1. Assistant Professor, Dept. of Civil and Environmental Eng., Sejong Univ., Seoul, South Korea.
2. Assistant Professor, Dept. of Civil and Environmental Eng., Univ. of Connecticut, Storrs, CT.
3. Professor, Dept. of Civil and Environmental Eng., Univ. of Michigan, Ann Arbor, MI (corresponding author).
4. Professor Emeritus, Dept. of Civil and Environmental Eng., Univ. of Michigan, Ann Arbor, MI.