Max point load on 2 x (6)(8)(10) Wood Beam

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doublereefed
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Max point load on 2 x (6)(8)(10) Wood Beam

Post by doublereefed » Mon Mar 15, 2021 5:35 pm

I turn to you all here because there's so many smart people on this list. I can't find information that tells me the safe max point load for a 2x6, 2x8, etc. wood beam. The Google results are all about floor systems with distributed loads and a system of beams on center. I need to build a rack related to train hauling and moving, will end up with a point load of about 1,500 lbs, centered on the beam. The span will be 10'. How many 2x(?) would I need to support that point load on that beam? Acceptable deflection is always part of the formula, I'm just looking for a safe design. If 1/2", 1", etc. of deflection will carry that load forever, that is fine. I just don't have the experience or background to figure out the info I am seeing online.

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rklopp
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by rklopp » Mon Mar 15, 2021 6:42 pm

Beware that you might be below whatever thresholds for stress and deflection, but your beam can fail by buckling in the mode of twisting over sideways. Be careful about lateral stability.


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John Hasler
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by John Hasler » Mon Mar 15, 2021 7:10 pm


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gwrdriver
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by gwrdriver » Mon Mar 15, 2021 8:49 pm

Richard,
You would benefit from using the deepest beam you can and I would look at the technical information for LVL (laminated veneer lumber) beams. For deep, possibly wide, and long span beams (and "long" is relative), LVLs are competitively priced against truss-joists and structural grade framing lumber. I would not recommend using common #2 framing lumber for such a beam. The national lumber manufacturers publish wood beam and LVL design tables which you can download.

As rklopp says, and depending upon the load and proportions of the beam, some means of lateral bracing would be prudent if not necessary.

Disclaimer: I am not a licensed structural engineer, . . I'm not even an unlicensed one.
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by curtis cutter » Mon Mar 15, 2021 8:57 pm

There are a lot of factors to consider. Wood species and grade are major players in span calculations.
Each species has a "modulus of elasticity" and that plays heavily in your calculations. Locally if I were to look to span I would use Doug Fir select. You can use John's site and use the Modulus numbers found here:
https://amesweb.info/Materials/Youngs-M ... -Wood.aspx
Also consider that two "2X's" laminated would be 3" and one 4X would be 3.5".
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Greg_Lewis
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by Greg_Lewis » Mon Mar 15, 2021 9:07 pm

Also consider that if you are going to use this rack for hauling in a truck or trailer there will be sudden forces most likely much higher than just the weight you put on it. I've discovered this the hard way. Particularly in a trailer that has no shock absorbers. I'd class the ride back there at times as violent. Even in the truck bed there will be unexpected forces that will add to the stress. I'd be very nervous about using wood for this, and of having a 10-foot unsupported span regardless of material. If it was me hauling in a truck or trailer and I absolutely had to have the 10-foot span, for a 1500 lb. load I'd make a steel truss cross braced and I'd be very sure of my welds.
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John Hasler
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by John Hasler » Mon Mar 15, 2021 9:19 pm

The Forestry Forum site has a table of wood design values. Click to the right of where it says "Reset". A simple way to add lateral stability is by making a box beam. The top and bottom can be 1x and need not be single pieces.

I'd use a 1.5 safety factor or at least 3 if this is going on a vehicle. Also inspect your wood carefully.

There are other similar sites.

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Chris Hollands
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by Chris Hollands » Tue Mar 16, 2021 11:08 am

When I built my shop i needed to be able to lift 500kg (1100lbs) point load down the centre of my workshop and this was calculated by a truss company
I end up with 2+10 - 3 pieces bolted together over a 14 ft span ( I bolted another 2+10 just to be safe ).
This is in 3 places at 10 ft spacing and I then attached a 4" "I" beam to them 30ft long .
So you should be able to work out from what I have done to have a safe lift of 1500 pounds .
If I can lift safely 1100lbs with 3 - 2+10 over 14ft then just do the maths from that and do a load test to check for sag etc when installed .
You could also make props to fit under the beam if you are doing heavy lifts either side of the load that you can place under the beam and that will increase your load capacity considerably .

Laminated beams are a better and simpler option if you want to go that way .
Last edited by Chris Hollands on Tue Mar 16, 2021 11:15 am, edited 1 time in total.

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BigDumbDinosaur
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by BigDumbDinosaur » Tue Mar 16, 2021 11:14 am

I would not use wood for this purpose. As Greg notes, instantaneous loads can substantially exceed static ones due to bumpy roads, sudden stops, evasive maneuvers, etc. I'd be building something out of light gauge square and/or rectangular steel tubing, whose modulus of elasticity per pound of material is many times greater than that of any wood.
Chris Hollands wrote:When I built my shop i needed to be able to lift 500kg (1100lbs) point load down the centre of my workshop and this was calculated by a truss company. I end up with 2+10 - 3 pieces bolted together over a 14 ft span ( I bolted another 2+10 just to be safe ).
That's not the same scenario as supporting a load in a trailer or pickup truck bed. In your case, you are (more-or-less) smoothly applying the load to the beam, so the dynamic loads are not much greater than the static ones. That won't be the case while transporting something in a vehicle.
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Chris Hollands
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by Chris Hollands » Tue Mar 16, 2021 11:28 am

Am I missing something he wants a point load of 1500 pounds in a static location to help load his train that is what I understand from his question and details , any lifting system exposed to shock loads if they are excessive is going to have issues that is why you have safety factors .
If Doublereefer wants to use wood then there is very safe ways to use it in this application ( as i read his question).
This is quite a simple and safe way to lift items if done correctly and used with in its limits .

- surely you would not transport a 1500lb train while attached to a lifting arrangement taking the full weight - again am I missing something

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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by Kevin S » Tue Mar 16, 2021 10:17 pm

Doublereefed, maybe you could help us by clarifying what you are actually building. Is it an engine stand to move about your garage/ shop or a rack system to go into a trailer to take the engine from house to track?
-Kevin S.

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BigDumbDinosaur
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Re: Max point load on 2 x (6)(8)(10) Wood Beam

Post by BigDumbDinosaur » Tue Mar 16, 2021 11:17 pm

Chris Hollands wrote:
Tue Mar 16, 2021 11:28 am
Am I missing something he wants a point load of 1500 pounds in a static location to help load his train that is what I understand from his question and details , any lifting system exposed to shock loads if they are excessive is going to have issues that is why you have safety factors .
If Doublereefer wants to use wood then there is very safe ways to use it in this application ( as i read his question).
This is quite a simple and safe way to lift items if done correctly and used with in its limits .

- surely you would not transport a 1500lb train while attached to a lifting arrangement taking the full weight - again am I missing something
I saw "I need to build a rack related to train hauling and moving..." in the original post and interpreted that as the structure he wants to build is going to support his equipment during transport.
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