1. Graduate Student, Dept. of Civil and Environmental Engineering, Univ. of Connecticut, Storrs, CT 06269.
2. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Connecticut, Storrs, CT 06269 (corresponding author).
3. Professor, School of Civil Engineering, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China.
4. Assistant Professor, School of Civil Engineering, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China.