1. Professor, Dept. of Civil Engineering, Nihon Univ., College of Science and Technology, Kanda Surugadai, 1-8-14 Chiyoda-ku, Tokyo 101-8308, Japan.
2. Associate Professor, Dept. of Civil Engineering, Nihon Univ., College of Science and Technology, Tokyo 101-8308, Japan.
3. Research Associate, Dept. of Civil Engineering, Nihon Univ., College of Science and Technology, Tokyo 101-8308, Japan.