| Research on nonlinear response and collapse damage of structure under earthquake is an important subject in structural engineering disciplinary and one of the research hotspots currently.Although scholars have already put forward several numerical analysis methods,these methods are still difficult to perfectly deal with the entire process simulation on the structure from elastic to plastic,from small deformation to large deformation and even to collapse.Discrete element method(DEM)as a non-continuous numerical analysis method,does not require the displacement of coordination between elements,and applies to solving the issues in structural collapse such as non-continuous displacement field,large displacement,large rotation.The discrete element method was firstly developed in geotechnical engineering,and has gradually applied in structural nonlinear seismic response and collapse mechanism analysis.However,the previous model based on DEM which are of undefined physical meaning in constitutive relation and oversize number of elements,so that these model are difficult for large complex collapse damage analysis.Furthermore,the accuracy of structural nonlinear behavior simulation before structural collapse using DEM also requires to be further studied.This paper focuses on the nonlinear performance analysis of RC frame structure using DEM,the specific work as follows:(1)Summarize the research status of numerical analysis method such as DEM in structural nonlinear and collapse analysis.And make an improvement in the segment-multi-spring model(SMSM)which was built based on DEM and the theory of frame structure nonlinear analysis model are studied.(2)In this paper,concrete and reinforced constitutive model proposed by Wang Qiang is modified.Compression of concrete skeleton curves proposed by Kent and Park and improved by Scott B.D.is used,the author get rid of the effect of concrete surface,and add the tensile performance of concrete.To perfect reinforced the constitutive rules of hysteresis,the calculated results are more in line with the experimental results.(3)Using FORTRAN language to write subroutine of constitutive model of concrete and reinforcing steel,and call the main program which was written in visual studio,imitate the ABAQUS to add unloading effect to check the program.(4)Using segment-multi-spring model(SMSM)and SMS-Collapse process,numerical simulation of RC plane frame specimens under low cyclic load has been carried,and the results show good agreement with the experimental test.The results show that SMSM with new constitutive model can accurately describe the axial force component of concrete beams and detailed description of the mechanical behavior of materials,can accurately describe reinforced concrete beams in nonlinear components under cyclic load hysteretic behavior.(5)Numerical simulation of RC space frame specimens under low cyclic load has been carried,and the results show good agreement with the experimental test.Therefore,the structural analysis model established is reasonable.The SMS-Collapse program can truly and correctly descript the structural reaction in this paper,and can be applied to the whole structural nonlinear analysis with high accuracy. |
