1. Graduate Student, Dept. of Civil and Environmental Engineering, Amirkabir Univ. of Technology.
2. Dept. of Civil Engineering, New Mexico State Univ., Las Cruces.
3. Dept. of Civil Engineering, Iran Univ. of Science and Technology, Resalat Square, Iran.
4. Dept. of Mechanical Engineering, Mazandaran Univ. of Technology, Mazandaran, Iran.