Research Of Promoting Concrete Bridge Durability

ABSTRACT:Concrete bridge is the most widespread bridge structure. In past centuries, a lot of concrete bridges were constructed in the word, and the bridge designer paid more attention to structural intensity, but ignored structural durability. As a result, a lot of constructed bridges were aging because of durability failing. To solve this problem, the research of concrete bridge durability is needed in urgent. There is important theoretical and practical value to research this issue.On the basis of summarizing the domestic and foreign research on structural durability, and combining with the research guide of Western Transportation Construction Technology Issues, the thesis carries out research with follow specific contents, and gets some achievements as follows:(1) On the basis of domestic and foreign documents, the main factors influencing durability of concrete bridge are analyzed in macro-perspective (construction and design) and micro-perspective.(2) On the basis of normal methods to detect durability diseases of bridge, further study on damage detection technology of Wavelet Energy Transformation is taken, and the particular use of this new method to detect internal damage of bridge is introduced by pier shaking table test.(3) In order to improve the structural durability, the methods to evaluate the durability of concrete bridge is elaborated systematic. According to the change state of durability related with time in the life cycle of bridge structure, the method of how to classify the durability levels into three levels is proposed. Durability levels are classified to five statuses, as Very well, Well, Slightly worse, Worse, Dangerous, and the practical process to evaluate the structural durability is described in this thesis.(4) The issue is researched through establishing finite element model, and researched in the perspectives of improving construction quality of joints and optimizing structure system transformation methods. It is found that construction age difference between up and down concrete should be shorten in order to prevent irrational shrinkage and stress. Apart from this, taking rational structure system transformation method is important to optimize structure deflection and stress, structure fold should be operated at the lowest temperature in the daytime.