Open Building Design

Chris Flory in Locust has found another bug with Aegis Design. Apparently, the program will not design a structural fascia member for an Open enclosure. Specifically, the program crashes when the wind loading is set to:

• Procedure: ASCE 7-05
• Wind Design Method: C & C
• Enclosure Classification: Open Buildings

Aegis is now aware of the problem (thanks to Chris), and has added it to their list of corrections.

Manufacturer Basics

One problem that seems to pop up every so often involves Manufacturer Basics.

The idea behind Manufacturer Basics is straightforward--these are your default settings that form the starting point for all new projects. You can specify things like steel end cuts, normal loading, etc. New projects should, in theory, use these settings as the "parent" of the Job Basics.

Unfortunately, this "Parent - Child" relationship is only used if you create new truss projects within the Design program (File, New Job). If you simply open an existing folder in Design (since a Job is equivalent to a folder), Design will create a new Job Basics file (job.var) if one does not exist. Most of the time, jobs/folders are already existing when the design process is ready to be started.

So this nice step of creating Job Basics based on Manufacturer Basics rarely occurs. Instead, Design uses a recent job.var file to create the new one--which can carry over loading and other settings from one project to the next. There's no telling who's the "Parent" of your "Child". I'm pretty sure there's some bad jokes there, just waiting to be made.

Worse yet, sometimes things like fastener settings can become corrupted or incorrect. Once that happens in one project, it can spread to all subsequent projects. Problems like that can be tedious to fix.

The best solution? Always check your Job Basics before designing (or importing) the first truss.

Inventory in Design (Update)

Turns out that our idea about using the "Inventory Length" settings in Aegis Design will not work.

Here's the problem: selecting only the stocked and available chord lengths caused errors with the Material Summary from the Summary program. The Material Summary normally produces a list of the steel needed for the selected trusses, broken down into one-foot increments. For example, the list will look sort of like this:



However, when we only had 32' checked in the "Inventory Lengths" in Design, Summary would list all these pieces as 32' long. Which then created a significantly higher Total Lineal Feet value. Which caused all sorts of confusion. This also happened for 35, 55, and 725 chords, both USC and USD.

Phil Neely at Aegis says this was not a known issue. We will be trying to re-create this error on both ends, so that Aegis can work on fixing the problem in future releases.

So for now, we are abandoning this experiment. Thanks to Pedro Hernandez for discovering and pointing out the problem.

Update: according to Phil Neely, this is not a bug. It's a feature. The "Inventory Length" code was written to round all lengths up to the nearest available length. This shows up in costing in Design, and well as on the Material Summary.

Given that information from Aegis, I'm not sure what purpose the "Inventory Length" tool has. I don't see any advantage to using it.

Manual Web Patterns

One useful tool for creating exactly the truss design you need is the Manual Web feature in Profile.

If you look at the picture to the left, you will see a check box for "Auto Web" at the bottom of the Profile dialog box.

Un-checking this box will cause the program to pause after you click "Build". The program will prompt you to create a web pattern by clicking from joint-to-joint.

This can be very useful for controlling whether webs are in tension or compression, and also to override the normal web patterns produced by the program algorithms.

Unfortunately, there is a bug in Aegis Design 8.05 that will cause the program to crash when "Auto-Web" is turned off for a truss with a cantilever. Aegis is aware of the problem, and it will be corrected in the next release. No word on when that will be.