1. Professor, Dept. of Civil Engineering, Tokyo Institute of Technology, 2-12-1-M1-17, O-okayama, Meguro-ku, Tokyo 152-8552, Japan (corresponding author).
2. Doctoral Student, Dept. of Civil Engineering, Tokyo Institute of Technology, Japan.
3. Assistant Professor, Dept. of Civil Engineering, Tokyo Institute of Technology, Japan.
4. Senior Researcher, Structures Technology Division, Railway Technical Research Institute, Tokyo, Japan.