Need a book? Engineering books recommendations...

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

Re: Seismic Expansion Joints

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Seismic joints are common in many applications.  Under the UBC, the
displacements are based on the Maximum Inelastic Response Displacement
(Delta M).  I am not up on the IBC terminology as well as I should be,
coming from the code challenged California region, but I think this is
equivalent to what you are saying. Under the UBC delta-m is based on
.7R(delta-s), which is the strength level displacement factored up by 70% of
the redundancy factor.  For a SMRF application R = 8.5, so in your example
delta-s calculated = 2", delta-m = 11.9".  Total joint width based on SRSS
as you indicate.

The joints become large.  In typical applications we are separating a SMRF
system from a shearwall system or other dis-similar response structure so
the joint is not as extreme as two SMRF structures, but the same conditions
apply.

There are several joint manufacturers who provide solutions to virtually any
joint condition, floors, walls, roofs.  Take a look at Balco as an example.
I believe it is www.balcousa.com




Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
----- Original Message ----- 
From: "Jimmy Jones" <jimmyjones(--nospam--at)carolina.rr.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, April 07, 2004 1:01 PM
Subject: Seismic Expansion Joints


> My firm is located in an area where every building ends up in Design
> Category "D". We typically try to exhaust all options before using moment
> frames because of the IMF or SMF requirement for this Design Category.
>
> Every now and then we will have a scenario where we want to split a
building
> into two separate structures (expansion joint) due to building geometry,
> inadequate diaphragm strength, re-entrant corners, etc.
>
> Which leads me to my question. When both or even one of these structures
> uses IMF or SMF the lateral deflections become a huge issue with regard to
> expansion joints.
>
> Are expansion joints typically sized for inelastic displacements (i.e.
using
> cd * elastic displacements)?
>
> Example:
> 50 foot tall buidling(s)
> building one displacement=2" w/ cd=5.5 yields delta=11
> building two displacement=2" w/ cd=5.5 yields dela=11
> per IBC building separation=sqrt((11^2)+(11)^2)=15.55
>
>
> How do you deal with an expansion joint this large? Floors? Wall and
> Windows?
>
> Any thoughts or experiences would be greatly appreciated
>
>
>
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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 
******* ****** ****** ****** ******* ****** ****** ********