1. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, 2314 Engineering Hall, Madison, WI 53706.
2. Research Intern, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, 2320 Engineering Hall, Madison, WI 53706.
3. Doctoral Candidate, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, 2320 Engineering Hall, Madison, WI 53706.