1. Professor, Dept. of Civil Engineering, Ritsumeikan Univ., Noji-Higashi 1-1-1, Kusatsu, Shiga 525-8577, Japan.
2. Research Associate, Dept. of Civil Engineering, Ritsumeikan Univ., Noji-Higashi 1-1-1, Kusatsu, Shiga 525-8577, Japan.
3. Structural Engineer, West Japan Railway Company, Shibata 2-4-24, Osaka Osaka, 530-8341, Japan.
4. Design Engineer, Aratani Civil Engineering Consultants Co., Ltd., Eba-Nishi 1-25-5, Naka-ward, Hiroshima, Hiroshima 730-0831, Japan.