1. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Cincinnati, P.O. Box 210071, Cincinnati, OH 45221 (corresponding author).
2. Graduate Student, Civil and Environmental Engineering Dept., Univ. of Alberta, 220 Civil/Elect. Engineering Bldg., Edmonton AB, Canada T6G 2G7.
3. Assistant Professor, Dept. of Electrical and Computer Engineering, State Univ. of New York, Room 202, Resnick Engineering Hall, 75 South Manheim Blvd., New Paltz, NY 12561.