Seismic Response Of Long-Span Spatial Structures Under Muti-Support And Multi-Dimentional Earthquake Excitations

The seismic spatial effect should be considered in the seismic response analysisfor the long-span spatial structures, because the support nodes remove inconsistentlyunder earthquake excitation. While the present seismic analysis methods in the "Codefor Seismic Design of Buildings"(GB50011-2001) are based on the hypothesis ofuniform excitation, so they do not suit for long-span spatial structures. So it isnecessary to study the seismic response methods for long-span spatial structureconsidering seismic spatial effect. In this dissertation, the seismic response analysismethods for long-span spatial structures under multi-support and multi-dimensionalearthquake excitations are studied. The main research work covers the followingaspects:(1) The pseudo excitation method is introduced to analyze the seismic responsefor long-span spatial structures. The random vibration approach for long-span spatialstructures under multi-support and multi-dimensional earthquake excitations isstudied.(2) The simulation approach for the stochastic earthquake ground motion modelis proposed and three-dimensional earthquake and multi-support stochastic earthquakeground motion model is established based on multi-support stochastic earthquakeground motion model.(3) Parameters and functions of the model are studied, self-power spectrumdensity,mutual-power spectrum density,time delay of the motion,mathematicalmodel of coherence function between two excitations and coherence function betweenthree-dimensional earthquake suitable for the long-span spatial structures areproposed. The method of transferring the response spectrum curve to power spectraldensity curves is investigated, and the PSD model parameter correspond to the "Codefor Seismic Design of Buildings"(GB50011-2001) is determined usingiteration-correct method .Therefore it is more convenient in seismic analysis to useresponse spectrum method to produce the equivalent stochastic vibration method.(4) A computer program has been developed for the random vibration analysis.And random vibration analysis is performed for a long-span spatial lattice structureunder multi-support and multi-dimensional earthquake excitations. Comparisons aremade between multi-dimensional and single-dimensional response,uniform excitationand considering traveling-wave effect and incoherence effects.(5) Numerical simulation for the seismic response of the spatial structure ofTianjin Olympics Sports center is performed under multi-dimensional andsingle-dimensional excitation,the uniform excitation and traveling wave excitation ofthe definite earthquake ground motion.A conclusion is drawn that the seismic response of the long-span spatialstructures under multi-support and multi-dimensional earthquake excitations is greatlydifferent from that under consistent excitation. The detailed seismic analysis must becarried out in the design process of the long-span spatial structures.