1. Assistant Professor, Dept. of Civil Engineering, Kyung Hee Univ., 1 Seocheon-Dong, Giheung-Gu, Yongin-Si, Kyunggi-do 446-701, Republic of Korea; formerly, Research Assistant Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721 (corresponding author).
2. Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721.