The determination of the stiffnesses can be found in the PDF file you can download below, in the "Downloads" section. The initial value is the corresponding I-section.
Using Stiffnesses in Orthotropic Hollow Core Slabs
Which stiffnesses does RFEM use for orthotropic hollow core slabs with rectangular cavities?
Mr. Rehm is responsible for developing products for timber structures, and he provides technical support for customers.

The aim of this technical article is to perform a design according to the general design method of Eurocode 2, using the example of a slender reinforced concrete column.




The "Nonlinear Material Behavior" add-on includes the Anistropic | Damage material model for concrete structural components. This material model allows you to consider concrete damage for members, surfaces, and solids.
You can define an individual stress-strain diagram via a table, use the parametric input to generate the stress-strain diagram, or use the predefined parameters from the standards. Furthermore, it is possible to consider the tension stiffening effect.
For the reinforcement, both nonlinear material models "Isotropic | Plastic (Members)" and "Isotropic | Nonlinear Elastic (Members)" are available.
It is possible to consider the long-term effects due to creep and shrinkage using the "Static Analysis | Creep & Shrinkage (Linear)" analysis type that has been recently released. Creep is taken into account by stretching the stress-strain diagram of the concrete using the factor (1+phi), and shrinkage is taken into account as the pre-strain of the concrete. More detailed time step analyses are possible using the "Time-Dependent Analysis (TDA)" add-on.

In the Concrete Design add-on, you can determine the required longitudinal reinforcement for the direct crack width analysis (w k).

For the design of reinforced concrete members, there is the option to automatically determine the number or diameter of rebars.

Want to automatically consider steel joint stiffness in your global RFEM model? Utilize the Steel Joints add-on!
Activate joint-structure interaction in the stiffness analysis of your steel joints. Hinges with springs are then automatically generated in the global model and included in subsequent calculations.
Is it possible to set user-defined values when viewing solid stress results?