Working with structural floors Part 1

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After completing this lesson, you'll be able to understand structural floors, create a one-way and two-way span in floor,

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create a sloping floor, attach walls to a floor, and add a slab edge.

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The objective domains covered are, 1.1b, work with structural floors, and 1.1c, work with structural walls, attaching a wall to the floor.

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A structural floor has load-bearing capability and is usually positioned horizontally within buildings.

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Revit has two implementations of a floor.

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An architectural floor can be converted to a structural floor.

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This type of floor will normally contain the finishes and the compound layers.

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A structural floor can be converted to an architectural floor.

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This type of floor will be used for load-bearing applications and structural analysis.

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A slab that is supported on its two longer sides is said to be a one-way spanning slab.

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The one-way spanning slab is designed only to resist bending moments in the short axes, and hence, the main reinforcement is placed within these axes.

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A one-way spanning slab will typically be composite and have corrugated structural steel deck applied.

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The two-way spanning slabs will bend in both directions and will need moment resisting reinforcement in both axes.

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A slab edge can be applied to a floor or foundation slab.

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It is typically applied to the edges of a floor and can create an edge for a raft foundation or upstands or downstands.

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It should be noted that a slab edge does not contain an analytical model, so careful consideration needs to be applied.

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An alternative to a slab edge is to utilize structural framing or a structural wall.

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Go ahead and open up the file 008-Work with structural floors part 1.

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You'll notice that this model opens up in the 00-Ground Floor plan.

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Now first task is to draw a two-way spanning slab in this area of the structure.

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To begin, let's select the Structure ribbon and then the Floor.

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You'll currently notice we're in the Boundary Line mode.

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We have three modes when working with floors.

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Boundary Line, which is where we draw our plan shape of our slab.

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Slope Arrow, which is where we can define a slope or a fall in one direction.

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Or Span Direction, which is how we can define a one-way or a two-way spanning slab.

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Let's go back to the Boundary Line mode and make sure we've selected Line.

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In the Properties palette, let's ensure that we've selected the RC Slab 12".

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As I start to draw my boundary, I require an 18" offset from the grid line.

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You'll notice on the options bar, we have the facility of adding in an offset.

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I can then begin to draw my slab.

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It's important that I draw in a clockwise direction, this would ensure that the offset comes out on the correct side.

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I can now switch to Start-End-Radius Arc.

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And then return back to Line.

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Clear my offset and set that to 0.

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And then finalize the shape of the slab.

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In this example, the span direction doesn't matter, but you can see here that we have span direction symbol.

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If I wanted to, I could pick on Span Direction and I could select another edge.

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In the Properties palette, you'll note here that we have a Height Offset from Level.

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So what this is going to do is place the slab at the level ground floor with an additional 6-inch offset.

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We want this to be on the level so we'll set that to 0.

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We can then go ahead and select the Finish Edit mode.

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Your slab is now created.

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Let's look in the 3D view and check our model.

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Next, we model our one-way spanning composite deck.

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To do this, let's open up the 01-First Floor plan.

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You will note here that we have some steel beams that are going to support our deck.

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And we'll begin by clicking the Structure ribbon and then selecting Floor.

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Let's ensure that in the type selector, we have selected our RC Composite Slab 8".

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Now before we go ahead and use this, let's take a moment to look at the buildup of this composite slab.

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Go ahead and select Edit Type, and then select Edit.

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You'll note here that we have our preview showing.

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If the preview's not showing, you can use this button in the bottom left at the dialog box just to show the preview of our assembly.

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And you'll note here that we have two layers.

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We have our main structural layer over here, which is our normal white concrete, 8 inches thick.

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And we then also have a structural deck underneath that.

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The structural deck is simply a profile family.

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Here are the different profiles loaded into this particular project, but of course, we could download a new profile or simply draw our own profile.

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It has to be noted that the structural deck will not be modeled in 3D.

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This is simply a two-dimensional detail that we'll see in section or elevation.

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Let's go ahead and click "OK" to the Edit Assembly dialog box, and "OK" again to the Type Properties dialog.

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We're now ready to create our boundary for our slab.

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Now the boundary we create is going to be a rectangular boundary representing the steel deck.

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So on the Draw tools, let's select Rectangle.

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We'll trace off the grid lines.

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And now we want to create the cantilever.

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So let's go ahead and select those boundary lines that we've just created.

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Along the options bar, you'll notice here that we have concrete cantilevers.

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So here, I want to achieve a 6" cantilever.

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So I'm going to put in -6".

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And you'll now notice that we have a black boundary line going around the outside of the structure.

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So this is going to be my plain concrete, the cantilever is beyond the deck.

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In the Properties palette, again, ensure that your Height Offset from Level is set to 0.

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We can now go ahead and complete the deck. Let's click the Finish Edit mode.

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To help us understand what we've modeled, we'll create a section through our floor.

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On the quick access toolbar, click the Section tool and create a section through your floor slab.

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We can then go ahead and look at that section.

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I'll set my scale to something appropriate and the detail level to Fine, and we can now see our floor.

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We'll note the steel deck is showing in two dimensions and we have our concrete cantilever over the edge of the steel deck.

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Next, we create a sloping floor slab.

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In the Project Browser, open up the plan 05-Fifth Floor.

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Here, we're going to create a slab on top of the core with a 6 degree floor.

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To do this, on the Structure ribbon, select Floor.

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Let's ensure here that we're using our 6" concrete slab.

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On the context ribbon, note we're in the Boundary Line mode, and here we are going to utilize Pick Walls.

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On the options bar, note that we have a 1 foot offset.

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I can then simply go around and pick the boundary of my walls, and then I can go to Slope Arrow.

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Now here, I would like to pick the line that's going to determine my slope, so that's going to be this line here.

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The Height Offset at Tail is going to be set to 0.

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I want to actually specify a slope.

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So here, I can put in 6 degrees.

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And now we can go ahead and Finish Edit Mode.

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Now Revit does ask me if I want to attach the walls to the underside of its floor, normally I'd click "Yes",

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but I want to show you how to do this using some other tools.

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So let's select "No", and then open up the 3D view.

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You'll now notice our walls and our slab.

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So we're then going to select all of our structural walls and attach them to the floor.

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To do this, let's select the walls with a crossing window.

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Upon the context ribbon, you'll note we have modify walls, here, we're going to attach top/base.

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On the options bar, I could determine whether I'm attaching the top of the wall or the base of the wall.

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In this case, it's top of the wall and we can then simply select our floor.

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The walls are now attached.

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If the slab changes angle, then the walls will adapt.

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So I'm going to select the slab, and note here we have our 6-degree pitch, let's change that to 12.

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And of course, we can see all of those walls adapt.

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Finally, we created a slab edge.

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In the 3D view, you'll note here that we have our original ground floor slab that we created.

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On the Structure ribbon, select the Floor dropdown and select Floor: Slab Edge.

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In the Properties palette, select Edit Type, and you'll note here that we're using this particular profile.

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We're going to change this to Slab Edge-Thickened: 36"x12".

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And here, we have our material.

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We'll then rename our slab edge, and I'll just amend the 24" to 36" and select "OK" and "OK" again.

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We can then simply select the edges where we want to apply our slab edge.

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You'll notice that we have an in-built flip tool, where we can actually flip the profile of the slab edge if it was in the incorrect position.

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Let's switch to our Ground Floor plan.

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To help us understand what we've modeled, we'll create a section through our slab edge.

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Again, we can go ahead and change the scale, and the detail level.

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And there's our slab edge.

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The slab edge will stay associated to the edge of our floor.

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So if the floor boundary changes, the slab edge will follow.