Truss Calculators

Started by Medeek, March 12, 2013, 03:33:08 AM

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Don_P

It probably makes no difference but I do align at the 4' intervals with 16" oc walls and 24" oc rafters/cj's.

Medeek

This is a quick study of a post frame roof using doubled trusses with 2x6 purlins @ 24" o/c.  This is pretty typical for a  pole barn or post frame building constructed locally:



View model here:

https://3dwarehouse.sketchup.com/model.html?id=0240f563-8350-460d-b07c-9f7dae117782

Notice how the rake and fascia boards are raised above the trusses so that they are flush with the roof plane and purlins.  The overhang can be achieved a number of ways but one method is to extend rafters from an inboard purlin and also attach to the post as shown.  There are a number of other ways to frame the overhang, a quick search online will attest to this.  Sometimes a header is used between posts which allows for a truss spacing which is closer than the post spacing.

Purlins position right at the peak seems fairly standard, based on some plansets that I have.

When you add end walls with posts you can usually eliminate the doubled truss at the gable ends and you often will see a gable end truss that has girts (horiz. members) instead of studs.

With a purlin roof I almost need to create a separate menu item and module to properly deal with it.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer


Don_P

Have you come across any post frame plans with a raised framed floor rather than a slab on grade?

Medeek

I've never seen one in person but I've come across a few pictures online.  Mostly what I've seen is slab on grade or stemwall with slab.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Don_P

I was thinking along the lines of an affordable cabin or small house foundation especially in sloping or remote terrain


Medeek

Version 1.6.6 - 07.15.2016
- Added roof battens option within the advanced options menu for common, scissor and vaulted trusses.
- Battens can be offset from the fascia board.
- Battens at peak option enabled.



View model here:

https://3dwarehouse.sketchup.com/model.html?id=e7f7a812-53da-4c57-b40a-b28bbacf96e2

Currently this feature is only available for truss roofs, I still need to add it to hip and gable rafter roofs.

If sheathing is enabled with battens, the battens are placed on top of the sheathing.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

Version 1.6.7 - 07.21.2016
- Added a counter battens option within the battens menu for common, scissor and vaulted trusses.



View model here:

https://3dwarehouse.sketchup.com/model.html?id=3bb5c81a-ffd0-4f2f-8cf0-34bf6279428e

Counter battens can be applied with our without sheathing.  The counter battens are centered on the trusses below therefore their spacing is not independently controlled. 

Based on my research it appears that counter battens are usually only applied when battens are laid on top of a sheathed roof.  However I have left the option open to apply them without the sheathing in case one wanted to apply them directly to the truss top chords over a vapor barrier.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

I can add another input field into the menu which will allow the offset from the peak:

Offset from Peak (mm):

I can also put in another option that will allow for the equal spacing between peak and eave battens with the spacing input serving as the max. batten spacing if this option is enabled:

Spacing Peak-to-Eave: YES/NO

I think this will then give you the flexibility you need to make this feature actually useful in real world applications.

Another thing to note is that the battens will work with the roof returns option but I currently have no logic in place to deal with the extension at the eave.  I may need to give this some more thought:

Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

Version 1.6.7 - 07.21.2016
- Added a counter battens option within the battens menu for common, scissor and vaulted trusses.
- Battens (at peak) can be offset from peak.
- Peak-to-Eave spacing enabled when "battens at peak" option is selected.

This was a very small update so I just tucked it into the latest revision.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer


Don_P

I don't remember ever coming across these details in manufacturer instructions but I have seen it built. I have run both over the top of 2x12's with 2x2's for more insulation space as well as 2x2's under the rafters, inside, for the same reason. 2x2's on top of the rafters gives more opportunity for venting problem areas. I think sprayfoam has taken that method away for the most part.

On raised floor post frame, I happened upon this website last nite. Not head over heels with the designs but fully agree with the thinking behind it.
http://www.polehouses.com/index.cfm?fuseaction=page.display&page_id=19

ChugiakTinkerer

Latest version is pretty darn cool.  I really like the flexibility in all the options.

Quote from: Don_P on July 22, 2016, 04:17:17 PM
I don't remember ever coming across these details in manufacturer instructions but I have seen it built. I have run both over the top of 2x12's with 2x2's for more insulation space as well as 2x2's under the rafters, inside, for the same reason. 2x2's on top of the rafters gives more opportunity for venting problem areas. I think sprayfoam has taken that method away for the most part.

On raised floor post frame, I happened upon this website last nite. Not head over heels with the designs but fully agree with the thinking behind it.
http://www.polehouses.com/index.cfm?fuseaction=page.display&page_id=19

Don, I'm exploring post frame with raised floor for my Alaska remote cabin.  If you want to share your thoughts they would be welcome.  http://countryplans.com/smf/index.php?topic=14235.msg188430#msg188430
My cabin build thread: Alaskan remote 16x28 1.5 story

ChugiakTinkerer

I've encountered a glitch with the truss generator in that it aborts when doing the outlookers.  I'll try to replicate it tonight, see if I can recreate it with an empty sketch.  What happens currently is I define the rectangle on my top plate corners, and the code generates the trusses at 0,0,0 but has no outlookers.  The gable overhang rafters are there.  All the trusses are individual entities; it seems to bail before making a group and relocating it to the top of the structure.  No error message pops up.
My cabin build thread: Alaskan remote 16x28 1.5 story

Medeek

Turn on the Ruby Console under the Window Menu and then cut and paste the error message(s) when you replicate the error.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

ChugiakTinkerer

Quote from: Medeek on July 25, 2016, 09:55:17 AM
Turn on the Ruby Console under the Window Menu and then cut and paste the error message(s) when you replicate the error.

Thanks for the tip!  Replicated this in an empty sketch tonight.

Error: #<ArgumentError: Cannot convert argument to Sketchup::Point3d>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5187:in `add'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5187:in `getExtents'
Error: #<NoMethodError: undefined method `x' for nil:NilClass>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5616:in `draw'
Error: #<ArgumentError: comparison of Fixnum with nil failed>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:3543:in `<'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:3543:in `draw_advoptions_common'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:1184:in `draw_truss_selector'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:488:in `main_menu'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5105:in `calculate_obj'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5124:in `update_state'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5170:in `onUserText'


I'm running Linux Mint 17.x and using Wine to run the Windows version of Sketchup.  Except for an occasional graphics quirk it runs nice.  Anyhoo, this is a set of scissor trusses with raised heel.  Asked for a gable overhang with structural outlookers. 

Screencast of the error is here: https://www.youtube.com/watch?v=DeFzFbYzTew&feature=youtu.be

Hope this helps, and glad to add any more info you need.

My cabin build thread: Alaskan remote 16x28 1.5 story


ChugiakTinkerer

Following up on the outlooker bug on scissor trusses, when I do not make the outlooker structural the script works exactly as it should.
My cabin build thread: Alaskan remote 16x28 1.5 story

Medeek

I haven't had any time this week or even this weekend to dive back into it yet but the icons for the Medeek Tools Menu (trim and extend for now) will look like this:

Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

Quote from: ChugiakTinkerer on July 28, 2016, 10:28:29 AM
Following up on the outlooker bug on scissor trusses, when I do not make the outlooker structural the script works exactly as it should.

Sorry I've been down in Vancouver working all last week, haven't had any access to my desktop and debugging tools.  I need to know the configuration you chose for the scissor truss (ie. 2/2, 4/4 etc...).
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

ChugiakTinkerer

I had the glitch on 2/2, 4/4, and 6/6 scissor trusses.  I wasn't even getting the script to run on 4/2 and 6/4 trusses.  Was.  Unrelated to this I rebooted my computer and have also disabled the Maxwell rendering extension in Sketchup.  I now have no problem generating the trusses with structural outlookers.  Sorry for the false alarm, I should have taken the rote IT guy first response to any technical problem, "Have you rebooted your computer?"

Well... just to be thorough I thought I would try out the 4/2 and 6/4 trusses.  I just did, and it keeps looping between the first dialog and the interactive rear corner selection.  This isn't an issue for me, just thought I'd flag it.  Of course, I don't know if it's just my odd system configuration.  Here's a capture from the Ruby console:
Error: #<ArgumentError: Cannot convert argument to Sketchup::Point3d>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5187:in `add'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5187:in `getExtents'
Error: #<NoMethodError: undefined method `x' for nil:NilClass>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5616:in `draw'
Error: #<NoMethodError: undefined method `create_scissor_42_geometry_rhvert' for #<Class:0x000000313ea090>>
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_scissor_roof_truss.rbs:223:in `get_truss_geometry_scissor'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:217:in `main_menu'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5105:in `calculate_obj'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5124:in `update_state'
c:/users/earle/application data/sketchup/sketchup 2015/sketchup/plugins/medeek_truss_ext/medeek_roof_truss.rbs:5170:in `onUserText'

My cabin build thread: Alaskan remote 16x28 1.5 story

Medeek

Version 1.6.8 - 08.20.2016
- Added the Medeek Tools toolbar with Trim and Extend icons.
- Added the trim function for (solid) groups and components.

Only the trim function currently works with this latest release.  I'm also not completely satisfied with the trim function as it tends to break down when dealing with components that have tranformed instances.  I am still working on this one.  The main reason I've released it is for a few of my SketchUp mentors to have the ability to test the trim function and hopefully help me work the bugs out of it.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

I've created a SketchUp model tonight using the truss and foundation plugins to further examine a structural design I am working on.



View and download model here:

https://3dwarehouse.sketchup.com/model.html?id=cb424537-7ad2-4afb-a53b-1ab547feec26

I think I will probably add a TJI roof that allows one to use two glulam beams with cantilevered rafters as shown in this model, this configuration seems to be fairly popular.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer


Don_P

Wow you guys tie stuff well. Does wind or seismic control the window wall? Tell me about the outlooker to tji connection also how the flange reacts when the overhang is loaded. One other thing I noticed in a quick spin through the model is the window headers framed "normally" rather than continuing to the corner. Is there a reason for one over the other in this case? Noticed the blocking behind the posts to tie them to the 2nd floor well. I assume that is a beveled dimensional lumber cant strip nailed on top of the glulams. I have built similar facing south to catch a view, that turned out to be not the best idea. Million dollar view but too much light and heat and difficult to shade the upper windows.

Medeek

Again I apologize for the delay in development, first it was my new job and then I re-injured my rotator cuff (old injury from 10 years ago) which has made sitting at my desk for prolonged periods very difficult.

This morning I sat down and thought about hip sets since I've had some recent requests for the their addition to the plugin.  What I show below is a fairly standard step down hip set with, with the midwest variant shown at one corner and the standard variant at the other corner. 



View model here:

https://3dwarehouse.sketchup.com/model.html?id=aa9db54b-4a66-412e-86fd-94e3e676e0b5

Note, I have not shown all of the internal webs for clarity, those will be generated automatically and not be user definable. 

Please review carefully and let me know if anything looks amiss.  I will also be adding in other variants of the hip set but I figured I would start with these two.

A stepdown hip set provides a girder truss, with a hip jack truss running from the corners up the ridge until they meet the hip girder.

The Midwest hip set also provides a girder truss, with hip trusses that step up to the peak.
However in a Midwest hip set, you run a rafter (dropped) up from the corner of the front wall to the hip girder.
All the bottom chords of the end jacks run to the hip girder, allowing for better attachment of the drywall on the ceiling.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

This is the Northeast Hip Set variant:



View model here:

https://3dwarehouse.sketchup.com/model.html?id=7a091720-b221-4b49-b59b-f797f95211e6

In a northeast hip set, you will find a short jack truss starting at the corner and running up the hip ridge. This hip jack stops at a sub-girder. All end jack bottom chords run to the hip girder, allowing for better attachment of the drywall on the ceiling. Hip cats must be field cut and installed between the hip trusses. Works well with dual-pitched hip systems.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Medeek

This is the California Hip Set:



View model here:

https://3dwarehouse.sketchup.com/model.html?id=c17f8767-de27-44bd-b589-fbb186ea09fc

The problem I am having with this variant is the conflict between the 2x6 hip rafter and the top chords of the step down hip trusses.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

Don_P

I see the problem there but don't have enough truss hip experience to be of any help.
I'm sure you know, don't push into the shoulder pain. Its not a no pain no gain thing... rest and take care of it, you have a long path ahead  :).