Bearing Capacity Analysis And Life Prediction Of The Prestressed Concrete Cooperative Cable-Stayed Bridge In Service

According to the beautiful appearance and unique mechanical properties, the prestressed concrete cable stayed bridge with cooperative span draws people’s attention. From the existing literature, there are few studies on the problems of structural damage, stiffness reduction and load carrying capacity reduction of cable-stayed bridges in the late stage of operation. In this paper, finite element method and real-bridge test were used to analysis the whole bridge static property and load carrying capacity after damage. Also, the bearing capacity of residual life was predicted according to the reliability method. In this paper, the main research contents:One prestressed concrete cable stayed bridge with cooperative span was taken as a sample to analyze the comprehensive static properties. Firstly, the whole model was built by the software Midas/Civil to analyze the effect of dead load and live load. Secondly, when the bridge experienced the different degrees of damage including the section flexural stiffness, suspension stiffness and auxiliary pier bearing stiffness, bridge tower section stiffness, the effect of displacement and internal force of the whole bridge under the situation that the car load is in the bridge were studied.We focus on the prestressed concrete cable stayed bridge with cooperative span that has been in service for 13 years. In order to stimulate the real operation state, we used the first-order optimization algorithm to modify the original material parameters, boundary conditions,etc.The calculation results show that the modified model model updating method is reliable and accurate.Based on the test results of the real bridge durability and the static performance test of the bridge, the bearing capacity of the component is analyzed by the method of the calculation and analysis. The calculation results show that the current carrying capacity of the bridge is reduced to 91% of the initial bearing capacity of the bridge. The calculation results of the bearing capacity of the main girder section still meet the design requirements. The finite element model of ANSYS is modified by the first order optimization algorithm based on the results of the cable force and the line shape of the real bridge. A modified model to simulate the dead load state of real bridge. The whole process analysis of the ultimate bearing capacity of the damaged cable stayed bridge is carried out. The live load factor of Max is 14.27, which shows that the system has a good ultimate bearing capacity under the current damage condition.Based on the time-dependent effect theory of reinforced concrete, the resistance attenuation curve of main girder of cable stayed bridge is predicted, and the equation of time varying limit state is established. Based on the reliability theory, the reliability of the bearing capacity of the main beam in the service period is predicted. The calculation results show that the reliability index of the structure is 5.308, and after 100 years of operation reliability reduce to 4.580.