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Offline TexasRedNeck

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Engineering Help
« on: May 16, 2019, 07:32:59 AM »
Is there a real man here that has access to engineering software that can help me with deflection calculations for a timber beam?

It’s been 30 years since I had to use calculus and I really don’t want to spend 2 days fumbling through a calculation trying to reeducate myself.

I can provide the load, span and modulus of elasticity and beam cross section if someone has access to software.

What I am attempting to do is design a simple outdoor structure to support a roof for an outdoor kitchen.  The main calculation will be for a simple span of 24 feet with evenly distributed load using a single southern pine timber beam.  Just trying to figure out if a 6x12 will work or if I have to go deeper to a 14.  Or if its not possible do I have to break the span to 2 12 ft spans

Thank you gentlemen


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Offline Bear9350

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Re: Engineering Help
« Reply #1 on: May 16, 2019, 07:58:27 AM »
I have access to the software.  Not sure if I would have the correct properties for pine.  Wood is very hard to get an accurate calculation like this done on.  The strength properties of wood will vary not only by the species but also the conditions it was grown in, location of knots, how it was dried etc...  24' sounds very long for an unsupported span though.  12' seems doable.  Maybe before spending to much time doing the calcs bounce it off BigDave.

Offline Bigdave_185

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Re: Engineering Help
« Reply #2 on: May 16, 2019, 08:07:54 AM »
Charles I am pretty positive that will meet your requirements but I’ll send the question to our structural engineer who does our homes today.  See what he kicks back,

Generally speaking a beam can go 1.5 it’s thickness.  In feet.   2x8 can span 12 feet and so forth.


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Offline Bigdave_185

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Re: Engineering Help
« Reply #3 on: May 16, 2019, 08:09:16 AM »
Charles I am pretty positive that will meet your requirements but I’ll send the question to our structural engineer who does our homes today.  See what he kicks back,

Generally speaking a beam can go 1.5 it’s thickness.  In feet.   2x8 can span 12 feet and so forth.


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Are you using a pine beam instead of a gluelam or orther beam for some reason?


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Offline stlaser

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Re: Engineering Help
« Reply #4 on: May 16, 2019, 08:16:43 AM »
Charles, most real lumber yards can access this info for you. And yes why not laminated beam?
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Offline Bigdave_185

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Engineering Help
« Reply #5 on: May 16, 2019, 08:53:20 AM »
Charles what’s the rafter length


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« Last Edit: May 16, 2019, 08:54:55 AM by Bigdave_185 »

Offline TexasRedNeck

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Re: Engineering Help
« Reply #6 on: May 16, 2019, 09:05:20 AM »
It’s going to be no more than 10 lb sq ft.

It will be a simple shed roof with a 2/12 pitch and 13 ft span.  Although I may do a 12/12 pitch to match the casita so lets solve for the worst case. But it will not be decked, it will be purlin and R panel with T&G on the underside.  No snow load. Likely 2x6 rafters on 16oc

The structure is a rectangle on a 14x24 slab so likely to be 13x23 actual.


The reason I wanted to use a beam if possible was because I wanted to leave it exposed and not see the lamination and I have a sawmill close by and I may even have the tree for the beam after the tornado came through and blew over a huge old growth pine.

Dave, thank you.  If you don’t mind solving for an Anthony power beam glue lam while you are at it for a fall back position


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Offline Bigdave_185

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Re: Engineering Help
« Reply #7 on: May 16, 2019, 11:11:08 AM »
From my engineer

I can’t get the solid beam to pass.  Will it work?   Probably.  A 5 1/8”x12” glu lam passes.    24’ is a long span.  It fails because of deflection, it’ll just bow down.  I’d use a cheap timber and put a post in the middle.   


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Offline stlaser

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Re: Engineering Help
« Reply #8 on: May 16, 2019, 02:37:49 PM »
Or use the lam beam and face it with the pretty wood.....
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Offline KensAuto

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Re: Engineering Help
« Reply #9 on: May 16, 2019, 03:16:34 PM »
^^ seen that done before.  Sucks to use any natural wood tho, for maintenance reasons.  Also Glue lam doesn't check and let moisture in
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Offline Flyin6

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Re: Engineering Help
« Reply #10 on: May 17, 2019, 01:14:57 PM »
Why not sandwich a piece of steel in between two slices of whatever

Or use an I-Beam
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Offline Farmer Jon

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Re: Engineering Help
« Reply #11 on: May 18, 2019, 05:36:19 PM »
Go to your local lumber yard. They can do that for you. Not Home Depot or Lowes but a REAL lumber yard. We had to have a beam engineered when we built the loft in the the shop.
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