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Starting a new project with some questions

Started by FeltzE, April 18, 2004, 05:13:19 AM

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FeltzE

I am beginning work on a  new 6 bay equipment shed. The bays are going to be 12 foot wide and 3 bays deep also 12 ft.

What is the easiest and structurally proper way to connect my Plates together?

I am looking at a 12 ft span on the bents with 8x8 beams and posts SYP, 4.6 knee bracing and a standard 2x6 rafter with a 2/12 roof pitch (tin)

I am going to put down a concrete sill for the posts to rest on,


Next question: Is there any benifit of cutting posts and beams with the heart centered? I get some pretty good sized SYP and was considering splitting the ones from 16 square to 8x8 for this project.

Eric

ARKANSAWYER

  I would not reccomend the splitting of the 16x16 for four 8x8's.  They will bow some what.  I would box the heart and make lots of boards for rafters and siding.   12 feet is not a very wide shead. ???   You could go with 6x6's and not have the extra weight over your head.
  ARKANSAWYER
ARKANSAWYER

Jim_Rogers

First of all, what is the footprint of the building?
When we say "bay" in timber framing, that is the area in-between two bents, and it doesn't matter how long or how wide that bay is it's one bay.
If I'm understanding you and your layout correctly, are you telling us it's 36'x36' square?
And as mentioned box the heart for strength, especially in all horizontal timbers.
Or locate your timbers in your log like the diagram shown in this thread:
Boxed heart beams or not?
And see pictures of the reasons why.
Good luck with your project.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

UNCLEBUCK

thanks for that detailed and well put together thread Jim. Good luck with your new project FeltzE .
UNCLEBUCK    bridge burner/bridge mender

FeltzE

The structure will be 36 feet deep and 72 feet wide, consisting of 7 bents.  12 feet center to center on the bents, this will provide me with the ability to come off the front with another rafter to a steel plate with a 24 foot span creating 3 24 foot bays on the front.

Eric

FeltzE


Buzz-sawyer

I see you have put thought into your design, .....
Is there a reason you are not building trusses?
You could easily biuld a series of free span trusses and do away with ALL the interior 12' on center posts, making room to move inside the shed or ocasionally, or in the future use it for other purposes.....
Can link to truss plan if you like...good luck!
Don
    HEAR THAT BLADE SING!

Jim_Rogers

Eric:
Thanks for the pictures.
Now we have some more information to work with.

My first thoughts were to lower the girts that go from post to post in each bent, away from the top of the post, so that you can connect the plates from post top to post top. That way making your bents more in the shape of an "H".

It can be difficult and structurally dangerous to have several timbers joining the posts at elevation. The simple solution is to lower one or two of the timbers.

Are you going to try to make some continuous plates by joining them with scarf joints?

If so then the posts would join the plates from the bottom using a standard mortise and tenon joint.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

FeltzE

The last barn I built was based on a truss type structure with good results.



I used 2x6 with 1x6 plates to connect rafters with horizontal (girt?) and a 2x4 as the king post. 24inch denters for the trusses. This gave me a 24 foot free span with some load bearing space built in to the truss.

If I were to do it again in tmy next project I would consider making steel plates and bolting 8x8 beams together, some for the asthetics and also for the stength. The question would be how far apart could the tusses be?

Here is another style I like a little simpler with a bent of only 3 posts then a shed roof to the front on the steel beam


I've been cutting some 8x8 12 and 14 foot lengths getting ready for the project, currently I only have about 22 or so stacked up. I am going to have to settle on a plan sooner or later I just can't make a stack of beams and let them build themselves... darn.. ::)

Here is how I was planning to join the plates.




I appreciate all your imput on the project because as it stands right now. I am the forman, planner, worker, bus boy, and mop expert on this job

Eric

Jim_Rogers

If you are going to have a continuous plate over the posts then a half lap joint could do you, if as you have mentioned you're going to bolt them together.

But you should not locate this joint over a post!

This is the most common error that can cause a failure.
At the point where the wood has to be the strongest you're cutting it in half. This is the point where almost all the roof load is being transferred to the posts. You need to have a full thickness beam here.
If you can imagine a plate being in place for years. This plate probably will sag some under the roof load, in between the posts. And then rise up as it passes over the post and then sag down again on the other side. Like a wave, a very low angle wave. At the point where the sag changes to a hump over the post is called "the point of inflection" as the sag is a deflection. At this point where the beam changes from sag to hump is the point where the lease amount of stress is. This is the point where the lap joint should be made. And it should be supported by a brace.
Here is a book diagram showing what I mean:

(if you need to see the image larger, I can email it to you, full size).
If you need more info on scarfs and locating them there is a free download available from the TFG site.
Let me know and I'll post a link.
Jim Rogers
Jim Rogers Sawmill.
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

FeltzE

Jim, I'll look further into it then, I've got several books on joinery I'll get back into them!

Thanks

Eric

Buzz-sawyer

Here is a link I got from this forum to a 48' truss plan....
you can simply cut what you need and build to the plan (and live load specs.)
http://www.public.iastate.edu/~mwps_dis/mwps_web/tr_plans.html
    HEAR THAT BLADE SING!

Jim_Rogers

Buzz:
Thanks for the link.
But be careful. There is a warning label on these drawing pages that says you need to do more research in another document not included in the set to completely understand and build trusses that will be safe.
It sounds simple and looks like you could build trusses from these plans, but anyone should be very careful not to assume these are a "one size fits all" type of thing.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Buzz-sawyer

Hey Jim
Right,
 on the understanding live load/ snow load, and also the species load bearing ability....
    the snow load zone is listed with these plans ....it ours to understand how strong the wood we use is....(and not hard info to come up with)

    the feel I got from the disclaimer,
is that due to legal liability the freely shared plans need a disclaimer...they are certified plans, and in a sense are build and go....with the affore mentioned dissclaimer...and possibly enough sense to build em accordding to gusset and fastener schedules....it is at least a good template, or starting point to building a stronger truss
Don
    HEAR THAT BLADE SING!

FeltzE

Great link,

I am considering changing my plan to put a timber frame on the back 1/4 of the building frame and put a 24 foot truss over my work area, using the steel beams I have for my front sill. (My plans are set in mud at the moment)

Eric.

Jim_Rogers

Eric:
There are methods to overcome the problems with a scarf joint being over a post.
The most common one used around here is to support the scarf joint with a pillow beam, like this:



This way your beams being joined at the scarf have full support at the post.

Some are more elaborate than others, like this:



These are just some methods that have been used to solve these problems, and make a structure stronger.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

FeltzE

Considering My load bearing requirements aren't going to be that high, I was thinking of a simple lap joint utilizing a 1 inch lap on to the post to reduce any shearing tendency.




I still haven't taken the time to get back  into the books though! Beat me with a wooden dowel.,  :-X

My load will be 2x6 rafters and a steel roof with 2x4 stringers.


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