Need a book? Engineering books recommendations...

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

RE: Alterations Chapter 34 2007 CBC

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Hi Scott,

Thanks for your input, I tend to agree with your take on this. But, it does
concern me that this could be interpreted different ways. I know of another
engineer who takes the most conservative approach on this issue, ie full
building upgrade for any element altered by more than 10%. I wonder if there
is any official commentary or examples on this?

Jeff

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu] 
Sent: Thursday, May 15, 2008 12:11 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Alterations Chapter 34 2007 CBC

I would believe the intent is that if you weaken an element enough (in this
case, "enough" being 10%), then the assumption is that you are changing the
distribution of lateral loads to the various elements and thus need to redo
the overall lateral system design.  If you weaken that element and then
strengthen it, then I would argue that you are not really triggering that
provision.  In otherwords, that provision to me assumes that you weaken the
element and you have no way to fix that weakness in otherways that keep its
performance level similar.  Another way to say it is if you just alter the
element, but don't really weaken it overall, then that provision would not
seem to be triggered...uless you alter it in a way that does not cause it to
substantially perform similar to how it would perform prior to the
alteration.

The point is that I believe the intent of such a provision is to ensure that
if the lateral system is altered "enough", then someone needs to make sure
that the altered system can still substantially resist the appropriate loads
and that the alteration does not "break" the entire lateral system by
causing it to behave in ways not originally designed and thus potentially
failing when needed.

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Jeff Smith [mailto:jeffsmith7(--nospam--at)comcast.net]
Sent: Thursday, May 15, 2008 1:17 PM
To: seaint(--nospam--at)seaint.org
Subject: Alterations Chapter 34 2007 CBC


 
I am interpreting section 3403.2.3.2 to require that an entire building
needs to be seismically upgraded if any seismically resisting element has
its strength reduced by more than 10%. In the case of a concrete shearwall
flexible diaphragm building, if you punch a whole in an exterior shear wall
and reduce the strength by 10% you have to upgrade the whole building, not
just the altered shear wall or do the exceptions 1-4 allow just the altered
wall to be strengthend?

Thanks,

Jeff


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


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