Seismic Vulnerability Analysis Of Double Layer Cylindrical Reticulated Shell Structure Based On IDA Methodology

The double-layer cylindrical reticulated shell structure,as a form of space structure,has obvious advantages and is widely used in practical engineering.Earthquake is a serious natural disaster.Once it occurs,it will pose a great threat to the safety performance of the structure.Therefore,it is necessary to carry out the seismic vulnerability analysis of the double-layer cylindrical reticulated shell structure to realize the seismic performance evaluation of the structure.To this end,this article mainly included the following work.Firstly,in order to establish a complete seismic vulnerability analysis system for double-layer cylindrical reticulated shell structures,the maximum joint displacement and yield member ratio were introduced as structural seismic response indicators,and our country’s relevant seismic codes was concerned,the maximum nodal displacement limit was used as the basis for division,five structural failure states and three types of performance levels were defined,and structural seismic vulnerability function was summarized and deduced.Secondly,in order to analyze the influence of the uncertainty of the random parameters of ground motion and structural modeling on the seismic vulnerability analysis of the structure,40 natural seismic waves were used as seismic input samples,and incremental dynamic analysis method was used to perform numerical simulations.10,20,30,and 40natural seismic waves corresponding to structural seismic vulnerability curves had been sorted out,and the comparison results of the vulnerability curves corresponding to 10,20,and30 seismic waves with 40 seismic wave corresponding curves respectively.It can be seen that a good balance of analysis accuracy and analysis efficiency can be achieved when 30 natural seismic waves were used.Based on this,30 natural seismic waves were used,and the amplitude of the seismic load corresponding to the probability of encounter and exceeding 10%in 50 years was used for amplitude modulation,and 10 random parameters for structural modeling including material parameters,structural characteristic parameters,load parameters and component geometric size parameters were selected.The sensitivity of the structure seismic response to the above parameters was analyzed through the seismic response index.It can be seen that the key structural modeling random parameters are steel yield strength f_y,structural viscous damping ratioξand elastic modulus E.Finally,in order to evaluate the applicability of different ground motion intensity parameters to the seismic vulnerability of the double-layer cylindrical reticulated shell structure,the uncertainty of ground motion and the uncertainty of random parameters of structure modeling were comprehensively considered.And firstly the simulation result with Peak Ground Acceleration（PGA）as the ground motion intensity parameter was converted to obtain the corresponding Average spectral acceleration of the first period（S_a（T₁,ξ））,Average spectral acceleration(S_a,avg),Peak Ground Velocity（PGV）and Peak Ground Displacement（PGD）.Then four evaluation indicators of effectiveness,practicality,relevance and usefulness were used to evaluate the intensity parameters of ground motion,and PGA,S_a（T₁,ξ）and S_a,avgwere selected for seismic vulnerability analysis.From the results of the incremental dynamic analysis and the seismic vulnerability analysis corresponding to the three levels of seismic fortification,it can be seen that the seismic performance corresponding to S_a（T₁,ξ）was the lowest,compared with PGA,the maximum decrease was 32%,and compared with S_a,avg,the maximum decrease was 15%.Therefore,the reliability of structural seismic performance can be further improved when the seismic vulnerability analysis result corresponding to S_a（T₁,ξ）was adopted as the basis of structural seismic design and optimization.