1. Visiting Researcher, Univ. of California, Davis, CA 95616; Assistant Professor, Dept. of Civil Engineering, Sharif Univ. of Technology, Tehran 145888-9694, Iran (corresponding author).
2. Ph.D. Student, Dept. of Civil, Environmental and Geodetic Engineering, Ohio State Univ., Columbus, OH 43210.
3. Ph.D. Student, Dept. of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401.
4. Ph.D. Student, Dept. of Civil Engineering, Univ. of British Columbia, Vancouver, BC, Canada V6T 1Z4.