#### Further Information

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• ### Why are the results of the load cases, e.g. the load case dead load, not identical with the first construction stage in the RF-/STAGES module?

If identical settings are defined in the main program, the missing consideration of the material-related partial safety factor in the load case is often the reason (Figure 1).

In the RF-/STAGES module, all calculations are always carried out, taking into account the partial safety factor. If not considered, it must be set specifically for the material.
• ### Various stiffness factors can be activated in the calculation parameters of a load case or load combination. What exactly is behind it?

The stiffness modifications can be controlled separately for the following elements:

• Materials
• Cross-Sections
• Members
• Surfaces

#### Materials

The first option 'Materials' is only activated for load combinations by default (see Figure 02) because the second-order analysis is preset for this. When the function is activated, the stiffness of all elements is reduced by the partial safety factor of the material (see Figure 03). This is especially important for timber construction in Europe. If the automatic load combination was selected for the standard EN 1990 + EN 1995, SIA 260 + SIA 265 or DIN 1055-100 + DIN 18008, the default settings are different. Provided that the partial safety factor of the material is defined as 1.0, it does not matter if the function is activated or not.

#### Cross-Sections

Use this option to control the multiplication factors of individual cross-sections. In the 'Modify' tab of the 'Edit Cross-Section' dialog box, it is possible to adjust the moments of inertia as well as cross-section surfaces. This affects the stiffness of the cross-sections.

#### Members

When editing a member, the 'Modify Stiffness' dialog tab is available. There are various definition types (see Figure 05). The "Multiplication Factors" option allows you to modify the stiffness of individual members in analogy to the cross-sections.

#### Surfaces

For surfaces referred to as 'Standard' and 'Without Tension', the stiffness of the surface can be adjusted in the 'Modify Stiffness' tab of the 'Edit Surface' dialog box. There, it is possible to modify the stiffness matrix elements by a factor (as with orthotropic surfaces).

#### Further options for stiffness modification

Additionally, a further option can be selected in the calculation parameters to adjust specifically stiffness of other elements (see Figure 07). When selecting the 'Modify stiffness' option, a new tab opens (see Figure 08). In addition to the member and surface stiffnesses, it is also possible to adjust the stiffnesses of supports and hinges individually.

#### Interactions of individual factors

If several factors have been defined for an element (e.g. cross-section and member), they are multiplied by each other. For the example shown in Figure 09:

#### Global control of stiffness modification

In the global calculation parameters (see Figure 10), it is possible to deactivate all options mentioned above at once. The local settings in the calculation parameters of the load cases or the load combinations are ignored.

• ### I perform a stability analysis according to the second-order analysis. Why is the partial safety factor γM1 used for the stress analysis here?

For cross-section and stability analyses, Eurocode provides different partial safety factors. It is important to pay attention whether the stability analyses are performed by using the second-order analysis and applying imperfections as cross-section designs. In this case, it is necessary to reduce the resistance with γM1.
• ### When displaying the deformations of LC1, the maximum is 0.39 in. If you look at the deformations of CO1 (defined as 1.0 * LC1), there is a larger deformation as a result. How is this possible?

FAQ 002533 EN-US

By default, load combinations are calculated according to the second-order analysis, load cases according to the linear static analysis. It is possible that the stiffness is reduced by a standard-dependent partial safety factor in the calculation according to the second-order analysis, which has the corresponding effect on deformations.

In order to obtain the same results in the load case and in the load combination, it is necessary for this case to regulate the consideration of stiffness factors in a uniform manner (see figure).

• ### Can I change the standard-specific partial safety factors and combination coefficients in the program?

FAQ 002497 EN-US

You can adjust all partial safety factors and combination coefficients. To do this, open the "Coefficients" dialog box in the general data of the model and then click the [New] button to create a user-defined standard (see the figure).

The concept of action categories of the new user-defined standard corresponds to the basic standard, which is preset when opening the "General Data" dialog box.

• ### Is is correct that the allowable soil pressure has to be entered as the characteristic value in Window 1.1 General Data of FOUNDATION Pro? Will be the design value determined automatically?

Yes, this is correct.

The characteristic value of soil pressure is entered in the input window 1.1 General Data. See Figure 01.

The design value is:
${\mathrm\sigma}_\mathrm{Rd}\;=\;{\mathrm\sigma}_\mathrm{Rk}\;/\;\;{\mathrm\gamma}_{\mathrm R;\mathrm v}$

The estimated partial factor for spread foundations can be found in the parameters of the National Annex you have selected for the design. See Figure 02.
• ### For a steel frame, I have manually created 20 load combinations with partial safety factors. The deformations, however, are to be determined without factors. I proceed as follows: I copy every single LC (several load combinations cannot be copied simultaneously) I set the factor to 1.0 in every LC. Is there no easier way to do this?

FAQ 001054 EN-US

For manually created load combinations with single loadings, there is, unfortunately, only the option that you described.

Alternatively, however, you can create the combinations automatically by using the General Data dialog box. As combination expressions, you can use not only the ultimate limit state, but also various design situations for the serviceability limit state: 'Characteristic', 'Frequent,' or 'Quasi-permanent'. In this way, the partial safety factors are automatically applied correctly.

If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

#### 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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