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• ### For a tapered member, I get the error message "Invalid (incompatible) arrangement ...". What can I do?

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A taper describes a member or a surface with a variable cross-section. The cross-section type must be consistent, for example, I-shaped cross-sections at both member ends.

In our example, we have a member with a PRO cross-section and a QRO cross-section.

To create a tapered member here, you should use a parametric cross-section for the member start and end:

This allows you to calculate the tapered member.

• ### I have defined a wind profile for RWIND Simulation up to a height of 100 m. Is the wind profile dependent on the size of the wind tunnel?

In the wind profile, you always define the height ranges from z. B. 0 - 5 m, then 5 m - 10 m, etc. If your wind profile ends at 100 m, it is not cut off, but the value for 100 m is also applied for greater heights. If your wind tunnel is smaller than the stored profile, only the wind speeds up to this height are considered.

You can check this visually by displaying the velocity vectors and deactivating the display on a reduced area.

For a wind tunnel with a height of 50 m, you get the following result:

For a wind tunnel with a height of 150 m, you get the following result:

• ### As part of my bachelor thesis, I would like to integrate the RSTAB printout report into LaTeX. There, you can completely integrate a PDF document as shown in the viewer. This also works with any PDF document, but not with the printout report created by RSTAB. What could be the reason?

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You can include the RSTAB printout report if you print it with a virtual PDF printer, for example PDF24.

It is necessary to pay attention to the PDF created by RSTAB or RFEM for "optimizing the web". Then it can be easily inserted into scientific programs.

• ### I would like to design an aluminum or lightweight structure. Is it possible to use RFEM or RSTAB for this?

Both RFEM and RSTAB can be the solution . For both programs, there are standards available with which the aluminium and light-weight structures can be calculated and designed.
In addition to Eurocode 9 with numerous National Annexes, the American standard ADM 2020 is also available.

Further add-on modules for membrane and cable constructions complete the options.

###### Main Programs RFEM or RSTAB
The main programs RFEM or RSTAB are used to define structures, materials, and actions.

If you also want to analyze membrane and cable structures, you need RFEM . When it comes to pure beam structures, the purchase of RSTAB is sufficient. In any case, RFEM is the more diverse option because it can be equipped and extended with the corresponding add-on modules for all materials and designs.

###### Available standards
• RF-FORM-FINGING/RF-CUTTING-PATTERN (only for RFEM)
Determines the shape and cutting pattern for cutting membranes
• RWIND Simulation
Complex analysis of any structures in the digital wind tunnel with transfer of load cases to RFEM or RSTAB for further processing.
###### Dynamic analysis
If it is necessary to perform seismic analysis or vibration designs of a building, the RF‑/DYNAM Pro add-on modules provide special tools for determining natural frequencies and mode shapes, for an analysis of forced vibrations, a generation of equivalent loads, or for a nonlinear time history analysis.

interfaces

If you have any question about the Dlubal Software programs, please do not hesitate to contact our sales department.
• ### How can I set the deformation coefficient kdef in the program?

The setting for the deformation coefficient kdef can already be made in the model data. There, you can specify the deformation coefficient manually or select it based on the service class.

The deformationfactor k def is considered in the load combinations for serviceability in the program (similar to DIN EN 1995-1-1, 2.2.3).

For the design of mixed structures made of timber materials, see FAQ 4325 .

• ### How is the load distributed to the members in the angular axis method if members are excluded from the load application?

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A surface load of 1 kN/m² delimited by nodes 1 to 4 is only applied to member 3 (Figure 1).

The entries made in the load generator are shown in Figure 02. There is no correction of the distribution according to the moment equilibrium (Figure 3).

The generated member load is shown in Figure 4. This is calculated as follows:

q = 1.00 kN/m² (area load)

h1 = 4.00 m

h2 = 6.00 m

btot = 12.00 m

$\mathrm\alpha\;=\;\arctan\left(\frac{{\mathrm h}_2\;-\;{\mathrm h}_1}{{\mathrm b}_{\mathrm{ges}}}\right)\;=\;\arctan\left(\frac{6,000\;-\;4,000}{12,000}\right)\;=\;9,46^\circ$

${\mathrm b}_1\;=\;\tan\left(\mathrm\alpha\right)\;\cdot\;{\mathrm h}_1\;=\;\tan\left(9,46^\circ\right)\;\cdot\;4,000\;=\;0,667\;\mathrm m$

${\mathrm l}_1\;=\;\sqrt{{\mathrm b}_1^2\;+\;{\mathrm h}_1^2}\;=\;\sqrt{0,667^2\;+\;4,000^2}\;=\;4,055\;\mathrm m$

${\mathrm l}_2\;=\;\cos\left(\mathrm\alpha\right)\;\cdot\;{\mathrm h}_2\;=\;\cos\left(9,46^\circ\right)\;\cdot\;6,000\;=\;5,918\;\mathrm m$

${\mathrm A} _ {\mathrm R}\; =\frac {\; {\mathrm b} _1\;\cdot\; {\mathrm h} _1} 2\; =\;\frac {\; 0.667\;\cdot\; 4,000} 2\; =\; 1.335\;\mathrm m ^ 2$ (remaining area marked in red in Figure 4)

${\mathrm l}_{\mathrm{ges}}\;=\;\sqrt{{\mathrm b}_{\mathrm{ges}}^2\;+\;\left({\mathrm h}_2\;-\;{\mathrm h}_1\right)^2}\;=\;\sqrt{12,000^2\;+\;\left(6,000\;-\;4,000\right)^2}\;=\;12,166\;\mathrm m$

${\mathrm q} _ {\mathrm c}\; =\:\frac {\mathrm q\;\cdot\; {\mathrm A} _ {\mathrm R}} {{\mathrm l} _ {\mathrm {ges}}}\; =\;\frac {1.00\;\cdot\; 1.333} {12.166}\; =\; 0.110\;\mathrm {kN}/\mathrm m$ (constant load component on loaded member)

${\mathrm q} _2\; =\: {\mathrm q} _ {\mathrm c}\; +\; {\mathrm l} _1\;\cdot\;\mathrm q\; =\;\: 0.110\; +\; 4.055\;\cdot\; 1,000\; =\; 4.165\;\mathrm {kN}/\mathrm m$ (member load node 2)

${\mathrm q} _5\; =\: {\mathrm q} _ {\mathrm c}\; +\; {\mathrm l} _2\;\cdot\;\mathrm q\; =\;\: 0.110\; +\; 5.918\;\cdot\; 1,000\; =\; 6.028\;\mathrm {kN}/\mathrm m$ (member load node 5)

q4 = qc = 0.110 kN/m (member load node 4)

• ### A rigid member should only be able to absorb tensile forces or only compressive forces. What are the options for considering these nonlinearities in the calculation?

There are two options for defining the failure:

1. Assignment of member nonlinearity
For the member types "Beam" and "Rigid", you can define a member nonlinearity for each member. You can find the corresponding option in the "Settings" tab (see Figure 01).

2. Assignment of nonlinear member hinges
Alternatively, you can define a member end hinge with failure criterion for the member. For the desired degree of freedom, you can assign the hinge condition with nonlinearity accordingly (see Figure 02).
• ### The installation of a Dlubal Software program is not possible due to the following message: "Program unsafe, protection by Microsoft Defender SmartScreen." How can I install the program?

You are probably using Internet Explorer or Edge to download the installation file. Since the installation file is an EXE file, the integrated SmartScreen takes effect.

The easiest solution would be to use another web browser, such as Firefox, Chrome, or Opera.

If you want to continue using the Internet Explorer, you can deactivate SmartScreen before downloading our software. Please use the web search for the instructions.

• ### How can I perform a stability analysis for a tapered member?

Tapered members must not be designed according to the simplified equivalent member method!

For steel structures, the design can be performed by considering the warping torsion or using the General Method. These methods are described in this technical article.

For timber structures, the design can also be performed by considering the warping torsion. The method for timber structures is explained in detail in thiswebinar.

According to the equivalent member method, the design can be performed if the provisions of the explanations for DIN 1052, Section E8.4.2 (3) for variable cross-sections are met. In various sources of technical literature, this method is adopted for Eurocode 5. An example of this can be found in the document on brettschichtholz.de, page 64 ff.

In the RX‑TIMBER program, the design of tapered members is performed according to the equivalent member method. This is briefly explained on a simple example.

Structural System (Figure 01):

• Span length: 8 m
• Beam height right: 80 cm
• Beam height left: 26 cm
• Roof inclination: 3.9°
No stiffening is defined. The lateral-torsional stability becomes governing with 99% (Figure 02) at the x‑location 1.598 m. The cross-section height is 36.8 cm. However, the slenderness ratio is based on the equivalent cross-section height of 60.9 cm (Figure 03).

The equivalent cross-section height results at the x-location 5.2 m about 0.65 × 8 m = 5.2 m.

If the stiffening is in the middle of the span, for example, the equivalent height for the x‑location changes to 45.3 cm.

Since the stiffening is usually applied over the member length, the height must be calculated according to a special algorithm. The supports are always applied as fixed points and the equivalent heights are calculated, based on the x-locations of the designs.

For the example, the following results: x0.65 = 0.32 x 4 m + 1.598 m = 2.878 m

1 - 10 of 1245 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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