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Frequently Asked Questions (FAQ)
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AnswerA collapse or tear-resistance according to DIN EN 1992-1-1, 9.4.1 (3) is not output separately in RF-PUNCH Pro and must be additionally taken into account by the designer.
AnswerRF-PUNCH Pro uses the support forces only for the punch supports for nodal supports.For the punching shear design on wall corners and ends, the member behavior is not used as the support force from the line supports but as the shear force in the critical perimeter. This has the advantage that a punching load can also be determined if a wall was entered in a 3D model instead of a line support. Thus, this approach in the add-on module is more general and can be applied regardless of the type of modeling.You can also find additional information about determining the punching load for wall corners and wall ends in an article on our homepage that you can open by clicking the following link.
AnswerWhen displaying the punching diameters by shear force in the critical perimeter, RFEM uses internal sections. The critical control perimeter automatically has an internal division. Thus, the result values are determined on each FE mesh node and on the internal division points. In the Display navigator, you can display all values for the sections or only the extreme value. Thus, a coarser division or output of values can not be set.
In RF-PUNCH Pro, RFEM displays all surfaces connected to the selected nodes for input in the "1.4 Longitudinal Reinforcement" dialog box. For example, in a punching shear design on a wall corner, the surfaces that actually represent the walls are also defined. I can also define a longitudinal reinforcement for these surfaces. Is this somehow applied? Why do I see these surfaces in the dialog 1.4?
AnswerYou are right. In the input dialog box "1.4 Longitudinal Reinforcement", we first display all surfaces connected to the selected node for design. That means also the walls at the wall corner you mentioned.However, the definition of the position of the longitudinal reinforcement for these walls does not become relevant for the punching shear design in the floor slab.Starting with version 5.19.01 of RFEM, a filter has been installed with which only the surfaces for which the definition of the position of the longitudinal reinforcement is relevant can be displayed.You can find the Filter button in input dialog box 1.4 on the bottom right. See Figure 01.
AnswerThe minimum shear reinforcement A sw, min is determined in RF-STANZ Pro using equation 9.11DE from DIN EN 1992-1-1, 9.4.3.The input values used for the determination of A sw, min are output in the result mask "2.2 Required punching shear reinforcement" in the section "Minimum punching reinforcement", so that the calculated value can be reconstructed.It should be noted that the calculated value A sw, min according to the standard refers to the "cross-section of a stirrup leg (or equivalent)". In RF-STANZ Pro, this value is then multiplied by the tangential number of individual rows of hoops, whereby the absolute value of the minimum reinforcement [cm²] in the individual round sections can increase outwardly with increasing length of the round section or increasing number of shackle legs.
AnswerIt is correct that singularities in the FE calculation also affect the results of the determination of the load increase factor β by means of the sector model.Smoothing ranges introduced in the RFEM model have no influence on the ß determination in RF-STANZ Pro.If the results in the critical round section are influenced by the singularities, you have the option of specifying the load increase factor ß yourself. To do this, you can display the "Shear force in sectors" in the result navigator of the RF-STANZ Pro results (see Fig. 01). The maximum value of all sectors is used to determine the β coefficient.You can now estimate in terms of engineering whether this value should be used to determine the load increase factor or not. If not, you as a user can evaluate the progression of the shear force in the sectors (see Fig. 01) and determine the load increase factor ß yourself (averaged value of the considered sector / average value over the entire round cut).In RF-STANZ Pro you have the option of directly specifying the load increase factor ß in the input dialog "1.5 Punching nodes". See Figure 02. Thus, you can handle values resulting from a singularity by individually specifying the load increase factor β.Important is:The program can not deliver automatic for this. These points must always be checked and evaluated individually by the planner.
AnswerIn fact, there is a shortcoming in the interface between Halfen HDB (version 13.21) and RF-PUNCH Pro (5.18.01). We have fixed this deficiency by updating it.You can find the download link for the update via the download area of your Dlubal Account or directly by the message of our hotline support.
Depending on the selected load determination type, RF-PUNCH Pro determines the punching load from the shear forces in the critical control perimeter. The internal forces in surfaces from the RFEM model are used here.
If the FE mesh in the area of the punching node is not fine enough, the results may be inaccurate. In this case, you get message no. 56.
To avoid the problem, you should perform an FE mesh refinement in the RFEM model in the area of the punching node . You can arrange them either directly on the node or on the connecting lines of the wall ends or wall corners.
If the FE mesh refinement is sufficiently fine, the warning message disappears automatically after a recalculation in RF-PUNCH Pro.
Yes, you can. It is possible to export the critical perimeter from RF‑PUNCH Pro as a line to the RFEM model. This is possible for all punching forms (supports, wall ends and wall corners). The corresponding button can be found in the result window 2.1 "Punching Shear Design" (see figure).
In the RFEM model, you will then get a line, where you can create a "section" for further analyses, for example. Please note that the line must be integrated into the FE mesh of the surface. The setting for this can be found in the general FE mesh settings.
The increase of the loading factor β = 1.0 is due to the fact that the "Non-smoothed distribution of shear force" is applied in Window 1.5. This is the default setting for wall corners and wall ends (see Figure 01).
If you change the setting to "Smooth distribution of shear forces in critical control perimeter", the load increasing factor β will be applied (see Figure 02). This is determined by the fully plastic shear distribution according to EN 1992-1-1, 6.4.3 (3) by default.
You can find further information about the topics "Punching Load at Walls and Corners" and "Determining the Load Increase Factor β" in the articles of our Knowledge Base that you can find under the links listed below.
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