Cable bracing for a building

[JStructsteel]

Got a 14 bay @ 25' building additon x 1 bay at 65'-0". Any advantage to where to put the X bracing along the long length? It has 1.5" B deck on the roof. I was thinking first and last bays. Any better places, door and window permitting?

 

[BAretired]

It would be better to brace the third or fourth bay from each end in order to minimize temperature effects.

 

[JAE]

We usually try to keep X bracing near the middle of the building due to thermal effects - to minimize overall deflections down the length.

 

[haynewp]

I recently made a RISA model with thermal loads to see what effects I would get using bracing close to the ends of a long building. The length was still less than what would trigger an expansion joint by the AISC graph . The loads were very high, to the level that it would seem that thermal loads would be more routinely considered in design, in general.

 

[HDStructural]

The loads were very high, to the level that it would seem that thermal loads would be more routinely considered in design, in general.

I have come across that as well. I've designed a few aircraft hangars and their doors are open in the summer and the winter, so there is a real change in temperature. The governing code didn't specifically require thermal loads to be applied since it is technically a conditioned space (I think heated to 50 deg in winter and only fans in the summer to keep it "cool").

Speaking with other engineers, they had not typically applied thermal loads.

I did apply them to one of the hangars and it caused me to shift braced bays towards the interior of the back wall to avoid large thermal stress buildup. It was surprising how much force built up only from a ±20 deg change in temperature.

 

[dik]

It would be better to brace the third or fourth bay from each end

Yup... I usually like the 2 or 3...