Create Floor Trusses with a Top Chord Vertical Step

Video Transcript:

 Welcome. In this video we will discuss how to create a vertical step in the top chord of a feature pattern truss To accommodate a recessed shower pan.

Open up the creation panel and navigate to the predefined truss shapes.

Select the feature pattern truss. Here we will set the length to 21 feet.

Then move down to the end conditions. Here we will set the left conditions as single ribbon. And we will do the same for the right end condition.

Click next.

We will keep the default webbing settings, as we'll adjust the webbing after defining the dropped top chord section. Click insert.

For this example, the start of the shower pan drop will be seven feet from the left end of the truss. The drop dimension will be one and a Half inches. Let's begin by removing all of the webs, because we are going to add verticals at the start and end of the drop top chord section. Hold the control key, which opens the multi-select filter. Set the selection filter to members. Use your mouse to click and drag a selection box across all of the interior webs.

You can also open the right panel. Here you can review and verify the selected members. Accept the selection we want to delete by pressing the delete key.

Pan over to the left end of the truss. Here, we will add a vertical web member. It will be placed seven feet from the left end of the truss.

So, let's right click. Then select member. Click on the left most reference, while holding down the shift key, drag the mouse to the right. This will change the increments of movement to feet. Once you're at seven feet, click.

Now we will adjust the member's location. While the web is still selected we will adjust the geometry location within the member properties panel. Click to change it from centered on line, to now be left of line.

Now let's add the next web.

Right click, and select member. Click and then while holding shift drag your cursor to the right. Once you see 12 feet appear, click to place the member. With the W2 member selected. Change the location geometry from the properties panel from centered on line to be right of line.

For this example, we're going to stack these vertical webs, which will create three separate zones for the truss.

So select W1. Then right click. Here select the Stack Web option. Notice when we stack the web, the placement location was adjusted. Such that the center of the stacked set is at the predefined location. Which we set at seven feet. In this particular case, we want to change that back to seven feet. So select the dimension and change that from seven foot, one and a half to seven feet.

Press escape.

Next, we will stack W3.

So, select W3. Then we can right click. And from the options select stack web once again.

As we see the stacked set, will shift. So, click on the dimension to change the location back to 12 feet and press enter.

Next, we'll stack a segment of the top chord, this will serve as the inch and a half vertical drop. Select T2.

Then right click, and select stack chord from the options.

Here we will stack just a segment of that. So, in the Member Stack Insertion panel we will modify the start location. Set this to be at six feet. And we will set the end location to be set to 13 feet.

Click insert.

Next we'll need to trim back the top chord members to accommodate the vertical drop.

Select T3. Then, press the shift key and select the left side of W3.

Repeat this for T 1.

Select T1, then shift click the right side of W2 to trim back to.

There you have it.

Next we'll verify the drop dimensions using dimension mode.

Right click and select dimension mode. Move over and select the lower left end of the truss. Then click to select the top right corner of T1.

There we are at seven feet. Let's repeat those same steps for the right side.

The dimension mode is still active, so select the lower left end of the truss. Then go over to the top, left, corner of T 3 and click. We can see that's at 12 feet.

That gives us our five foot shower pan void, or drop.

Now we're going to define the webbing for all three zones. Because, we added the stacked vertical webs, the feature pattern truss will automatically be recognized with three separate zones, so we'll start by auto webbing the left zone.

Click to Edit truss. Then select Reweb truss. Here, we see Zone one is selected as the default Zone, because it is the left most zone.

We will keep the default settings for the webbing and for the chase. Next click to generate the new webs. You'll notice that only zone one was webbed.

Next, we'll, reweb zone two. So, we'll click edit Truss. Then from the menu select reweb. And from here select zone two from the pulldown. We'll leave the webbing settings as is. However, the chase settings will need to be adjusted to accommodate a shower drain, which will be on the left side of the shower, so we'll set that to fixed.

We will leave the width set to variable.

We will adjust the fixed location so to be set at eight feet, putting it at the left side of the shower.

We need to leave plenty of room for that plumbing drop. So, let's set the minimum width to one foot six. And Set the max width to be two feet.

Let's click to Generate new webs.

Next, we need to define the webbing for the right side, or zone three. Click to Edit truss, then select reweb truss from the options. Now we need to select Zone three from the zone pull down.

We will leave webbing settings as default. We could change this to no chase, but because it's unclear where the duct work will be running. We'll go ahead and leave the location set to floating.

Move down, and we will change the minimum width and Maximum Width to both be at 2 feet.

Let's click to generate.

There we have it. Now that we've defined our webbing, let's see how this truss performs. Click analyze, or control A.

Members denoted in red are over capacity. By hovering above the top chord member we can see this is 106% of capacity.

And then we can hover over the bottom chord members, and see we are at 122% capacity.

The first thing we'll do is address the bottom cord members that are over capacity. Because the bottom chord is already spliced into two members, we don't want to stack the individual members.

So here we will select B2. and then Press the delete key. Which will automatically extend the bottom chord all the way across.

Next, select B1. Then right click, and click to stack chord.

We're going to stack the entire bottom cord, so we can accept the settings and move down to click insert.

Next, we'll analyze and see how the truss performs.

We did receive a notification about a plating error. An error occurred while plating the joint at B2 and W8.

We can see there is a splice right there at this joint. We need to move this splice to better distribute the loading.

To do so, select the splice. Next click the gear icon to define the increments to move the splice each time you press an arrow.

Make sure to change that to one foot. Then click Close.

Here we will click on the right arrow. This will move the splice one foot to the right.

Press escape to exit, and deselect the splice.

Let's analyze this once again. You can also press Ctrl A as the keyboard shortcut for analyze, which is a great shortcut to use!

Let's reset the view. Here we see that all checks pass. And we have no notifications.

This Truss is ready for review.

That wraps up this instructional demo for how to define a top cord vertical step, and leverage rewebbing by zone to accommodate specific plumbing requirements. We hope this gives you a better understanding of the many tools available when designing feature pattern trusses.

See you in the next one.