Need a book? Engineering books recommendations...

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

Re: out of plane anchorage Question

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Chris,

A nailed strap will behave in a ductile manner.  As I stated the original
intent as published was for bolted connections.  There may have been some
concern over narrow face attachment splitting, but this does not make sense
to me as you would be limited to a strap that fits on the narrow face of the
member.

As I also stated, it is not too difficult to develop a quality code
compliant system and still use plated trusses.  If in your "engineering
judgment" you wish to ignore the requirements, so be it.  I can picture
applications where your attitude is justifiable as well as applications
where it is not.


Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
----- Original Message ----- 
From: "Chris Roper" <christophermroper(--nospam--at)hotmail.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, November 12, 2003 7:19 AM
Subject: Re: out of plane anchorage Question


> It's interesting to note that companies such as Trus Joist have gotten
> rulings from code enforcement agencies that exempt their products from
> 1633.2.8.1, item 5.  In their literature they state "Connections made to 1
> 1/2" thick Trus Joist structural composite lumber may be used for
> out-of-plane wall anchorage to flexible diaphragms in lieu of the minimum
2
> 1/2" wood elements specified in item 5 of Section 1633.2.8.1 of the UBC."
> It was always my understanding that this 2 1/2" code blurb was really
aimed
> at stopping people from using wall anchorage straps into the narrow 2x
face
> of panelized type framing systems because of problems with these narrow
> members splitting.  It seems to me that if this nailed strap connection is
> made to the wide face of a 2x4 flat type member (such as the top chord of
an
> open web or I-joist), splitting becomes much less of an issue.  It also
> seems ludicrous to me that typical framing systems with 2x plated trusses
at
> 24" o.c. and low wall anchorage forces can no longer be used to anchor
> walls.  I know I still do it.  There is such a thing as "engineering
> judgment".
>
>
> >From: "Paul Feather" <pfeather(--nospam--at)SE-Solutions.net>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: <seaint(--nospam--at)seaint.org>
> >Subject: Re: out of plane anchorage Question
> >Date: Tue, 11 Nov 2003 17:47:59 -0800
> >
> >Pat,
> >
> >I do not think they intentionally wanted to remove plated truss
> >construction
> >from masonry or concrete wall structures, and I do not think these
> >provisions prohibit their use, but in essence the provisions have made
this
> >traditional construction approach more difficult.
> >
> >The primary wall anchorage failure experienced was for tilt-up and
masonry
> >warehouse structures with tall walls and large diaphragms.  These are
> >typically panelized systems with parapets utilizing sub-diaphragm design
to
> >develop wall anchorage.  According to the SEAOC blue book, the limitation
> >on
> >the net thickness of the wood member for bolted connections, where wood
> >member thickness should be a minimum of 4.5 times the bolt diameter for
> >ductile behavior in the connection.  When translated into code language
> >this
> >became "The wood element shall have a minimum net thickness of 2.5
inches",
> >without differentiation regarding bolted or nailed construction.
> >
> >In my personal opinion, most of the thought at the time was of limited
> >focus, similar to the rho issues with wood construction.  The subject of
> >study was failures of one type and the consideration of the impact on all
> >the other types of construction was not 100% realized until the
> >applications
> >were applied in practice.  However, with all that being said I personally
> >don't think this is such a bad idea.  It is possible to design
accordingly.
> >The wall anchorage is the weak link in any bearing wall system.
> >
> >I am reasonably confident that a double truss adequately joined to act as
a
> >single element, similar to a girder truss, would comply with the
provisions
> >of the code.  I am also reasonably confident that this could be
adequately
> >explained to most plan checkers.
> >
> >I also think there is definite room for improvement in these
"traditional"
> >systems anyway.  Top bolts set in the grout cells acting perpendicular to
> >the wall perform poorly.  The table values in the UBC do not adequately
> >address this, but if you read the actual equations the calculated
allowable
> >value is pretty limited.  The top plate perpendicular to grain bearing is
> >not the most efficient and reliable way to resolve dynamic out of plane
> >wall
> >forces.
> >
> >It is not too difficult to detail a more appropriate direct connection
> >system and still use a plated truss system.
> >
> >
> >Paul Feather PE, SE
> >pfeather(--nospam--at)SE-Solutions.net
> >www.SE-Solutions.net
> >----- Original Message -----
> >From: "Pat Clark" <bcinc(--nospam--at)nanosecond.com>
> >To: <seaint(--nospam--at)seaint.org>
> >Sent: Tuesday, November 11, 2003 4:23 PM
> >Subject: RE: out of plane anchorage Question
> >
> >
> > > I thought that the requirement was for the sill plates or ledgers.
Did
> > > they intentionally want to remove all plated truss construction from
> > > masonry and concrete wall structures?
> > >
> > > Patrick Clark, P.E.
> > > Building Concepts, Inc.
> > > 1228 Pep Circle
> > > Gardnerville, NV 89410
> > > (775) 782-8886 x22
> > > (775) 782-8833 fax
> > >
> > >
> > > -----Original Message-----
> > > From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net]
> > > Sent: Tuesday, November 11, 2003 3:59 PM
> > > To: seaint(--nospam--at)seaint.org
> > > Subject: Re: out of plane anchorage Question
> > >
> > >
> > > Correct, you would have 3x minimum chords for anchorage attachment if
> > > you are using the truss for anchorage.  This makes this "traditional"
> > > construction system a bit harder to implement.
> > >
> > > Paul Feather PE, SE
> > > pfeather(--nospam--at)SE-Solutions.net
> > > www.SE-Solutions.net
> > > ----- Original Message -----
> > > From: "Tarek Mokhtar" <tarooky(--nospam--at)earthlink.net>
> > > To: <seaint(--nospam--at)seaint.org>
> > > Sent: Tuesday, November 11, 2003 3:25 PM
> > > Subject: out of plane anchorage Question
> > >
> > >
> > > >
> > > > consider a 35' x 18' one story masonry building with a wood truss
roof
> > >
> > > > The masonry walls have a 4x nailer on top, where the trusses are
> > > > attached for bearing and out of plane forces.
> > > >
> > > > Section 1633.2.8.1 states that wood elements of the anchorage system
> > > > shall be 2 1/2" minimum, does this mean that the trusses have to be
3x
> > >
> > > > thick?
> > > >
> > > > Tarek Mokhtar, SE
> > > >
> > > > Laguna Beach, CA
> > > >
> > > >
> > > >
> > > > ******* ****** ******* ******** ******* ******* ******* ***
> > > > *   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
> > > ******* ****** ****** ****** ******* ****** ****** ********
> > >
> >
> >
> >******* ****** ******* ******** ******* ******* ******* ***
> >*   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
> >******* ****** ****** ****** ******* ****** ****** ********
>
> _________________________________________________________________
> >From Beethoven to the Rolling Stones, your favorite music is always
playing
> on MSN Radio Plus. No ads, no talk. Trial month FREE!
> http://join.msn.com/?page=offers/premiumradio
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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 
******* ****** ****** ****** ******* ****** ****** ********