1. Research Asst., Dept. of Civ. Engrg., Solid Mech. Div., Univ. of Waterloo, Waterloo, Ontario, Canada
2. Assoc. Prof., Dept. of Civ. Engrg., Solid Mech. Div., Univ. of Waterloo, Waterloo, Ontario, Canada
3. Prof., Dept. of Civ. Engrg., Solid Mech. Div., Univ. of Waterloo, Waterloo, Ontario, Canada