1. Assistant Professor, Dept. of Civil and Environmental Engineering, California State Univ., Fullerton, CA 92834 (corresponding author).
2. Research Scientist, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093.
3. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093.