1. Dept. of Civil Engineering, Zhejiang Univ., 866 Yuhangtang Rd., Hangzhou, Zhejiang 310058, China; Scientist, Applied Computing and Mechanics Laboratory, School of Architecture, Civil and Environmental Engineering, Swiss Federal Institute of Technology, Lausanne CH-1015, Switzerland.
2. Professor, Dept. of Civil Engineering, Zhejiang Univ., 866 Yuhangtang Rd., Hangzhou, Zhejiang 310058, China (corresponding author).
3. Professor, Dept. of Civil Engineering, Zhejiang Univ., 866 Yuhangtang Rd., Hangzhou, Zhejiang 310058, China.