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• ### 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?

New FAQ 003598 EN

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 unusual combination. This combination is, for example, in the EN 1990 clause 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 unusual 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. Such a combination can be seen in Figure 02.

This unusual 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.
• ### What type of procedure is carried out by the RF-/DYNAM Pro add-on module - Equivalent Loads?

New FAQ 003510 EN

Like the 'Forced Vibrations' module, the 'Equivalent Loads' add-on module performs the multimodal response spectrum analysis.

Contrary to what the name suggests, the simplified response spectrum method is not carried out here, as it is explained, for example, in EN 1998-1.

The equivalent loads are determined separately for each direction of excitation according to the following formula:

$\begin{Bmatrix}{\mathrm F}_{\mathrm X}\\{\mathrm F}_{\mathrm Y}\\{\mathrm F}_{\mathrm Z}\end{Bmatrix}\;=\;\mathrm\Gamma\;\ast\;\begin{Bmatrix}{\mathrm u}_{\mathrm X}\\{\mathrm u}_{\mathrm Y}\\{\mathrm u}_{\mathrm Z}\end{Bmatrix}\;\ast\;{\mathrm S}_{\mathrm a}(\mathrm T)\;\ast\;\begin{Bmatrix}{\mathrm M}_{\mathrm X}\\{\mathrm M}_{\mathrm Y}\\{\mathrm M}_{\mathrm Z}\end{Bmatrix}\;$

The differences between the two add-on modules are described in this FAQ .

• ### Why does the online service 'Snow, Wind, and Seismic Zone Maps' display a different load value than the corresponding standard in some cases?

New FAQ 003408 EN

The online service 'Snow, Wind, and Seismic Zone Maps' can only save a constant value over a surface area.

If the respective load standard specifies an isolines representation of the load over the land instead of a conventional zone classification, the interactive load map shows the areas between the isolines as zones with a constant value. In each case, these zones are assigned the larger value of the two enclosing isolines.

• ### I have generated the earthquake loads manually. How can I combine them according to the superposition rules of the standard?

New FAQ 003346 EN

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

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

• Create one result combination per direction. Add all load cases where you have defined earthquake actions in this direction. The type of superposition can then be defined in the calculation parameters.
• Next, the directions are superimposed in further result combinations. For this purpose, the Eurocode 8, for example, specifies the 100/30% rule. To do 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 create always one result combination for each direction.

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

• ### How are the site-specific Geo-Zone Tool data queries calculated to determine the various building loads?

New FAQ 003319 EN

The online service " Snow, Wind and Seismic Zone Maps" shows the snow load, wind and seismic zones according to the relevant standards on the Google Map in many countries and shows the site-specific loads of the corresponding displayed zone map for the selected location on the map.

The location on the map can be defined either by using the search function offered on the website or by clicking the desired location on the map.

The connected load determination is linked to the selected location and always shows the site-specific load depending on the local load zone information and the height above sea level.

Since our online service uses the fee-based Google Maps services as a basis, we offer our users only a limited number of free geo-data queries (load determinations). In the event that this limited number of load determinations is not sufficient, our Geo-Zone Tool Data Queries packages are available. These packages release a certain number of site-specific data queries for all stored contacts of a company.

A data query corresponds to a load determination depending on the selected zone map (load type) and location on the map. A possible change of the load type leads to another data query due to new zone information. Thus, in the standard case, each location requires at least 3 queries with regard to the determination of the local snow, wind and seismic load.

• ### Is it also possible to integrate the online service 'Snow, Wind, and Seismic Zone Maps' into external applications?

FAQ 003268 EN

Yes, it is possible to integrate the complete frame 'Snow, Wind and Seismic Zone Maps' including the search function, location description and load output by means of the URL in other applications.

After entering the "Full Screen" mode, you receive the required URL in the browser address bar.

For determining the location-specific building loads, there is – additionally to this - an online web service in the background. If providing the necessary data (location, load type, load standard, etc.), this web service allows the data to be called up digitally for transfer to an external application.

→ see FAQ

• ### How do I determine the stiffness center of my system?

FAQ 003230 EN

With the RFEM program, you can determine the center point of a system. This is explained in this FAQ .

However, the center point does not have to be necessarily confused with the stiffness center. It can be determined with the program SHAPE-THIN according to the theory of stiffening systems. The following webinar will also explain the practical application of the stiffness center in the seismic design.

To determine the center, it is also possible as a third and final option to consider the stiffness with a stiffness model in RFEM. In this series of technical articles, this will be explained in the following articles.
• ### In which way is it possible to determine loads at particular geographic coordinates in the online service 'Snow, Wind and Seismic Zones'?

FAQ 003210 EN

As the text box used to search for the location in the online service 'Snow, Wind and Seismic Zones' does not search the map's location database but completes the input automatically with each new character, the numerical specification of Geocoordinates in this area is not successful.

One of the modifications of the URL in full-screen mode, however, allows moving the pointer to the load determination to the desired geo-position.

To do this, enter the geocoordinates in the format [Latitude, Longitude] separated by a point in the last URL module after the "=" character.

• ### Is there a possibility in the module RF-DYNAM Pro to generate a "response spectrum according to standard" with user-defined parameters?

FAQ 002901 EN

Yes the possibility exists. In many standards we have implemented this possibility. Here you can select the option "Other" as subsoil class and thus adapt some parameters according to your wishes.

The following annexes to EN 1998-1 have this option: CEN, NBN, CSN, DIN, UNI, NP, STN, CYS, BS, NS and NF.

• ### How do I superimpose generated equivalent loads from the seismic analysis?

FAQ 002720 EN

When calculating by using the Equivalent Load Method, an equivalent load is determined from the individual mode shapes as the name implies. After a successful determination, you can export these equivalent loads in RFEM. RFEM automatically creates load cases in this way.

These exported load cases are now displayed in a result combination is superimposed. One always uses a quadratic superposition for earthquake storm loads. Two types of superposition are possible here. First, the frequently used SRSS Rule and the CQC Rule. All load cases from the earthquake will always be considered as Stöndig and superimposed according to the respective regulations. The calculation rules are governed by the common standards.

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