BEAM

[gnash68]

Hi All,

Can somebody help me on how to determine in actual condition if a beam is fix or pin?

 

[Lion06]

Basically, if the end of the beam is able to rotate relatively freely it would be considered pinned. If it is not able to rotate freely it would be considered (at least partially) fixed depending on the stiffness of what it is framing into.

 

[HgTX]

"Rotate freely" is kind of misleading. We're not talking a hinge with a lubricated pin here; even a multi-bolt connection can be considered pinned. It doesn't take much rotation to make something not fixed.

I have to say that when I was in school, this wasn't covered very well either.

This is a good resource:

http://wwweng.uwyo.edu/connections/

The connections that are labeled "moment connection" are fixed; the rest are not.

Hg

Eng-Tips policies: faq731-376

 

[parrot77]

What structuralEIT means that the end of the element is connected such that moment cannot be transfered/ carried at the connection. 'Rotate freely' is an assumption we make to simplify analysis. For example if a column is fixed to a foundation that is not capable of transmitting bending moment to the ground, it should be treated exactly as per your lubricated hinge.

 

[Lion06]

I did say "rotate RELATIVELY freely"