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Frequently Asked Questions (FAQ)
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According to DIN EN 1993‑1‑1, 220.127.116.11 (2), the reduction factor χLT can be modified by the f factor for χLT,mod. You can activate or deactivate this option under National Annex Settings.
AnswerIn addition to the stability analysis in Sections 6.3.1 to Section 6.3.3 of EN 1993‑1‑1 (Equivalent Member Method), RF‑/STEEL EC3 also provides the General Method according to Section 6.3.4 of EN 1993‑1‑1.This can be extended with the following options:~ The European lateral-torsional buckling curve, which is regulated in the German National Annex to EN 1993, for example.~ Extension of biaxial bending according to the dissertation by Dr. Naumes.~ The interpolation between lateral buckling and lateral-torsional buckling.When designing sets of members according to the General Method, a window is available in the Window "1.7 Nodal Supports - Sets of Members" where the nodal supports are displayed graphically on the set of members. In this way, the General Method represents a useful supplement to the other design methods, which has proven itself, particularly when designing tapers. It is not necessary to enter effective lengths in this method.In the "Details" of the add-on module, you can select the method to be used for sets of members in the "Stability" tab (see Figure 01).The equivalent member method may only be used for straight sets of members with a uniform cross-section (that is, not for tapered joints). For members with a variable cross-section, use the preset General Method.
AnswerThis is not possible directly in RFEM, but the RF‑/STEEL EC3 add-on module allows you to create a list of steel parts. In Details of the add-on module, you can specify whether the parts list should apply to all members or only for members to be designed. Then, you can simply carry out the calculation and the parts list will be displayed. It is also possible to export the parts list to Excel and further edit it.
AnswerThe Design According to Formula column lists the equations of the standard used to carry out the design.The abbreviations stand for the following designs:CS Cross-section designST Stability analysisSE Serviceability (SLS design)The numbers directly behind it are internal information.The lower table of the intermediate values shows the design formulas with the design conditions that are relevant for the selected design.
AnswerUnfortunately, groups of members cannot be designed in STEEL EC3. A continuous member can only be created and selected to design continuously connected members.
AnswerUnfortunately, this is not possible. The design module can only be used together with the internal forces from RFEM or RSTAB.
AnswerIn this case, it is recommended to use the module extension RF‑/STEEL Warping Torsion:RF-/STEEL Warping Torsion is an extension of the RF-/STEEL EC3 and RF-/STEEL AISC add-on modules. It performs flexural-torsional (flexural-torsional) buckling analysis of members according to the second-order theory with seven degrees of freedom and application of imperfection with regard to mode shape.You can find more information under the links below this FAQ.
You can find this setting in "Details," under the "Fire Resistance" tab.You can also control the time of fire resistance individually for each member or set of members.Then, it is possible to find the input in Table 1.10 for members, or Table 1.11 for sets of members.
AnswerIn the RF‑/STEEL add-on module, the equivalent stress analysis is carried out according to von Mises. The elastic stress analysis (EL-EL) is to be performed. In RF‑/STEEL EC3, a classification is done before the design. If a cross-section is classified as Class 1 or Class 2, the design is carried out against the plastic limit internal forces. The EL-PL design is to be performed. If you do not want to use the plastic load reserves, you can switch the design to EL‑EL in the details of the RF‑/STEEL EC3 add-on module. The results are then comparable with RF‑/STEEL.
Most likely, the error is in the selection of the cross-section:
For steel design, a thin-walled flat bar cross-section should be selected instead of a rectangular solid cross-section, see Figure 01.
The reason for the high shear stress of a solid cross-section is caused by the existing stress points of the cross-section or by the corresponding thickness of this stress point.
In the case of a thin-walled flat bar cross-section, there are four stress points at the corner points of the cross-section with the corresponding thickness t = 10 mm, see Figure 02.
For a solid cross-section, however, there is another stress point in the center, where the maximum of height h or width b is assumed as the thickness t for this cross-section type. In this case, the width b is 200 mm, see Figure 03.
This results in a small torsional section modulus Wt and the correspondingly high shear stress.
The solution is, as described above, to select a flat bar in the main program.
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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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