A surface support can be assigned to any surface entered in RFEM graphically or using tables. Support conditions can be set either to completely 'rigid' or 'elastic' by defining a spring stiffness.
Support or Springs in Cu,x, Cu,y, Cu,z
The direction of the supports or springs refers to the local coordinate system of the relevant surface which is assigned to the surface support. The local coordinate system of the surfaces can be displayed by using the Display Navigator or the shortcut menu.
The support perpendicular to the surface is controlled by entering Cu,z. The entries for Cu,x and Cu,y describe the resistance against the displacement of the plate in the x- and y-direction.
Shear springs Cv,xz, Cv,yz
By entering values in these boxes, the shear resistance of the soil is considered in the direction of the surface axes x or y. In most cases, the Pasternak constant Cv is between 0.1 ⋅ Cu,z (low shear resistance) and 0.5 ⋅ Cu,z (average shear resistance). Cv,xz = Cv,yz can usually be applied. If the support in uz has been set to 'rigid' (see Figure 01), no entry is possible for the shear springs Cv,xz and Cv,yz.
The theoretical background about the 'effective soil model' implemented in RFEM is documented in Chapter 4.9 of the RFEM manual.
Results for Surface Supports
Once surface supports have been used in a model, the contact stresses σz, τyz and τxz are available as a result after the calculation. In Table 4.21 'Surfaces - Contact Stresses', the columns H to J including the reaction forces Rx, Ry and Rz are additionally available for the entire surface.
For the design of concrete surfaces, the rib component of the internal forces can be neglected for the ULS calculation and for the analytical method of SLS calculation, because this component is already considered in the member design. To this end, select the check box in the ‘Details’ dialog box. If no rib was defined, this function is not available.
The material model Orthotropic Masonry 2D is an elastoplastic model that additionally allows softening of the material, which can be different in the local x- and y-direction of a surface. The material model is suitable for (unreinforced) masonry walls with in-plane loads.
- Is it also possible to reduce the shear force on a support or perform design with the shear force at a distance d to the support in RF‑CONCRETE Surfaces?
- For design with CONCRETE NL, is the creep applied to the entire cross-section, or to the concrete compression zone only?
- When I create a user-defined result value, the RFEM solver window opens briefly and the calculation is apparently performed again. Why? I have already performed the calculation before.
- I am trying to verify RF‑CONCRETE Surfaces on the basis of the results of the example from the manual. Chapter 2.4.3 describes the determination of the statically required reinforcement. Unfortunately, I cannot create an example that exactly represents these results. Can you send me the corresponding example?
- Do I have to add the reinforcement for ribs from RF‑CONCRETE Members and RF‑CONCRETE Surfaces?
- Is the compression reinforcement calculated for the ultimate limit state design in RF‑CONCRETE Surfaces? Or is it only possible in RF‑CONCRETE Members?
- Is it possible to use the add-on modules for RFEM to design concrete solids?
Which units are specified in the result display of the support reactions (kN or kN/m)? A note about this is missing in the graphic.
In the case that the support reactions are given in kN/m, for which distance does the value apply?
Is it possible to specify shrinkage effects as loads?
- Where do I find the setting to specify the entered structural component as a "wall" or "slab"?
Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements