Preliminary Analysis Of Site Response Variability Using Ground-motion Data From Sichuan Region

Ground motion at site has been paid close attention by seismic researchers.and engineers for a long time,and it is also the basis for seismic design of engineering structures.Theoretical calculation and numerical test are common methods currently in the study of ground motion response.Nowadays the strong motion network construction in China is nearly completed that a wealth of seismic data can be collected.Then site response studies based on real seismic data are more widely used.The site amplification function(SAF),is a comprehensive indicator of seismic response,reflects the features that frequency spectrum of seismic wave through the soil.Computation of SAF has some variability,which will inevitably lead to uncertainty in calculating of ground motion.This thesis set SAF as the research targets,using the seismic recordings collected in Wenchuan earthquake to analysis the impact factors of SAF's uncertainty.Then,the thesis discusses the probabilistic analysis method of SAF with its uncertainty considered,providing another way to evaluate the seismic risk in a site.The main work completed in this thesis are as follows:1.Systematically collect a series of seismic recordings of Wenchuan earthquakes in Sichuan area,especially the single-station recordings,establish the site response analysis database,and analyze the characteristics of the seismic database.2.Study the impact factors of SAF's uncertainty and its influence laws by the single-station recordings.3.Study the SAF under the site conditions,give results of the SAF fitted by linear and nonlinear under the site conditions,compare and assess the variability of the two fittings.4.Input different ground-motions which are recorded on bedrock,establish two simple site model,study the impact of the nonlinearity of soil on SAF's uncertainty by using numerical method,provide a way for studying the influencing factors on SAF's uncertainty respectively.