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• We investigate the capacity of CFRP repaired RC beams under heavy pre-load level. • The results indicated that the CFRP sheets significantly affected increased the flexural capacity and flexural stiffness. • An equation is proposed herein to calculate the flexural capacity of pre-damaged reinforced concrete. This paper presents an experimental study to determine the effectiveness of carbon fiber reinforced polymer (CFRP) sheets as a flexural repair system for reinforced concrete (RC) beams. One reference beam and nine CFRP repaired RC beams under heavy pre-damaged level are designed and tested in this study. The effects of several parameters including pre-damaged level, CFRP sheet layer and reinforcement ratio on failure mode, flexural deflection, moment-curvature relation and stress-strain behavior of CFRP sheet are investigated. In the first scenario, a reference beam is tested to determine load levels that can be used as pre-damaged for the tests. With respect to the second experiment, the test beam is subjected to a pre-damaged load equivalent to 40% or 80% of the yield load of the reference beam, respectively. Two failure modes such as the debonding failure of CFRP sheet and the fracture failure of CFRP sheet are found for the strengthened RC beams. The flexural bearing capacity of strengthened RC beams increases as the CFRP sheet layer or reinforcement ratio increases, while it decreases with the pre-damaged level increases. The decrease of pre-damaged level or the improvement of CFRP sheet layer or reinforcement ratio will decrease the deflection of CFRP repaired RC beams. Considering the effect of pre-damaged level and strengthening layer of CFRP sheet, a reduction coefficient of the CFRP sheet layer and an effect coefficient of pre-damaged level are introduced and then a formula for predicting the flexural capacity of CFRP repaired RC beams under heavy pre-damaged level is proposed and it agrees well with the test data. [ABSTRACT FROM AUTHOR]

• The humid environment with different rainfall times and rainfall intensity was simulated in the laboratory. • The surface chloride contents showed decreasing trends and were strongly affected by the rainfall parameters. • The convection zone depth and peak chloride ion concentration in chloride profiles was studied. • Numerical simulation of chloride transportation in the humid environment with rainfall was conducted. • A prediction model for chloride transportation under different rainfall parameters was proposed. Reinforced Concrete (RC) structures eroded by chloride ions will reduce the chloride ion concentration on the concrete surface under the effect of sustained rainfall dilution and erosion, and there will be rainfall convection areas and peak chloride ion contents. In this study, the influence of rainfall environment on the transporting behavior of chloride ions in concrete is studied through capillary absorption test and rainfall experiment. A numerical prediction model of chloride ion transporting behavior in concrete was established by COMSOL Multiphysics based on the rainfall tests. The chloride behavior is analyzed and studied. It is found that the numerical simulation results are in good agreement with the experimental results, and the predicted models of chloride ion diffusion under different rainfall conditions are obtained, and the transporting behavior of chloride ions can be effectively predicted. The results also show that with the increasing of rainfall intensity and rainfall time, the chloride ion contents on the concrete surface decreases obviously. When the rainfall time and rainfall intensity increase, the chloride ion contents of concrete decreases, and the binding capacity of chloride ions in the matrix weakens. This research provides some resulting information of RC structures in rainy marine areas. [ABSTRACT FROM AUTHOR]

• The rainfall environment was simulated in the laboratory. • The influence of rainfall intensity on the distribution of chloride ions in concrete was studied. • The distribution of chloride ions in concrete under different saturations was discussed. • In this environment, the relationship between total chloride ion and free chloride ion in concrete is analyzed. • The SEM, MIP and XRD phase analysis of the compounds under different rainfall intensities were explored. Reinforced concrete (RC) structures located in coastal salt spray areas are subjected to rainfall erosion and chloride ion corrosion throughout the year. Consequently, this study simulates a rainfall environment with artificial rainfall simulation devices and applies a potentiometer to determine the chloride ion concentration. The microstructures and chemical compositions of the concrete were revealed through microscopic experiments. The research results show that with a greater rainfall intensity, the surface chloride ion concentration decreases more obviously, the surface chloride ion loss is more serious, and the chloride ion binding capacity becomes weaker. As the saturation decreases, the binding capacity of chloride ions also decreases. This study can provide some theoretical ideas for the durability design of PC structures in rainy environments. [ABSTRACT FROM AUTHOR]