Need a book? Engineering books recommendations...

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

RE: Wind Uplift on Footings

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The controlling ASD combination for uplift design is 0.6D-W, which already includes the required safety factor. Therefore the footing size designed for this resulting uplift force is adequate with FS=1.0.
 
Javier Encinas, PE
-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Wednesday, November 21, 2007 5:09 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Wind Uplift on Footings

Years ago, I designed a lot of foundations for pre-engineered metal buildings.  PEMB foundations are often designed for a net uplift.  The practice (not the code) was to design for a SF of 1.5.  Since the foundation size was predicated on the gravity load, the reinforcing for uplift (in the top of the footing) was sized based upon the uplift foundation moment and 2 #4's each way in the top was generally adequate for most conditions. 
 
The book "Foundation Design and Construction Manual" by Butler and CSD "recommends" a SF of 1.5. 

Regards,
Harold Sprague

> From: t.w.allen(--nospam--at)cox.net
> To: seaint(--nospam--at)seaint.org
> Subject: Wind Uplift on Footings
> Date: Tue, 20 Nov 2007 12:57:19 -0800
>
> Am I hallucinating or is there a provision in the UBC for a F.S.>1.5 against
> uplift?
>
> For some reason, I can't find that requirement. I found it for sliding and
> overturning relative to retaining walls, but not uplift on footings. I'm
> reviewing shop drawings for a lightweight shade structure.
>
> TIA,
>
> T. William (Bill) Allen, S.E.
> ALLEN DESIGNS
> Consulting Structural Engineers
>
>
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> * Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> * This email was sent to you via Structural Engineers
> * Association of Southern California (SEAOSC) server. To
> * subscribe (no fee) or UnSubscribe, please go to:
> *
> * http://www.seaint.org/sealist1.asp
> *
> * Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> * send to the list is public domain and may be re-posted
> * without your permission. Make sure you visit our web
> * site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********



Get the power of Windows + Web with the new Windows Live. Power up!