| Space latticed structures are widely used in civil engineering with the advantages of large space,various styles,light weight,reasonable force and easy construction,and the related theories have also been improved.In recent years,domestic scholars have gotten many achievements on the field about static and dynamic performance and seismic study of latticed shell.However,most of these studies do not consider the effect of soil or substituted simplified model for the soil,which will produce large deviation with the actual situation.Therefore,it is important to study the dynamic analysis of the latticed shell structure considering the interaction of the lower soil under the action of earthquake.This paper selects the three-dimensional grid-type single-layer cylindrical latticed shell to research the seismic responses considering different soil-foundation-structure interaction.In this paper,ANSYS Workbench finite element software is used to build the calculation models of the latticed shell structure.Based on the ANSYS parametric design language(APDL)command flow,the viscoelastic artificial boundary is established,and the whole models under different soil-foundation-structure interaction are established.Firstly,the self-vibration characteristics are obtained to extract the first 30 order natural vibration frequency and vibration mode 6 order under different soil for comparison.And then select the adjusted EL-Centro wave and Taft wave as the three-way input ground motions of the structure.The seismic response of structure system is obtained by time history analysis method.The nodes and rods with the maximum response value are selected,and the displacement,acceleration of the joints and axial force of the rods are analyzed respectively.By comparing the structural self-vibration characteristics and the seismic response results of different soil types,the following main conclusions are obtained:(1)The frequency of the structure in the model is relatively dense.The natural frequency of the whole structure is gradually reduced with the softening of the foundation soil,especially in the weak soil.At the same time,it can be seen that the first vibration mode is horizontal.The vibration frequency of the model decreases with the increase of roof load.(2)Under the three-way earthquake,the maximum horizontal displacement of the latticed shell node increases with the softening of the foundation soil,however,the maximum value of the vertical displacement and the maximum vertical acceleration of the node will decrease under the weak soil.(3)Under the action of three-way earthquakes,the maximum axial force of the latticed shell rod increases with the softening of the foundation soil,but the maximum value of the diagonal axis force is suddenly reduced under the weak soil.(4)Under the action of two kinds of seismic waves,the response peak under the action of EL-Centro wave is slightly larger than the response peak under the action of Taft wave,but the difference of the response value at the same time point is large. |
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