1. Tianjin Urban Planning and Design Institute, 81 Huangpu South Rd., Hexi District, Tianjin, China 300201.
2. Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721.
3. Assistant Professor, Dept. of Civil Engineering, Kyung Hee Univ., 1 Seocheon-Dong, Giheung-Gu, Yongin-Si, Kyunggi-do 446-701, Republic of Korea; formerly, Assistant Professor, Dept. of Civil Engineering, Univ. of Suwon, Wauan-gil 17, Bongdam-eup, Hwaseong-si, Gyeonggi-do, South Korea (corresponding author).