Research On Ground Motion Characteristic Considering Site Condition

Research on ground motion characteristics is the fundation of compiling the earthquake resistant design codes. In this paper, based on the strong motion records of Chi-Chi earthquake in 1999 and the latest site drilling exploration data of Taiwan strong motion station, the ground motion characteristics of different site coditions are analyzed. It has very important scientific significance and engineering practical value.Based on the review of site classification methods and regulation of site effects in earthquake resistant design codes of China and abroad, the following works are carried out:1. According to the current earthquake resistant design code of China, the drilling exploration data of Taiwan strong motion stations are arranged and the 257 stations are regrouped.2. By using the records from stations that the site conditions have been classified, the PGA attenuation laws of different site conditions are analyzed. Then the changing trend of ratio of the horizontal to vertical PGA is studied. The difference of the characteristic periods and plateau values of normalized response spectrum of different site conditions are also analyzed.3. Ground motion attenuation relationship suited for Chi-Chi earthquake is choose and verified, and then the ground motion calculated by the attenuation relationship and that observed at rock stations are compared and analyzed. At last, the bedrock ground motion at the soil station is generated by the attenuation relationship and the correction method, and the amplification factors of different site conditions are statistically analyzed.