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Re: Bracing in a Freezer Building

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Rich,
 
        Here are some ideas for your consideration.
 
1.)    Get the structure outside of the freezer.  This should reduce your temperature range and, hence, your thermal stresses.
 
2.)    Change your bracing pattern.  Separate the braced bays so that you can have an expansion joint in between braced bays.  This would reduce the thermal forces to only those values caused by the statically indeterminate values caused by the X braced themselves.  Combining this with changing to single diagonal tension/compression braces would eliminate the thermal loading altogether.
 
3.)    Eliminate the bracing altogether and use a rigid frame design.
 
        The above may help your structural problem but you will still have significant architectural problems in dealing with thermal expansion and contraction of the walls, floors. and ceilings of the freezer.  as Matthew Stuart has pointed out there are a lot of important details to consider in the design of this freezer.
 
Regards,
 
H. Daryl Richardson
----- Original Message -----
From: Rich Lewis
Sent: Sunday, March 18, 2007 8:09 PM
Subject: Bracing in a Freezer Building

I?m working on a freezer facility.  The primary framing is steel.  It is approximately 275? x 325?.  I?m looking at ?X? bracing for wind loads.  Seismic is small in comparison.  It is being built in Texas.  The operating temperature is zero F to minus 15 F.  The steel has a potential swing of 75-100 degrees.  Right now I?m looking at 3-4 bays of ?X? bracing.  The ?X? bracing would be in consecutive bays.  The problem I?m finding is the outer columns have extreme uplift loads from the temperature swing.  The steel at the roof level contracts horizontally and doesn?t at the foundation.  The ?X? wants to resist this movement.  This in turn causes large uplift forces on the outer columns of the bracing.  I?ve looked at several different bracing layouts and still end up with the large uplift forces. 

 

I?m hoping there are others who can give me insight into freezer building bracing systems that can accommodate the large temperature swings.  I?m also looking for resource on the design of freezer facilities from a structural standpoint.  I?ve looked through SEAInt archives and found information on the foundation, slab, etc., but not the steel framing.  I did a search of AISC site and didn?t find anything.  Are there any good articles or books on freezer building design, particularly the structure?

 

Thanks for your help.

 

Rich