# Frequently Asked Questions (FAQ)

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• ### When calculating a result combination, I receive the "Warning No. 30014 – Incorrect addition of load cases in the result combination!  The result combination contains load cases or load combinations with results containing second-order effects, which points towards nonlinear relationships and therefore cannot be added together..." What does this warning mean?

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This warning appears in the case of the following result combination definitions when the load cases/load combinations are analyzed according to a nonlinear analysis such as second-order or large deformation analysis.

Case 1:  RC = LC1/CO1 + LC2/CO2

For Case 1, load cases/load combinations cannot be superimposed together in a result combination when each case/combination is ran according to a nonlinear analysis such as a second-order (P-Delta, p-delta) or large deformation analysis.  Deformations in both load cases are based on different structural systems and will result in incorrect results as P-Delta effects cannot be simply added together.

The solution for this case is to either run the load cases/load combinations according to a geometrically linear analysis where the results can be superimposed together in a result combination, or the consideration of the combined load cases must only be considered under the Load Combinations tab and evaluated individually rather than in a result combination.

Keep in mind, this same warning will appear when creating a result combination in a model where geometric nonlinearities are also defined.  An example includes a slab foundation where a nonlinear surface support is defined to fail in the case of uplift.   Geometric nonlinearities can accurately be considered in load combinations opposed to result combinations which may yield incorrect summary results.

Case 2:  RC = factor* LC1/CO1 or factor* LC2/CO2

For Case 2, if a load case/load combination is calculated according to a nonlinear analysis, it is not possible to additionally apply a factor to the result combination.  The factor would not only be applied to the defined loads on the structure, but also to the nonlinear effects such as P-Delta which is incorrect.

The solution for this case is to either run the load cases/load combinations according to a geometrically linear analysis where the factor can be applied to the result combination, or the factor can be considered under the Load Combinations tab where it will be applied directly to load cases only according to a geometrically linear analysis without consideration to the second-order effects
• ### I have purchased the RF‑/JOINTS add‑on module. After importing the new authorization file, the demo version is only available. Why?

RF-/JOINTS is divided into several joint groups. Each of these joint groups requires a separate license key. If RF‑/JOINTS detects a key, the joint group is marked with a green circle.

In your case, you have probably selected a joint group that is not licensed. Therefore, please set the joint group that you have purchased. The message about the demo version should disappear then.

• ### Are there no 32-bit versions of RFEM and RSTAB anymore?

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As of April 2017, we only provide 64-bit versions of our software. The last versions, which are still available as 32-bit versions, are RFEM 5.07.13 and RSTAB 8.07.13.

If you are still using the 32-bit Windows, we recommend you to switch to the 64-bit version of Windows. This operating system version runs virtually on all computers. Windows 64-bit allows to use much more RAM, which is a big advantage for our software.

• ### So far, all data of our office have been stored locally. Now we would like to store the project data on the network drive. During the installation, I could not specify the network drive. How can we add our projects to the Project Manager?

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In the Project Manager, you can include folders from any drive (that is, also network drives). For this, select the menu "Project → Connect Folder" and set the desired folder in the following dialog box.

If there is already an existing project structure, it is sufficient to select the top folder and activate the option "Connect folder including all subfolders." Thus, all subfolders will be included and displayed in the Project Manager tree.

Local projects are stored under "C:\Users\Public\Documents\Dlubal\Projects" by default. Use the Windows Explorer to move this folder to the any directory of the network drive you want and then include it within the Project Manager as described above.

You will get a message saying that the connection with the "old" projects does not exist anymore (as they have been moved). In this case, you can disconnect the project: right-click on the relevant project and select the option "Disconnect."

• ### Is the update installed over the old version? Or is a parallel version of the program created?

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The main versions of the program (for example, RFEM 5.20.xx, 5.21.xx, 5.22.xx, and so on) are always installed in parallel and can be used concurrently. If this is not desired, you can uninstall the previous versions at the end of the installation.

On the other hand, the intermediate updates (RFEM 5.20.x1, 5.20.x2, and so on) are always installed over the previous version.

The projects are imported in the case of any update, of course. Just in case, it is recommended to save the personal settings in the configuration manager before uninstalling the old version.

If necessary, the user-defined settings can be imported into the configuration manager after the update.

• ### During the installation, I get the message 'File security for File XY could not be set. Error 0. Check if you have sufficient rights to change the security rights for this file.' What does it mean?

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This error message is probably caused by is the specification of network paths for the installation. Unfortunately, the installation in the network is not possible.

• ### I cannot find the autorization file on the dongle.

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The AUTHOR.INI file is sent to you separately by e-mail or you can download it directly from your Dlubal account.
• ### When trying to calculate a result combination, I get Warning No. 30014:"Incorrect addition of load cases in the result combination!The result combination contains load cases or load combinations with results containing second-order effects, which points towards nonlinear relationships and therefore cannot be added together."What does this warning mean?

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5.xx

8.xx

The warning appears if load cases or load combinations are nonlinear according to the second-order analysis or the large defrmation analysis, and then superimposed in a result combination according to the following criteria:

###### Case 1: RC = CO1 + CO2

Since each load combination is analyzed nonlinearly according to the second-order analysis, the superposition of the respective results is problematic: Deformations and internal forces are based on different structural systems. It would not be correct to simply add up the individual CO results.

###### Case 2: RC = "Factor" * CO1 or "Factor" * CO2

Both load combinations are superimposed with factors. Since each CO is calculated according to the second-order analysis, the results show a nonlinear relation. The factors ensure that each internal force is multiplied by the corresponding factor. For example, the duplicatio of the axial force is not necessarily accompanied by the duplication of the moment. It is assumed that the results have a linear relation. This discrepancy (nonlinear calculation of the results with linear multiplication) results in the warning described above.

The solution for both cases is to calculate the load cases or load combinations linearly according to the geometrically linear analysis and then superimpose them in an RC. If there are only load cases, you can analyze them in a load combination.

Nevertheless, the results of nonlinear analyzes can be superimposed in an RC if the criterion "permanent" is used: RC = CO1/s or CO2/s. In this way, the result envelope is determined, which covers the unfavorable constellation from both COs. In this case, click [Yes] to confirm the warning. The RC internal forces then represent the extreme values from both COs and can be used for further design.

If there is a result combination with geometric nonlinearities n the model, a similar message appears. It is described in FAQ 003065.

• ### After closing a file (without saving it), the file includes a new modification date. Why?

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5.xx

8.xx

When closing a model, the view and window settings are always backed up by default. For this reason, the modification date is updated, too.

If you want to avoid this, deactivate the corresponding function in the 'Program' tab of the 'Program Options' dialog box (see Figure 01).

• ### I have an RFEM license with USB dongle. Can I install and use the program on several computers?

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5.xx

8.xx

Yes, you can install the program on several computers. During the installation, the driver of your USB dongle is usually installed automatically.

In order to use RFEM on a single computer, simply insert your dongle and start the program.

When opening the program for the first time, it is necessary to import the authorization file AUTHOR.INI (see the figure) to activate the full version on your computer.

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#### First Steps

We provide hints and tips to help you get started with the main programs RFEM and RSTAB.

#### Wind Simulation & Wind Load Generation

With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.

The generated wind loads acting on these objects can be imported to RFEM or RSTAB.

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