Beam unbraced length

[haynewp]

I would like to get some opinions on the maximum unbraced length that others design for. I will usually limit my max unbraced length to about 12' before I add in braces, no matter how much extra capacity the beam should still have under the loading. After doing this, I will also check that my allowable stress from the equations is still above about 15ksi or so also.

Is this overkill? Are others using larger unbraced lengths if the stress is still under the theoretical allowable?

 

[redhead]

If there is no torsion present, I am happy to use the full unbraced length consistent with the reduced stress formulae.

 

[kvram]

For practical point of view and erection point of view, 10' to 12' is a right choice for unsupported length. If it is designed as a plane frame , restrict to 10 -12' and for space frame with/WO P-Delta analysis one can go for full length as all types of forces will be called in.

 

[kvram]

For practical point of view and erection point of view, 10' to 12' is a right choice for unsupported length. If it is designed as a plane frame , restrict to 10 -12' and for space frame with/WO P-Delta analysis one can go for full length as all types of forces will be called in.
How ever , in case of requirement like in portals , one has to go for full length regardless of 2D or 3D .

 

[haynewp]

Theoretically, I guess if it works by the formulas no matter what unbraced length it is, I think you would be covered in the eyes of the building official. I used to design with that state of mind until I got the advice from other engineers later.