Research On Safety Evaluation Index System Of Urban Bridge

Owing to structure aging, vehicle weight increasing, lack of maintaining and unfavorable circumstance, there exist inevitable structural defects in some existing bridges, thus the reliability assessment and strengthening technologies for existing bridges is becoming more and more important.In this thesis, the current situation and the development of assessment theories and applied methods at home and abroad for existing bridges are discussed. The definition and content of assessment for the existing bridge are presented, and the differences between the assessment and the design of bridge structures are also detailed presented. Commonly used methods for existing bridge assessment are described in detail. The content and advantages or disadvantages of these methods for existing bridge assessment are summarized.AHP (Analytic Hierarchy Process) is adopted as the assessment method of concrete bridge in the city. The main contents are as follows:Firstly, the development of bridges and many defects existing on them are introduced, and some usual evaluation methods are summed up briefly.Secondly, AHP is introduced. And based on the Code for maintenance of highway bridges and the mechanical property of cable-stayed bridges, bridge specialists, the weight of every index is determined. Then in compliance with the need for condition assessment the statistical weight is analyzed properly.Thirdly, the condition level and grade code is established. According to the theory of Variable weight synthesizing, the bridge's whole grade can be calculated to determine its condition level. And also the degree of grey incidence of some index is calculated to supply some reference to concerned department.