Reliability Analysis Of Existing Concrete Beam Bridge Under The Background Of Overweight Transportation

With the acceleration of China's industrialization process and the development of vehicle load variation,many existing bridges are less reliable under operation load.Due to the large volume and wide characteristics of beam bridges in China,the research on reliability of existing beam bridges has become a hot topic at present.Based on the measured truck data of the Beijing Zhuhai highway,this paper analyses the load characteristics,simulate the load distribution model and calculate the load effect of the typical beam bridge.According to the reliability theory and the extreme value theory,the reliability of the typical beam bridge is calculated under the different evaluation datum period.Finally,calculate and analysis load effect on reinforced bridges and restricted load type girder bridges under target reliability based on the reliability theory.The main research is as follows.1)The dynamic weighing system is used to collect the data of Beijing Zhuhai highway North Guangdong toll station,and the vehicle load data are analyzed according to the axle load and weight classification.According to the limit load standard,the ultra limited vehicles are analyzed at different over limit levels.Finally,the "combined distribution"(the multimodal distribution add GPD distribution)is used to carry out the axle weight and the weight of the vehicle.2)Based on the actual load data,the Monte Carlo method is used to simulate the random vehicle flow,and the load effect of the virtual beam bridge under different span is calculated by the influence line loading.The vehicle load effect model under different datum period constructed with the threshold model,maximum likelihood estimation theory and extreme value theory,then comparative with "JTGD60-2015" highway I level load effect.3)According to the original design data of the bridge to obtain the bridge bearing capacity,combined with the vehicle load effect GPD model,considering the load impact coefficient,the Monte Carlo method is used to calculate the failure probability of the limit state equation,and the reliability of the "85 standard","04 standard" simple supported beam bridge and the "04 standard" continuous beam bridge are obtained.Finally,Based on the vehicle load model and the stationary stochastic process,the reliability of beam bridge in recent(near 10 years)and long term(nearly 50 years)is analyzed..4)Based on the principle of the annual failure probability in the follow-up period and the principle that the structure is equal to the failure probability within the design working life,the target reliability of the different evaluation datum period is determined.According to the reliability of the different datum period,the value of the load effect is calculated according to the reliability principle under the different datum period,and the load effect is compared with the I load effect of the highway bridge and culvert design general specification JTGD60-2015 highway.