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Frequently Asked Questions (FAQ)
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The RF‑CONCRETE Columns add-on module allows you to define a "creep-producing permanent load." You can find the corresponding tab in Window "1.1 General Data."
The reason for the entry is that RF‑CONCRETE Columns can apply this "creep-producing permanent load" for the automatic determination of the effective creep ratio according to EN 1992‑1‑1, 5.8.4.
In contrast, there is no explicit input option for this creep-producing permanent load in RF‑CONCRETE Members. In RF‑CONCRETE Members, the stability analysis of reinforced concrete columns by means of nonlinear design does not automatically reduce the effective creep ratio. You can find the background to the effective creep ratio applied in RF‑CONCRETE Members in Chapter 2.4.6 of the RF-CONCRETE Members manual.
The same applies to the CONCRETE Columns or CONCRETE add-on modules for RSTAB.
RF-CONCRETE Columns determines the equivalent moment M0e from the moment M02 at the column head and M01 at the column base according to EN 1992‑1‑1, 18.104.22.168 (2), and performs the design according to the model column method with this equivalent moment M0e.
Now, it may happen, for example, that a computationally larger required reinforcement area would result from the cross-section design with the moment M01 at the column head.
To ensure this, message 28) is displayed, according to which the user should perform a standard design with the internal forces according to the linear static analysis. To do this, simply open the RF‑CONCRETE Members add-on module and perform pure design of the internal forces according to the linear static analysis for the member designed in RF‑CONCRETE Columns.
In RF-/CONCRETE Columns, a column is designed as a "structural component."When displaying the results "Bending," "Shear Force," and "Bending - Fire Resistance," the resulting maximum value of the design criterion is displayed as a single value at the governing location (x‑location) of the respective design. For example, at the column base, column head, or in the center of the column.If you select the "Highest Design Criterion" result display option, the maximum value of all design criteria is displayed across the entire "structural component" (column).
AnswerNo, it is not possible.A member or a set of members is designed by the model column method as a "structural component."It means that the longitudinal reinforcement is constant over the entire length of the structural component.The design is carried out by means of the governing internal forces at the governing location of the structural component (a member or a set of members).The stability analysis involving a curtailed reinforcement over the column can be performed by using the nonlinear analysis of compression elements in RF‑CONCRETE Members (RFEM) or CONCRETE (RSTAB).
AnswerThe RF‑CONCRETE Columns add-on module uses the model column method with the nominal curvature or the nominal curvature method according to EN 1992‑1‑1.More information about the program features of RF‑CONCRETE Columns can be found on the product homepage that you can access by using the following link. See Links below.
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.
AnswerIt is difficult to name one or particular reasons for the deviations. Basically, the design in RF‑CONCRETE Columns uses an analytical method, the nominal curvature method according to EN 1992‑1‑1, 5.8.8. An advantage is that it is a standardized method, and so all resulting intermediate values of the calculation are displayed in the add-on module.By using the intermediate values, it is possible to search for the cause of the deviation between the different design programs.If you cannot find the cause, please contact our hotline. In this context, however, we need a printout, including the input and the intermediate values from the program used for the comparison.
AnswerCurrently, there is no option to perform a stability analysis in the RF‑CONCRETE Surfaces add-on module. However, you can use a result beam to perform a simplified design by means of the nominal curvature method in RF‑CONCRETE Columns.
AnswerYou can usually set the standard and the National Annex in the top right corner of an add‑on module (see Figure 01). In most cases, it is also possible to display the factors of the National Annex and edit them, if necessary (see Figure 02).
AnswerThe add-on module determines the required reinforcement for the ultimate limit state. The fire resistance design is performed as design based on the determined reinforcement. The reinforcement will not be increased in this process. If the design is not fulfilled, you can either define a higher reinforcement manually or adjust the concrete cover to prevent the applied reinforcement from being damaged too much by the effects of fire.
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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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