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• ### Is it easy to prevent RF-SOILIN from recalculating the foundation any time load changes are carried out in the governing load case?

New FAQ 003212 EN-US

No, that is not possible. The calculation of the foundation parameters in RF-SOILIN is performed iteratively. For the first iteration step, it is necessary that the start values for the foundation parameters are selected internally by the program. With these start values, a finite element analysis of the
FE model in RFEM.

The result is a distribution of the soil pressure. The soil contact stress of the first iteration step is included as an initial value in the RF-SOILIN calculation. Together with the stiffness modulus of the entered soil layers, it is possible to calculate the settlement for each finite element. The settlement and soil pressure are then used to calculate the foundation parameters.

In the next iteration step, the new foundation parameters replace the old one and a new finite element analysis is started, which in turn yields a new distribution of overloading pressure. As a convergence criterion, we compare the new distribution of soil pressure with the old one.

As long as the deviation exceeds a certain convergence limit, the new distribution of soil pressure in RF-SOILIN is considered in the calculation of new foundation parameters. When the deviation of the distribution of the soil pressure of two consecutive iteration steps is not reached for the first time, the iteration is ended and the foundation parameters of the last iteration step are output as the result in RF-SOILIN.

• ### How can I specify different subgrade moduli for a large floor slab?

New FAQ 003148 EN-US

The definition of surface supports (foundation) in RFEM is a property of the surface.

This means that you have to divide the entire floor slab - depending on the areas with different subgrade moduli - into several surface components.

• ### Is it possible to reinforce a foundation with pure steel bars?

New FAQ 003146 EN-US

Yes, this is possible.

To do this, switch to the input dialog box “1.3 Materials”. There, you can deselect the “Available Reinforcing Steel Mats” and select the rebars that you want to consider for the reinforcement of the foundation.

Alternatively, it is also possible to specify an alternative reinforcement proposal for the foundation plate in dialog boxes 2.4 or 2.5 after calculation made before, whereby this proposal would not take into account e.g. any mesh reinforcement.

After having changed the provided reinforcement in dialog boxes 2.4 and 2.5, it is necessary to calculate the result once again. If you switch to another dialog box after making a modification to the reinforcement, a message appears informing you of the required recalculation of the results.

• ### How can I implement the support of a member on a bracket with fittings?

New FAQ 003136 EN-US

The most suitable combination is a member elastic foundation with nodal supports, which may fail each.

Figure 1 shows a model with such a support. As it is obvious from the results, the member elastic foundation absorbs the compressive forces and the nodal supports absorb the tension forces.

• ### Unfortunately, I currently have the problem that the calculation in RF-SOILIN takes extremely long and does not converge. What can I do?

New FAQ 003051 EN-US

Often, these problems can be solved easily and effectively.

Especially in the edge areas of plates, the results often oscillate. In this case, the result can be improved by modeling a foundation collar with a negligible thickness around the surface. It is assigned the same foundation as the main plate. The support collar shows the edge area of the slab more accurately and the convergence behavior is often better.

It is important that the foundation collar at least reaches sufficiently far that the settlement depression has subsided completely. Thus, it is also possible to graphically represent the influence of settlement on surrounding buildings graphically.

• ### Can I also rotate a foundation about the Z-axis in the add-on module RF-FOUNDATION Pro?

New FAQ 003036 EN-US

Yes, that is possible. If a nodal support in RSTAB or RFEM is arranged at a certain angle, the geometry of the foundation at the node is also oriented according to this coordinate system (see Figure 1).

• ### I have a foundation, which is held by subsequent frost aprons (Zerrbalken) in one direction (X or Y direction). From the internal force determination in RFEM I get horizontal bearing forces in the X- and X-direction. This is correct so far. Due to the frost aprons, the foundations are stored in the X-direction but. Can I "switch off" or ignore a bearing response from RFEM for the design of the foundation in RF- / FUND Pro?

FAQ 002979 EN-US

Yes, this is possible.

You will find the controller in the design details of the respective design case in RF- / FUND Pro.

On the one hand, you can select the bearing load (Px, Py, Pz, Mx or My) that should not be taken into account in the design. On the other hand, you can also determine whether the forces or moments should only be deactivated for a specific direction or for all directions.

It is important, however, that disabling the bearing load works for all proofs of the design case. If the bearing load Px is to be deactivated only for the proof of sliding, but not for all other checks, then you can control this with two design cases.
• ### Why is it possible to switch off individual proofs in RF- / FUND Pro? This entails a danger for the user to turn off certain proofs "by mistake" and to dimension a foundation under certain circumstances undersized?

FAQ 002976 EN-US

We want to give the user as much freedom as possible in controlling the proofs in RF- / FUND Pro. By default, the relevant verifications according to EN 1992-1-1 and EN 1997-1 are activated when creating a new case.

These can be partially deactivated. On the one hand, if proof is not required due to the structural design of the foundation. On the other hand for testing or verification purposes.

However, it should be noted that at least one geotechnical certificate according to EN 1997-1 must be activated.
• ### Can I also determine the stiffness of an existing column instead of a fixed nodal support?

FAQ 002894 EN-US

Yes, it works. For this, it requires the activation of the elastic foundation in the table "Edit nodal support". On the basis of some input parameters such as type of support, column shape, material and the column height, the program determines the springs of the column (see Fig. 1).

Another advantage in addition to the elastic support is that the surface area of the column cross-section is disabled during the result output. Therefore, singularities are hidden and thus the concrete design applies design cross‑sections.

• ### I would like to save foundations with certain dimensions as a template in the library. Is that possible? For me the button is disabled in the dialog "1.2 Geometry".

FAQ 002827 EN-US

If you "lay out" the dimensions of the foundation plate, then the option to save the foundation dimensions is inactive. Even if results from a previous calculation are already stored and available. See picture 01.

However, after the first calculation in the "layout" mode, you can use the configured dimensions of the foundation plate as the "start values" for a new calculation using the "Apply foundation plate dimensions from the calculation" button. See Figure 02.

This deletes the results from the first calculation and runs the program in Define Dimensions mode. In this mode, the option to save the foundation dimensions in the foundation library is now also available. See picture 03.

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