1. Research Structural Engineer, National Institute of Standards and Technology, Gaithersburg, MD 20899-8611 (corresponding author).
2. Principal Engineer, Applied Research Associates, Mountain View, CA 94043.
3. Senior Project Manager, Simpson Gumpertz & Heger, Inc., Waltham, MA 02453.
4. Senior Staff, Simpson Gumpertz & Heger, Inc., Waltham, MA 02453.
5. Senior Principal, Simpson Gumpertz & Heger, Inc., Waltham, MA 02453.