1. Research Associate, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Dow 854, Houghton, MI 49931.
2. Associate Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Dillman 201F, Houghton, MI 49931 (corresponding author).