Hi Farzinassadi,
I just did one of these myself yesterday...
My particular method, while needs a couple of steps worked out well...
1) Floor slab the ramp footprint, and make the slab height equal to the complete height of the ramp
(Layer - 'Ramp')
2) Draw a fill pattern to show the section of the ramp
(My ramp had undulations so the curved ramp object was not applicable)
Use Profiler to 'extrude' the section as an object
(Layer - SEO_Ops)
3) Align the slab and the object
Group them together
4) Use Solid Element Operations - Intersection, with the slab as the target and the object as the operator
5) Hide the 'SEO-Ops' layer
6)Select the floor slab in Plan and look at it in 3D....hopefully Voila...
See the image of the car park ramp... (no need for D.A. to advise on the rendering...its OK, its only 3D
)
HTH...
Alan