The formula for Courbon's distribution factors is
K = 1 * [ 1 +6(N+1-2*i) * e]
N (N*N-1) * L
where N is number of girders
e is eccentricity of loading with respect to the
L is the spacing of girders (c/c)
i is the i th girder ( 1, 2, 3 etc)
The loads (shear or moment) carried by each girder
will be Courbons factor times the TOTAL LOAD.
Courbon's factors apply to cases where intermediate
cross girders or diaphragm/s are provided.
However, grid analysis conducted for cases without
diaphragms reveal there is marginal difference between
the values and COurbon's factors are conservative.
Another fact is that courbon's factors give higher
distribution to outer girders and lower for inner
girders. Hence, it's better to assume the values for
the inner girders as equal to the outer girders.
Final word- Though courbon's factors are conservative,
they offer a quick estimate as compared to grid
Hope this will be useful for you.
Arvind Salecha, BTech (IIT B), MS(OKlahoma)
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