Multi-scale Damage Evolution Analysis Of Large-span Space Reticulated Shell Structure Under Strong Earthquake

Lattice shell structure has the advantages of large span,reasonable stress on members,single member form and convenient installation and manufacture.In recent years,such structural forms of buildings have gradually increased and are most widely used in curved grid structures.However,the stress of reticulated shell structure under earthquake is very complex.Once destroyed,it will bring serious losses to people’s production and life.Therefore,it is of great significance to study the damage mechanism and collapse mechanism of space reticulated shell structure under earthquake load.In this paper,single-layer reticulated spherical shell structure is taken as the research object.Through numerical simulation,the damage evolution law and collapse mechanism of reticulated spherical shell structure under earthquake are systematically studied.Firstly,the stability of single-layer Kewitt type,single-layer rib ring,single-layer joint square grid and single-layer Schwedler type spherical reticulated shell structures are analyzed to find out the spherical reticulated shell structures with better stability.Then,the nonlinear dynamic characteristics of the reticulated shell structures under earthquake load are studied by time-history analysis method,and the weak positions are determined according to the equivalent plastic strain distribution of the reticulated shell structures.The results show that under strong earthquakes,the outermost diagonal bars of single-layer reticulated spherical shell structure are the weak parts of the structure.With the further increase of earthquake load,the proportion of members entering yield in the structure also increases.Finally,the structure collapses due to the growth and penetration of yield members.Secondly,according to the time-history analysis results of the structure,a multi-scale model of the reticulated shell structure is established by using the spatial multi-scale modeling method,adopting shell elements for weak parts and beam elements for general parts of the structure,and realizing cross-scale connection by using MPC method to obtain the local plastic evolution law of the structure.The rationality of the multi-scale model is verified by comparing the relationship between the structural energy consumption,the maximum displacement response,the maximum acceleration amplitude and the proportion of plastic members of the macro model and the multi-scale model.Finally,the multi-scale damage constitutive model of the structure is established,and the entire damage evolution process of the reticulated shell structure is analyzed by introducing VUMAT subroutine through ABAQUS finite element analysis software.The strength and stiffness degradation criteria of reticulated shell structures under earthquake load are studied,including damage evolution law,failure load variation characteristics and structural collapse law of reticulated shell structures under earthquake load.The results show that after introducing the material damage constitutive model,the ultimate bearing capacity of reticulated shell structure decreases sharply and the displacement response characteristics also change greatly compared with that without considering damage.With the increase of load amplitude,the plastic region in the structure expands continuously until it penetrates,eventually leading to collapse and failure of the structure.