Abstract
In this research, we propose the classification method of the soil condition to determine the design earthquake using the shear strength index of the whole ground as an index for classification. The method makes it possible to select the appropriate soil condition considering the upper limit of the ground response for a large-scale earthquake. We verified that more precise ground motion could be evaluated by the proposed method rather than by the ordinary method with only a natural period. Finally, we proposed the simple method for estimating the shear strength index of the whole ground, and confirmed its efficiency. By using this method, the accuracy of the ground classification for a large-scale earthquake is improved by only ordinary the usual ground survey and a simple calculation method.
