1. Staff Engineer, Dawood Engineering, Enola, PA 17025; formerly, Graduate Student, Bucknell Univ., Lewisburg, PA 17837.
2. Professor and Chair, Dept. of Civil and Environmental Engineering, Bucknell Univ., Lewisburg, PA 17837 (corresponding author). E-mail: evans@bucknell.edu
3. Professor, Dept. of Civil and Environmental Engineering, Colorado State Univ., Fort Collins, CO 80523-1372.