1. Preston Wade Professor, Dept. of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061 (corresponding author).
2. Engineer, Bechtel Power Corporation, Frederick, MD.
3. Professor, Dept. of Civil Engineering, Univ. of Puerto Rico,Mayaguez, Puerto Rico.
4. Research Structural Engineer, U.S. Army Research and Development Center, 3909 Halls Ferry Rd., Vicksburg, MS.