1. Lecturer, Engineering Dept., Asian Univ. of Science and Technology, Box 15, Bhan Amphur, Chon Buri 20250, Thailand.
2. Professor, Dept. of Civil & Environmental Engineering, Univ. of Michigan, 2340 G. G. Brown, Ann Arbor, MI 48109.
3. Assistant Professor, Dept. of Civil & Environmental Engineering, Univ. of California, 721 Davis Hall, Berkeley, CA 94720.