## Truss Calculators

Started by Medeek, March 12, 2013, 06:33:08 AM

0 Members and 2 Guests are viewing this topic.

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

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

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

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

#### Don_P

Now that roof, if you ran a steel strap around the rafter tails under the fascia, you wouldn't need any interior framing?

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

#681
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.
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

#### Medeek

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.
Designer, Programmer and Engineer

#### FoxKeegan

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.

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

#685
Version 2.0.0 - 09.30.2017
- Added a hip & ridge option for dutch gable rafter roofs.

View model here:

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

#### Medeek

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

#### Medeek

#687
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
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

Version 2.0.1b - 10.06.2017
- Added ceiling joist option for Hip Rafter Roofs.

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

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

#691
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
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer

#### Medeek

Version 2.0.2b - 10.07.2017
- I-Joists are branded with respective manufacturer's logo.

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

#### MountainDon

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.

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

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

#### Medeek

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

#### Medeek

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.
Designer, Programmer and Engineer

#### Medeek

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

#### Medeek

#699
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)
Nathaniel P. Wilkerson, P.E.
Designer, Programmer and Engineer