1. Assistant Professor, Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65409.
2. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093-0085 (corresponding author).
3. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093-0085.
4. Assistant Professor, Harbin Institute of Technology, School of Civil Engineering, Nan’gang District, Harbin 150090, P. R. China.