#### Further Information

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• ### How can I only calculate specific load cases, load combinations, or result combinations by using a command with the COM interface?

FAQ 004337 EN

In order to only calculate specific load cases, load combinations, or result combinations in the same way as the "To Calculate..." command (see Figure 01), you can use the CalculateBatch method of the ICalculation interface. For the transfer, the method expects a field with the load type of Loading. This Loading includes the number of the load, and the type (for example, a load combination):

Sub batch_test()    '   get interface from the opened model and lock the licence/program    Dim iModel As RFEM5.IModel3    Set iModel = GetObject(, "RFEM5.Model")    iModel.GetApplication.LockLicense    On Error GoTo e        '   get interface for calculation    Dim iCalc As ICalculation2    Set iCalc = iModel.GetCalculation        '   create array with loading types    Dim loadings(3) As Loading    loadings(0).no = 1    loadings(0).Type = LoadCaseType        loadings(1).no = 4    loadings(1).Type = LoadCaseType        loadings(2).no = 4    loadings(2).Type = LoadCombinationType        '   calculate all loadings from the array at once    iCalc.CalculateBatch loadingse:  If Err.Number <> 0 Then MsgBox Err.description, , Err.Source        Set iModelData = Nothing    iModel.GetApplication.UnlockLicense    Set iModel = NothingEnd Sub
• ### Why are there no resultant support forces for result combinations?

FAQ 004200 EN

For a resultant, a concrete combination of loads is required, which result combinations cannot provide.

The problem is apparent in the following example. A single-span beam is loaded with three different load cases. For the support at node 1, the result envelope of the 6 possible load combinations gives a maximum P-Z of 11.25 kN based on the result of CO2 (see Figure 01). The support at node 2 has a maximum P-Z of 12 kN based on the result of CO1. The resultant of 23.25 kN, however, does not exist in any of the involved load combinations and is therefore too large (maximum LK 1 and LK 2 with 22.5 kN).

The situation is similar to the pure result combination of the load cases which have the same maximum values P-Z of the nodal supports 1 and 2. However, it is not apparent here that a resultant would give incorrect results.

For this reason, a resultant is not used for result combinations, since the results can be incorrect.

• ### I have used the RF-/DYNAM Pro add-on module to generate the governing result combinations of seismic loads. What is the next way to perform a design of the individual components?

With the Equivalent Loads and Forced Vibrations add-on modules, you can create result combinations that contain the governing combinations of seismic loads. To perform a design with them, they have to be combined further on the basis of the extraordinary combination. This combination is defined, for example, in EN 1990 Art. 6.4.3.4:

${\mathrm E}_{\mathrm d}\;=\;\underset{}{\sum_{}^{}\;{\mathrm G}_{\mathrm k,\mathrm j}\;+\;\mathrm P\;+\;{\mathrm A}_{\mathrm{Ed}}\;+\;}\overset{}{\underset{}{\sum{\mathrm\psi}_{2,\mathrm i}\;{\mathrm Q}_{\mathrm k,\mathrm i}}}$

This accidental combination has to be defined manually in RFEM. Make sure that (for a direction combination with the 100/30% rule), both created result combinations from RF-/DYNAM Pro have to be added with the "Or" condition. A combination like this is displayed in Figure 02.

This accidental combination can then be used for further design. It is possible to evaluate the governing internal forces as well as to import and calculate this combination in the design modules.
• ### For my result evaluation, the extreme values of the vertical support forces with the corresponding horizontal forces from a result combination are required for several support nodes. Is it possible to set this in the program?

FAQ 003358 EN

The graphical result display always shows the extreme values of all support reactions. That is, the largest and the smallest values across all combination possibilities. The individual support forces cannot be combined in this way as they usually occur in different load situations.
However, the extreme values with the corresponding results are displayed in result tables. Furthermore, Column H shows the corresponding load combination or the corresponding load cases by default.
If you only need to display the extreme values of PZ with the corresponding horizontal forces, you can use the filter function of the result table as shown in the figure.
• ### I have manually generated earthquake loads. How can I combine them according to the superposition rules of the standard?

If you have defined the load cases with earthquake loads and cannot combine them by using the RF‑/DYNAM Pro add-on module, the automatic combinatorics should not be used for this. The following steps describe how to define the manual combinatorics:

• Depending on whether you want to use the SRSS or CQC rule, it may be necessary to activate it in General Data (in the case of the CQC rule only). For the CQC rule, you have to activate the additional parameters, which can be set in the load cases.

• Create a result combination for each direction. Add all load cases where you have defined the earthquake actions in this direction. In Calculation Parameters, you can then define the type of superposition.
• As a next step, the directions are superimposed in further result combinations. In this case, Eurocode 8 provides the 100/30% rule, for example. For this, add "and" to the result combinations of the individual directions, and change the factors to 1.0 for the dominant direction and 0.3 for the other directions. It is necessary to always create one result combination for each direction.

• Finally, a further result combination is created, which can then be used for the design. In this combination, the earthquake loads are superimposed with the permanent and the imposed loads (creation of an accidental combination). Please note that the result combinations for earthquakes must be added with "or".

• ### Is it possible to renumber load cases, load combinations, and result combinations?

FAQ 003345 EN

Yes, you can access this feature via Tools - Renumber - Move. The attached video shows it.
• ### How can I display the corresponding internal forces of the maximum results in result combinations in the printout report?

In RFEM or RSTAB, you can easily display the corresponding support reactions / internal forces in a result combination in tables. This is automatically set by default.

If you want to also display them displayed in the printout report, it is necessary to activate the extreme values in the corresponding tables. You can do this in Selection.

In this example, the extreme values were only activated for the support force Pz, which means that the maximum support forces in the Z direction are displayed with the corresponding support reactions of the other directions.

If you want to include a graphical display, you have to print the graphic of the displayed load cases or load combinations in the printout report.

• ### Why do I get different design results for a load combination (CO) and a result combination (RC) in STEEL EC3 in spite of the same internal forces?

The difference between the design with RC and CO is mainly in the moment distribution applied for the calculation of the ideal elastic critical moment Mcr. For a load combination (CO), it is possible to clearly apply the moment distribution for the present load position. For a result combination of the "+" type or an RC that does not correspond to the "permanent/or" type, however, you can only analyze the enveloping moment distribution. In this case, the more unfavorable distribution (Max or Min) is applied. As a consequence, unfavorable values result for the critical load factor.
Furthermore, the design according to Section 6.3.3 of EN 1993‑1‑1 requires the moment distribution coefficients set to 1.0 (constant distribution) if the moment distribution cannot be clearly determined, which may also lead to more conservative results.

###### Summary:
The internal forces applied to the design can be the same in LC and RC, but the moment distribution in the result combination is applied more unfavorably to determine the critical factor. Thus, the RC provides a higher design ratio for the design with STEEL EC3.

• ### After running a time history analysis, I am not able to see all results on surfaces. Is there a possibility to show them?

In the results of the RF‑/DYNAM Pro add-on module, "Basic Internal Forces" and "Basic Stresses" on surfaces are only provided. However, you can use the option to export the results in a result combination to display all results after the time history analysis.

Simply use this option to create a result combination in the add-on module as shown in Figure 01, and show the results in the graphic. All results, such as "Design Internal Forces" or "Stresses," are available then.
• ### For the min/max support forces, the maximum forces are only displayed graphically, even though it is possible to display both for the result combination. Why is that?

FAQ 003251 EN

You have probably selected the "Absolute Extreme Value for Result Combinations" option in the Results navigator. Therefore, only the absolute highest value of both is displayed.

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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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