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[SEAOC] RE: [SEAOC] Rigid frame with masonry walls

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Prefabricated metal buildings routinely employ masonry walls and rigid 
frames.  Proper allowance for lateral drift and deflection must be made. 
 This tends to be a serviceability problem as opposed to structural as long 
as the connections allow differential in plane movement.  (i.e. provide 
masonry expansion joints within 18" of the corner of the building)  Out of 
plane force resistance for the masonry wall is generally provided by the 
steel building unless you are designing a short masonry wall in which case 
it is usually cantilevered from the foundation.

Guidance for serviceability can be obtained from the AISC Design Guide #3 
"Serviceability Design Considerations for Low-Rise Buildings".  Note that a 
10 year wind is used for serviceability.  Use the ASCE 7-95 for the 10 year 
wind as opposed to the AISC Design Guide #3 rule of 75% of the 50 year wind. 


Greater care must be employed when seismic loads govern because of the 
amplification requirements for deformation compatibility.  But if it is a 
low seismic high wind area, simply provide detailing and joints to allow for 
the calculated differential in plane movement.  A number of connectors are 
available (Re: Heckman, Hohmann & Barnard, and AA)   Look at the AA400 with 
the AA401C as an example of a connector that allows differential in plane 
movement while resisting out of plane forces.  This is also the connector of 
choice for differential seasonal and thermal movement.  Also bear in mind 
that the brick will have to move parallel differentially from the block. 
 Avoid truss reinforcing.

Harold Sprague
Black & Veatch
spragueho(--nospam--at)bv.com
 ----------
From: seaoc
To: seaoc
Subject: [SEAOC] Rigid frame with masonry walls
Date: Tuesday, August 13, 1996 2:14PM


Question: Is it practical to provide a high bay single story building with
steel rigid framing and masonry walls?

I've seen buildings detailed this way, but I question whether the masonry 
can
handle the lateral movements to develop rigid frame action if it is tied to
the steel frame.  I am currently working on a building with a 3-ton bridge
crane, to be steel framed with masonry veneer (brick/CMU).  While a rigid
steel frame could handle the loads, I am inclined to go with a braced frame
to
prevent damage to the masonry.  Has anyone encountered a rigid frame 
building
with masonry walls which has had damage due to the frame movement due to
lateral loads?  (This structure is in a low seismic area but potential
hurricane winds.)



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