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Frequently Asked Questions (FAQ)
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Answer
The design points in CRANEWAY have been adopted in compliance with the standard. In this case, the stresses are calculated for the following locations:- Design Point 0
A periphery of the flange at the web edge or at the fillet start - Design Point 1
A flange at load application point (this can be checked as wheel spacing in Window 1.4) - Design Point 2
The flange edge
These points are not displayed in the resulting cross-section graphic in the CRANEWAY program. However, there is always a stress point at the design points 0 and 2 for which the result values can be directly displayed. - Design Point 0
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Answer
In the graphic, imperfections are always oriented on a support. In the attached model and in Figure 01, the only support of an imperfection is defined at the column head. Therefore, the imperfection is oriented at this point.Since the graphical imperfection is virtually an equivalent load, the display is only of visual relevance in this case. The display is not important for the calculation.In order to orientate the imperfection graphically to the upper column head, you could use a rigid member, for example, and arrange the support there (Figure 02). -
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RF-CONCRETE Columns determines the equivalent moment M0e from the moment M02 at the column head and M01 at the column base according to EN 1992‑1‑1, 5.8.8.2 (2), and performs the design according to the model column method with this equivalent moment M0e.
Now, it may happen, for example, that a computationally larger required reinforcement area would result from the cross-section design with the moment M01 at the column head.
To ensure this, message 28) is displayed, according to which the user should perform a standard design with the internal forces according to the linear static analysis. To do this, simply open the RF‑CONCRETE Members add-on module and perform pure design of the internal forces according to the linear static analysis for the member designed in RF‑CONCRETE Columns.
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Answer
RF-/STEEL Cold-Formed Sections is a module extension of RF‑/STEEL EC3. The only thing you need to do is to activate the design for cold-formed cross-sections in the detailed settings of RF‑/STEEL EC3 (Figure 01).
Figure 01 - Activating Module Extension RF-/STEEL Cold-Formed Sections
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Answer
Common cold-formed cross-sections can be modeled in SHAPE‑THIN. In General Data, select the "c/t parts and effective cross-section properties" check box (Figure 01).
Then, select the "EN 1993‑1‑3 (Cold formed cross-section)" option in the "c/t-Parts and Effective Cross-Section" tab of the Calculation Parameters dialog box (Figure 02).
You can optionally check the geometric conditions for the applicability of the standard specified in EN 1993‑1‑3 [1], 5.2. To do this, select the corresponding check boxes. If the geometric conditions are not met, an error message appears before the calculation.
Figure 02 - Calculation Parameters
First, enter the elements of the cross-section. The notional flat widths are usually generated automatically from the geometry conditions, but can also be created as user-defined in Table "1.7 Notional Flat Widths | EN 1993‑1‑3" (Figure 03) or in the corresponding dialog box.
Figure 03 - Table 1.7 Notional Flat Widths | EN 1993-1-3
Then, you can define stiffeners in Table "1.8 Stiffeners" or in the corresponding dialog box (Figure 04).
Figure 04 - Table 1.8 Stiffeners
Furthermore, you should specify the buckling panel in Table "1.9 Buckling panels" (Figure 05) or in the dialog box. To do this, select the elements of the buckling panel. The stiffeners located in the stiffened panel are identified automatically.
For the design of a cold-formed cross-section in RF‑/STEEL Cold‑Formed Sections, it is sufficient to define the stiffeners and panels of the cross-section. It is not necessary to additionally calculate the effective cross-section in SHAPE‑THIN. Thus, you can start the calculation and click "OK" to confirm the warning message (Figure 06).
Figure 06 - Warning "Effective Cross-Section Values Cannot Be Calculated"
After saving the calculated cross-section, it can be imported into RFEM or RSTAB.
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The reason for the different results is probably the settings of effective lengths for the stability analysis. According to the default setting, these are determined automatically in the RF‑/CONCRETE Columns add-on module. However, this method does not work for divided members, and thus no stability analysis is performed (a corresponding warning message appears).If you have entered the effective lengths manually, this only applies to a single member. In order to perform a correct stability analysis of the column as an entire structural component, it is necessary to define it as a set of members. -
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With the PLATE-BUCKLING add-on module, you can only calculate rectangular buckling panels.The panel is entered via 1.1 of the add-on module. Alternatively, the panel can also be created from an existing RFEM or RSTAB file by selecting the respective c/t-part. -
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Yes, for the nonlinear calculation in RF-CONCRETE Members, it is possible to select the high-strength steel SAS 670 for the design. In this way, you can perform stability analysis for columns, among other things.The steel can be selected in the Materials section of the module (see Figure 01). Since DIN EN 1992-1-1 only allows fyk = 500 N/mm² by default, this limit must be adjusted when using SAS 670.In the general data, you can create a user-defined National Annex where the maximum value of yield strength is increased to fyk ≥ 670 N/mm² in Point 3.2 (see Figure 02). -
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Since concrete has a nonlinear material behavior that can only be simulated with the CONCRETE NL module, it is not possible to analyze it by using the RF‑STABILITY add-on module.
The use of another material model such as isotropic linear elastic or isotropic plastic would not represent the crack formation correctly, and the results are therefore not usable.
The stability analysis on columns can be performed with RF‑CONCRETE Columns or RF‑CONCRETE NL. You can find a small example under Downloads.
This example includes the design of a column by the RF‑CONCRETE Columns add-on module. Make sure that the calculation of the internal forces in RFEM is performed according to the geometrically linear analysis and that no imperfections are required because the method used in the add-on module takes them into account.
The example also includes the design with RF‑CONCRETE NL. Here, it is also necessary to calculate according to the second-order analysis and it requires the imperfections in the form of inclinations. For better comparability, the layout of the longitudinal reinforcement was aligned with the result from RF‑CONCRETE Columns, as shown in Figure 01 and Figure 02. Since the reinforcement is optimized by the module after a new calculation, the desired reinforcement was saved as a template (see the red arrow).
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Yes, that is possible.
First, RF-STABILITY (or RSBUCK in RSTAB 8) can be used to determine the effective lengths for a particular structure and loading.They can then be imported in the 'Effective Lengths' of the RF-/TIMBER Pro dialog box.
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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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