Sorry if the question is confusing as such, here's an image that makes it hopefully clearer:
So let's say this building consists of two elevated concrete slabs. The first elevated slab is supported by the 9 massive reinforced concrete piers arranged at even intervals of 5m x 5m, and connected with massive reinforced concrete beams. Thus the building is 10m x 10m in dimensions.
The second concrete slab is supported by eight of the 9 massive concrete piers, the ones around the perimeter, but the concrete pier in the middle is only one-storey high. Instead two less massive piers (labelled A & B) start from the height of the first elevated slab and support the second slab.
In this case, my questions are
- is this design potentially safe & practical as a way of supporting the top slab?
- does this mean that the beam along the junction of A-B requires extra reinforcement compared to a design where the top slab is supported by the same (extended) pier as the bottom slab.
- are there any other major ways that the forces differ, e.g, in terms of the forces transmitted by the lower columns, or the loads experienced by the lower slab?