1. Visiting Scholar, Dept. of Civil Engineering and Geophysical Sciences, Univ. of Notre Dame, Notre Dame, IN 46556; on leave from Takenaka Corporation, Research and Development Institute, Chiba, Japan.
2. Research Associate, Laboratorio de Estructuras, Univ. Nacional de Tucumán, Avenue Roca 1800, (4000) San Miguel de Tucumán, Tucumán, Argentina.
3. Leo Linbeck Professor of Civil Engineering, Univ. of Notre Dame, Notre Dame, IN 46556.