Research On Assessment Of Durability For Existing Reinforced Concrete Bridge

The durability of RC (reinforced concrete) bridge is concerned by civil engineers since near semicentennial. Because of the facts of concrete structure materials and used environment, some problems occurr in reinforced concrete structure. The related information in domestic and overseas indicate that, the economy loss due to concrete structure durability disease is enormous, also along with environment variance and function demand improved, structure durability becomes more and more severe. In this paper , the effect on durability of RC bridge due to multi-factor coactions was studied based on statistic data and other people's research works.In this paper, studied the effect on durability of bridge due to multi-factor coactions, combined fuzzy Neural Network to fuzzy comprehensive assessment, used Visual Basic programming language and Matlab language programming, developed the intelligent durability appraisal system of RC (reinforced concrete) bridge.Some theories and methods of condition evaluation were reviewed, especially noted that analytic hierarchy processs was used in the durability evaluation of bridge. In this paper, discussed the damage mechanism of those factors that affect the durability of existing reinforced concrete bridge,bringed out the ambiguity function for the quantitative indexes of assessment by using fuzzy theory. To the non-quantitative indexes that are hard to be defined, the grading vectors were given according to the current code. Furthermore, it gived the weight value of each factor according to its importance by using the analytic hierarchy process (AHP). Finally, the grade of assessment of durability for existing reinforced concrete bridge was classified by using the asymmetric approach degree method. According to the reliability analysis of bridge durability based on concrete carbonization, the author proposed the method to calculate the failure probability of bridge durability,moreover introduced the fuzzy neural network theory. It's utilization showed that the cases created by fuzzy comprehensive assessment were put into the neural network training and studying in the Inference frame. Then Fuzzy neural network model that evaluate durability of brdge was created. The significant of Combining Fuzzy neural network to fuzzy comprehensive assessment is that: Fuzzy neural network can deduce the uncertainty and randomicity of the algorithm degree of membership. Because Fuzzy neural network has the positive attributes of adaption and learning. The enough training samples based on the fuzzy comprehensive assessment of bridge'durability was get to training fuzzy neural network. This method was proved that it can reappeared the empirical knowledge and instinctive thinking of bridge engineering experts, reduced the contrived influence and assure the objectivitity of the evaluating result better.In this paper, presented the practical method on fuzzy comprehensive assessment of durability for existing concrete bridge and tested the rationality and the practicability of this method on engineering example. Expandability, the author developed the intelligent durability appraisal system of R.C. (reinforced concrete) bridge.