1. Research Structural Engineer, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 21702 (corresponding author).
2. Research Structural Engineer, Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 21702.
3. Graduate Research Assistant, Dept. of Civil Engineering, Univ. of Maryland, College Park, MD 20742.
4. Assistant Professor, Dept. of Civil Engineering, Univ. of Maryland, College Park, MD 20742.