1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Washington, 214C More Hall, Box 352700, Seattle, WA 98195 (corresponding author).
2. Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Washington, 201 More Hall, Box 352700, Seattle, WA 98195.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Washington, 201 More Hall, Box 352700, Seattle, WA 98195.
4. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Washington, 201 More Hall, Box 352700, Seattle, WA 98195.