1. Boyd Prof., Dept. of Civ. and Envir. Engrg., Louisiana State Univ., Baton Rouge, LA 70803.
2. Asst. Prof., Dept. of Civ. Engrg., Mustafa Kemal Univ., Iskenderun, Hatay, Turkey.
3. Prof., Lab. of Mech. and Mat., Polytechnic School, Aristotle Univ. of Thessaloniki, Thessaloniki, 54006 Greece.