Ok..
put a side the steel Fy= 360N/mm^2

due table (4-1) in the egyption code ,, which verified in Shaker El-Behery Design manual page 386 v.6/2002

the factors (c/d)max, Rmax, and C1 :
related to steek grade :

thus u see that for steel 400/600 of Fy=400N/mm^2
c/d max = .42 ..... limaitations for chart C page 401
Rmax = 0.187
C1min= 2.83 ....... j= 0.721

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if steel 360/520 of Fy =360N/mm^2
c/d max = 0.44 ............ limitations for chart C page 401
Rmax= 0.194
C1 min = 2.78........... j =0.717

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if the Fy =420 or 460 N/mm^2 ... what shall the above factors would be??? i think the only people who response to answer this question ..

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