3D Truss Models

medeek

A 9:12 barrel vault truss with a 16' wide barrel:

PDF:

http://design.medeek.com/resources/truss/BARREL_VAULT/BARRELVAULT_STUDY1_REVA3.pdf

The design of this type of truss is controlled by the following parameters:

1.) Out-to-out span
2.) Top chord pitch
3.) Barrel vault width
4.) Barrel vault radius

Assuming a typical web configuration as shown above the truss design is really only dependent on these four inputs. Minor details with regards to member depths, overhangs and ply thickness also factor in as well but don't really change much.

I can also see the possibility of running a raised heel variant but I don't know how common that would be.

medeek

Same truss as above but in SketchUp:

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

medeek

Version 1.4.5 - 03.24.2016

Structural outlookers (vert. & horz.) enabled under advanced roof options for Scissor (4/4) truss type.

I guess I somehow missed enabling structural outlookers for scissor trusses. Anyhow this issue was brought to my attention this evening so I've tried to rectify it as much as possible. After delving into the code I realized that the scissor truss module needs a major rewrite and cleanup so I was only able to get structural outlookers enabled for the 4/4 configuration. Later next week I will jump back into this module and work on the 2/2 and 6/6 configuration.

medeek

I had someone ask me if it would be possible to create a small house or cabin based entirely on a raised heel attic truss profile, probably with some skylights for light. I've never seen this type of design before but I don't see why it might not work. Has anyone ever seen something like this done? Basically an attic truss with a raised heel (48') resting directly on a stem wall foundation with post and beams or something similar.

The one issue I could see is if there were no windows for a bedroom (no egress) that was midway the length of the structure. The design shown is 36' wide, 42' long with a 21' wide attic room. 6"x24" stemwall foundation, with a 12"x6" footing.

Typically large attic trusses are quite expensive so it would seem that this would be an expensive way to build a house perhaps there is some other reason that makes this method of construction viable?

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

medeek

Another look at the cambered truss:

pbacot

Nice trusses with the arc shapes.

medeek

Version 1.4.6 - 03.26.2016

Added Cambered truss type, configurations: (6/X).
Metric input enabled for cambered truss type.
Added gable end trusses for cambered truss type.

Six variants of the (6/X) configuration dependent on the ratio of the camber width to span. Notice that in all cases the top chord has six panels, the bottom chord varies from 4, 5 and 6 panels.

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

medeek

Second look at cathedral trusses (6/X) family:

The logic required to triangulate these type of trusses becomes tedious.

medeek

I've been meaning to add in cathedral trusses for quite some time and I finally had the chance last night. Configuration (3) shown below for a catheral 6/X truss:

Now I only need to code in the other six configurations and its ready to release as a new update.

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

medeek

A breakdown of the configurations for the Cathedral 4/X family:

medeek

Version 1.4.7 - 03.28.2016

Added Cathedral truss type, configurations: (4/X, 6/X).
Metric input enabled for cathedral truss type.
Added gable end trusses for cathedral truss type.

Note, that not all configurations have webs enabled however the top chords, bottom chords, gable end trusses and all advanced options are enabled.

juju

Thanks for the continued development Nathaniel.

In case anyone missed it, the plugin price went up from $20 to $30.

Sorry for you if you've been holding out to get it...

medeek

Just as a word of warning this plugin is far from a polished or finished product. There are still a lot of loose ends that need tying up. Case in point I have not yet enabled gable end trusses for the attic truss type. The reason is the complication of dropping the top chord for structural outlookers where the attic truss has a spliced top chord. Below is an example of a attic truss with a dropped top chord that I have encountered in the past but I don't know if this is the best method of handling this situation.

I would like to enable structural outlookers for attic trusses in the next few days just to wrap this up. Any thoughts or suggestions or examples of similar configurations are very much appreciated.

Postscript: It may not be totally clear but the gable end truss is the one with all of the vertical members (nearest the viewer) in this isometric view. Note that the outlookers are oriented vertically in this particular case, partly due to an approx. 4' backspan over a stairwell. If the same top chord depth is maintained over the diagonal portion of the attic then the dropped top chord will be lower than the other common trusses in this segment of the attic. This will complicate the framing of the end wall slightly but should not prove to be an insurmountable problem.

medeek

To further clarify the framing details with regards to attic trusses and structural outlookers I've created a sample model with a proposed dropped top chord gable end attic truss:

Please download and review the model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

I've also included the infill wall framing to help put everything into reference (light green).

Is this the appropriate way to frame an attic truss (gable end) with structural outlookers?

medeek

The reason I provide the full attic opening at the gable end truss is so that the framed in wall can be the nominal ext. wall thickness of 5.5 inches and allow for R-21 insulation. I've had some truss plants provide the typical vert. webs for nailing off the sheathing over this space but then one has to fir it all out anyways to get the appropriate wall thickness for the insulation.

If the wall below the gable end truss is sufficient for bearing then the gable end truss really does not need to have any structural capability so all of the diagonal webs can go away. One could also get away with a 2x4 dropped top chord with the stacked top chord at the eaves as shown. It would make sense to have the same depth at the bottom chord though so that the floor sheathing has a convenient nailing surface right to the edge of the building.

Alternatively one could do away with the gable end truss entirely and just balloon frame the wall from the ground floor up or from the attic floor up.

The question is which method should be employed within the plugin. I would prefer to use the most commonly employed solution.

medeek

The gable end truss as shown is structural, just to clarify. I will probably go with what I have shown as modeled unless there are any objections.

medeek

Six possible end details for a flat truss (Pratt 4 panels), there are probably others but these seem to be the most common:

1.) Mansard w/ Parapet
2.) Parapet
3.) Mansard
4.) Overhang
5.) Cantilever
6.) None

Both Mansard configurations can also have an optional overhang as shown. The Parapet configuration should allow for customizing the thickness of the parapet wall.

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

This truss type with its many end configurations would work well with an HTML UI, that is the direction I will be going with future user inputs and interfaces since the ability to customize is unlimited.

With the flat trusses I will initially offer both Howe and Pratt with the ability to utilize a low slope or zero slope.

medeek

Version 1.4.8 - 04.01.2016

Added Mod Fan common truss type.
Structural outlookers (vert. & horz.) enabled under advanced roof options for Common (Mod Fan) truss type.

View model here:

3D Warehouse

3D Warehouse is a website of searchable, pre-made 3D models that works seamlessly with SketchUp.

(3dwarehouse.sketchup.com)

With the addition of the Mod Fan (Triple Fan) the line up of common trusses is complete. I still need to add in raised heels and structural outlookers for some of the configurations.

Theoretically I could add in additional configurations of the Fink and Howe truss types for extremely large roofs but the largest I've ever seen is a raised heel Quad Fink (10/9). Large spans beyond 70'-80' are probably not practical as far as a single span common truss roof. At that point you pretty much go with large flat roofs with interior columns and girders and all steel construction (think Walmart or Cosco).