1. Prof. of Civ. Engrg., Univ. of Pittsburgh, Pittsburgh, Pa.
2. Research Asst.; Dept. of Civ. Engrg., Univ. of Pittsburgh, Pittsburgh, Pa.
3. Engr., Bernard Johnson, Inc., Washington, D.C.; formerly, Research Asst., Dept. of Civ. Engrg., Univ. of Pittsburgh, Pittsburgh, Pa.