1. Ph.D. Candidate, School of Civil Engineering, Chongqing Univ., Chongqing Shaping St. 174, Chongqing 400045, China.
2. Professor, School of Civil Engineering, Chongqing Univ., Chongqing Shaping St. 174, Chongqing 400045, China.
3. Professor, School of Civil Engineering, Chongqing Univ., Chongqing Shaping St. 174, Chongqing 400045, China (corresponding author).
4. Professor, Dept. of Civil and Environmental Engineering, Univ. of California, Irvine, CA 92697.