1. Professor, Div. of Engineering, Colorado School of Mines, Golden, CO 80401 (corresponding author).
2. Assistant Professor, Dept. of Civil Engineering, Korea Maritime Univ., Busan 606-791, Korea.
3. Professor and Vice Chancellor for Research, Univ. of Colorado–Boulder, the Regent Administrative Center, Boulder, CO 80309.
4. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Missouri–Columbia, Columbia, MO 65211.