1. Associate Professor, Dept. of Mechanical Engineering, Seattle Univ., 901 12th Ave., Seattle WA 98122 (corresponding author).
2. National Earthquake Hazards Reduction Program, Building and Fire Research Laboratory (MS 8604), NIST, 100 Bureau Dr., Gaithersbury, MD 20899–8604; formerly, Assistant Professor, Dept. of Civil and Environmental Engineering, Seattle Univ., 901 12th Ave., Seattle WA 98122.