Truss, Frame, and Beam Generation I

For anything but the most simple structures, it is convenient to use the Auto Truss, Auto Frame, or Auto Beam… commands under the Modeling menu.

Choosing the Auto Frame... command will bring up the following dialog box:

The parameters allow one to set the number and dimensions of bays and stories, and to select how the background grid should relate to the frame's dimensions. Note also the message indicating that the Auto Frame command will delete any existing structure (recoverable via Undo, though).

The following frame is an example of using the Auto Frame command:

It should be noted that all members will be identical, being based on the current default member properties. Using the select tool one can select members individually or in groups (e.g., drag a selection rectangle to get all the beams on a particular floor), and then change the properties as desired. Area selection can also be used to chop out portions of a structure, alter particular bay and story dimensions, and so on as indicated in the following structure:

In similar fashion, the Auto Truss... command brings up the following dialog:

This dialog provides a means for generating various styles and configurations of trusses. A typical result is as follows:

As in the case of frames, additional modifications can be made as desired.

The Auto Beam command makes it very simple to set up basic beam configurations, which can then be modified directly to create more general models. Choosing the Auto Beam command brings up the following simple dialog:

The result of selecting OK is a configuration as shown below:

Remember that it is very simple to change support conditions, add internal supports, relocate ends, etc., so the starting beam parameters should be chosen to reflect the overall length of the entire beam (i.e., all spans together for a multi-span beam). Also, rounding the starting length to ensure a convenient grid size is recommended (the beam dimensions can easily be adjusted subsequently)