Evolution analysis of bearing capacity of existing concrete beam bridge under actual vehicle load

In order to explore the evolution law of bearing capacity failure probability of existing concrete beam bridge in future service time, the Monte Carlo random sampling method was used to generate the random traffic flow load firstly. Then, the randomness of vehicle-induced load effect and the time variability of bridge resistance degradation were comprehensively considered. Based on the classical extreme value theory and structural reliability principle, the evolution analysis method and steps of bearing capacity of existing concrete beam bridge were given. Finally, an existing simply supported T-beam bridge was taken as an engineering case and the failure probability of its bearing capacity under actual traffic load was analyzed. The results show that the mean value and standard deviation of bridge resistance gradually decrease with the increase of the service time of bridge, while the mean value of extreme value of vehicle-induced load effect increases, and the standard deviation decreases. The failure probability of bearing capacity increases with the increase of service time of the concrete beam bridge, and the main beam direct under the vehicle load is greater than that of the main beam not direct under the vehicle load. The bearing capacity of the whole bridge system depends on the main beam with the largest bearing capacity failure probability. The bearing capacity of bridge is greatly affected by the operating environment, and the failure probability of low-speed degradation resistance is 5.6 times higher than that of the non-degradation resistance. In order to ensure the operation safety of existing concrete beam bridge, for bridge with high frequency of heavy truck and harsh service environment, safety reserves should be improved during construction, and appropriate policies can be taken to intervene in management and maintenance. © 2022 Central South University of Technology. All rights reserved.