Using Analysis Results to Identify and Address Over-Capacity Design Checks

Video Transcript:

  Welcome! In this video, we will go over truss analysis, how to run a detailed analysis, and modifying truss settings to change analysis results.

Let’s get started!

For this example, we are going to create a component using the pre-defined truss shape. Let’s click the Create button from the Actions toolbar or you can right click in the scene and select Component. We will select the Common Truss from the preset trusses. Let's accept the default settings, and click Next. Now, click the Insert button.

Once inserted, the truss can be analyzed. To analyze the truss click the “ANALYZE” button in the actions toolbar. The status of the truss analysis can be seen in the explorer subpanel in the left sidebar. If all checks pass, the label will show green, if the label is red, it indicates some checks are over-capacity. And if blue, the label notes the truss needs to be analyzed. All checks should pass for this truss, and should be showing green.

Let’s say your project calls for a bottom chord, live load of 30. To edit this setting we will click the Truss Settings button, and then select, Load Settings. We will change the Bottom Chord Live Load to 30. To confirm these changes, Press Enter. Then, we will click the “Change Settings for This Component” button.

Great. Before we analyze the truss, let’s take a look at the current lumber grade. Move your cursor, and Hover over the Bottom Chord. Information on the lumber will appear. Note, the current lumber grade is set to Southern Pine, and Number 1. Let’s now re-analyze the truss, by clicking Analyze, from the Actions toolbar. Now, if you hover over the bottom chords again, you will notice the grades have automatically upgraded to address the increase in load; however, we want to use Number 2 Grade for the bottom chords. While you are hovering over one of the bottom chords, Right click, and then select Edit Lumber. Here, we will change the grade. Select Number 2 from the Grade list. Press Escape, and then repeat the process for the other piece of lumber. Once again, hover over the other bottom chord and right click. Now, select Edit Lumber. And Select Number 2 from the Grade list.

Whenever a Manual change is made to chords, members, or plate pairs, the modified item is Locked. When a truss is analyzed, locked items will not change, therefore they will not be automatically upgraded. You can see the status by hovering over each to display the tooltip, which will show Locked or Unlocked. Items can be locked or unlocked by hovering over and then right-clicking, then selecting Lock or Unlocked. You can also use the Lock Options tool in the actions toolbar to lock and unlock all items at once. And from the same Lock Options you can hover over “Lock Lumber” to show items with the “Lock” status.

Now, with our bottom chords changed to Number 2, let’s click to Re-Analyze the truss. This time, we have over-capacity design checks. Let’s click the Analysis and History button from the Actions Toolbar. This will open the analysis panel to provide a list of what’s going on for the selected component.

At the top of the panel, we can see the history of changes and analysis. Further down we can see the information on, Load Cases, Plates {if part of your plan}, Members, and Joints. If we expand the Members dropdown we see the bottom chords are at 167 percent. For more information we will run a detailed analysis. To do so, click the Gear icon on the Analyze button. Here, select Detailed, then click the Analyze button again. This will run a detailed analysis. Detailed analysis, is disabled by default due to the potential increase in analysis time, especially for larger projects. Now, we can dig back into the Analysis and History panel to see specifically which checks are over-capacity. You'll also notice, references, listed here to where those checks come from within the TPI codes.

Moving along. We want to keep the grade at No. 2, so given this extra information let’s change the dimensions of the boards to 2x6. We can modify both bottom chords if we click to select one of the bottom chords then while pressing the Control button we can add the other bottom chord to the selection. Now we can right-click, select Edit Lumber, and from the Dimensions list select 2x6. Press escape or click off into the scene somewhere to clear the dialog box. We want to now reanalyze the truss. To see the truss has passed we can review the values in the left sidebar. Let’s close out the Analysis and History information by pressing the X. We can now see that all checks pass!

And that does it for an introduction to truss settings and analysis! Thanks for watching and see you in the next one!