1. Professor, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, 325 John Tickle Bldg., Knoxville, TN 37996 (corresponding author).
2. Postdoctoral Research Fellow, Dept. of Civil and Environmental Engineering, Technological Institute, Northwestern Univ., 2145 Sheridan Rd., Tech A236, Evanston, IL 60208.