Failure Mechanism And Collapse Judgement Analysis Of Masonry Structure Subjected To Seismic

After the earthquake,it is found that masonry structures are generally damaged.It is necessary to study the failure mechanism of masonry structures under earthquake.Due to the limitation of experimental conditions and the rise of finite element analysis,it is one of the mainstream methods to analyze the seismic response of masonry structures by using finite element software.In order to study the seismic response of masonry structure,this paper starts with the basic unit of masonry structure----the mechanical properties of monolithic wall.By using the experimental results of the previous scholars,the finite element model of the monolithic wall under the same condition is established.The LS-DYNA software is used to calculate the structure under horizontal monotonic load.The comparison of the experiment results and numerical analysis proves the validity of the model and the contact algorithm,and the finite element model is established the rationality of the results in subsequent studies.Then,according to the principle of mechanics,the reaction force displacement curve of the structure is divided into four stages,which describe the characteristics of each stage and the signs of entering stages.After that,the finite element model of the wall under different vertical load is established,and the mechanical analysis is carried out.It is proved that the shear capacity of the wall can be improved by increasing the vertical pressure.For the wall under cyclic loading,three different types of walls(different opening positions)are established,and the counterforce-displacement curve of the wall is compared and analyzed.From the curve,the stiffness degradation and the bearing capacity decline of the walls are obtained in the loading process,and the stiffness degradation and the bearing capacity decline are explained in detail.It is concluded that wall openings are unfavorable to the aseismic capacity of walls.Using the above-mentioned reasonable verification results,a three-dimensional finite element model of a three-story masonry structure reinforced with unreinforced masonry structures and structural columns was established using a separation method,and the model was subjected to finite element calculation by applying a seismic acceleration wave.Quantitative analysis of the destruction of the structure after loading,the in-plane and out-of-plane displacements,and the inter-layer displacement of the structure.The results show that for the two types of masonry structures,the damage of the top layer is higher than that of the bottom layer under the action of earthquake;due to the strengthening effect of the structural columns,the masonry structure with structural columns has better integrity and lighter damage,which is obviously reduced.Deformation between vertical and horizontal walls and structural layers.Based on the above parameters,the failure mode and safety of the structure were evaluated according to the ―Classification Criteria for the Seismic Destruction of Buildings‖ and the ―Civil Building Reliability Appraisal Standard‖,and it was concluded that the top failure mode was collapsed after the end of loading of the unreinforced masonry structure.Destruction,and the top layer is not suitable for continuous loading,the failure mode of the masonry structure reinforced with structural columns is moderately damaged,and the top layer of the structure can continue to withstand seismic loads until the specification limits are not met.Finally,it was concluded that the reinforced masonry structure can effectively improve the seismic bearing capacity.