1. Research Structural Engineer, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8611 (corresponding author). E-mail: dduthinh@nist.gov
2. Research Structural Engineer, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8611.
3. Graduate Student, Dept. of Civil and Environmental Engineering, Carnegie Mellon Univ., Pittsburgh, PA 15213-3890.
4. NIST Fellow, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8611.