1. Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin–Madison, 2256 Engineering Hall, 1415 Engineering Dr., Madison, WI 53706.
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin–Madison, 2314 Engineering Hall, 1415 Engineering Dr., Madison, WI 53706 (corresponding author).
3. Research Fellow, Construction and Economy Research Institute of Korea, 71-2 Nonhyundong Kangnamgu, Seoul 135-701l, Korea.