1. Ph.D. Candidate, School of Civil Engineering, College of Engineering, Univ. of Tehran, 11155-4563 Tehran, Iran.
2. Assistant Professor, Dept. of Engineering Science, College of Engineering, Univ. of Tehran, 11155-4563 Tehran, Iran.
3. Professor, School of Civil Engineering, College of Engineering, Univ. of Tehran, 11155-4563 Tehran, Iran (corresponding author). E-mail address:
4. Professor, Dept. of Civil, Environmental and Architectural Engineering, Univ. of Colorado, Boulder, CO 80309-0428.