by Dennis Collin
Modelling helical ramps can be a little awkward in Revit. This is partly because the Ramp tool is somewhat old and has not enjoyed any development enhancements over the years unlike its Stair family cousin!
Fig 1. Floors are a very powerful and useful Revit family!
Ramps are also limited in their construction detailing options and do not host structural rebar or behave as a valid target for supporting walls or columns. They are capable of hosting railings, but they cannot be set with a camber or be properly modelled to allow for such features like the runoff of water. Therefore, when modelling such elements as site features, or pedestrian or vehicular access ramps I tend to instead recommend users to model elements as floor families.
Fig 2. Sketching out a floor slab to behave as a vehicle ramp.
For the example of a carpark ramp, I would construct a floor slab as per the image below. Sketched as half a doughnut shape. Width and radii dimensions can be set during the sketching process as desired.
Fig 3. Use Sub-Element modification tools to define the ramp ‘slope’.
Once complete, finish the sketch, enable sub object modification tools and select the top edge of the ramp and provide a height offset to the level above (or below).
Fig 4. Editing a vertex height.
If necessary, vertices can also be adjusted to apply a cross-sectional slope, or intermediate points added and modified to provide a non-uniform slope. Revit’s out-of-the-box ramp tools do not allow this! However, using the floor modelling options complex bespoke structures can be formed, modified and detailed.
Fig 5. Walls and columns can be attached to floor slabs.
In addition to railings elements like walls, columns and beams can be ‘attached’ to floors to support the structure, as well as applying concrete reinforcement (note Ribbon options).
For scheduling purposes, it is recommended to add notes to a custom floor style indicating its purpose as a ramp. Such distinctions can be leveraged with Revit’s view filters.
Fig 6. Remembering the ‘I’ in BIM – Information!
Floors also have the advantage over ramps in terms of structural buildup. This means when section such elements a more detailed view can be obtained without having to resort to manual drafting detailing.
Fig 7. Floor slab assembly showing material function and list.
I have written previously about the benefits of floors as ramps here:
Using floors to behave as ramps is often discussed during various Revit training courses. For more information on training, Revit or other products please visit https://training.cadline.co.uk/ or ask a question on the sites’ chat facility where a member of the team will be able to help and discuss your requirements.