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Frequently Asked Questions (FAQ)
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AnswerBy default, the compute core of the cross-section program SHAPE-THIN is used in the RF- / ALUMINUM add-on module to determine the stresses of the effective cross-section in an iterative procedure. This method is precise because all vertices and edges of the cross-section are considered, but can be very time-consuming for complex sections.Alternatively, it is possible to determine the effective cross-section by means of a simplified analytical method (see Figure 01) that runs much faster. In this approach, corners, fillets, etc. are neglected and subsequently compensated by a factor. No iterative calculation is performed. Therefore, the effective cross-section values may be higher than with the SHAPE-THIN calculation.In such a case, it is recommended to carry out the calculation with the analytical method and then to design only the governing structural component with the governing load combination with the SHAPE-THIN solution.
AnswerUnfortunately not. Intermediate supports and nodal supports have to be set manually. The default configuration for effective lengths is 1,0*member length and for set of members, one nodal support with definition u_y' and phi_x' is defined on each side of the set of member.To speed up the process of defining nodal supports, you can pick more nodes in one step by using the highlighted function in the attached picture.
AnswerIn the basic information, the rod sets must first be selected so that they can be dimensioned for the corresponding limit states. Thereafter, various requirements for the proof of serviceability can be made in the usability parameters.
AnswerIn the printout report selection, you will find filter options, for example, to display only the maximum amount of evidence in the table. These filters reduce the size considerably. The filter options are also available directly in the module.
AnswerThe DUENQ cross-section consists of several non-contiguous partial cross-sections, so that in DUENQ it is calculated according to the theory of stiffening systems. DUENQ also gives a hint before the calculation. The dimensioning of such cross sections is not possible in add-on modules such as RF / STEEL EC3, RF / ALUMINUM etc.In most cases, however, the cross-sectional parts should be connected to each other. The FAQ describes how this connection can be modeled.
AnswerAll effective length factors are preset to 1.0 by default. There is no calculation of the factors based on the model.
One or more stress points of the cross-section have a thickness that is not covered by the material properties. Therefore, the add-on modules cannot go back to the yield strength for the design and display the warning.
Please select another material that covers the thickness range, or change the thickness range of the existing material.
The individual designs, for example, bending and compression according to Sec. 6.3.3 EN 1993‑1‑1 cannot be deactivated. For a successful analysis, all required designs are to be fulfilled.
I have modified cross-section properties or reduced stiffnesses of a members in RFEM/RSTAB. After a new calculation, the deformation of the structural system has adjusted itself to the new cross-section properties. However, this change is not taken into account when performing design in add-on modules.
In principle, the modified cross-section properties are not transferred into add-on modules, such as RF‑/STEEL or RF‑/STEEL EC3. They are only used for the calculation of internal forces.
In the add-on modules, stresses are calculated using the real cross-section dimensions, which cannot be modified. This would be difficult to implement as many designs require the element width or height and due to the modification, it is not known which parameter has been reduced exactly. This is important for the c/t-designs in RF‑/STEEL EC3, for example.
If a different cross-section is used in the add-on module than in RFEM / RSTAB, it is displayed in blue. It should also signalize that the internal forces are determined with the cross-section defined in RSTAB / RFEM (in Figure 01: IPE 300), but the design is carried out in the add-on module with the cross-section assigned there (see Figure 01: IPE 80). The cross-sections have different cross-sections if the cross-section in the add-on module has been modified manually or optimized by the program.
You can either read the cross-section from the RFEM / RSTAB again (select "Edit → Import Cross-Section from RFEM / RSTAB") or transfer the cross-section of the add-on module to the main program (menu "Edit → Sending Cross-Section to RFEM / RSTAB", see Figure 02). And. The cross-sections are then identical again and are displayed in black.
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