1. Associate Professor, Dept. of Bridge Engineering, Tongji Univ., Room 711, Bridge Bldg., 1239 Siping Rd., Shanghai 200092, P.R. China (corresponding author).
2. Master Student, Dept. of Bridge Engineering, Tongji Univ., Room 704, Bridge Bldg., 1239 Siping Rd., Shanghai 200092, P.R. China.