Answer:
When determining surface stresses or surface internal forces in RFEM, the entered reinforcement is not taken into account initially.In this case, RFEM applies the isotropic linear-elastic material model.
However, you can optionally use the RF‑CONCRETE NL add-on module to perform the nonlinear serviceability limit state design in the RF‑CONCRETE Surfaces add-on module. Here, you can define the provided reinforcement before the calculation.
The add-on module determines nonlinear stiffness, taking into account the applied reinforcement and the cracked state.
You can then optionally export this nonlinear stiffness to RFEM and activate it for a new calculation of the surface internal forces for the individual load cases and load combinations.
![Spans Based on Figure 5.2 from [1]](/en/webimage/039540/3493372/01_Abmessungen_EN.png?mw=512&hash=3cc425f1463bd5981b358d5889e3109e07ae1233)
