1. Lecturer, Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, School of Civil Engineering, Southeast Univ., Nanjing 210096, PR China.
2. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Pittsburgh, Pittsburgh, PA 15260.
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Pittsburgh, Pittsburgh, PA 15260.
4. Associate Professor, Key Laboratory of Mechanics on Disaster and Environment in Western China of Ministry of Education, College of Civil Engineering and Mechanics, Lanzhou Univ., Lanzhou 730000, PR China (corresponding author).