Hi Aslam

Here force & moment should be local branch element force & moment.
We have to model small element for branch & from local element force of that branch we need to take the force & moment data to input in branch calculation. We should not pick data from header side.
I understand that value will be very minimum.
Stiffness we ignore will produce more conservative result hence no issue. Displacement data make the system as displace anchor point.
Yes sometime we model upto two three additional support that produce more realistic result.

You mention correctly SIF we must feed for branch calculation.

I summarized like
1)Branch element force & moment very small ( taken from header calculation)
2)For branch calculation we are using displace anchor hence conservative.

So we can forget force & moment , only displacement & SIF data require to go for branch calculation.


Regards

Habib