1. Department of Civil Engineering and Engineering Mechanics, Columbia UniversityNew York, NY 10027, USA
2. Department of Mechanical Engineering, Osaka University2-1 Yamadaoka, Suita-shi, Osaka 565-0871, Japan
3. Department Mechanical Engineering, National Defense Academy1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan