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Frequently Asked Questions (FAQ)
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If the punching load in RF-PUNCH Pro is to be determined from the shear forces in the critical perimeter, the lower right corner of the input dialog 1.5 provides the option “Consider Surface Load Inside the Critical Perimeter”.When selecting the “Determine” option, the program requires a unique load situation. This unique load situation is not given when applying the result combination (RC). Therefore, you receive the mentioned message No. 58.You can avoid this problem by manually defining the area load within the critical perimeter or by using the load combinations (COs) instead of the result combinations (RCs) in your calculations.
Yes, as of the program version RFEM 5.20.01, it is possible to consider the load on the surface within the critical control perimeter.When determining the punching load in the critical perimeter e.g. at a wall corner or at a wall end, the add-on option 1.5x is available at the end of the input dialog. See Figure 01.You can also select if the area load is to be determined or preset automatically.In the results dialog box 2.1., the program provides you with a list of area load or additional load.
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 is automatically assigned 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 either 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, the input dialog box "1.4 Longitudinal Reinforcement" shows all surfaces that connect to the selected node for design. 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 box 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. This also includes the walls in the wall corner that you mentioned.However, the definition of the position of the longitudinal reinforcement for these walls does not become relevant for the punching design in the floor slab.Starting with version 5.19.01 of RFEM, a filter has been installed with which you can only display the surfaces for which the definition of the position of the longitudinal reinforcement is relevant.You can find the Filter button in the input dialog box 1.4 on the bottom right. See Figure 01.
AnswerWe would like to give the user as much freedom as possible when controlling the designs in RF- / FOUNDATION Pro. By default, the relevant designs according to EN 1992-1-1 and EN 1997-1 are activated when creating a new case.Some of them can be deactivated. On the one hand, if a design is not necessary due to the structural design of the foundation. On the other hand, for testing or verification purposes.Please note, however, that at least one geotechnical design according to EN 1997-1 must be activated.
AnswerThe minimum shear reinforcement A sw, min is determined in RF-PUNCH Pro by means of Equation 9.11DE from DIN EN 1992-1-1, 9.4.3.The input values used for determining A sw, min are shown in result table "2.2 Required Punching Shear Reinforcement" in the section "Minimum NB" so that the calculated value can be retraced.Please note that the calculated value A sw, min according to the standard refers to the "cross-section of a stirrup arm (or equivalent)". In RF-PUNCH Pro, this value is then multiplied by the tangential number of the individual stirrup rows, which means that the absolute value of the minimum reinforcement [cm²] in the individual perimeters can increase outwards with increasing round perimeter length or increasing number of stirrup legs.
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.
It seems that the RFEM 5.18.01 and Halfen HDB 13.21 versions are not compatible.I get the error message in RF-STANZ Pro, according to which the design program Halfen HDB is not found. This is with me but installed and registered.What can I do?
AnswerIn fact, there is unfortunately an inadequacy in the interface between Halfen HDB (version 13.21) and RF-STANZ Pro (5.18.01). We have fixed this inadequacy with an update.You can find the download link for the update via the download area of your Dlubal account or directly via the message of our hotline support.
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