Performance Evaluation And Maintenance Strategy Optimization Of Bridge Network Based On Reliability

Transportation network plays a significant role in the survival and development of modern cities and regions,and it’s also a link to maintain the normal production and life.As an important part of urban transportation network,the reliability of bridge determines the connectivity performance of the network.It’s of great significance to make maintenance plan scientifically for bridge network and allocate limited maintenance funds rationally and effectively to maintain a satisfactory level of bridge network performance in view of the severe damage and aging and limited maintenance funds of bridges in China.A regional bridge network model was established to evaluate the connectivity performance of the bridge network based on the theory of reliability and network.Taking the reliability deterioration of bridges and maintenance impact on bridge network performance into consideration,an optimization model of maintenance strategy for bridge network was built,and a Pareto optimal solution set was obtained.The main contents include the following items.Firstly,the statistical parameters of structural resistance and load were modified based on actual situation of an existing bridge to build a probabilistic model of structural resistance and load evaluation and a reliability analysis function of bearing capacity of bridge component,and the reliability index of bridge component in maintenance period were analyzed by taking time-dependent reliability theory into structural calculation.Then the bearing capacity reliability of an existing bridge was evaluated based on the static analysis results calculated by FEM program MIDAS and a computer program adopting JC method built by MATLAB.Secondly,the reliability degradation curve and maintenance cost of the bridge under different maintenance measures were analyzed based on current specification.Then,an optimization model was established with minimum maintenance cost of the bridge as the objective function and minimum reliability index of the bridge as the constraint condition.Then,the optimal maintenance strategy of the bridge in maintenance period was obtained after the equation was solved by genetic algorithm(GA)with elitist strategy.Thirdly,a regional bridge network model was established based on the network theory and the connectivity reliability of bridge network was calculated by using the minimal path method based on reliability of single bridges in the bridge network.Then,by taking the reliability deterioration of bridges and maintenance impact on bridge network performance into consideration,a time-dependent connectivity reliability curve of bridge network was obtained,which laid the foundation for optimization of maintenance strategy of bridge network.Fourthly,a multi-objective optimization equation was established with optimal performance and minimum maintenance cost of the bridge network as the objective function and minimum reliability index of single bridge as the constraint condition.Then,the non-dominated sorting genetic algorithm with elitist strategy(NSGA-Ⅱ)was introduced,and the NSGA-Ⅱ was improved by modifying the definition of dominance relations after the constraint tournament method was employed to deal with the minimum reliability constraint of single bridge.Finally,a case study was conducted by using the proposed method(improved NSGA-Ⅱ),the result was a range of Pareto optimal solution set.The optimal maintenance plan could be made based on actual situation by management department.Finally,the research work was summarized and conclusions of the study were drawn to provide theoretical basis and technical support in the choice of maintenance measures for regional bridge network manager.