1. Faculty Affiliate, Dept. of Civil and Environmental Engineering, Colorado State Univ., 1372 Campus Delivery, Fort Collins, CO 80523.
2. Professor and Head, Dept. of Civil and Environmental Engineering, Colorado State Univ., 1372 Campus Delivery, Fort Collins, CO 80523 (corresponding author).
3. Professor, Dept. of Civil and Environmental Engineering, Bucknell Univ., Lewisburg, PA 17837.