1. Associate Professor, Civil Engineering, Univ. of Washington, Seattle, WA 98195-2700 (corresponding author).
2. Professor, Civil Engineering, Univ. of Washington, Seattle, WA 98195-2700.
3. Engineer, Toltz, King, Duvall, Anderson & Assoc., Inc., St. Paul, MN 55101-2140.
4. Associate Researcher, Arch. Eng., Tokyo Inst. of Tech., 2-12-1 Meguro-ku, Tokyo 152-8552, Japan.