1. Civil and Environmental Engineering, Virginia Tech, 418 Durham Hall, 1145 Perry St., MC 0246, Blacksburg, VA 24061.
2. Civil and Environmental Engineering, Virginia Tech, 409 Durham Hall, 1145 Perry St., MC 0246, Blacksburg, VA 24061.
3. Civil and Environmental Engineering, Virginia Tech, 221-B Patton Hall, MC 0103, Blacksburg, VA 24061.
4. Civil and Environmental Engineering, Virginia Tech, 413 Durham Hall, 1145 Perry St., MC 0246, Blacksburg, VA 24061 (corresponding author).