Parametric Tapered Footing in FreeCAD

In this article, I’ll be writing a detailed transcript of how to create a parametric tapered footing in FreeCAD, similar to the one given in SP-34

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So, the resulting model will look something like this:

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We’ll start by creating a new file and then opening the sketcher workbench. Then we’ll select the create new sketch option and set the orientation to XY plane.

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One may increase the grid size as per convenience. Now, simply create a rectangle any size from sketcher geometries toolbar. Always create the geometries around the origin for better references of constraints.

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Now by simply selecting the end points of any side of the rectangle and the axis perpendicular to that side, create a symmetry constraint between them from sketcher constraints toolbar. Similar apply this operation for any of the adjacent sides of the rectangle.

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Then selecting any horizontal side, fix its horizontal distance and give it a name say length. Similarly, do it for the other side too by setting its vertical distance and name it as width. Here in this example I’ve taken L=1200 mm and B=1000 mm.

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After getting a fully constrained sketch, close the sketch and rename it as Base from the tree view and also save the file with the name Tapered Footing.

Now, once again create a new sketch on XY plane but with an offset of 150 mm, as this will be the top of the footing.

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Similarly, as of the previous sketch, create a new rectangle with relatively smaller size and apply all the operations as done earlier. Set L=350 mm & B=250 mm.

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Close the sketch and rename it as Top.

Then open the part workbench and select the utility to loft from the part toolbar.

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Add both the sketches to loft and tick the create solid. Then press OK.

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Now, create a new sketch on XY plane at the same offset of 150 mm. This sketch will define the extrusion of the column to be attached to the footing.

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Once again, create a similar rectangle with relatively more smaller size and apply all the operations as done earlier. Set L=300 mm & B=200 mm.

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Rename this sketch as Column. Then opening the part workbench, click on extrude a selected sketch option.

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Select custom direction and set Z=1.0 and leave others as zero. Set length along to be around 50mm and tick create solid. Then press OK.

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Rename the extrusion as Column’s Height.

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Now we’ll select the base sketch of the footing and extrude it in direction Z=-1 and length along 150 mm.

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Rename this extrusion as Depth(d).

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Now, create the final sketch for the base of the slab for the footing, i.e, PCC. Set the orientation to XY plane and set an offset of -150mm.

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Once again, create a similar rectangle with relatively Larger size than the base of footing and apply all the operations as done earlier. Set L=1300 mm & B=1100 mm.

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Rename this sketch as Base of Slab.

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Then opening the part workbench, click on extrude a selected sketch option. Select custom direction and set Z=1.0 and leave others as zero. Set length along to be around 80mm and tick create solid. Then press OK.

Rename this extrusion as Slab Thickness.

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Now select all the part objects created till now and select Make compund from part toolbar. This will result in a single part object.

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Now opening the Arch workbench, create the structure by selecting the the compund object.

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Change the role of the newly created structure to Foundation from the data properties.

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The modeling of parametric structural tapered footing is completed here. There are some other BIM related parameteres that we’ll also define here.

Create a building object from the structure and change building type to Residential-House.

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Then create a Site object from the building object and change its GIS parameters.

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One thing more that we can add material to the structure from create material definition in arch workbench only.

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Now selecting the site object, export the file as IFC.

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Finally you recheck it by opening the IFC file just created.

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Thank you.

NOTE: There can be other methods too for modeling such parametric tapered footing. However, satisfactory results can be obtained from this method too.

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