1. Graduate Student, Dept. of Civil and Environmental Engineering, North Dakota State Univ., Fargo, ND 58108.
2. University Distinguished Professor, Dept. of Civil and Environmental Engineering, North Dakota State Univ., Fargo, ND 58108.
3. Professor, Dept. of Civil and Environmental Engineering, North Dakota State Univ., Fargo, ND 58108 (corresponding author).