A Study On Moisture Transport In Fatigue Damaged Concrete Under Dry And Wet Conditions

Concrete structures are all working under loads and environmental actions. The study on the water transport in concrete subjected to loads, and dry and wet actions is of great significance for the whole life design of reinforced concrete structures. Aiming at this problem, this thesis studies the water transport in fatigue damaged concrete under the dry and wet condition through experiment and numerical analysis. The main conclusions are as follows:(1) A set of experimental apparatus for the axial tension fatigue of reinforced concrete structures is designed to conduct the constant amplitude axial tension fatigue on concrete specimens. The variations in the stress-strain curve of concrete subjected to fatigue loads are analyzed. The fatigue damage coefficient of concrete is calculated by the residual strain method and the ultrasonic method. Their applicability is determined by comparison of the two methods.(2) An experiment of moisture transport on the surface of fatigue damaged concrete is conducted. The variations in humidity on the surface and quality of concrete specimens are measured. The effects of external environment and fatigue damage on the water transport on the surface of concrete are analyzed.(3) By introducing the equivalent diffusion coefficient and the load influence coefficient, a moisture transport model of fatigue damaged concrete under the dry and wet condition is established and solved by the single-point precise integration method. An experiment of moisture transport in fatigue damaged concrete under the dry and wet condition is conducted within an artificial environmental chamber. The good agreement between the numerical results and experimental results verifies the validity of the numerical model.