Preliminary structural sizing
Spans, loads and ground: the tool sizes the slab, beam, column, footing, load-bearing wall and stair to the Eurocodes, and says which one fails.
The building
Sets which loads are assumed and which members get sized.
Occupancy (imposed load) : Residential (2 kN/m²)
Distance between supports. This is the parameter that governs the depth.
How many floors the structure carries, ground floor included.
How the member is held at its ends. It changes the effective span, and so the section.
On site this support condition is built like this: Simple bearing (beam on corbel/masonry), Pinned connection (double angle cleats), Pinned column base. Choosing it here is a promise about what gets welded and bolted. Connections
The soil assumed under the foundation: it sets the bearing capacity used in the calculation.
The concrete class used in the calculation, not necessarily the one that gets poured.
The reinforcement grade. It sets the yield strength used to size the bars.