1. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093-0085 (corresponding author).
2. Assistant Project Scientist, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093-0085.
3. Visiting Researcher, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA, 92093-0085.