1. McCormick Institute Professor and W. P. Murphy Professor of Civil Engineering and Materials Science, Northwestern Univ., 2145 Sheridan Rd., CEE/A135, Evanston, IL 60208 (corresponding author).
2. Graduate Research Assistant, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208.
3. Engineering Consultant, 12 Uplands Ave., Hamilton, Ontario, Canada L8S 3X7.
4. Professor Emeritus, School of Electrical Engineering and Computer Science, Washington State Univ., Pullman, WA 99164.