Research On Durability Assessment Methods Of The Reinforced Concrete Bridge

The bridge, as the throat of modern transportation, plays an important role in promoting the country’s economic construction and development. Due to the lack of General Code For Design of Highway Bridges And Culverts about the durability, as well as attention was not pay to the existing reinforced concrete bridges by the bridge management department, in a result, the materials was aging, the damage of appearance was serious, the loading capacity decreased rapidly, and most of the reinforced concrete bridge was far from the service life and had been closed the traffic or even forced to tear down for the reconstruction. Therefore, the durability assessment of reinforced concrete bridges is an urgent problem needs to solve, how to assessment scientifically and rationally has become a very concerned subject at home and abroad. The research of theories and methods on durability assessment of reinforced concrete bridge not only has important theoretical significance, but also provide a basis for the decision-making of bridge management department, and is with a wide range of engineering applications prospects and important social and economic benefits. Research was carried on from the durability assessment methods of bridges in this paper, mainly in the following aspects:1. The research background and significance of the durability assessment of the reinforced concrete bridges were elaborated, and the existing durability assessment methods of the bridges at home and abroad was summarized.2. According to the common diseases of reinforced concrete, a durability assessment model of the reinforced concrete bridges was established with the Analytic Hierarchy Process. And the standards about the durability status grading were established with the Standards for Technical Condition Evaluation of Highway Bridges, the Specification for Inspection and Evaluation of Load-bearing Capacity of Highway Bridges, the Code for Maintenance of Highway Bridges and Culvers and some literature about the durability assessment of bridges.3. The extension theory was introduced into the durability assessment of the bridges, the durability assessment method of reinforced concrete bridge based on extension theory was researched, the extension theory was described in detail, a two-level extension integrated assessment model was established and the correlation function of side-distance was put forward based on the actual situation of the bridge project. Finally, this assessment model was used to a real bridge, the results show that the durability assessment method of the reinforced concrete bridge based on extension theory was feasible, and provided a new way for the durability assessment of bridges.4. Neural network theory was applied to the durability assessment of the bridge, the durability assessment method of reinforced concrete bridge based on based on the neural network model of Learning Vector Quantization (LVQ) was researched, the training set of reinforced concrete bridge durability index based on LVQ neural network is established and trained by using the software of MATLAB (R2010b). Finally, a lot of instances of reinforced concrete bridges were assessed with the simulation function of MATLAB (R2010b), and the assessment results were contrasted and analyzed with these of existing literature and extension assessment, the results show that it was basically as same as the assessment results of extension theory under the same level standards of the durability indexes, and verified the durability assessment method of the reinforced concrete bridge based on LVQ neural network was feasible, provided a new approach to achieve scientific and rational result for the durability assessment of reinforced concrete bridges.