3D Modeling - Slab, beam & wall 'negative' intersections

[Anonymous]

I have beams on a demo layer in the same location where a new slab will go. When I view the model in 3D, the new slab has negative space where the demo beams are, even though the demo layer is turned off. See attached image. This goes away if I elevate the new slab to be out of plane with the beams. How do I set the view settings to correct this?
Thanks!

[Laszlo Nagy]

This is standard behavior.
You can avoid it if you place the Beams on a separate layer and set the Layer Intersection Number of that layer to something different from that of the Slab's Layer.
If the intersection of the Layers of Beams and the Slabs are not the same, no intersection will occur in 3D.
Just remember that the Layer Intersection Number may need to be modified for other Layer Combinations as well.

[Karl Ottenstein]

An additional note/tip on this topic:

If you are trying to trim a beam with a slab using a Solid Element subtract (and upwards or downwards extrusion) ... note that the beam and slab must be in layers with different intersections priorities. Otherwise, since the beam would automatically cut a hole in the slab if the layer priorities were the same, there is no slab present to trim the beam.

I only just ran into this with a client who used angled profiled beams to represent custom stair stringers. Had never realized that beams interacted with slabs as Laszlo notes below.

Cheers,
Karl