Changes In Humidity, Creep Of Concrete And Reinforced Concrete Beam Under Long-term Performance Research

Creep as one of the most important long-term properties of concrete has important influences on the suitability, security and durability of RC structures. In complicated natural environment, the overlarge long-term deflection of reinforced concrete bridges structure due to the underestimation of creep may impact its usage effect. Seriously, this problem may lead to vicious engineering accidents. Creep is affected by many factors, and it is generally accepted that the relative humility of the environment has significant effects on concrete creep and the long-term properties of reinforced concrete structure. The environmental humility cycling also has significant effects on concrete creep. In present researches and domestic specifications, studies on the humility cycling are relative inadequate and the environmental humility is taken as constant. This showed quite disagreement of the practical. Thus, the study on the effect of the cyclic humility is quite meaningful to both the theoretical research and the engineering practice. This research presents herein focuses on the concrete creep and the long-term properties of RC structures under cyclic environmental humility. The study includes:1. The concrete creep experiment under cyclic humility is carried out, which including3environmental conditions:the lab environment condition, the short-term drying-wetting condition and the long-term drying-wetting condition. The deformation of the concrete creep has been recorded and the creep deformation laws under different environmental condition are analyzed. The experimental results have been compared with the domestic specifications models. It is concluded that the domestic model can not predict the development of the concrete creep under cyclic humidity.2. The long-term properties experiment of RC structure under cyclic humility is carried out, which also including3environmental conditions:the lab environment condition, the short-term drying-wetting condition and the long-term drying-wetting condition. The mid-span deflection of the RC beam has been recorded and the mid-span deformation laws under different environmental condition are analyzed.3. The material-structure coupled analysis framework is applied to simulate the concrete creep experiment under cyclic environmental humility. The finite element results are compared with the experimental results and shows good agreements. It is concluded that the analysis method and models used can better simulate the creep properties of concrete.