1. Assistant Professor, Dept. of Civil and Environmental Engineering, Tufts Univ., 200 College Ave., Medford, MA 02155 (corresponding author).
2. Assistant Professor, Dept. of Civil, Structural and Environmental Engineering, Univ. at Buffalo-The State Univ. of New York, Buffalo, NY 14260; formerly, Dept. of Civil Engineering, Univ. of Texas at Arlington, Box 19308, Arlington, TX 76019.
3. Associate Professor, Dept. of Civil Engineering, K. U. Leuven, 3001 Leuven, Belgium.
4. Professor, Dept. of Structural Engineering, Univ. of California at San Diego, 9500 Gilman Dr., San Diego, CA 92093.