1. College of Architecture and Civil Engineering, Beijing Univ. of Technology, Pingleyuan No. 100, Chaoyang District, Beijing 100124, China (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, E1A-07-14, Blk E1A, #07-03, 1 Engineering Dr. 2, Singapore 117576, Republic of Singapore.
3. Professor, College of Architecture and Civil Engineering, Beijing Univ. of Technology, Pingleyuan No. 100, Chaoyang District, Beijing 100124, China.