1. Assistant Professor, Amirkabir Univ. of Technology, 15875-4413 Tehran, Iran; formerly, Visiting Scholar, Tufts Univ., Medford, MA 02155.
2. Professor, Amirkabir Univ. of Technology, 15875-4413 Tehran, Iran.
3. Professor, Dept. of Civil & Environmental Engineering, Tufts Univ., Medford, MA 02155 (corresponding author).