Author Topic: Truss Calculators  (Read 188407 times)

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Offline Medeek

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Re: Truss Calculators
« Reply #675 on: September 17, 2017, 09:09:57 AM »
Correct, what is not shown is all of the required bracing to actually make this roof work.  There would need to be some vertical members attaching to bearing walls below.
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #676 on: September 17, 2017, 09:11:48 AM »
If you really want a headache try and truss out this same roof outline:

https://3dwarehouse.sketchup.com/model/1e909f8f-b9ca-4b16-a51b-4b9a8f785a1f/Complex-Roof-3-Truss

After about 45 minutes I've given up, not because it can't be done but because the amount of custom truss profiles and manual editing required far exceeds my patience and determination.
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Offline Medeek

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Re: Truss Calculators
« Reply #677 on: September 17, 2017, 04:18:21 PM »
Needing a break from the rigors of the straight skeleton code I realized that I have still not implemented the octagon hip roof yet.  On a related note the circular roof could also use my attention:



View model here:

https://3dwarehouse.sketchup.com/model/1cf9c6bc-46fd-47c6-8aa3-49a8536dc2be/Circular-Roof

The number of rafters can be given by this equation N = 8 + 8n where n = 0,1,2,4 etc...

In this model n = 3
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #678 on: September 17, 2017, 07:51:46 PM »
Nathaniel P. Wilkerson, P.E.
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Offline Don_P

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Re: Truss Calculators
« Reply #679 on: September 18, 2017, 08:04:28 PM »
Now that roof, if you ran a steel strap around the rafter tails under the fascia, you wouldn't need any interior framing?

Offline Medeek

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Re: Truss Calculators
« Reply #680 on: September 19, 2017, 08:22:44 PM »
You would need to anchor the ends well so you can form the tension ring, interesting idea.  Then you could leave the interior vaulted.
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #681 on: September 19, 2017, 08:26:00 PM »
Now I'm trying to figure out how to calculate the tension in the strap given a uniform (snow load) on the turret roof.  The steeper the pitch the less the tension in the strap.  This reminds me of some of my calculus problems from my college days, but it is probably much simpler than that.

A larger overhang would counter the flattening effect of the load on the roof and reduce the tension in the strap.

If you take the tributary load at the center of the roof as half the distance from the center to the outside wall the point load at the center would be given as P = (S + D) * pi * (d/4)^2.

The horizontal force exerted by each rafter would then be: Fh =  P/tan(Theta) * (1/n) where "n" equals the number of rafters.

The tension in the strap from basic statics would be T = (Fh/2) / cos(omega) where omega = 90 * (1 - 1/n)

I'm assuming an overhang of zero or at least conservatively ignoring the countering affect of the overhang.
« Last Edit: September 19, 2017, 09:20:29 PM by Medeek »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #682 on: September 24, 2017, 12:57:39 PM »
Working on adding in the inset floor joists per the  details given by dpaul:

Parameters are the following:

1.)  Stemwall Thickness (inset amount)
2.)  Ledger Option:  Yes or No
3.) Ledger Height
4.) Ledger Width
5.) Hanger Option: Yes or No

I'm still waffling on what to do if the hanger option is "yes".  I was considering having the option of selecting one of the many Simpson-Strongtie hangers from a long list of hangers.  However, no models exist for the bulk of these hangers and I don't have the time or data to try and model a bunch of them.  Item 5 may not be feasible.

I also have a question on the ledger board option:



As you can see in the image the 2x12 PT dimensional lumber ledger is smaller in height (11.25") than the 11-7/8" TJI.  In this case would the ledger be run flush to the bottom of the TJI or is this not a concern?  I was thinking that one would probably call out an LVL or LSL ledger with felt backing between the ledger and the concrete so that the ledger matches the height of the I-joist.  Additional information when the floor joists are I-joists or EWP would be helpful here.

View model here:

https://3dwarehouse.sketchup.com/model/754bd742-3505-45d4-9941-5f445b49542a/Inset-Floor-Joist-Study
Nathaniel P. Wilkerson, P.E.
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Offline FoxKeegan

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Re: Truss Calculators
« Reply #683 on: September 29, 2017, 04:34:59 AM »
Came across this post as I'm a layman attempting to learn, in a sense, exactly what this program helps to calculate and frankly I'm just amazed.

Not only that calculating a basic truss requires 26 pages of paperwork, but that you've kept with this and documented exactly how much work it really is.
All I was trying to do was figure out the TCDL of my modified queen to see if I could hang XPS & GWD.

Rather than Kickstarter, have you considered doing a Patreon? You're clearly sticking with this project and it has an amazing +150k views.

Offline Medeek

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Re: Truss Calculators
« Reply #684 on: September 30, 2017, 09:39:12 PM »
Everyone must find their raison d'etre, after dabbling in various businesses and careers until about the age of 40, I think I finely found mine.  The truss calculator is still very limited in what it can do, for now it primarily remains as a academic exercise.  If I can ever find the time and money I will be able to do more with it and various other programs and software I am developing.  I appreciate your interest and your suggestions, I may have to look into Patreon further.
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #685 on: September 30, 2017, 09:40:19 PM »
Version 2.0.0 - 09.30.2017
- Added a hip & ridge option for dutch gable rafter roofs.



View model here:

https://3dwarehouse.sketchup.com/model/ee54ad84-9428-4e9b-ba7f-ab6e5726660f/Dutch-Gable-Rafter-Roof

Not exactly how I should terminate the hip cap where it meets the gable section of the roof.  What I have now seems reasonable enough for presentation and estimating purposes.

Quite a bit of convoluted code to get those sections of hip cap just right, where there is a will there is a way.
« Last Edit: October 01, 2017, 05:00:16 PM by Medeek »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #686 on: September 30, 2017, 11:12:32 PM »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #687 on: October 01, 2017, 04:39:22 PM »
Version 2.0.0b - 10.01.2017
- Enabled roof cladding for shed and shed w/ ledger rafter roofs.



View model here:

https://3dwarehouse.sketchup.com/model/074ab446-7fa3-439f-aba7-694d3823335f/Shed-Roof-Variants
« Last Edit: October 01, 2017, 06:28:17 PM by Medeek »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #688 on: October 04, 2017, 10:15:37 PM »
Version 2.0.1 - 10.04.2017
- Added (FULL) roof return option within the advanced options menu for common, scissor and vaulted trusses.

Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #689 on: October 06, 2017, 09:59:17 PM »
Version 2.0.1b - 10.06.2017
- Added ceiling joist option for Hip Rafter Roofs.

Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #690 on: October 07, 2017, 12:32:56 PM »
Inset floor joists for sawn lumber and I-joists is now running, (with and without ledger).  I will need to test it further and then roll a new revision:



Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #691 on: October 07, 2017, 04:35:06 PM »
Version 2.0.2 - 10.07.2017
- Added the option to inset floor joists with ledger.
- Added the option to inset floor joists without ledger.

I just realized that today is the two year anniversary of the Truss Plugin, crazy to think that I've already been working on this thing for two years.  Progress has been incremental but fairly steady.  There are still some big obstacles and goals ahead.

The new inset option also works well if you are using joist pockets in the foundation:



This model was created with the Truss Plugin and the Foundation Plugin.  Foundation wall is 8" thick with the pockets set at 2.25" deep and the bearing length of the joists set at 2".  The floor sheathing layer is turned off for clarity.

View model here:

https://3dwarehouse.sketchup.com/model/cfa8f834-6a60-4175-b393-cfa39223c244/TJI-Floor-and-Foundation
« Last Edit: October 07, 2017, 05:00:31 PM by Medeek »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #692 on: October 07, 2017, 09:14:30 PM »
Version 2.0.2b - 10.07.2017
- I-Joists are branded with respective manufacturer's logo.

Nathaniel P. Wilkerson, P.E.
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Offline MountainDon

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Re: Truss Calculators
« Reply #693 on: October 07, 2017, 10:04:24 PM »
 [cool]  You have done amazing things with this Nathaniel.
Just because something has been done and has not failed, doesn’t mean it is good design.

If you didn't have the time or money to do it right in the first place, when will you get the time and money to fix it?

Offline Medeek

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Re: Truss Calculators
« Reply #694 on: October 09, 2017, 10:13:23 PM »
With the inset joists I thought it would be really cool to have the plugin be able to auto-select the correct joist hanger and insert it at both ends of the I-joist or sawn lumber.  I quickly modeled up a simplified version of an IUS1.81/11.88 Simpson Face-Mount I-Joist hanger and with the addition of one simple function I was able to do this:



View model here:

https://3dwarehouse.sketchup.com/model/96cd27dc-3e84-43d6-98cf-b22575c0526d/TJI-Floor-and-Foundation-with-Hangers

I haven't yet released this most recent addition because I only have two sizes of hangers created so far.  There are five typical flange widths and the following typical I-joists depths:  9.5, 11.875, 14, and 16.  So if you do the math I need to model 20 different face mount I-Joist hangers and 20 top flange I-joist hangers (IUS and ITS series).  For sawn lumber a similar situation exists for 2x6, 2x8, 2x10 and 2x12 joists.

I was considering using the official Simpson models from the 3D Warehouse but they are too complex, a minimalistic hanger gets the point across just as well.

When I get home from work I usually only have a couple hours to hammer away at things so some more low hanging fruit gets picked.
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #695 on: October 10, 2017, 05:09:15 PM »
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #696 on: October 11, 2017, 09:27:40 PM »
Top flange hangers without a ledger:



This is a Simpson ITS1.81/9.5, this is the equivalent to the the IUS series but in  top flange configuration.
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Offline Medeek

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Re: Truss Calculators
« Reply #697 on: October 13, 2017, 06:41:25 PM »
The ITS hanger family:

https://3dwarehouse.sketchup.com/model/5bafc450-3dda-4443-a526-f10019c16ddf/Simpson-Strong-Tie-ITS-Face-Mount-Hangers

The following hangers are included:

ITS1.81/9.5
ITS1.81/11.88
ITS1.81/14
ITS1.81/16

ITS2.06/9.5
ITS2.06/11.88
ITS2.06/14
ITS2.06/16

ITS2.37/9.5
ITS2.37/11.88
ITS2.37/14
ITS2.37/16

ITS2.56/9.5
ITS2.56/11.88
ITS2.56/14
ITS2.56/16

ITS3.56/9.5
ITS3.56/11.88
ITS3.56/14
ITS3.56/16
Nathaniel P. Wilkerson, P.E.
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Offline Medeek

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Re: Truss Calculators
« Reply #698 on: October 13, 2017, 08:23:50 PM »
Version 2.0.3 - 10.13.2017
- Added the option to provide a face mount hanger for inset floor joists with ledgers.
- Added the option to provide a top flange hanger for inset floor joists without ledgers.
- Added an option in the global settings to enable or disable manufacturer's logos.
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Offline Medeek

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Re: Truss Calculators
« Reply #699 on: October 14, 2017, 10:53:36 AM »
Version 2.0.3b - 10.14.2017

- Face mount hangers added for solid sawn floor joists.





LUS24
LUS26
LUS28
LUS210 (this hanger used by both 2x10 and 2x12 joists)
« Last Edit: October 14, 2017, 11:17:02 AM by Medeek »
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer