1. Assistant Professor, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, Taiwan.
2. Professor of Applied Mechanics and Civil Engineering, California Institute of Technology, Pasadena, CA 91125.
3. George W. Housner Senior Researcher in Civil Engineering, California Institute of Technology, Pasadena, CA 91125.
4. Graduate Student in Applied Mechanics, California Institute of Technology, Pasadena, CA 91125.