Detection And Evaluation Of Durability For Existing R.C. Bridges

R.C. (reinforced concrete) structures are widely used in civil engineering. The deficiency of durability appears in lots of existing R.C. structures. It causes many aging problems and has an ill effect on people's productivity and life. It also brings people loss of money. So more and more scholars and engineering technical staff pay attention to the problem. The influencing factors relate intricately and interact complexly. So how to make an assessment of durability has become an urgent task in the research of R.C. structure durability.Supported by the Youth Teacher's Teaching & Scientific Research Reward Plan in University, Foundation Application Research Program of Sichuan Province and some engineering examples, some subjects in structures durability are studied in this paper. The main contents are as follows:1. The paper carefully analyses the factors that influence the durability of concrete structure from some effects, such as carbonization, chloride, anti-freeze, anti-osmosis, alkali, erosion of reinforcing-bar, etc., especially introducting erosion of reinforcing-bar and carbonization in detail.2. The present research works of concrete durability are systematic elaborated. Combined with new programs in sthdy works, the problems existed in the research are pointed out.3. The contents and courses of durability detection for R.C. structure have been described in detail. The material of the structure has been tested by some means in order to provide some date for assessing the structure.4. An improved 3-grade fuzzy comprehensive evaluation method for reliability assessment of existing R.C. structures is presented in this thesis. The peculiarities of this method include the establishment of the membership functions of the non-quantitative factors by analogy method, determination of the weight value of each factor according to its significance by the analytic hierarchy process (AHP), use of the weighted average model in evaluation and classification of the grade of durability by the asymmetric approach degree method.5. The feasibility for this system was proved by the detection and evaluation oftwo different engineering examples. It is useful to draw experinence from the textual on the durability detection and evaluation of existing R.C. structures.