Discussion on site classification method based on consistency of characteristics of calculated seismic motion

Based on site models derived from 1137 drilling data and corresponding computing results of seismic response analysis of soil layers, this paper analyzes and discusses site classification methods in the Chinese Code for Seismic Design of Buildings (GB50011-2016) and the American Code IBC (International Building Code) from the perspectives of peak acceleration and characteristic period of the site ground motions. According to the consistency analysis of site seismic effects, it can be concluded that: in medium-to-hard soil sites, the dispersion of Class C sites in the United States is the smallest; in soft-to-medium soil sites, Class Ⅲ sites in China exhibit certain weaknesses; in soft soil sites, China's Class Ⅳ sites have more obvious advantages. Overall, China's double index classification method demonstrates certain advantages. Therefore, a new site classification method is proposed, in which equivalent shear wave velocity is calculated based on the soil layers in the depth range of smaller values between the covering layer thickness and 30 m. In current Class Ⅱ sites are divided into class Ⅱ₁ and Ⅱ₂ sites, and Class Ⅲ sites with a soil layer thickness greater than 50m and equivalent shear wave velocity less than or equal to 170 m/s are classified as Class Ⅳ sites, the boundary limits of equivalent shear wave velocity below 500m/s are increased by 20 m/s. The study provides a new solution to establish a more reasonable site classification method.