Time-dependent Reliability Analysis Of Existing Concrete Beam Bridge In Guangzhou City Considering Load Limit Policy

The existing urban concrete bridge is an important part of the urban traffic network.With the increase of the bridge service time,under the influence of the external environment and the deterioration of materials,etc.,the bearing capacity of the existing bridge decreases gradually with the service time.At the same time,with the acceleration of China's urbanization process,vehicle congestion has become a common phenomenon of urban traffic,vehicle congestion is becoming more and more serious,bringing different degrees of damage to urban bridges.Therefore,it is necessary to study the safety performance of the bearing capacity of the existing urban concrete bridge with time.This paper analyzes the characteristics of the resistance of the existing concrete beam bridge with time,the current status of the load of the urban operating vehicles,the time-dependent reliability evaluation of the existing concrete beam bridge,and the impact of the load limitation policy on the reliability of the existing urban bridge.and the main work is as follows:(1)Considering the characteristics of the resistance of the concrete beam bridge changing with time,a time-dependent failure probability model of the bridge resistance is established based on the bridge detection data and considering the reduction of the concrete strength,the reduction of the cross-sectional area of the corroded reinforcement,the reduction of the yield strength and the degradation of the bond performance between the corroded reinforcement and the concrete.At the same time,the method to verify the bridge resistance by using the bridge detection index is put forward.(2)The vehicle load model is constructed according to the current situation of vehicle load in urban operation,and the random traffic flow is simulated by Monte Carlo method,the load effect of virtual beam bridge under different span is calculated by influence line load,and the maximum value of vehicle load effect is compared with the standard load effect value of every city bridge design code.(3)Based on the theory of structural time-dependent reliability,the time-dependent resistance and vehicle load effect are calculated with the measured data of a typical existing urban concrete continuous bridge,and the time-dependen reliability analysis is carried out.(4)The time-dependent reliability of typical bridges under different load-limiting tonnage is analyzed,and the influence of load-limiting policy on the reliability of existing urban bridges is studied.And it provides an effective reference for the scientific and reasonable limit value of vehicle load for urban bridges.The research results of this paper provide reference for the maintenance,inspection,maintenance and reinforcement of existing urban bridges in the subsequent service period and the load limitation policy.