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Frequently Asked Questions (FAQ)
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The "Simulate and Generate Wind Loads" interface application allows you to exchange member, surface, and solid elements in RFEM, and member elements in RSTAB.
To avoid too fine mesh and thus too long calculation time, the program simulates all members with a rectangular cross-section by default. In this case, the size of the rectangular cross-section is selected in such a way that it barely includes the real cross-section geometry.
By deactivating the "Export optimized member topology" option, you can avoid this additional optimization of the model and allow consideration of the real cross-section geometry within the existing cross-section settings.
If the exact display of the cross-section geometry requires more than 1,000,000 elements, the interface automatically switches to the simplified rectangular cross-section display.
AnswerBy using the FE mesh refinement, the program allows you to create a mapped FE mesh. The automatic FE mesh generator can thus be controlled to a certain extent. However, a specified mesh geometry cannot be set.
AnswerThe load from the form-finding load case (FF) is fixed to the structural system 1.0‑times. If you want to factorize the dead load related to the combinations, it is possible to additionally create a permanent load case for the dead load with a 0.35‑fold load.
AnswerSuch an effect could be caused by free edges, which can be deformed almost infinitely during the form-finding process. In this case, it is difficult to achieve the state of equilibrium.As a basis for the form-finding, there should be no free edges on the membrane surface. There must be cables arranged on the free edges of the membrane whose stiffness can be based, for example, on the folded or strengthened membrane edge strips.
For form-finding, it is primarily important to apply the prestress for the membrane and the border cables that are possibly available. It is not necessary to prestress the riggings.
The riggings can be created as a tension member with its initial length (see the figure). Due to the prestressed membrane and the border cables, the load for the rigging results during the calculation.
By activating the RF‑FORM‑FINDING add-on module, a high-quality form-finding process according to the URS method is determined for each element with form-finding properties before the very structural analysis. After the calculation, this process results in an optimum equilibrium shape that almost exactly corresponds to the preset form-finding parameters (prestress, sag, and so on).
Since this URS method requires an iterative calculation to display the results, the program provides an interactive graphic mode based on the force density method for pure modeling. This mode displays the resulting element shape on the basis of the defined form-finding properties already when entering the elements.
To avoid possible initial complications due to the incompletely defined models, it is possible to switch the mode on and off at any time by using the "Show Preliminary Form-Finding" option in the shortcut menu.
During the determination, the graphic mode considers all force-related form-finding entries on the member and surface elements. A stable boundary condition is assumed in the respective direction for all relevant nodes with a connected element or support definition. Furthermore, the integrated openings in surfaces are considered for the optimized display of tent points.
Generally, this interactive form-finding is only intended for graphical display of the elements with imposed loads and works independently of the URS form-finding, which is always carried out before the pure structural analysis. However, the surface meshing is based on the currently displayed shape and can thus be influenced by the activation of the interactive form-finding.
AnswerThis message is usually displayed in the case that the member dimensions do not correspond.In the example model, the beam has a flange width of 200 mm and the column support of 160 mm.This joint is not valid in the add-on module as the flange width of the column should be at least as large as the flange width of the structural element to be connected. As soon as the cross-sections are defined according to this rule, the connection design can also be performed.
AnswerNo, the program does not currently provide any wind load generation according to DIN EN 13782. In the "Tools" menu, however, a large number of load generators is available and independent of various standards. You can find an overview of all load generators at the following link.
Since the generation of wind loads on any model geometry is a very complex issue and the standards only output the cp values for certain body shapes, there is an alternative program RWIND Simulation in our product portfolio. This program simulates the wind flows around any building in a numerical wind tunnel and generates the resulting wind loads for further structural analysis. You can find more information at the following link.
This is used to provide proof of longitudinal joints of welded cross-sections. [NOT_TRANSLATED]
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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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