1. Postdoctoral Fellow, School of Civ. Engrg. and Mech., Shanghai Jiao Tong Univ., Shanghai 200030, People's Republic of China.
2. Prof., Dept. of Civ. Engrg., Dalian Univ. of Tech., Dalian 116024, People's Republic of China.
3. Prof., School of Civ. Engrg. and Mech., Shanghai Jiao Tong Univ., Shanghai 200030, People's Republic of China.