ORION 18: HOW TO MODEL, ANALYSE AND DESIGN RAFT FOUNDATIONS

In this tutorial, we will learn how to model analyse and design raft foundations.

Step 1

As with all our previous tutorials on foundations here, here and here, open the 'St:00' storey. With the storey open, delete all the pad foundations there. In the region slated for raft foundations in our 'LearningOrion' tutorial, Create a slab of 600mm depth using the Axis Region  slab insertion method (because there are no beams in the foundation.)

Step 2

Next, we model 1m cantilever slabs around the edges of the created slab. We do this by selecting the slab icon in the members toolbar. Among the slab types, select '12', then click on one end of the axis line along the edge of the beam. Without releasing the mouse, click on the second end to create the cantilever slab. Do this around the four edges of the first slab we created.

Step 3

To carry out reinforcement design, introduce an FE slab strip. For this, click 'Slab Strip' in the members toolbar, then under 'Type', select 'FE Strip'. Click the left side of the slab (outside the slab), and without releasing the mouse, draw the strip across the slab. This will be used at the end of our analysis stage.

Step 4

The analysis and design for raft foundation is based on Finite Element (FE.) Click 'Run' in the menu toolbar, then 'FE Raft Foundation Analysis'. Under 'Floor Mesh and Analysis' in the dialog box that appears, click 'Raft Foundation Mesh And Analysis'. In the 'Mat Foundation Analysis' view, click 'Generate Model'. The mesh for the slab is generated. Close this view to automatically begin the analysis.

Step 5

Click 'Analysis Post-Processing' to view the contour diagrams for different areas of the raft foundation. To design reinforcement, click, then right click on the slab strip created earlier, select 'Properties' and click 'Update'.

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