1. Associate Professor, Institute of Structural Engineering, Zhejiang Univ., Hangzhou 310058, P.R. China (corresponding author).
2. Professor, Institute of Structural Engineering, Zhejiang Univ., Hangzhou 310058, P.R. China.
3. Associate Professor, Dept. of Civil and Environmental Engineering, Hong Kong Univ. of Science and Technology, Hong Kong Special Administrative Region, Hong Kong.
4. Assistant Professor, Dept. of Civil and Environmental Engineering, Princeton Univ., Princeton, NJ 08544.
5. Graduate Student, Institute of Structural Engineering, Zhejiang Univ., Hangzhou 310058, P.R. China.