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RE: canopy footing[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: canopy footing
- From: "Haan, Scott M POA" <Scott.M.Haan(--nospam--at)poa02.usace.army.mil>
- Date: Mon, 13 Feb 2006 14:44:13 -0900
If the restraining slab is not in contact with the cube I would tell them to use formula 6-1 or clarify how the slab is restraining the top of the foundation. Formula 6-1 makes the footing deeper because it puts the whole overturning couple into the soil where formula 6-2 makes a couple between the slab and the soil.
The pre-amble also says posts embedded in concrete footings. If they are just bolting the canopy column to a cube and you wanted to nail them on semantics you could tell them to design it some other way, but if they are embedding the column then they are following the wording of the code. If it looks scary I would make sure they did their numbers right - it would be deeper with formula 6-1 if there is not a slab restraining the top of the footing.
From: S. Gordin [mailto:mailbox(--nospam--at)sgeconsulting.com]
Sent: Monday, February 13, 2006 12:02 PM
Subject: Re: canopy footing
Plain concrete is not allowed for structural applications in California. Anyway, the specified reinforcement of the "cube" was inadequate (as many other things in this design were). For example, the restraining slab (as designed) is not even in contact with the "cube."
My main problem with the design is that - according to CBC/UBC Section 1806.8 preamble - the formulas 6-1 and 6-2 are both for distinctively column-like (3:1 aspect ratio) foundations. Apparently, this is how it was tested back in the 1930s-1940s. I am not sure that these formulas were intended for such use at all.
When drawn to scale, the canopy on such footing looks scary.
Steve Gordin SE
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