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Frequently Asked Questions (FAQ)
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Yes, that is possible. If the add-on module PLATE-BUCKLING is not opened as a stand-alone version, but via RSTAB or RFEM, the panels (c/t parts of a member cross-section), as well as the respective load cases in PLATE-BUCKLING of the RSTAB or RFEM Models, can be loaded (see picture).
For solids, we do not provide any internal forces in the program. Converting the stresses into internal forces would also be very complex, because not only mx, my, and mz would be available, but also the torsional components, mxy, myz, mxz, as well as shear and axial forces. For solids, the general rule is a direct stress evaluation. If you still need internal forces, you can refer the internal forces of the solid to a member. The result beam has been implemented in the program for this purpose.
It depends on the choice of the model type. In this case, a plane system was selected. Thus, the relevant results are displayed even for this plane because they are reduced due to the limited coordinates and degrees of freedom (see Figure 1). However, if you select a 3D structure as the model type, all stresses and internal forces are displayed (see Figure 2).
AnswerFor the surface type with the "glass" stiffness, no stresses are displayed in RFEM. The reason is that this stiffness type is only a placeholder for the RF-GLASS add-on module. This means that it is necessary to enter further data for the glass pane, such as the layers, nodal supports, edge members, and the load duration data. You can enter these data in the RF‑GLASS add‑on module. It is also possible to evaluate the stresses, loads and deformations by layer in the add-on module (see Figure 01 and Figure 02).On our homepage, you can find two interesting webinars about the RF-GLASS add-on module.
AnswerIf you want to get the results of the edges of a surface, you can view the result diagrams on the line by right-clicking it.
If a member lies on the line, you have to hide it first. The easiest way is probably to deactivate all members in Display Navigator --> Model Data.
Why do I get no stresses on the top or bottom side of a member loaded with temperature (heating on the top side) if the member has no elastic foundation? Or more specifically, why does the upward curved member (due to heating on the top side) have tension stress on the bottom side if the member has elastic foundation? There must be compression stress on the bottom side.
The topic can be easily illustrated on a single-span beam. For this, three structural systems are described below. These models are documented in the attached file.
Statically determined system (no foundation), dT = 80 ° on the top side
The member is curved upwards, but is free of stress in itself.
Like System 1, but with an additional member elastic foundation. The member elastic foundation is entered without a possible failure (nonlinearity).
If you would display the stresses sigma_x of the member for System 2a, you obtain compression on the top side of the member and tension on the bottom side of the member (see Figure 01).
Due to the curvature of the member and the existing member elastic foundation, the contact force p-z occurs, which should prevent the member curvature upwards (see Figure 02).
These contact forces p-z (Figure 02) are caused by the member curvature due to the temperature and the applied member elastic foundation. The illustrated contact forces can be replaced by the member load opposed to the curvature. This is shown in System 2b in the example file.
The member elastic foundation is removed and a variable member load is entered in the Z-direction.
When comparing the results (for example, deformations u-z) on both System 2a and System 2b, you obtain the results with the same value (see Figure 03).
Moreover, you can also display the stresses sigma_x for both System 2a and System 2b. These have also the same value (see Figure 04).
System 3 should only document the stresses due to the temperature difference on a statically determined system (without foundation).
The results documented in the "single-span beam" example can also be transferred to the surfaces with elastic foundations.
In RF-CONCRETE Surfaces, you can use the [Info] button to display the corresponding steel stresses for each design location for the ultimate limit state (see Figure 01). A graphical display is not possible here.
For the serviceability limit state design, it is possible to display the steel stress graphically as the corresponding design can be performed (see Figure 02).
When designing a wall corner or a wall end in RF-PUNCH Pro according to DIN EN 1992-1-1, you do not have to enter the counteracting soil pressure separately.Reason:The module determines the punching load for the design at a wall corner or a wall end from the integration of shear forces in the critical perimeter.Thus, the part of the soil pressure within the critical perimeter is not used for the determination of the punching force anyway, so it is not necessary to deduct it separately.The situation is different if you analyze the punching of a single column.Supb intersection standard force is applied for the punching load by default. In this case, you can specify a soil pressure under the floor or foundation slab. You can find the input option in Table 1.5 of the RF-PUNCH Pro add-on module.The size of the area load to be subtracted can be determined in RFEM by evaluating the contact stress σzdetermined from the governing load case or the governing combination and entered manually in the module in window 1.5.
AnswerWith the new member type "Result Beam" it is possible to greatly simplify the results evaluation of deep beams. This virtual member has no stiffness and is used to integrate the internal forces of members, surfaces and solids in order to show them as member internal forces.
By defining a cross-section you can use the result beam also for a design in add-on modules like RF-STEEL EC3 or RF-CONCRETE Members.
As an example, the graphic shows the determined reinforcement of window and door lintels and a split-level ceiling.
No, they are not. In RFEM/RSTAB or the RF‑/STEEL add‑on module, the warping torsion does not play a role. For members, the warping resistance has no effect here.
RF-/STEEL calculates torsional stresses close to reality by using MT/WT or MT/(IT/z). With this approach, the warping torsion (primary and secondary torsion or warping bimoment) is not considered.
The warpage is considered in the add‑on modules RF‑/FE‑LTB, RF‑/STEEL Warping Torsion and the cross-section properties program SHAPE‑THIN.
RF-/STEEL Warping Torsion is an extension of the RF‑/STEEL EC3 add‑on module. It performs lateral‑torsional (flexural-torsional) buckling analysis of members according to the second‑order theory with 7 degrees of freedom and application of imperfections with regard to mode shapes. The designs are based on the standard EN 1993‑1‑1:2005 + AC:2009.
Find more information in the webinar "New Modules RF-/STEEL Warping Torsion and RF-/STEEL Plasticity," that you can download under Links below.
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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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