1. Department of Civil and Environmental Engineering, Purdue University, West Lafayette, IN 47906, USA
2. Department of Civil and Environmental Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Iran
3. Department of Civil Engineering, University of Tehran, P.O. Box 14155-6619, Tehran, Iran
4. Department of Railway Engineering, Iran University of Science and Technology, P.O. Box 16765-163, Tehran, Iran