1. Postgraduate Research Student, School of Civil Engineering, Univ. of Sydney, Sydney, NSW 2006, Australia; formerly, Graduate Research Assistant, Dept. of Civil Engineering, Johns Hopkins Univ., Baltimore, MD 21218 (corresponding author).
2. Senior Structural Engineer, NBM Technologies, 8534 Gwynedd Way, Springfield, VA 22153.
3. Professor, Dept. of Civil Engineering, Johns Hopkins Univ., Baltimore, MD 21218.