1. Professor Emeritus, Dept. of Civil Engineering, Auburn Univ., Auburn, AL 36849-5337 (corresponding author).
2. Assistant Professor, Dept. of Civil and Environmental Engineering, Cheongju Univ., Cheongju, Chungbuk 360-764, Korea.
3. Senior Researcher, Korea Railroad Research Institute, Uiwang, 437-757, Korea; formerly, Postdoctoral Fellow, Dept. of Civil Engineering, Auburn Univ., Auburn, AL 36849-5337.
4. Assistant Professor, Dept. of Construction Management and Civil Engineering, Georgia Southern Univ., Statesboro, GA 30460-8047; formerly, Postdoctoral Fellow, Dept. of Civil Engineering, Auburn Univ., Auburn, AL 36849-5337.