1. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, Madison, WI 53706 (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, Madison, WI 53706.
3. Associate Professor, School of Civil, Urban, and Geosystems Engineering, Seoul National Univ., 151-742 Seoul, Korea.