1. Professor, School of Civil Engineering, Iran Univ. of Science and Technology, Narmak, Tehran 16846-13114, Iran; Professor, College of Civil Engineering, Iran Univ. of Science and Technology, Narmak, Tehran 16846-13114, Iran.
2. Assistant Professor, Dept. of Civil Engineering, Najafabad Branch, Islamic Azad Univ., Najafabad, Iran University Blvd., Najafabad, Isfahan 8514143131, Iran (corresponding author).