1. Assistant Professor, General Engineering Dept., Univ. of Puerto Rico, Mayagüez Campus, P.O. Box 9044, Mayagüez, P.R. 00681. E-mail: jrarroyo@uprm.edu
2. Research Civil Engineer, Information Technology Laboratory, U.S. Army Engineer Research and Development Center, 3909 Halls Ferry Rd., Vicksburg, MS 39180 (corresponding author). E-mail: ebelinr@wes.army.mil