There are no beams between the columns. Instead, the floor is heavily reinforced in both directions. In addition there is reinforcing steel in the floor at the columns to transfer the loads.
The joists act like small beams. This floor system is very economical because the formwork is readily available, and less reinforcing is need. Because there's only a small span between each joist, the slab can be thinner.
This system is not only economical but can use flying form systems. It also utilizes smaller columns than the traditional flat plate system. Provides uniform clear space below slab as well as providing flexible layout of columns/partitions.
This system is similar to the two-way flat plate system except there is a drop panel to provide extra thickness around the columns. This strengthens the column-floor connection. The rest of the floor can be slightly thinner with less dead weight.
One-way wide module joist slab in the lower middle is a variation on the one-way joist slab. Provides the depth required for stiffness and readily accomodates HVAC and floor penetrations.
Two-way joist slab, also called a waffle slab. Because there are joists in both directions, this floor system is the strongest and will have the least deflection. It's typically used when stiffness is important or if there are abnormally heavy loads.
The floor loads are transferred to the beams, which are then transferred to the columns thus making it ideal for heavy load areas. It is a common system for parking structures, elevator and stair areas.
The concept of the voided slab is simple in that concrete mass is removed from the areas in the slab where it is not needed to resist load and as a result of the reduced dead load, voided slabs can span further. Because of this efficiency, this system can withstand an increased load capacity, create larger spans without beams and larger open floor areas, is inherently earthquake resistant and is resource efficient.