Damaged plastic analysis of concrete around dowel bars at joint in cement pavement

To reveal the mechanical characteristics and damage mechanism of concrete around the dowel bars at the joints in cement pavement, the concrete damaged plasticity (CDP) model and the method for determining its parameters were introduced on the basis of the finite element software ABAQUS. The uniaxial tension and compression tests of concrete specimens were simulated by the CDP model, and the accuracies of the CDP model parameters were verified by the comparison of model test results. On this basis, a three-dimensional finite element model of cement pavement with dowel bars at joints was built to analyze the distribution and development laws of the plastic strain, damage factor, and equivalent stress of concrete around the dowel bars at the joints subjected to different axle loads. Under the CDP model and elastic model of concrete, the difference between the two models in the stress of concrete around the dowel bars was compared. Analysis results show that for the uniaxial tension and compression specimens of concrete, the entire stress-deformation curves achieved by the simulation with the CDP model are consistent with the test results, indicating that the CDP model and its parameters are accurate. For the cement pavement with dowel bars at joints, when the load is applied at the edge of upper slab of the bonded end of a dowel bar, the stress in the concrete around the bonded end of the dowel bar is most disadvantageous. With the increase in the axle loads, the damaged plasticity is encountered first in the concrete at the bottom of bonded end of the dowel bar, and the equivalent stress reduces gradually. When the axle load raises from 100 kN to 250 kN, the range of plastic zone extends from 135°-225° at the bottom to 60°-300° for the concrete around the dowel bar. The concrete in the range of 150°-210° at the bottom is subjected to failure due to the complete damaged plasticity, and the equivalent stress becomes zero. More loads are borne by the concrete on both sides and at the top of the dowel bar due to the stress redistribution. If the elastic model is adopted for the concrete around the dowel bar, the equivalent stress of the concrete at the bottom of the dowel bar will be on the rise to exceed the ultimate strength. Therefore, the CDP model is recommended to analyze the stress concentration of concrete around the dowel bars.