1. Guest Scientist, National Institute of Standards and Technology, Gaithersburg, MD 20899-1070 (corresponding author).
2. Research Structural Engineer, National Institute of Standards and Technology, Gaithersburg, MD 20899-1070.
3. Professor, State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji Univ., 1239 Siping Rd., Shanghai 200092, China.