Determination of "connection rigidity percentage"

[amini06]

Hi dear members

For a steel horizontal frame( H shape),I want to analyze the forces & momentums.
But I do not know how we can determine the percentage of connections rigidity.in the other words let's think we connect the middle beam(in H frame)to the sides beams by some bolts in their webs.As you know,this connection is not completely rigid ,but it can bears some momentum too.
How we can analyze it?We must design it as a rigid connection or not?
Respects.
Amini

 

[Lion06]

You would NOT want to design this as a rigid connection. First this is very expensive, and unless you have some unique reason to do this I don't know why you would. In addition, this will obviously put torsion on your supporting beam (it seemed from your post that the supports were beams, not columns), and WF shapes do not take torsion well.
If you absolutely have to, provide slip critical bolts and do a quick check in the green book using the "C" charts for eccentrically loaded bolt groups in section 4. This will give you a moment capacity, but not a "stiffness". The stiffness has more to do with moment-rotation than moment capacity. Using a simple shear connection, you generally don't get more than 20% end moment.

 

[sdz]

Model as either fully rigid or pinned then design connections accordingly.

 

[jetmaker]

You could analyze as if it were a pinned connection, then repeat using a fixed connection. The answer would lie between the two, and if you are good for both, then it is often assumed that you are good for your actual condition.