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

Re: stack foundation

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I think I may have interpretted the meaning of overturning. You have to
check two things: the code requires you to have some FOS for overturning
(1 or 1.5) and for the soil not to exceed the allowable bearing stress.
You check moments about the toe, which implies that there is an infinite
stress at this point. I thought the structure should be checked for
overturning about the resultant of the soil pressure. However, it seems
the convention is to take it about the toe.

On Sun, 24 Sep 2000, Roger Turk wrote:

> If you get anything other than zero when including soil pressure in your 
> moment calculations, then, yes, you are doing it wrong.  From elementary 
> statics, Sum(M) about *any* point must equal zero.  If it does not equal 
> zero, then your reaction calculations are wrong.
> 
> Basic statics requirements must always be met:
> 
>    Sum(Fhoriz) = 0
>    Sum(Fvert) = 0
>    Sum(M) = 0
> 
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona
> 
> Michael Bryson wrote:
> 
> >>Maybe I've been doing it wrong all these years, but I thought the lever
> arm is a function of the allowable soil pressure and weight. If you are
> taking moments about the toe then you should include the soil pressure
> acting at this distance. Summing the moments will then tell you whether
> you have a overturning or not.
> 
> Incidentally, I assume a rectangular stress block for the soil pressure
> distribution since overturning can't happen without this occurring.<<
> 
> ******* ****** ******* ******** ******* ******* ******* *** 
> *   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) to the list, send email to 
> *   admin(--nospam--at)seaint.org and in the body of the message type 
> *   "join seaint" (no quotes). To Unsubscribe, send email 
> *   to admin(--nospam--at)seaint.org and in the body of the message 
> *   type "leave seaint" (no quotes). For questions, send 
> *   email 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 
> ******* ****** ****** ****** ******* ****** ****** ********
> 


******* ****** ******* ******** ******* ******* ******* *** 
*   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) to the list, send email to 
*   admin(--nospam--at)seaint.org and in the body of the message type 
*   "join seaint" (no quotes). To Unsubscribe, send email 
*   to admin(--nospam--at)seaint.org and in the body of the message 
*   type "leave seaint" (no quotes). For questions, send 
*   email 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 
******* ****** ****** ****** ******* ****** ****** ********