Truss Calculators

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

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Medeek Engineering

Here is a simple schematic of a slightly more convoluted roof to try and understand the methodology a bit better:

The two girders in the center of the structure could probably be combined into one larger girder, but maybe it is better to distribute the loads across to trusses instead of one.  The shaded areas are the valley sets or overframing required to fill in the voids.

This design requires 10 main girders and 5 cross girders.  Notice how there is a hip truss at each outside corner and a half valley set at each inside corner.  When to inside corners are symmetric we end up with a full valley set.

Based on these patterns that are emerging I might be able to auto place the girders or at least provide an initial placement which then can be further refined by the user.

Nathaniel P. Wilkerson

Medeek Engineering

Each girder will break up the roof outline into zones.  Then using a combo of boolean subtraction and intersection we should be able to generate this as a starting point:




The blue shaded truss outlines are the girders, the purple shaded are the trusses requiring a further subtraction step to make the correction for the valley truss sets, notice the third purple truss  from the right. 

Basically I'm walking you through my algorithm for generating the truss geometry data so I can then draw each truss.  As you can see this is not a trivial process.  Lots of steps and lots of "edge cases" that can potentially trip it up.  That is what I mean when I say the devil is in the details.  However if the basic algorithm is sound one should be able to add in logic to deal with the issues and in the end you end up with a robust piece of code.  These are the kinds of things that keep me up at night.

Based on these slices we should be able to extract the key geometric points that define each truss and then send that data to the separate truss "draw" algorithm which sorts out all the messy details on how to place the webs, plates and all that fun stuff.
Nathaniel P. Wilkerson


Medeek Engineering

Version 3.8.1 - 05.13.2026

- Enabled a second layer of wall sheathing for common and scissor trusses.
- Enabled XPS (blue, green, pink and grey), ISO, EPS, GPS, and PU foam insulation within the wall sheathing and wall sheathing 2 options.
Nathaniel P. Wilkerson