1. Doctoral Candidate, Dept. of Civil and Environmental Engineering, Tufts Univ., Medford, MA 02155.
2. Doctoral Candidate, Dept. of Civil Engineering, The City College of New York, New York, NY 10031.
3. Professor, Dept. of Civil and Environmental Engineering, Tufts Univ., Medford, MA 02155.
4. Professor, Dept. of Civil Engineering, The City College of New York, New York, NY 10031.