Currently if you make your view range up to the ceiling of your building you won't see the structural elements, only windows etc
Elements Above the Cut Plane and Below the Top Clip Plane
These elements are not displayed in a plan view unless their categories are window, casework, or generic model. Elements in these 3 categories are drawn using the projection line weight as viewed from above.
It should be an option to make the beams etc visible at all times, without having to make an underlay and use the linework tool to show the beams in overhead lines.