Design with Additional Loads

Video Transcript:

Welcome! In this video, we’ll walk through adding manual load cases to our truss. For this project, we are going to simulate the added load of an HVAC unit on a roof. This video is not intended to be prescriptive for a specific situation, but rather it demonstrates how to use some of the loading tools available within Paragon Design. First, let’s duplicate the truss so we can keep our existing work separate. In the actions toolbar let’s click on the duplicate truss icon. Let’s rename the truss in the Component Properties panel to be Dual Pitch with HVACML.

Before we begin let’s make the original truss active in the components panel along the left sidebar. Click on the Dual Pitch with HVAC to make it the active truss.

As you see, we’ve designed this dual-pitch truss and we need to add a manual load to the flat area on the left side.

• We know that our HVAC unit weighs 2000 pounds

• The size is 8 feet by 5 feet

• Will be on a stand with legs spaced 3 feet apart, so we need to add two point loads to account for this.

Navigate to the Additional Loads in the Collection Subpanel and click the menu button. Click Create Manual Load to open the Manual Load Insertion subpanel. Click the Load Insertion Method and use the Select Member option. Make sure the load distribution is set to Concentrated. Use the member select to specify T1 as the target member. This will be a dead load with the direction set to down. We know the first leg is 1 and a half feet from the left along the x axis. We will set the load magnitude to 500 pounds and give the manual load a name Leg 1 for easy identification and click ADD LOAD. The next leg is at 4 and a half feet. Update the Point X and name it Leg 2. Then click ADD LOAD. Now that we’ve added both point loads, click insert. Given the dimensions of this HVAC, we could divide the weight over multiple trusses, but for this example we are going the conservative route.

Great, we’ve added two manual point loads for the HVAC unit. By default, “Show Manual Loads When No Other Loads Visible” should be checked. If you do not see your manual loads, open the View Options Menu to verify this is checked.

Now let’s analyze this truss. Great! This truss will work in this scenario.

Let’s consider another example. Here we don’t know exactly where the HVAC unit will be placed, so we need to place a moving load along the entire top chord.

Next, select the truss we duplicated earlier with the name Dual Pitch with HVACML.

Now navigate to the Additional Loads menu, then to Create Moving Loads.

Here we will select Distributed for Load Distribution.

Set the Load Magnitude to 175 psf.

Make sure “Use Panel and Mid-Panel” points is checked.

Set the Distributed Load Length to 3 feet.

Make sure the Load Type is set to Dead.

And for Along Member Type  make sure Top Chord is selected.

We will name this moving load HVAC ML.

Next click insert.

Now analyze this truss.

If we navigate to the load cases and then expand the list. We can see the truss has the moving load applied along the top chords.

It looks like this truss will be adequate as long as the top chords are upgraded to 2x6 Number 1 Southern Pine. By hovering over the top chords the member’s information will display.

We hope this provided a better understanding of some of the tools available for designing trusses with unique loads.