Need a book? Engineering books recommendations...

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

RE: WARNING against using Staples in shear walls/diaphragms

[Subject Prev][Subject Next][Thread Prev][Thread Next]
All the previous is not to say that use of staples will seal your fate and the wood structure you designed with them WILL collapse in an earthquake.  It's that the probability of the structure with staples incurring MORE damage than a structure built with nails is greater.  The building code is tasked with establishing minimum performance characteristics for given systems.  If a deviation creates a situation where one system previously thought to be equal now appears deficient, then the code writers have some work to do.
 
It may seem like shades of gray - and it is - but explain that to the home owner who sees the same model house across the street or next door with a green tag on the front door compared to his red tag.
 
From what I see from engineers who live in places that actually have weather, there are serious reservations that come with the use of staples.  And for people like me who live in places with no weather and occasional earthquakes, there could be increased probability of issues using staples.
 
I'll stick with the nails.
 
-Ben

"Haan, Scott M POA" <Scott.M.Haan(--nospam--at)usace.army.mil> wrote:
Before you guys in CA go changing the response modification factor on
everyone, where are the bodies? Wasn't anyone using staples down there before
Northridge? Alot of staples are used in Alaska and I didn't hear about all
the stapled houses in Mentasta and Slana collapsing during the 2002 Denali
Fault earthquake.

I think the bigger concern with staples is that they installed in exterior
wood panel APA 303 siding and the corrosion resistant finish gets bumped off
during installation.

The building code groups have not had the juevos to make provisions that you
can't use staples in exterior wood panel siding. APA used to discourage
staples in 303 siding, but they didn't say by no means install that way.
ISANTA's ESR-1539 section 5.6 says you need to have 1.5 oz zinc per square
foot or equivalent on exposed fasteners - Do they make staples with a coating
like this? I've seen staples that were so corroded you could break them off
with your car keys.

-----Original Message-----
From: Richard L. Hess [mailto:RLHess(--nospam--at)HessEng.com]
Sent: Wednesday, February 06, 2008 10:38 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: WARNING against using Staples in shear walls/diaphragms

David,
In addition to the fact that the ability of staples to resist cyclical loads
has not been determined by test, I believe that the following considerations
indicate that they should not be permitted for shearwalls:
1) There are additional problems with quality control because you cannot see
by inspection if the staple has penetrated the support member or merely bent
over at its surface under the sheathing;
2) In post-disaster evaluation, it is very difficult to see if the staple has
sheared off behind the sheathing, whereas a nail would be visibly bent out of
its original position;
3) Unlike nails, the staples lack ductility to bend without breaking;
4) Staples are much more subject to corrosion than nails because of their
thin cross section.
This has been discussed at length at SEAOC Code Committee meetings and all of
those present have agreed to this position. This conclusion, like any other,
could be found incorrect if adequate testing proves otherwise; and that
testing should be done. However I think that prohibiting them on the basis
of what we now know is prudent.
Richard Hess, SE

-----Original Message-----
From: mrkgp(--nospam--at)winfirst.com [mailto:mrkgp(--nospam--at)winfirst.com]
Sent: Wednesday, February 06, 2008 8:10 AM
To: SEAINT
Subject: WARNING against using Staples in shear walls/diaphragms


My first impression of stapling plywood is that it may be a better system
than nails. Design factors may need to be re-considered. My strongest concern
is corrosion of the staple, not its resilience in a seismic event. A water
repair should include a review of the staples.

Following are what I intend to find answers for and these are followed by
some facts that can help.

What spans are the drift values for?
When is the drift limited by the gaps between the panels edges?

If drift exceeds 1", how probable is it to not witness a permanent
deflection? Is a nailed diaphragm allowed to remain if there is evidence of a
1" drift?

Over the shorter distance of the staple drift could the staple demonstrate a
higher resistance than the nail and absorb more energy? Could more staples
develop this equivalent energy absorption?

What are the COLA/SEAOSC and CUREE test methods as they relate to the above
questions.

I have talked to a contractor who I had remove a stapled diaphragm. The
stapled plywood, was twice as difficult to remove than a similar nailed
system. That suggests that when panel edges bind it might be more likely for
a nailed panel to separate, out of plane, from the framing.

Like gypsum, there might need to be more staples. Gypsum, with the proper
design penalties and correctly installed, can out perform the equal plywood
option.

Lately I have heard of testing of shear walls, at SJSU. Inadvertently, they
discovered the shear wall nails were not yielding before the hold-downs
failed. That probably results in little energy absorption. Could it be that
we cannot rely on the code design benefits of nail yielding when brittle
hold-downs trump the energy absorbing capacity?

David B Merrick, SE

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


--
Internal Virus Database is out-of-date.
Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.16/1251 - Release Date: 1/30/2008
9:29 AM



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



Benjamin H. Maxwell, S.E.


Looking for last minute shopping deals? Find them fast with Yahoo! Search.