Research On Key Issues Of Seismic Response Analysis Of Steel Industrial Buildings

The dynamic interaction and the non-classical damping of the structure-equipment system,and the influence of the panel zone deformation are two key issues in the seismic analysis of the steel industrial buildings.This paper studies these issues through the parameter analysis of the lumped mass-shear spring model and the finite element（FE）analysis of the typical steel industrial buildings.The main work and conclusions are as follows:（1）The lumped mass-shear spring models of single-story and multi-story structure-equipment systems were established based on MATLAB,and the uncoupled method,real mode superposition approximation method and complex mode superposition method are adopted for seismic response analysis.The error of responses calculated by the two approximation methods（i.e.,the uncoupled method,real mode superposition approximation method）are investigated by comparison with the results of the complex mode superposition method,and the major factors that influence the errors are discussed.The analysis results indicate that the errors of the uncoupled method and the real mode superposition approximation method are primarily affected by the equipment-structure frequency ratioγ_f,the equipment-structure mass ratioγ_m,and the difference in damping ratios between the equipment and the structure.While the characteristic site period,height of the structure,and equipment locations also have some influence on the errors of the two approximation methods,they do not affect the range of applicability of the methods.（2）According to the results of the parameter analysis,the range of applicability of the two approximation methods are established,which is related to the equipment-structure frequency ratios,equipment-structure mass ratios and equipment damping ratios.The uncoupled method is applicable only when the equipment-structure mass ratioγ_m is less than 1%.In the equipment-structure tuning region（0.9≤γ_f≤1.1）,the limit for applicability of the uncoupled method is even stricter（i.e.,γ_m≤0.04%）.For the real mode superposition approximation method,only when the equipment is close to the first-order frequency of the main structure（0.9≤γ_f≤1.1）and the mass is relatively small（γ_m<7%）,the error will exceed 10%.In other conditions,this method is applicable.For the case that these two approximate methods are not applicable,the complex mode method should be used for an accurate estimate of seismic responses.Finally,FE analysis of a steel industrial building using PMSAP is presented as a case study to validate the proposed range of applicability of the two approximation methods.（3）Two FE models of a typical steel industrial building are established using the Open Sees program,where one model includes the panel zone elements while another does not consider the panel zone behavior.The steel industrial building is designed as per Chinese design codes.The response spectrum method,pushover analysis and nonlinear time history analysis are used to calculate the seismic responses of the industrial building.The results indicate that the deformation of panel zones has a limited influence on the dynamic properties and seismic response of the structure under the service level earthquake,with errors of less than 5%.Under the maximum considered earthquake and very rare earthquake,inclusion or exclusion of the panel zone affects the locations and development of plastic hinges,and thus results in an error of more than 10%in the calculated displacement responses of the structure.