Chloride diffusivity and service life prediction of fatigue damaged RC beams under seawater wet-dry environment

The effects of low fatigue load level with lower limit of 0.1 Pu and upper limit of 0.2 Pu or 0.3 Pu on chloride diffusivity of RC beams were experimentally studied after 100 times of seawater wet-dry cycles, where Pu is the static ultimate strength of the RC beams and the cycles of fatigue loading was 200,000. Based on the test results, residual service life was also discussed here. Results show that, chloride diffusivity was accelerated as fatigue load level increased. When the load level was 0.2, based on Fick's 2nd law, chloride diffusion coefficient of tensile concrete was higher than that of compressive concrete, but the result was reverse for the load level of 0.3. Furthermore, based on the Monte-Carlo Method, the predicted residual service life in one-dimensional state of chloride diffusion would be shortened by 85 percent when the fatigue load level was 0.2, and by 95 percent when fatigue load level was 0.3, compared with that of no fatigue damaged RC beam. The predicted service life in two-dimensional state was about half of that in one-dimensional state. It was concluded that fatigue damage has a more considerable effect on shortening service life of RC structures in chloride environment.