1. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Southern California, Los Angeles, CA 90089.
2. Formerly, Graduate Research Assistant, Dept. of Civil Engineering and Geological Sciences, Univ. of Notre Dame, Notre Dame, IN 46556.
3. Newmark Endowed Chair in Civil Engineering, Univ. of Illinois, Urbana, IL 61801.
4. Professor, Dept. of Civil Engineering, Univ. of Tokyo, Bunkyo-ku, Tokyo 113, Japan.