1. Formerly, Graduate Student, Ferdowsi Univ., Mashhad, Iran; and Postdoctoral Researcher, Civil Engineering Dept., Catholic Univ. of America, 620 Michigan Ave. N.E., Washington, DC 20064 (corresponding author).
2. Associate Professor, Civil Engineering Dept., Ferdowsi Univ. of Mashhad, P.O. Box 91775-1111, Mashhad, Iran.