1. Professor, Dept. of Civil Engineering, Univ. of Kurdistan, Sanandaj 66177-15175, Iran (corresponding author).
2. Ph.D. Candidate, Dept. of Civil Engineering, Univ. of Kurdistan, Sanandaj 66177-15175, Iran.
3. Assistant Professor, Dept. of Civil Engineering, Behbahan Khatam Alanbia Univ. of Technology, Behbahan 63616-63973, Iran.
4. Assistant Professor, Dept. of Mathematics, Firoozkooh Branch, Islamic Azad Univ., Firoozkooh 39818-38381, Iran.
5. Assistant Professor, Dept. of Civil Engineering, Univ. of Kurdistan, Sanandaj 66177-15175, Iran.
6. Professor, Dept. of Civil Engineering, Isfahan Univ. of Technology (IUT), Isfahan 15848-11888, Iran.