1. Graduate Student, Dept. of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401.
2. Professor, Dept. of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401 (corresponding author).
3. Graduate Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, Madison, WI 53706.
4. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, Madison, WI 53706.