1. Prof., MST Civ. Engrg., Dept. of Phys., Facu. of Sci. and Techniques at Tangier, B.P. 416 Tangier 90 000, Morocco.
2. Prof., Group of Mech., Dept. of Phys., Facu. of Sci. at Tetouan, B.P. 2121 Tetouan 93 000, Morocco.
3. Prof., URGC—Struct., INSA de Lyon Bat. 304, 20, Ave. Albert Einstein, 69 621 Villeurbanne Cedex, France.