Study On The Method Of Ground Motion Selection And The Descending Rule Of Long-period Spectrum

Due to the high randomness of ground motion in time domain and frequency domain,different ground motions input can make a huge influence on the results of dynamic timehistory analysis.Meanwhile the existing methods are limited in application,so it is of necessity to develop a systematic,complete and reliable method of selecting seismic records,which can also be consistent with the Chinese code.Besides,as the basis of structural seismic design,the design response spectrum is artificially raised at long-period range,which results in the characteristic distortion of spectrum.Therefore,it is necessary to discuss the rationality of the descending form at long-period range of the design response spectrum.The research of this paper includes several aspects as following:(1)By collecting 52572 seismic records from several earthquake networks around the world,a strong earthquake database called SeismoDatabase,which is format uniformed,have global coverage,rich earthquake types and sufficient quantity is established.(2)Several commonly used method for selecting records are compared and qualitative evaluated on applicability.Based on the basic principle of structural dynamics,a method called MBM3 D is derived which can take account of the influence of high order modes and the coupling between translational and rotational modes.(3)Two typical ground motions are taken to conduct the parameter sensitivity analysis of inelastic response spectra.Correlaton analysis of inelastic displacement spectra is used to determine the seismic intensity index in vector form.(4)A complete flow of selecting ground motions is proposed,which can consider seismic hazard,elastic and inelastic structural response at the same time.Based on the normal skyline algorithm,each tuple is normalized and weight-considered,the dominance relationship is redefined,and a optimized skyline algorithm is proposed to estimate the seismic damage potential.A frame-shell wall structure is analyzed in OpenSees simulating rare earthquake,and result shows that the optimized skyline algorithm can select the most unfavorable seismic records more efficiently than other methods and can conduct the grade assessment of seismic damage potential.(5)A elastic-plastic analysis platform for high buildings called OpenSees Building is secondary developed based on OpenSees.This platform provides the complete solutions for modelling,computing and post-processing of large-scale structures in Opensees.(6)Imperfections of the design response spectrum at long-period range is discussed.Besides,rationality of the artificially raise at long-period range is evaluated.Based on the random vibration theory,7274 seismic records which have reliable long-period components are analyzed.According to the relationship between Fourier amplitude spectra,power spectral density and response spectrum,the statistically descending regularity of long-period spectrum is regressed and recommended values are proposed.