Need a book? Engineering books recommendations...

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

Re: Question regarding seismic joints

[Subject Prev][Subject Next][Thread Prev][Thread Next]
You may not eliminate pounding, but the joint will certainly minimize the
impact.  Even if the existing structure was designed solely for wind, there
is still a lateral system.  Can you approximate the existing structures
response deformation?  In a way, you are protecting the existing from the
addition.  If the addition is pounding against an already weak existing
structure it certainly will not help the situation.

There is judgment in all things.  If the existing structure is really so
weak that you believe it will simply collapse in a moderate earthquake,
maybe separation of the addition is not the best solution.  It could be you
would provide a better service to tie the new to the existing as a support
retrofit, and add some additional selected retrofit to the existing to make
a new single integrated structure with adequate response characteristics.
Alternatively, maintain the separation but make some recommendations as to
how to retrofit the existing.  Owners do not always balk at additional costs
and increased scope if they can see a long term cost benefit.  What type of
structures are you separating?  What are the lateral systems?


Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
----- Original Message ----- 
From: "Benjamin Cornelius" <bcorneli(--nospam--at)hotmail.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, April 23, 2004 9:06 AM
Subject: RE: Question regarding seismic joints


> Thanks, Mark.  I suspect you are correct about pressure from developers.
I
> have been thinking more about this.  My addition is to an existing
building
> that was not originally designed for seismic loads, just wind.  The system
> is such that it will almost definitely not stand up to the code prescribed
> loading.  Should the design earthquake occur, the existing building would
> likely fail and possibly impact the addition, which makes me ask the
> question:  what am I accomplishing by providing this seismic joint?
Perhaps
> I am protecting the EXISTING BUILDING from the addition.  Or perhaps I am
> providing increased protection to the combined building during a smaller
> event.  But, logically, I am not preventing pounding in the event of the
> design earthquake.  Any thougts?
>
>
> >From: Mark Gilligan <MarkKGilligan(--nospam--at)compuserve.com>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: "INTERNET:seaint(--nospam--at)seaint.org" <seaint(--nospam--at)seaint.org>
> >Subject: RE: Question regarding seismic joints
> >Date: Fri, 23 Apr 2004 02:35:39 -0400
> >
> >The reality is that if adjacent buildings are not seperated enough they
> >will pound together.  Pounding buildings can either damage columns thus
> >leading to collapse or the pounding can increase the acceleration that
each
> >structure sees.
> >
> >The formulas are compromises that are expected to control but not
eliminate
> >damage.
> >
> >Many jurisdictions (both on the East coast and the West coast)  have
turned
> >a blind eye to these seperation provisions at property lines.  Just think
> >how developers would respond to reducing the floor platein a tall
building
> >because of seismic joints.  The fact that separation joints are not
> >mentioned for seismic design catagories B and C might be influenced by
> >these same pressures.
> >
> >You should keep these three points in mind whenever deciding the size of
> >seismic joints.
> >
> >Mark Gilligan
> >
> >******* ****** ******* ******** ******* ******* ******* ***
> >*   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
> >******* ****** ****** ****** ******* ****** ****** ********
>
> _________________________________________________________________
> MSN Toolbar provides one-click access to Hotmail from any Web page - FREE
> download! http://toolbar.msn.com/go/onm00200413ave/direct/01/
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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 
******* ****** ****** ****** ******* ****** ****** ********