Numerical Simulation Of Reinforced Concrete Members Strengthening With Increasing Section Area

China’s construction industry in the stage of social development can be positioned in the new building and existing building reinforcement and reconstruction stage,the relevant data reflect that,whether domestic or foreign,the status of the field of building reinforcement is becoming more and more important.Among them,as the most traditional reinforcement method of structure member strengthening with increasing section area,its performance is improved obviously and the construction technology is simple.It is widely used in all kinds of buildings,industrial plants,bridges and dams.Although there are many experimental and numerical studies on the method of increasing section area at home and abroad,there are few cases considering the secondary stress and the development of the weak interface between the new and old concrete.Especially in the numerical aspect,most of the numerical studies are based on the finite element method,which can not effectively simulate the concrete cracking and interface development The main work of the numerical simulation is as follows:In this paper,based on the discrete element theory,combined with the previous experimental data and phenomena,using PFC3 D to establish the uniaxial compression simulation test of cube test block and the double-sided shear test of new and old concrete bonding test block.The stressstrain curve,load displacement curve and crack development process obtained from the simulation are verified with the test,and the influence of parameters is discussed to verify the effect of PFC on concrete failure The feasibility of process mesoscopic research.PFC3D discrete element software is used to simulate the double-sided shear test of new and old concrete bonded blocks,and the results are compared with the test data.The mechanical characteristics,crack evolution process and distribution law are studied from the micro perspective,so as to verify the applicability of particle flow to the bearing capacity,failure mode and interface problems of concrete members.Based on the above reliable research of particle flow on the test block,the axial compression test of reinforced concrete column strengthening with increasing section area is numerically simulated.The influence of thickness ratio and strength ratio of new and old concrete on the mechanical properties of reinforced concrete column is considered,and the influence degree of each factor is analyzed by using orthogonal test analysis method,which is verified with the test;The failure mode of concrete column and the interface development of new and old concrete under different stress levels are studied.Single factor analysis is used to study the improvement effect and application scope of a certain factor on bearing capacity.The four point bending test of reinforced concrete beams strengthening with increasing section area is simulated to study the shear performance and failure mode of unreinforced contrast test beams,reinforced concrete beams strengthened by directly increasing cross-section method and reinforced concrete beams strengthened after pre damage under different stirrup ratios;Considering the influence of the secondary stress,the failure mode of the interface between the new and old concrete is studied when the reinforced concrete beam is strengthened with increasing section area.