1. Civil and Environmental Engineering Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima 739-8527, Japan
2. Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran P.O. Box 14115-397, Iran
3. Department of Civil Engineering, Marand Technical Faculty, University of Tabriz, Tabriz P.O. Box 54138-89741, Iran