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Frequently Asked Questions (FAQ)
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Warning 155 appears if the distance of the stirrup legs of a beam in the transverse direction exceedsthe limit value of the standard s t, max. (See Eurocode 2, Section 9.2.2 (8)). The problem can be solved by increasing the cutting ability of the stirrups in the settings for the stirrup reinforcement.
AnswerThis setting is used to reduce the effective concrete tensile strength fct, eff. If you expect a Crack formation in the first 28 days, you should reduce the effective concrete tensile strength fct,eff according to EN 1992-1-1, 7.3.2 (2). You can enter the appropriate reduction factor into the input field. The German National Annex recommends to use fct,eff = 0.50 ⋅ fctm (28d). If you cannot determine a definite point of time for crack formation within the first 28 days, a tensile strength of at least 3 N/mm2 for normal concrete should be assumed in accordance with the German National Annex.
The list of possible diameters can be extended or modified in the modules CONCRETE, RF CONCRETE Members, or RF/CONCRETE Columns using the "Edit List of Possible Diameters" button.
AnswerThe RF-/FOUNDATION Pro add-on module only works as part of the main program RFEM or RSTAB. Unfortunately, it is not possible to run this program on its own.
AnswerIn RF‑CONCRETE Members, you can only find the utilization for a nonlinear calculation. For a linear calculation, the value of a partial safety factor (safety factor = NRd/NEd) is available. You can obtain the utilization by reversing the value of the partial safety factor.
The design of a column with RF‑CONCRETE Columns determines a provided reinforcement, among other things. This is displayed in Table 4.1 and illustrated in the graphics below and in the table on the right.
You can use the "Edit Reinforcement" button to change the reinforcement, if necessary. Click the button to open the "Edit Longitudinal Reinforcement" dialog box (see the image). It includes the table for the "Position of Reinforcement Bars." Here you can delete rows by selecting the row that contains the member to be removed and then clicking the button below.
If "Uniformly surrounding" is set for the reinforcement distribution, the longitudinal reinforcement can be increased or decreased by selecting the number of members in four steps.
Then, it is necessary to recalculate the design for the modified reinforcement arrangement in order to update the design ratio.
The described procedure is shown in the explanatory video.
In RF‑CONCRETE Members, you can select the option to consider a precamber due to temperature gradient under the "Fire Resistance" tab in Window "1.6 Reinforcement." For the calculation, the program internally creates a member load as precamber of the cross-section.
However, the result beam is a virtual member that does not have any stiffness nor consider any support, which is not suitable to absorb loads. Therefore, an error message appears when starting the calculation if the precamber due to temperature gradient is selected in RF‑CONCRETE Members for the design of result beams.
Yes, the load can be entered in RFEM as a surface load. In the Edit Surface Load dialog box, you can find the Generate Load due to Shrinkage... button. This allows you to obtain the internal forces due to shrinkage.
In order to consider the shrinkage in the RF‑CONCRETE Surfaces design, it is not necessary to enter a load. The RF-CONCRETE Surfaces add-on module automatically apply the loads due to the shrinkage.
AnswerThe shrinkage and creeping parameters can be found in Table 1.3 in the last column of the table Creep Coefficient / Shrinkage Strain.
When creating a new element (a member, a surface, a solid), there is a corresponding function at the bottom of the dialog box that allows you to import the properties of another element (see Image 01).
After activating the function, click the element from which you want to transfer the properties. In addition to the geometry and the material, other settings, such as eccentricities or stiffness modifications, will be transferred as well.
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Wind Simulation & Wind Load Generation
With the stand -alone program RWIND Simulation, you can simulate wind flows around simple or complex structures 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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