In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.
Frequently Asked Questions (FAQ)
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After the calculation, you can switch to the result window "2.4 Required Reinforcement by x‑Location" in the RF‑CONCRETE Members (RFEM) or CONCRETE (RSTAB) add-on module.
Here, you can select a certain result row for a particular design and x-location (upper table in Window 2.4). Then, you can evaluate the intermediate results in the lower table in Window 2.4. This covers the "Neutral Axis Depth x", for example. The location of the neutral axis for the selected design location is displayed in the graphic on the right of Window 2.4 .
Furthermore, you can display the distribution of the neutral axis depth along the member length graphically in the model or in "Result Diagrams on Member."
You can find the setting in Window 1.5 Support.
Here, you can enter the support width and type, and specify whether to carry out the moment redistribution, or the reduction of moments or shear forces.
Depending on the standard selected in Window 1.1, there are different options available. The option applies to RF‑CONCRETE Members (RFEM 5) and CONCRETE (RSTAB 8).
There is very likely no uniform member orientation, see Figure 01.
As soon as the member orientation is uniform (right-click on the member → "Reverse Member Orientation"), the signs of the shear force diagram also match, see Figure 02.
AnswerYes, it is. If you specify the longitudinal reinforcement to be used for punching shear design, the RF‑PUNCH Pro add-on module increases the reinforcement ratio by increasing the longitudinal reinforcement. In this case, the specific punching shear reinforcement only results if the design value of the punching shear resistance without the punching shear reinforcement is less than the stress action of the punching shear force, even with the maximum longitudinal reinforcement ratio.In order to ensure that RF‑PUNCH Pro does not increase the longitudinal reinforcement to avoid the punching shear reinforcement, but directly calculate the last one for the user-defined longitudinal reinforcement ratio, it is necessary to select the Define check box of the Cross-Section entry in Window 1.5 Nodes of Punching Shear in RF‑PUNCH Pro, and enter a constant value of the longitudinal reinforcement.
AnswerIn the add-on module, the shear design is performed in the following sequence:1. VEd/VRd,c
3. VEd/VRd,pIn the course of VEd/VRd,max, the inclination of the concrete strut is determined, and in the course of VEd/VRd,s, the reinforcement amount is determined iteratively.If VEd/VRd,max is not fulfilled in the design process, the subsequent design of VEd/VRd,s is not performed and the design criterion VEd/VRd,c is displayed.
AnswerIn the case of significant deviations, the problem may be caused by the applied bending theory (Mindlin or Kirchhoff).For this, see FAQ Mindlin Kirchhof.
AnswerIn the case of a rib member, the shear force Vz consists of member internal forces, which relate to the eccentrically connected rectangular member, and of surface internal forces, which are integrated over the defined integration width.A decreasing value of the shear force Vz directly above the support (see Figure 01) usually results from the distribution of the surface internal forces (basic internal force vx or vy). See the distribution of basic internal forces v‑y in Figure 02. A "zero crossing" of the surface internal forces results above the support. This "zero crossing" results from smoothing of the surface internal forces within the surface and is also reflected accordingly in the member internal forces of the rib member.To avoid the "problem," it is possible to divide the continuous surface above the support into a surface before and behind the support.During the integration of the surface internal forces, the smoothed distribution of the surface internal forces "within the surface" is applied. If you enter a surface before and behind the support, you will obtain a result value exactly on the location next to the nodal support without zero crossing. In Figure 04, it corresponds to +112.63 kN/m or -112.63 kN/m.
AnswerThe RF‑CONCRETE Surfaces add-on module uses the resulting shear force from the basic internal forces vx and vy. The internal force vx corresponds to the shear force distribution in the direction of the local axis x of the surface, and the internal force vy to the shear force distribution in the direction of the local axis y.The resulting shear force, which is also used in the shear design, is then calculated as:vEd = √(vx² + vy²)
AnswerThe stress calculations are performed on stress points of a cross-section.
The cross-sections of the cross-section types
- Flat steel
- Square steel
- Hexagonal steel
- Octagonal steel
- Wide flats
If a member with one of these cross-sections is subjected to the shear force or torsion, it is necessary to select solid cross-sections.
AnswerIt is correct that singularities in the FE calculation also affect the results of the determination of the LO ratio ß by means of the sector model.Smooth ranges applied in the RFEM model have no influence on the determination of ß in RF-PUNCH Pro.If the results in the critical control perimeter are influenced by the singularities, you can select the Load increasing factor ß yourself. You can display the "Shear force in sectors" in the result navigator of the RF-PUNCH Pro Results window (Figure 01). The maximum value of all sectors is used to determine the ß-factor.You can also find an article describing the load increasing factor ß in our Knowledge Base .Now, you can estimate by the engineer whether this value is to be applied for the determination of the LO-factor, or not. If not, you as the user can evaluate the distribution of the shear force in the sectors (see Figure 01) and determine the load increment factor ß yourself (averaged value of the considered sector / averaged value over entire control perimeter).In the input dialog box "1.5 Nodes of Punching Shear" in RF-PUNCH Pro, you can directly specify the loading increase factor ß. See Figure 02. Thus, you can avoid values resulting from a singularity by individually specifying the load increasing factor β.The following is important:The program can not provide automatic control for this. These points must always be individually checked and evaluated by the designer.
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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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