Need a book? Engineering books recommendations...

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

Re: CSA A23.3 PG 9-16

[Subject Prev][Subject Next][Thread Prev][Thread Next]
----- Original Message -----
From: Zhang, Michael <michael.zhang(--nospam--at)shawgrp.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, May 28, 2002 10:59 PM
Subject: RE: CSA A23.3 PG 9-16


Daryl,

Thank you very much for your explanation. Now I know much more of the Design
Example.

In addition, your practical experience is especially helpful.


Regards,


Michael

-----Original Message-----
From: Daryl Richardson [mailto:h.d.richardson(--nospam--at)shaw.ca]
Sent: Tuesday, May 28, 2002 4:31 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: CSA A23.3 PG 9-16


Michael,

Thank you for the clarification yesterday.  Sorry I couldn't get back
to you yesterday but something else came up.

I am not familiar with the derivation of the subject equation; but if
you accept the values for r1 and r2 (which actually come from step 6)
then, using reverse engineering, perhaps I can make the following
clarifying statements.

1.)  The equation seems to be dealing with a phenomenon similar to
punching shear in slabs and this is an attempt to assess what part of
the pile loading is outside of the critical d/2 distance from the
support.

2.)  The first term in the equation, r1(2Qpr) deals with the two side
piles.  Qpr is the individual pile load; 2 is the number of side piles;
and r1 is the fraction of the pile loading which is beyond the critical
d/2 from the side face of the column (support) and would, hence,
contribute to the shear force.

3.)  The second term in the equation, (1-(1-r1)(1-r2))(4Qpr) deals with
the four corner piles.  Again, Qpr is the individual pile load; 4 is the
number of corner piles; r1 is the fraction of pile loading beyond the
critical d/2 from the side face of the support; and r2 is the fraction
of the pile loading which is beyond the critical d/2 from the end face
of the column (support) and would, hence, contribute to the shear force.

4.)  The ingenious part of the equation is the part (1-(1-r1)(1-r2).
Note that if either or both r1 and r2 are 0 (all of the pile loading is
closer than d/2 from the "support" and should not get included in the
analysis this term becomes 0; if both r1 and r2 are 1 (all of the pile
loading is further than d/2 from either face of the support and should
get included in the analysis this term becomes 1.0; if r1 and/or r2 are
fractional then this term is a positive fraction and a fraction of the
pile loading is included in the shear force.

This equation seems to me to be completely valid academically
speaking.  Practically speaking I do have some doubts.  I have no
comment on the validity of the values for r1 and r2; you didn't ask and
I didn't review the matter.  On the practical side, I have yet to see a
piling job that didn't have some piles out of position by 4 or 6
inches.  As a question, what should you do when you have non uniform
pile spacing or unequal loading (say from an applied moment); should you
not design for the most critical pile?  My personal philosophy in these
matters is: don't design these things too close to the limit; if
something can go wrong it probably will; foundations (and columns, for
that matter) are a very cheap place to over design and a very expensive
place to have problems.

Anyway, Michael, I hope my ramblings have been helpful to you.

Regards, and sorry I took an extra day,

H. Daryl Richardson



> Zhang, Michael wrote:
>
> For Engineers familiar with Canadian code:
>
> In Step 7 in page 9-16 of CSA A23.3-94, there is a formula Vf =
> r1(2Qpr)+(1-(1-r1)(1-r2))(4Qpr), I failed to get it from basic
> mathematical method, could anybody inform me of its background?
>
> Thanks in advance.
>
>
> Regards,
>
>
> Michael
>
> ****************Internet Email Confidentiality
> Footer******************
>
> Privileged/Confidential Information may be contained in this message.
> If
> you are not the addressee indicated in this message (or responsible
> for
> delivery of the message to such person), you may not copy or deliver
> this message to anyone. In such case, you should destroy this message
> and notify the sender by reply email. Please advise immediately if you
> or your employer do not consent to Internet email for messages of this
> kind. Opinions, conclusions and other information in this message that
> do not relate to the official business of The Shaw Group Inc. or its
> subsidiaries shall be understood as neither given nor endorsed by it.
> _______________________________________________________________________
> The Shaw Group Inc.
> http://www.shawgrp.com

******* ****** ******* ******** ******* ******* ******* ***
*   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
******* ****** ****** ****** ******* ****** ****** ********



****************Internet Email Confidentiality Footer******************

Privileged/Confidential Information may be contained in this message. If
you are not the addressee indicated in this message (or responsible for
delivery of the message to such person), you may not copy or deliver
this message to anyone. In such case, you should destroy this message
and notify the sender by reply email. Please advise immediately if you
or your employer do not consent to Internet email for messages of this
kind. Opinions, conclusions and other information in this message that
do not relate to the official business of The Shaw Group Inc. or its
subsidiaries shall be understood as neither given nor endorsed by it.
_______________________________________________________________________
The Shaw Group Inc.
http://www.shawgrp.com
















******* ****** ******* ******** ******* ******* ******* ***
*   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
******* ****** ****** ****** ******* ****** ****** ********


******* ****** ******* ******** ******* ******* ******* ***
*   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 
******* ****** ****** ****** ******* ****** ****** ********