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Frequently Asked Questions (FAQ)
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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 buckling analyzes of members according to the second-order analysis with seven degrees of freedom and a form of imperfection affecting the mode shape.You can find more information in the links below this FAQ.
AnswerThe load application point in the detail settings of RF‑/STEEL EC3 Warping Torsion only refers to the transverse loads.
AnswerThe axes, to which the support rotations and support eccentricities refer, are preset to the local member axes, which can be displayed with the button under the partial view. However, they can also be switched to the global axis system.
AnswerFor a stability analysis of any cross-section, the add-on modules RF‑/STEEL EC3 Warping Torsion (extension for RF‑/STEEL EC3) and RF‑/FE‑LTB (stand-alone module) are particularly suitable.By using the calculated critical buckling value, you can determine critical loads and perform the design according to the second-order analysis.
The setting of the load application specified in the Details refers to the principal axes of the respective cross-section. For a Z-section as an example, a box with nine edge nodes is set around the cross-section. The load application is then always related to the rotated principal axis angle and the corresponding eccentricities.
AnswerThere is no general answer to this problem. In the RF‑/STAGES add-on module, however, there is a specific feature regarding the structural system. Similar to some other add-on modules, such as RF‑/STEEL Warping Torsion, it is possible to consider the structural system detached from the main program. Thus, there are some advantages regarding the definition of construction stages, and so on. However, this possibility means that the modifications in the main program RFEM or RSTAB are not updated automatically with these add-on modules. Such an update would inevitably lead to incorrect calculations and is therefore blocked.
AnswerThat is correct. For the verification of the relevant components, these must be defined as rod sets and selected for design. It is also important that in the design case of the wölbkraftanalyse no bars are selected for the dimensioning, which are either already included in the staff sets or claimed to torsion, since the module RF- / STEEL EC3 then want to measure these by means of replacement rod method and this possibly no proof due to the torsion is possible and the warning appears.
AnswerIf you have edited the cross-section values of a cross-section or the stiffnesses of a bar with the function "Modify stiffnesses", these are not used in the additional module STAHL EC3. The modified stiffnesses are only used in the internal force calculation. Therefore, it is better to work with double bars when using the STAHL EC3 design.
In RF‑/STEEL Warping Torsion, the imperfection is applied in both directions (+/-). Therefore, the + imperfection can be governing at one x‑location while the - imperfection prevails at the adjacent x‑location. The governing result is shown in the result tables and in the graphic. This could be the cause of the described effect.
Please check the boundary conditions, that is the definition of nodal supports and especially the application of imperfection in Window 1.13 "Parameters - Sets of Members." The imperfection is preset as L/150, which can represent a conservative solution.
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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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