Need a book? Engineering books recommendations...

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

RE: Timber Truss Gusset Plate

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Hi Rich,
Even i feel there will be some unbalanced forces at truss joint..even when
center lines of all load lines from diiferent members doesnt meet at one
point at gussent joint there will be some twisitng in plate..
But if you consider force lines and lever arm between them ,you
understnd.Lever arm is too less,so moments generated could be ignored.
regards,
Haresh
--------------------------------------------------
-----Original Message-----
From: Rich Lewis [mailto:sea(--nospam--at)lewisengineering.com]
Sent: Monday, January 10, 2005 2:46 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Timber Truss Gusset Plate

David,

Thank you for your response.  I'm not sure if this is an insult, or just
pointing out statics.  I understand the joint equilibrium concept.  That
is a theoretical model of sticks.  Now that I'm detailing a 3D joint of
sticks, plates and bolts and I want to make sure the theory doesn't
blind me of the reality of how the overall joint will behave.

I am working with a common work point.  As I see it all the member
forces are transferred into the gusset plate.  The gusset is where all
the X & Y components equalize themselves.  The chord and web members
apply there axial loads to the plates as axial loads.  Why I am
questioning is because I am not 100% convinced that a member like the
sloping diagonal web will not put a perpendicular to grain load in the
bottom chord.  Theory states the vertical component goes into the
vertical web.  But in the real world will there be a perpendicular to
grain force in the bottom chord? It's a matter of lower bolt shear
values, a lot lower.


Rich Lewis
Lewis Engineering



-----Original Message-----
From: David Topete [mailto:davetopete(--nospam--at)yahoo.com]
Sent: Monday, January 10, 2005 11:17 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Timber Truss Gusset Plate

I would agree that the joint is in equilibrium, and
that the axial member forces are resolved into their
respective vert and horiz components.  So, no, there
should be no/minor perp-to-grain forces on the bottom
chord for example...  I would then to think that the
first quarter undergrad lectures in Statics should be
true.  Otherwise, why would the method of joints be
taught???
David Topete, PE
SF, CA

--- Rich Lewis <sea(--nospam--at)lewisengineering.com> wrote:

> I am designing a timber truss using Parallam lumber.
>  The panel points
> are connected with steel side plates and bolts.
>
> I have a question as to how I see the bolted
> connection designed.  I
> analyzed the truss with a frame analysis program and
> I have all the
> member forces for various load combinations.  I
> modeled the web members
> as pinned ends and the top and bottom chords as
> continuous members.  As
> I see the joint connection design I design the
> number of bolts based on
> the member forces.  The forces in the members are
> primarily axial forces
> so the bolts are designed based on parallel to grain
> values.  The top
> and bottom chords have some minor shear due to the
> continuous modeling.
>
> Let me see if I can explain this further.  I will
> illustrate this with a
> specific joint, a bottom panel joint that has the
> bottom chord
> horizontal on either side, a diagonal going up to
> the top chord and a
> vertical going up to the top chord.  The force from
> the diagonal goes
> into the steel plate.  The vertical component of the
> force is resisted
> by the vertical web and the horizontal component is
> resisted by the
> bottom chords.  The force is distributed to these
> members through the
> gusset plate.  As I see it I don't have any
> perpendicular to grain
> forces in the bottom chord (except the minor shear
> forces) or the
> diagonal or the vertical.
>
> I need a sounding board to bounce my thoughts off
> of.  Am I looking at
> this correctly?  Would this plate put a twisting
> force in the joint that
> will put perpendicular to grain loading in the
> bottom chord?  Would
> joint equilibrium negate this possibility?
>
> Thanks for your help.
>
>
> Rich Lewis
> Lewis Engineering
>
>
>




__________________________________
Do you Yahoo!?
All your favorites on one personal page - Try My Yahoo!
http://my.yahoo.com

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



--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.298 / Virus Database: 265.6.8 - Release Date: 03/01/2005




-- 
Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.298 / Virus Database: 265.6.8 - Release Date: 03/01/2005


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