1. Assistant Professor, Civil Engineering Dept., Boise State Univ., Boise, ID 83725-2060; formerly, Associate Professor, Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8615 (corresponding author).
2. NIST Fellow, Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., 8615 Gaithersburg, MD 20899-8615.