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RE: 14' Tall concrete Wall[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: RE: 14' Tall concrete Wall
- From: "Casey K. Hemmatyar" <khemmatyar(--nospam--at)gmail.com>
- Date: Fri, 16 Mar 2007 09:44:01 -0700
I do not envision problems assuming that the wall is supported as pin-pin at top and bottom, as long as the connection of the plywood diaphragm floor at the top of concrete wall and the diaphragm itself, are adequately detailed.
Are you placing your joists/rafters on the sill plate over the concrete wall?
With plywood diaphragm, I generally design tall walls (with high lateral earth pressure) as cantilevered; using "at-rest" (restrained) lateral soil pressure. I generally use a 4x ledger and hang the joists. In addition, I provide a minimum anchorage with Simpson ties at 48" O.C. for interconnection of floor diaphragm with perimeter concrete walls.
Another consideration is that the generally the values in IBC for wood floor diaphragm are for Wind and Seismic only, I believe these values need to be reduced for normal loading condition.
In regards to the piles, they have to be designed for both Axial and flexural forces. First for Embedment into bedrock and then for material (in this case concrete). This means, the embedment of the pile has to be designed in for 2 separate loading conditions and the deeper embedment controls. First, you find the depth required for Axial loading (generally Gravity service loading), next you apply the lateral load based on the moment arm above the fixity point, and calculate the embedment requirement.
Another aspect of the pile design is the strength/unified design of the concrete based on 1.7 factor for earth pressure and the maximum moment usually occurs several feet below fixity point.
The last thing is the lateral ties at pile has to comply with ACI 318 214.4.1 & 10.9.3 which normally gives you about 3" of spacing.
Casey (Khashayar) Hemmatyar
Private email <k(--nospam--at)hemmatyar.com>
Hello, I have a 14' tall wall for a residence, the joist, roof are sitting on top of wall, the wall is 8" thick and sitting on pier foundation spaced about 13'
o.c. I designed it as a cantilever beam and another case supported on both ends, I end up having a big shear at the base connection. The concrete will not resist the shear base, I was thinking to reinforce it at the base with stirrups a the the pier wall connection.
Is there anybody who faced this situation? Thank you
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