1. Associate Professor, School of Civil Engineering, Southeast Univ., No. 2 Sipailou, Nanjing 210096, China (corresponding author).
2. Graduate Student, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801.
3. Graduate Student, School of Civil Engineering, Southeast Univ., No. 2 Sipailou, Nanjing 210096, China.
4. Professor, School of Civil Engineering, Southeast Univ., No. 2 Sipailou, Nanjing 210096, China.