1. Department of Civil and Environmental Engineering; Tohoku University; 468-1 Aza-Aoba, Aramaki, Aoba-ku Sendai 980-0845 Japan
2. International Research Institute of Disaster Science; Tohoku University; 468-1 Aza-Aoba, Aramaki, Aoba-ku Sendai 980-0845 Japan
3. Department of Civil and Environmental Engineering; Tohoku University; 6-6-06 Aza-Aoba, Aramaki, Aoba-ku Sendai 980-8597 Japan
4. Department of Mechanical Engineering and Science; Kyoto University; Kyotodaigaku-katsura CIII, Nishikyo-ku Kyoto 615-8540 Japan