1. Research Associate, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., Houghton, MI 49931-1295.
2. Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., Houghton, MI 49931-1295 (corresponding author).
3. Associate Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., Houghton, MI 49931-1295.
4. Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., Houghton, MI 49931-1295.