A high-rise steel structure is to have bracings in every level.
The first level, however, is to be made out of reinforced concrete. Therefore, the horizontal bracing should function via this concrete plate. How can I model this rigidly fixed concrete plate in RSTAB?
If you want to model bracing membranes in your structural system, you can use members of the types Rigid and Coupling. To model a bracing ceiling, you can specify a diagonal member (or two) that simulates the surface.
If two nodes are connected by a coupling with each other, then this means that the internal forces are directly transferred from node to node. There are no "losses" because the members have an infinite stiffness.
You can add any hinges to the member type "Rigid." For the couplings, there are four variants with and without hinges.
A more accurate modeling is possible in the FE program RFEM because the beam model covers the plate and membrane effect only approximately. You can, for example, create the beam model in RSTAB, then open it as a copy in RFEM and add surface elements to it.