The Seismic Response Analysis Of Ultra-long And Ultra-wide Steel Structure Factory Under Multi-dimensional And Multi-support Excitation

With the rapid development of China’s manufacturing industry,large steel structure industrial factory emerge as the times require and more and more ultra-long and ultra-wide steel structure factory are used.The influence of traveling wave effect on the seismic response of this kind of structure becomes more and more obvious as the plane size increases.In this paper,the traveling wave effect of ultra-long and ultra-wide steel column and steel truss structure is analyzed.Based on SAP2000 finite element software,the direct displacement input method is used to analyze the time-history response of the structure under multidimensional and multi-support earthquake,and the results are compared with those under multidimensional consistent excitation.Through the analysis of the traveling wave effect of structural members under multidimensional and multi-support input,the seismic response law of ultra-long and ultra-wide steel column and steel truss structure is obtained.The main work is as follows:（1）The structural model is established,and the natural vibration characteristics of the structure are analyzed.The natural vibration characteristics,stiffness in all directions and the main vibration forms of the structure are obtained,which is prepared for the later research.Through modal analysis,it can be seen that:The structure belongs to plane stress and its z direction>y direction>x direction at the level of structural stiffness.It can also be analyzed that the length of the structure is long and the dynamic performance is complex,that the vibration mode of the structure is regional vibration.（2）According to the site conditions,two occurred seismic wave data and one artificial fitting seismic wave synthesized by seismic wave generator are selected by response spectrum method,and amplitude modulation and duration are defined according to the code.Based on the analysis of one-dimensional and three-dimensional seismic response,the deformation,displacement and internal force of main members of the structure are taken as reference.Come to conclusions that:The multi-directional seismic input has great influence on the displacement of the structure in Y direction and the rotation of the structure in R₁direction.The axial force of the steel column in the middle of the span is basically as the same as that under one-dimensional and multidimensional seism,and the axial force of the side span column is much greater than that of the middle span column.However,the axial force of the steel column on the side span under multidimensional action is much greater than that under one-dimensional action,and the shear force V₃in X direction of steel column under threedimensional seism is much larger than that under one-dimensional seism,and the bending moment M₂in X direction is also much larger than that under one-dimensional seism;The axial force response curves of the top chord,web member and bottom chord of the superstructure under multi-dimensional earthquake are very close to those under one-dimensional seism.（3）Through the calculation and analysis of multi-support input of the structure under different apparent velocities,four different apparent velocities are input,and the internal force response of structural members under different apparent velocities is compared and analyzed.The result shows that with the decrease of the apparent velocity,the percentage of overload members increases,which shows that the structure changes regularly under different apparent wave velocities,the smaller the apparent wave velocity is,the more obvious the structural response is.（4）The time history response of the structure under multidimensional and multi-support excitation is analyzed,and the acceleration,displacement and internal force of main members are taken as the research objects.Research shows:The traveling wave effect will change the peak displacement and acceleration of the structure,and the influence degree is closely related to the selection of seismic wave and apparent velocity.For the ultra-long and ultra-wide steel column and steel truss structure,it is necessary to consider the input of ground motion in multiple directions when designing the structure.It is not perfect to consider only one-dimensional seism.Therefore,multidimensional and multi-support ground motion input should be carried out in seismic analysis of such structures.Considering the effect of traveling wave,the axial force of steel column decreases and the shear force increases.In seismic design,the axial force of the top chord,web member and bottom chord of the steel roof truss should be enlarged by 1.16,1.10 and1.25 times respectively,and the shear force of the side column should be enlarged by 1.2 times.This paper has 48 pictures,21 tables and 64 references.