1. Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762 e-mail:
2. Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS 39759 e-mail:
3. Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35406 e-mail:
4. Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180 e-mail: