Multi-scale Modeling Analysis Of Reinforced Concrete Component Based On Cmpc Method

The damage of the structure under load is usually caused by local material failure,and then the overall structure is destroyed by local damage.Aiming at the cross-scale failure process of the structure,the multi-scale analysis can simultaneously simulate the macro-overall behavior and local micro-damage of the structure,and improve the computational efficiency by establishing the unit models with different scales.However,the current multi-scale interface constraint relationship is based on a single MPC method,which exist problems of interface over-constraints and limitation of nonlinear analysis.In this paper,a combined multi-point constraintmet hod(CMPC)based on the displacement and energy is established for the consistent multi-scale inter face constraint.Then by using the non-flat-section strain function of reinforced concrete component,the CMPC equation in the plastic phase is optimized.At last,through the simulation of bond-slip performance for multi-scale components,the validity of the CMPC method after considering the slip effect is verified.The main results are as follows:Research on combined multi-point constraints method based on uniform multi-scale model.In order to solve the problem of the unreasonable constraint of the single MPC method under complex forces,a combined multi-point constraints method was established by the combination of displacement method and energy method with different DOF in the inter face.And then the CMPC equation expressions of typical multi-scale components are deduced.The FEM analysis of RC multi-scale model proves that the CMPC method is in accordance with the deformation and constraint relationship of the interface nodes,and improves the accuracy of multi-scale model in the plastic phase of reinforced concrete components.Research on CMPC optimization based on non-flat section.By using the non-flat cross-sectional strain function of concrete under bending moment and axial force,the combined constraint equation is modified in stages.According to the two-stage analysis before and after yielding,the non-flat section CMPC equation is in accordance with the deformation law at the plast ic stage under bending failure,which can effectively improve the calculation precision of interface stress,plastic strain and displacement.Based on the equivalent plastic hinge theory of RC structure,the influence of the selection of non-flat section position on the calculation accuracy of multi-scale model is analyzed and the optimum inter face selection range of multi-scale model for frame column is obtained.Perfor mance analys is of CMPC multi-scale model considering bond-slip effect.Based on the bond-slip constitutive relationship of rebar,a finite element model considering bond-slip behavior was establis hed.And the mechanical properties of multi-scale model by CMPC method are studied.Through the establishment of the contrast model,the effect of the steel slip on the microscopic characteristics and the macroscopic characteristics of the multi-scale interface is analyzed.The results show that the failure mode of the multi-scale model basically agrees with the fine model,and the validity of the CMPC method after considering the slip effect is verified.