Multiple Anchors Work Individually for Side
Blowout Check Along Depth Edge

ACI 318-11 D.5.4.1

When s11 > 6c , edge anchors work individually.
Nsbg = nbd x Nsb x [1+(c1 or c3) / c] / 4

where  s = s1    s11= s1 / (nbd-1)    c = min(c2 , c4)

For edge anchors work individually, if c1 / c<=3 or
c3 / c<=3, Nsb of corner anchors shall be multiplied
by edge reduction factor (1+c1 / c)/4 or (1+c3 / c)/4,
respectively.


ACI 318-11 D.5.4.1