Week #17 – Complex Modeling
17-6. TrussMaker

ArchiCAD Training (Best Practices Lesson 17-6)

In this 67 minute ArchiCAD training session we explore TrussMaker, a convenient tool for creating custom truss structures, along with some other methods for placing similar elements.

TrussMaker is a command found in the Design menu > Design Extras submenu. It expects you to have drawn and pre-selected lines and/or polylines on the floor plan OR in section or elevation. It will then create a new object based on those lines, with various settings and options available to specify the type of members (e.g. timber, hollow steel or rolled steel profiles) and cross-sectional dimensions.

These lines define the axis lines for the members, although there are some settings that allow you to specify different relationships of the body of the profile to the axis line. If you use more than one line pen, then you will have options for creating different settings for lines with each pen number.

The resulting object is added to the Embedded Library (ArchiCAD 13 or later) or saved as a new library part on your hard drive (ArchiCAD 12 and earlier). If you create a new TrussMaker object on the floor plan, the Object tool will then be “loaded” with that new object, so you may immediately place it into your model. If you create the TrussMaker object in section or elevation, an instance of the new object is immediately placed into the model, with its center line on the line defined by the section or elevation. You may need to use the View menu > Rebuild > Rebuild from Model (or right-click and select this command) in order to see the new truss element in the section or elevation window.

This object may be placed multiple times, of course, and each instance is tied to the original object definition. It is possible to select a TrussMaker object and use the Design menu > Design Extras > TrussMaker > Edit TrussMaker Object command to revise or update this definition. When you use this command, it will place a copy of the original axis lines wherever you click, which will allow you to rework them and then save them as a new TrussMaker object, or overwrite the original one.

LIMITATIONS AND ALTERNATIVES

Some of the serious limitations of TrussMaker are as follows:

  • The lines define the axes, rather than the outer extent of the truss, which can make it awkward to place precisely
  • While different pen numbers will allow you to define different cross-sections, all members are the same material or surface appearance
  • Short line segments can cause geometry issues as demonstrated in the lesson

As an alternative to using TrussMaker, one may draw a truss structure “lying on the ground” using the wall, beam or slab tools, then select and view in 3D from a 90 degree side angle and save as an object that is standing up. This allows more flexible geometry options to be defined.

In addition, there are many parametric truss objects in the standard ArchiCAD library. These will quickly model regular truss structures, meaning that one might want to use TrussMaker only for “custom” designs, and ONLY for ones that it can “handle” (since there are serious limitations). Thus it is a convenient tool but only for a very limited set of design contexts.

Thank you for visiting the Best Practices Course website. The video lessons are available for members only. If you are an active member and would like to watch the ArchiCAD training video on this page, please login to the website. If you are not currently a member, please visit the following pages for more information and to sign up for the Best Practices Course, the QuickStart Course or for the Best Practices ArchiCAD Coaching Program. Eric Bobrow, Creator of the Best Practices Course

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Eric

ArchiCAD Training: TrussMaker

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