| Masonry structure is the most common form of building structure in our country’s villages and towns.The damage to masonry structures in previous earthquakes is often the most serious,causing irreparable losses to people’s lives and property.The masonry is made of mortar and blocks with two materials with large differences in performance,with significant discontinuity.At present,most of the numerical simulation research on masonry is carried out based on the displacement continuous finite element method,but the failure process of the masonry is accompanied by the cracking of the wall and the continuous increase of the overall deformation,which is a discontinuous and large deformation problem.Based on the displacement continuity assumption in the simulation analysis,the finite element method often has problems such as difficulty in defining failure criteria and difficulty in convergence,which is not completely suitable for dealing with masonry structure problems.Discrete element method is a characteristic and promising numerical method to solve the problem of discontinuous medium in recent years.It assumes that the research object is a collection of scattered medium,which is suitable for the analysis of large deformation and large displacement of masonry structure.In this paper,the discrete element method is introduced into the analysis of masonry.Masonry is defined as a collection of blocks with continuous medium characteristics and joints（mortar joints）with discontinuous medium characteristics,which fits the non-continuous composition characteristics of masonry to the greatest extent.Around the discrete element method,the main work content and conclusions are as follows:（1）The basic idea,basic equation and basic operation process of the discrete element method are introduced in detail,and the selection of relevant calculation parameters when the discrete element method is applied to the analysis of masonry structure is briefly introduced.（2）Based on the 3D discrete element method program,the pseudo-static tests of three unreinforced masonry walls were simulated.The skeleton curves and failure modes of the test walls were taken as comparison standards to verify the validity of the modeling method and the selection of material parameters.It is shown that the block constitutions and joint constitutions based on Mohr-Coulomb theory can effectively characterize the mechanical behavior of masonry walls subjected to external loads.（3）Establish masonry wall models under different aspect ratios,opening ratios and vertical loads,and study the changing laws of wall performance under the condition of changing wall parameters based on the discrete element method.The simulation results show that the changing law of wall performance when changing the aspect ratio,opening ratio and vertical load is basically similar to the previous test results and simulation results.The discrete element method can be effectively used when the masonry wall is subjected to static load.The bearing capacity estimation and failure mode prediction.（4）The rigid discrete element models of single-layer and double-layer masonry structures are established,and the time-history of strong earthquake velocity after amplitude modulation is input into the bottom of the structure to study the damage process of masonry structures under earthquake action.The results show that the discrete element model can accurately simulate the cracking mode of masonry wall under earthquake action,and the cracking position and phenomenon are basically consistent with the actual earthquake damage phenomenon.The conclusion is reasonable,and the discrete element method can be effectively used for the simulation of the failure of low masonry building. |
