1. Graduate Research Assistant, Texas A&M Univ., CE/TTI Building, Suite 603, College Station, TX 77843-3135.
2. E.B. Snead Chair Professor, Texas A&M Univ., Dept. of Civil Engineering, CE/TTI Building, Suite 603E, College Station, TX 77843-3135 (corresponding author).
3. Associate Professor, Texas A&M Univ., CE/TTI Building, Suite 508, College Station, TX 77843-3135.