Crack Simulation And Ultimate Bearing Capacity Calculation Of RC Bridges Under Load-environment Coupling

Under load-environment coupling, cracks of RC bridge will emerge and propagate during the service period. The ultimate bearing capacity will also decrease. Combining research programs of National Natural Science Foundation of China (51178416) with Scientific and Technological Plans of Zhejiang Communications Department (2013H58), the main objectives of this work include simulation of chloride ion erosion, calculation of steel bar corrosion, analysis of bond-slip performance of the reinforcement-concrete interface, prediction of ultimate bearing capacity and cracks propagation of RC bridges. Details of this study are mainly summarized as following:(1) The cellular automata model of spatial irregular element to calculate the chloride ion diffusion in concrete was proposed. The diffusion induced by concentration gradient, permeation induced by pressure gradient and their synergetic effects were considered in the proposed model.(2) The â… -â…¡ mixed mode concrete multi-cracks propagation model considering cohessive stress in the fracture process zone based on XFEM was established. LATIN alogrithm was applied for solving the nonlinear boundary value problem.(3) The concrete damage crack initiation factor Dc0 for predicting the fracture position was derived from the theory of concrete damage energy release, traditional strength theory and the microcrack probability model on the crack tip plastic zone.(4) The reinforcement-concrete interface discontinuous bond-slip model based on XFEM was proposed. And the finite element propram of RCIDBSM-XFEM based on the proposed model was compiled with MATLAB. The proposed model could be used for simulating the crack initiation, propagation and calculating the ultimite bearing capacity of RC beam bridges.(5) The steel bar corrosion rate multi-models based on Baysian update was established, which could predict the steel bar corrosion rate. The steel bar corrosion, crack development and ultimite bearing capacity could be obtained under load-environment coupling by combining the Baysian update model, cellular automata model with RCIDBSM-XFEM.(6) The simulation module of prestressed effect was compiled in RCIDBSM-XFEM. The prestress was transformed into element equivalent nodal force by initial strain method. So, crack initiation, propagation and ultimite bearing capacity of PC beam could be predicted by RCIDBSM-XFEM.