Hello there; You can define slabs on steel beams in three ways 1) Reinforced concrete slab (reinforced concrete slab defined on steel beams) 2) Metal slab or slab defined from glass or another material 3) Composite slab The first two of the three above-mentioned slab types can be defined between the post steel beams. However, secondary secondary beams are needed to define composite flooring. secondary beams; If a composite slab is defined, its designs are made by j-checking it as a composite beam. At the same time, the main beams, where the secondary beams are defined, take the loads from the composite slab. In the attached example, you can see the difference in the moment diagram between the tiled and unfloored models. However, you cannot read the moment difference on the main beams because it is not suitable for the program logic to define composite flooring without defining the secondary beam. Necessary notes have been taken regarding this situation. If you are going to define composite flooring, be sure to define the secondary beams in your modeling. Good work.