Uniformly Loaded Beam Overhanging One Support

[Sedgehammer]

Putting in a big beam for my barn build. it'll hold up the upstairs and and over hanging balcony that has 4' of it unsupported. Least wise that's what I am wanting. The area that this covers is 20 deep x 32 wide. The balcony is 4 additional depth and still 32' wide. A SYP beam that has one support at the 19' mark only needs to be a 10x14, yet to over hang it 4' unsupported if my cypherin is correct needs to be a 12x18. Is my cypherin wrong? 

Thanks

[Sedgehammer]

I'm trying to get by using one post. If I need to go to 2, then i'll not overhang. Thus the fuss.

[mike_belben]

Im not exactly picturing it. But can you brace the overhang back into the post that the beam is on?

[Don P]

Ditto, full drawings needed. People tend to forget, a brace puts a side buckling load on an already end loaded post. Push down on a yardstick from the end. Now while doing that also push on it from the side. That complex combined interaction equation is a whole other level of fun and depending on the slenderness ratio of the post often results in "don't do it".

[mike_belben]

Double the post.  Truss the post.  Add another member in a Г + /  configuration all the way to the ground with plywood sides to form a monocoque structure. Or make it a steel beam.  


A poor guy woulda had this built from pallet wood already cmawn.  ;D

[Sedgehammer]

This is all exposed. Post be a 12x12 or a matching post to beam. 

I'll try and do some drawings, but they'll prolly be later after ballgames. I'll try and splain it betters now

Total length on beam is 24'6". The 6" is buried in north wall. Beam runs south 24'. Post is at the 19' mark. This beam is in the middle of a 20' deep (north/south) X 32' wide (east/west) kitchen and dining room. Above this beam is the 3x12x16'6" floor joists 2" OC that are under the 2 upstairs bedrooms. The 4' over hanging balcony is south side of the bedrooms. 

[Sedgehammer]

Pictorial of the drawing





 

[Tom King]

I have almost always used a steel flitch plate for cantilevers.  One can be hidden inside two beams.

[Sedgehammer]

Yeah, i used that on my old farm house remodel years ago. needed the ceiling height, so used i think 5, 2x8 and put a thin plate betwix them all. worked great.

I could use 2 beams, but prefer one. The 10" x 14" SYP beam i can order is about $1,250 dried. I can get a green one much cheaper, but prefer not the hassle of the green build. I can also make the SYP beam bigger. I can also buy some reclaimed, but they are darn expensive. around $2,700 for a 12" x 15"

[mike_belben]

For wide span doorways my dad would sister a pair a 2x lumber with a steel flat plate bolted in tbe center rather than plywood to shim for thickness.  No sag or sheetrock cracks 20yrs later. 

[Sedgehammer]

Ditto, full drawings needed. People tend to forget, a brace puts a side buckling load on an already end loaded post. Push down on a yardstick from the end. Now while doing that also push on it from the side. That complex combined interaction equation is a whole other level of fun and depending on the slenderness ratio of the post often results in "don't do it".

knock, knock if ya ain't too busy

[Don P]

I was politely thinking, "that bunch of chicken scratches ain't goin on the fridge". I can't make heads or tails of it. Back out and draw more of the footprint, surrounding walls, you've lost me.

[Sedgehammer]

I was politely thinking, "that bunch of chicken scratches ain't goin on the fridge". I can't make heads or tails of it. Back out and draw more of the footprint, surrounding walls, you've lost me.

Alrighty

Oh you're fine. Frankness is best although I don't know frank......

Be later, at ball games

[mike_belben]

I cant tell if its a ground view or a birdseye view. 

[Sedgehammer]

I was politely thinking, "that bunch of chicken scratches ain't goin on the fridge". I can't make heads or tails of it. Back out and draw more of the footprint, surrounding walls, you've lost me.

Heres ya goes. Was able to get this done

They won again, so one more game at 4

Anyways, the yellow is what will be up upstairs. Orange is the beam

Floor joists are 3x12 2' OC
Proposed beam is 10x14x24 SYP

[Sedgehammer]

I cant tell if its a ground view or a birdseye view.

birdy

[Don P]

"Plan view"

And that is why we use drawings, that is nothing like what the word pictures had conjured up in my head. Don't try to describe stuff, draw it and draw it well.

Tributary area supported by the beam is highlighted within the red box;


 

Trib width would be 16' x 50psf (40LL+10DL) = 800 lbs per lineal foot load on the beam.

This calc;
https://forestryforum.com/members/donp/oerhangbm.htm

You're cutting it mighty fine in #1SYP

[Sedgehammer]

"Plan view"

And that is why we use drawings, that is nothing like what the word pictures had conjured up in my head. Don't try to describe stuff, draw it and draw it well.

Tributary area supported by the beam is highlighted within the red box;


 

Trib width would be 16' x 50psf (40LL+10DL) = 800 lbs per lineal foot load on the beam.

This calc;
https://forestryforum.com/members/donp/oerhangbm.htm

You're cutting it mighty fine in #1SYP

Yup, that all be correct

Makes it all like easy. No confusing what someone thinks they spellin and what someone thinks they readin.......

passes by 5% if I include the post area span of 234"

passes by 20% if i don't include post area span of 12", since that area isn't spanned

seems since you mentioned skinny (well ok, you didn't say that directly, but you're not talking beauty ;D), that the post area should be included.......?

what % over do you consider is 'healthy'

Thanks

[Don P]

A pass is good, just watch the material quality. For kicks try an LVL... Fb 2800, E 2.0, Fv 280. Each ply of an LVL is 1-3/4" thick, 11.875 tall or 14" tall

[moodnacreek]

I got an overhung beam [shed type roof] sitting on 2 posts, reaching way out to hold up this roof, no post. I was afraid if snow stayed up there it could tip and fail so I hung a barrel of concrete on the back. The beam is steel tube. 

[Don P]

For this it isn't a tipping, see-saw, problem. The "control" is bending failure in the main 20' span rather than in the 4' overhang. I would not use tile in the bathroom on that kind of beam span or joist span and spacing. Experiment with making the overhang longer and watch what it does to the main span bending moment and point of max moment, the see-saw is on that end.

[Sedgehammer]

For this it isn't a tipping, see-saw, problem. The "control" is bending failure in the main 20' span rather than in the 4' overhang. I would not use tile in the bathroom on that kind of beam span or joist span and spacing. Experiment with making the overhang longer and watch what it does to the main span bending moment and point of max moment, the see-saw is on that end.

shucks. Thought that'd be alright on the span. 3 questions if I may.

1. what size beam wood you be comfy with if one wanted tile

2. and if not tile, but just what you'd put

3. how far could you move the post back if any and if any, wood that solve the above question? Reason I had post there was the wall upstairs being directly above
thanks

[Don P]

With a 20' beam span and wide centers on joists I doubt tile would hold up, I'd use sheet vinyl or a laminate. Don't move the post back if there is a wall above, adding another post would help but the joists are long span and widely spaced so bag the tile. Basically get all deflections, beam, joist, floor sheathing to L/480 or stiffer and it has a chance, but it probably still will crack.

[Sedgehammer]

Having an issue with getting that SYP beam i was suppose to be getting...... I can go reclaimed, but that's over 4k. Nope. Thinking about metal. Prefer rec tubing. I'm coming up with a 12x16x.5 has .314 deflection vs .220 for the wood beam. That can't be right, can it? I'm using 16,440 lbs for the force.

Here's the link Rec tubing calculator

"Plan view"

And that is why we use drawings, that is nothing like what the word pictures had conjured up in my head. Don't try to describe stuff, draw it and draw it well.

Tributary area supported by the beam is highlighted within the red box;




Trib width would be 16' x 50psf (40LL+10DL) = 800 lbs per lineal foot load on the beam.

This calc;
https://forestryforum.com/members/donp/oerhangbm.htm

You're cutting it mighty fine in #1SYP

[Don P]

That is a simple beam calc, a beam between 2 supports. What we've been talking about is a beam with an overhang. That is a different set of equations, the load on the overhang is reducing the deflection. I also do not recognize the equation he is using, not saying I've run it against the standard equation to see if he is getting the same result by another path but based on the spelling and notational peculiarities I'm a little leery. Might try engineers edge for a calc.

It would take more rewriting than I have time to modify the wood calc for this. This is the equations you need, it comes from the AISC steel construction manual. The bottom 2 equations are deflection;


For I his equation is correct;

MI for hollow rectangle beams = ((Width * Height³) - (Inside_width * Inside_height³)) / 12

E is 29,000,000
For x use the equation locating the point of zero shear in the middle graphic. for x¹  use a.