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Re: Curved GLB

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scott-  is all of your analysis time billable, or is it just after hours stuff you would do?

On Wed, Jul 16, 2008 at 6:02 AM, Scott Maxwell <smaxwell(--nospam--at)umich.edu> wrote:
Yes...basically some "plate" type action.  The key is how much is "some".  Just lateral bending of the wall itself will provide "some" thrust resistance.  The tough part is how to quatify how much thrust resistance such elements can provide...especially without doing some full tilt FEA analysis (talk about fun).
 
Regards,
 
Scott
Adrian, MI
-----Original Message-----
From: Steve Gordin [mailto:sgordin(--nospam--at)sgeconsulting.com]
Sent: Wednesday, July 16, 2008 12:08 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Curved GLB

Scott,
 
Do you think that the roof diaphragm of reasonable proportions may provide some thrust resistance by spanning between the end walls (e.g., gables)?  
 
V. Steve Gordin, SE
Irvine CA
 
----- Original Message -----
Sent: Tuesday, July 15, 2008 20:14
Subject: RE: Curved GLB

What he said...<grin> 
 
Or if you are anal like me and you enjoy creating computers just for the fun of it, you could always model it in a structural analysis program.  Of course, you will have to model the curve as a bunch of small line segments to get your "arch" shape.  And it is more work.  And if you REALLY like to have fun, then you can play with the supports as springs to try to model the stiffness/lateral resistance that the wall might present...but that will likely rather tough to really reproduce and would likely not be worth it (other than for a fun educational experience in structural modelling).
 
Regards,
 
Scott
Adrian, MI
-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Tuesday, July 15, 2008 7:00 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Curved GLB

It would appear that it would be just a pin roller support.  Calculate the vertical deflection predicated on the properties of the GLB.  Then translate the vertical deflection to the outward deflection at the supporting walls with simple trigonometry. 

Regards,
Harold Sprague


Subject: RE: Curved GLB
Date: Tue, 15 Jul 2008 12:27:46 -0600
From: GordonGoodell(--nospam--at)harmonydesigninc.com
To: seaint(--nospam--at)seaint.org

Scott & Harold,

 

Right.  What I'm wondering is, if there were no tie rod, sitting on 9' tall light-framed wood walls ~28' long (so essentially unbraced), how much would that curved GLB (radius ~20') really unwind?

 

regards,

Gordon Goodell

 

 

 

From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Tuesday, July 15, 2008 12:10 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Curved GLB

 

Gordon,
If you use a tie rod, it will become a point of restraint as the arch tries to deflect.  Therefore the tie rod will have to resist the full static thrust load of approximately (w * L squared) / (8 * H).

Regards,
Harold Sprague



Subject: Curved GLB
Date: Tue, 15 Jul 2008 11:04:46 -0600
From: GordonGoodell(--nospam--at)harmonydesigninc.com
To: seaint(--nospam--at)seaint.org

I'm working on a project with curved GLB roof framing, ~16' span, 5'o.c. w/ joists hung btwn them.  The architect is expecting a tie rod at plate level, but I'm wondering how to calc the thrust at the base of these things.  Considering how they're manufactured, it seems like there should be a lot less horizontal force at the plate than a simple statics analysis would indicate.

thanks,

Gordon Goodell


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