Column Theory

[DevinTheStudent]

Hello All,

I have a quick question about column theory

If my steel column in attached photo is pinned to the beam connected on top and fixed to to the foundation on the bottom is that moment connection at the foundation taking any moment?

furthermore, if that connection to the foundation is pinned that would require a lateral load resisting system (bracing)? this column and beam are both located within the walls of a residential home.

 

[JoshPlumSE]

Just an FYI: this isn't "column theory". It's more like structural analysis or something along those lines.

If there is any lateral drift in the structure, then the column with a fixed support will have moment at the base.

If the column is pinned, then it is laterally unstable and needs something else to provide stability. Usually, this happens via connection to a floor diaphragm that ties back to the lateral force resisting system.

 

[KootK]

For routine design of residential steel columns, the place to start is probably to ask yourself if you want the column to participate in resisting globally applied building lateral loads such as wind or seismic. If the answer is yes, and the column is part of a moment frame etc, then you may want to have a rigid connection between the column base and foundation. If the answer is no, and the top of the column is restrained against lateral translation a floor or roof deck that is itself laterally braced, then many designers will pin the column base connection.

Whether or not your column base connection will actually "listen" to the direction you give it is of course another question, one that's been covered ad nauseum in other threads.

 

[DevinTheStudent]

Can the fact that this system is located within the walls of a home be considered laterally braced and therefore we can make the connection to the foundation pinned?

 

[KootK]

Probably but you still need to answer this question for yourself:

For routine design of residential steel columns, the place to start is probably to ask yourself if you want the column to participate in resisting globally applied building lateral loads such as wind or seismic. If the answer is yes, and the column is part of a moment frame etc, then you may want to have a rigid connection between the column base and foundation. If the answer is no, and the top of the column is restrained against lateral translation a floor or roof deck that is itself laterally braced, then many designers will pin the column base connection.

If you don't know the answer to that question, you probably need to get yourself into a room with somebody who does.