design of short column BS8110

[Anonymous]

in BS 8110  .... in order to find Ultimate axial load capacity 
we use these equations 

I've tried dozens of example using Robot .... 
Robot alway give different results 
should interaction diagram & these equation give the same results?? or even clos results 
I've attached an example 
a column having 196 ton Ultimate load 
if we use any of these eqaution it gives ultimate load capacity of 169 & 192 Ton 
which means it's unsafe 
Concrete used C25 
Fy=3600
any Ideas ?

[Artur.Kosakowski · Accepted solution]

This approach is not implemented in Robot. The design of RC Columns according to BS is always done according to the paragraph 8.3.2 Moments and forces in columns and in the situation there is no bending Robot assumes the provisions of the paragraph 3.8.2.4 Minimum eccentricity.

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