Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: 3" Concrete Cladding on light framed walls

[Subject Prev][Subject Next][Thread Prev][Thread Next]
This may be a non-starter.  Have you considered fire issues?  You will need to search a little, but the UBC says that masonry must supported by "non-combustible" supports.  The idea being that the masonry can fall on fire-fighters during a fire if the support begins to burn.  You may have a similar issue if you try to hang the concrete off the bearing walls instead of directly bearing it on a foundation.  Then again I could be completely out in left field depending on all the conditions you have.....I have the following comments in response to your list below:
 
a) Can you bolt an angle to the stud wall then set the concrete on the angle?  Maybe cast inserts into the back the concrete, you can then bolt directly studs / blocking directly to the inserts (see Hilti HDI for similar concept).
 
b)  Good luck, no idea here.  You need to account for wood shrinkage and lateral deflections.  Pay attention to the corner details.  This is always an issue with masonry veneers as well.
 
c)  For quality control, I would precast them by someone that does it for a living.  You will get a much more predictable product and the finish will be easier to control.  If it is done on site, conditions are much harder to control.  Locally, a company known as Eagle Precast does architectural precast (and much more) as its prime business.
 
d)  If you get the proper joints, I don't think the stiffness will matter.  The joints will allow for movements.  Under a worst-case condition, the concrete will take forces until it fails then the wood shearwalls will take over.
 
e)  Interesting concept.  You might look into how this is done as a skin on a steel frame.  There will likely be quite a few insights / solutions to your problems.  If you have press-plate wood trusses with a gable, pay attention the gable end.  The framers will want to use a truss to form the gable.  This will not work for out-of-plane forces and likely will cause problems with the precast.  Lastly, if you are using 3" concrete panels, why not go 6" and make it a tilt-panel job?  Quite a few times there are more issues involved than put forth in the question, but I at least had to ask.....
 
Best of luck,
 
Jake Watson, P.E.
Salt Lake City, UT
 
 
-----Original Message-----
From: ShirishM(--nospam--at)aol.com [mailto:ShirishM(--nospam--at)aol.com]
Sent: Thursday, July 04, 2002 9:44 PM
To: seaint(--nospam--at)seaint.org
Subject: 3" Concrete Cladding on light framed walls

A single story, light framed structure with wood structural shear panels is being proposed for local area (Southern California vicinity - Seismic Zone IV). Architect wants to use 3" of concrete cladding all around the building attached to the light framed walls ( Concrete cladding panels are approximately 6' x 8' and are to be cast on site). Note: this is not veneer and cladding being much stiffer than the light framed construction, I have some concerns (see below). Building is approximately 50' x 30' x 17' in height with roof diaphragm at 14' elevation.

Per some of your past experiences I need your opinions, views and suggestions as to the following:
a) Typical details of anchoring this cladding to light framed walls.
b) Typical expansion joints and material being used to make this system work.
c) Casting of panels on site - any pluses or minuses from construction aspects.
d) Performance of such light framed shear walls during earthquake knowing that the cladding is very stiff when compared to light framed shear walls.
e) Sincerely would appreciate any other information or input that would assist in making this project practical or....


Shirish V. Mistry S.E.