1. Prof. of Civ. Engrg., Univ. of Minnesota, Minneapolis, Minn.
2. Research Struct. Engr., Center for Building Tech., National Bureau of Standards, Washington, D.C.
3. Prof. of Civ. Engrg. Univ. of Alberta, Edmonton, Alberta, Canada
4. Prof. of Civ. Engrg., Stanford Univ., Palo Alto, Calif.