Risk Assessment Of Existing PC Concrete Beam Bridge

Bridge is the key project of transportation system, and plays a pivotal role in thenational economical and social life. With the increasing of demands of transportationand extending of service time of bridge, a certain kind of PC beam bridge showvarious kinds of structural damage and diseases inevitably due to natural aging ofstructural materials, increasing of vehicle loads, affects of deteriorating environments,curing improperly, and so on. Lack of load-carrying capacity, aging, and breakage hadaffected the normal using of many existing bridges. Haw to access these bridges hasbecome a very important problem at home and abroad.1. This paper settles down to risk identify of PC beam bridge, and takes theFAHP method to find the risk factors. In order to discuss the occurrence discipline ofrisk events of existing bridges and give assistance to risk identify, this paper developsbridge risk events inquiring and prewarning system which can accumulates data foranalyzing and studies on bridge risk events also can proceed prewarning.2. According to codes of bridge design, establish equations of flexuralload-carrying capacity in ultimate state of structures of PC beam bridge, andcombines statistic parameters in references. JC method is adopted to calculatestructural reliability index and failure probability of flexural load-carrying capacity ofPC beam bridge, and PNET method is adopted to calculate the reliability index andfailure of the whole bridge.3. The value that failure probability multiplies Miss Penalty measured in uniformform of currency is value-at-risk. Risks are sorted into different grades according tothe probability of risk and value-at-risk. Then assess the risk through establishing riskmatrix and enacting the accepting principle of risk with ALARP.4. Based on the Yaohu grand bridge, the risk grade is3rd of this bridge by therisk assessment method in this paper, which result shows that this bridge need to berepaired. And this result is agreement with Standards for Technical ConditionEvaluation of Highway Bridges and the result of load text. All of these prove that therisk assessment method in this paper is correct. Calculate the value-at-risk andpropose the risk index of every sort of bridges in Standards for Technical ConditionEvaluation of Highway Bridges, which can provide a reference for further studies onrisk assessment of existing bridge.