Condition Assessment Research Of Existing Concrete Bridge's Carrying Capacity By The Method Of Risk Analysis

Because of over-load,heavy-load,environmental deterioration and so on , some diseases of the Service concrete bridges such as concrete's crack,carbonization and corrosion of steel bar appeared, which will influence the service concrete bridges'functionsofuse and carrying capacity seriously. If we continue using these service concrete bridges, their failure risk and carrying capacity are the focus which we must pay attention to.This paper jointed with science and technology project of Hunan province researches service concrete bridges'carrying capacity assessment method based on risk analysis. First of all, this paper picks up the most important loads and resistance factors according to the Fuzzy Analytic Hierarchy Process method. Then, it combines the Structural Reliability Theory and inspecting data to revise the loads and resistance parameters at the present time. The dead load is revised by introducing the reduction coefficient ? . Automobile loading's revision is implemented by introducing the live load's correction coefficientξq. When revising the resistance parameters, this paper mainly considers the revision of the strength of materials and pressure zone's change aroused by cracks. Besides, the paper uses the reliability calculation method (JC method and PNET method) to get the construction member's and system's reliability (probability of failure) respectively. It also takes the time variables of loads and resistance parameters into account, besides, regression analysis is used to get the statistics law of the resistance attenuation. From the existing literatures, the paper may quotes resistance attenuation's ready-made formula. Finaly, the probability of failure is multiplied by Miss Penalty which is quantized to economic indicator to get the quantized value-at-risk. The value-at-risk is used to compare to the acceptable risk criterion, so the service concrete bridge's risk level is gotten.This paper uses this method to implement the carrying capacity assessment of the TuangShanHe-bridge which is located in the HuangShi-HuangMei super highway. The assessment result indicates that value-at-risk of this bridge exceeds the normalized value, the relative authorities must take some measures to anticipate the risk.