1. Graduate Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, Knoxville, TN 37996.
2. Research Associate, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, Knoxville, TN 37996.
3. Edwin G. Burdette Professor, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, Knoxville, TN 37996 (corresponding author).