1. Associate Professor, Departamento de Materiales, Universidad Autónoma Metropolitana, Mexico City, Mexico 02200.
2. Professor and Chair, Dept. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (corresponding author).
3. Professor and Chair, Dept. of Civil and Environmental Engineering, Northeastern Univ., Boston, MA 02115.
4. Design Engineer, Stanley D. Lindsey and Associates, 2300 Windy Ridge Parkway SE, Suite 200S, Atlanta, GA 30339.