Column Effective length

[engTC]

Hi everyone. This question might seem stupid but I am still not very sure. Lets say I have two steel columns running in Y direction simply supporting a steel beam , which supports timber floor joist in X direction. Can I assume the steel columns are restrained in both Y and X direction or just Y direction?

 

[jayrod12]

Does the beam sit on the top of the column or frame into the side?

 

[KootK]

You can probably use:

Kx = 1.0
Ky = 1.0

This assumes that your timber floor is itself laterally restrained by a lateral load resisting system that is not the steel frame containing your columns. If your steel frame IS the lateral load resisting system for any part of the building, that's another story.

 

[engTC]

Hi jayrod12, it is frame into the side? May I ask why will it make a difference? The column-beam is hidden in the wall.

 

[engTC]

Hi KootK,
So I have a triple story that use this steel frame from ground floor to roof (3*3m high). so if I make it as all pinned (base and connection) which means they have no lateral resisting capacity while provide other wall bracings for the structure. Does that mean I can use 3m as the effective length then? a 90x5 SHS gives me over 200kN compression capacity if so, is the figure seems reasonable to you?
I do have some portal frames as well, which means the column-beam frame has lateral resisting capacity but I still have some other lateral resisting metal strap used in the walls parallel to floor joists. So how do I work out the Le in this scenario?
Thank you.

 

[KootK]

It does sound as though your column unbraced would be 3m.