1. Graduate Student, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Houghton, MI 49931.
2. Professor, Dept. of Civil Engineering, Univ. of New Mexico, Albuquerque, NM 87131.
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Houghton, MI 49931 (corresponding author).