1. Skidmore, Owings & Merrill LLP, 224 S. Michigan Ave., Chicago, IL 60604; formerly, Graduate Research Assistant, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208.
2. McCormick Institute Professor and W.P. Murphy Professor of Civil Engineering and Materials Science, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208 (corresponding author).
3. Graduate Research Assistant, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208.
4. Predoctoral Visiting Fellow, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208; on leave from Ecole Polytechique, France.
5. Ramón y Cajal Fellow, Technical Univ., of Catalonia (UPC), Barcelona, Spain; formerly, Visiting Scholar, Northwestern Univ., 2145 Sheridan Rd., CEE, Evanston, IL 60208.