1. Asst. Prof. of Civ. Engrg., Univ. Católica de Chile, Santiago, Chile; formerly, Research Asst., Dept. of Civ. Engrg., Univ. of Illinois at Urbana-Champaign, Urbana, Ill.
2. Prof. Emeritus of Civ. Engrg. and in Center for Advanced Study, Univ. of Illinois at Urbana-Champaign, Urbana, Ill.