of bridge deck slabs reinforced with CFRP bars. The fatigue capacity was investigated using indirect fatigue evaluation when the number of cycles to failure was unknown, by using the equivalent number of cycles. The variable amplitude cyclic loadings effectively contribute to damage acceleration even at fatigue cycles of 1,000,000. The evaluation of fatigue capacity with respect to serviceability showed that deflection and crack width under variable amplitude loading were evaluated over a reasonable range to ensure that serviceable capacity is satisfied for CFRP bar reinforced bridge slabs. For fatigue design, S-N curves were analyzed using the different fatigue life models proposed by previous studies. It was found that the fatigue limit under variable amplitude loading should be analyzed by using the fatigue life model based on the variable amplitude loading cases.