Research On Some Issues Of Site For Seismic Design

For a deep effect on surface ground motion, site condition directly influences theestimate of design seismic. Countries and regions classify sites as categories in seismic designcode to evaluate different sites impact on seismic with site coefficient or characteristicperiod.But as classified by different countries and regions in seismic design code, the sitesmay manifest as sort of coefficient or characteristic period values.This paper compared our nation with the countries and regions of Europe, the UnitedStates, and Taiwan on seismic design code of site classification and site effects on the designresponse spectrum, has studied site classification correspondence relationship for seismicdesign code between China and foreign countries and site effect on ground motion.In the aspect of site classification correspondence relationship research for seismicdesign code between China and foreign countries, the paper using detailed site drilling data in235 stations of the United States, Taiwan and other countries and regions around the world,has found out the relations on regulating site classification index links between China and theUnited States seismic design code, as well as other countries and regions, indicated thatclassifying the sites under 01 seismic code according to the equivalent shear wave velocity'sVs30 value within the depth of 30m belowground, It makes us in full and efficient use of strongseismic data of the countries and regions aboard.In the aspect of site effect on ground motion research, the paper has studied theamplification effect of site soil on bedrock peak ground acceleration by using 327 sets ofstrong seismic records of KIK-NET in Japan, calculated the ratio of peak ground accelerationand bedrock peak ground acceleration, concluded that when the seismic input of undergroundbedrock with same level, Classâ…¡site manifests the largest ground motion amplification,Classâ…¢closed to Classâ…£with less amplification and Classâ… with the least;after Classâ…¢site; the amplification of bedrock peak ground acceleration of the sites with different classesdecreases as the input ground motion intensity increases ,which indicates that in China,thedesign response spectrum value with T=0 should be adjusted by site conditions. Besides, with252 sets of strong seismic records of KIK-NET in Japan, calculated acceleration responsespectrum with 5% damping ratio of underground bedrock and surface of each site,the paperhas also found out that, Classâ…¡site manifests the largest ground motion amplification in short period, less of Classâ…¢,and Classâ… with the least amplification, the amplification ofresponse spectrum of the sites with different classes decreases as the input ground motionintensity increases, which shows that in China the maximum response spectrum needsadjusting by site classification. This paper has given proposed maximum coeddicient valuesof design response spectrum with different site classifications.