Numerical Simulation And Analysis Of Reinforced Concrete Structures Under Sulphate Attack Based On ABAQUS

Reinforced concrete structure is an important structural form,widely used in civil and industrial construction,highway,bridge,tunnel and other fields.However,due to complex service environment,some reinforced concrete structures have appeared a variety of diseases after a period of use and their durability and reliability have been greatly reduced.As one of the important methods of numerical analysis,finite element method can be used to make a calculation by establishing a suitable model.When the numerical simulation results are consistent with the test results,numerical simulation analysis can be used to replace tests.Based on these finite element models,the relevant information of materials and structures in the simulation process can be extracted.At the same time,the method of numerical simulation analysis can reduce the cost of testing,greatly improve the efficiency.In this paper,based on the test results,the constitutive relationship of concrete under uniaxial compression,the bond-slip constitutive relationship between reinforcement and concrete and the mechanic properties of large eccentric column under the actions of sulfate,wet and dry cycles and freeze-thaw cycles were simulated respectively.The finite element three-dimensional model was established by Abaqus and compared with the results of tests to verify the accuracy of the simulation.Based on the effective of simulation,the influences of various factors on simulation results were explored under three conditions.The main research contents of this paper are as follows:(1)Based on the test results,the stress-strain constitutive relationship of concrete under different sulfate corrosion degrees was established.By using a concrete prism model established by ABAQUS,based on the concrete plastic damage model,finite element simulation was carried out on the uniaxial compression of concrete prism under sulfate,wet and dry cycles and freeze-thaw cycles.The simulation results were compared with the experimental results to verify the effective of the established stress-strain constitutive relationship of corroded concrete.(2)The influence of mesh size on simulation results of uniaxial compression of concrete was explored by dividing grids of different sizes.The results show that the mesh size of the finite element model has a certain influence on the accuracy of simulation results.The smaller the mesh size,the higher the fineness of the finite element analysis results,but the calculation time also increases rapidly;therefore,the selection of 10 mm grid is more in line with the requirements of this paper.(3)Based on the bond-slip constitutive model between rebar and concrete published in CEB-FIP,the bond-slip constitutive relationship of corroded reinforced concrete was established by analyzing the test data.A 3D model was established by ABAQUS to simulate the centre tensile testing of reinforced concrete.The effective of the finite element simulation of the central tensile testing of reinforced concrete was verified by comparing the finite element simulation results with the test results.Through the analysis of the tensile data of reinforced concrete under different corrosion degrees,the variation law of the relative slip amount of reinforcement and concrete,reinforcement strain and the bond strength of reinforcement and concrete at different anchorage depth under different loads was further found.The position function of the bond strength of reinforcement and concrete at failure was obtained by fitting.(4)Based on experimental results,a three-dimensional model of reinforced concrete large eccentric colum was established by ABAQUS.The simulation results were compared with experimental result and verified it effective.The results show that considering the influence of the bond-slip of reinforcement and concrete,that is,the longitudinal reinforcement and concrete are reconnected by the nonlinear spring element,the finite element simulation of the reinforced concrete structure can be prediction accurately.(5)The finite element models of reinforced concrete large eccentric column with different sizes and different stirrup ratios were established to study the law of ultimate bearing capacity.The results show that the stirrup desification at both the bull leg and the concrete column has the greatest increase on the ultimate axial capacity of reinforced concrete large eccrentic column.When the shear span ratio of RC large eccentric column is small,with the increase of shear span ratio,the ultimate axial load of the column is larger,the ultimate mid-span deflection is smaller,the ductility coefficient and energy are larger.When the shear span ratio is large,the large eccentric column is affected by the second-order effect,and the ultimate axial load,mid-span deflection,ductility coefficient and energy are small.