1. Graduate Research Assistant, Dept. of Civil Engineering, New Mexico State Univ., P.O. Box 30001, MSC 3CE, Las Cruces, NM 88003-8001 (corresponding author).
2. Professor, Dept. of Civil Engineering, New Mexico State Univ., P.O. Box 30001, MSC 3CE, Las Cruces, NM 88003-8001.