1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Michigan, 2340 G. G. Brown, 2350 Hayward, Ann Arbor, MI 48109-2125.
2. Associate Professor, Dept. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State Univ., 200 Patton Hall, Blacksburg, VA 24061-0105.