1. Ph.D. Candidate, Dept. of Structural Engineering, Tongji Univ., Shanghai 200092, China.
2. Graduate Student, Dept. of Engineering Technology, Univ. of North Texas, Denton, TX 76207.
3. Professor, Dept. of Structural Engineering, Tongji Univ., Shanghai 200092, China.
4. Professor, Dept. of Engineering Technology, Univ. of North Texas, Denton, TX 76207 (corresponding author).