1. Professor, Dept. of Structural Engineering, Tongji Univ., Shanghai 200092, China.
2. Ph.D. Student, Dept. of Structural Engineering, Tongji Univ., Shanghai 200092, China.
3. Assistant Professor, Dept. of Structural Engineering, Tongji Univ., Shanghai 200092, China (corresponding author).
4. Professor, Dept. of Civil Engineering, Zhejiang Univ., Hangzhou 310058, China.