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Frequently Asked Questions (FAQ)
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The selection in the "Limit of Crack Widths" tab of Window "1.3 Surfaces" has a direct impact on the kc factor for the analytical calculation of the minimum reinforcement As,min for effects due to restraint according to Equation (7.1) of DIN EN 1992‑1‑1, 7.3.2.If selecting the "pure tension restraint," the value kc = 1.0 applies in Equation (7.1). In the case of the approach of "bending Restraint," the add-on module sets the kc factor strictly to 0.4.If you select "Depending on the defined load," the program interpolates the element of the kc value by the element depending on the stress distribution in the cross-section using the defined load.This results in a constant distribution of the minimum reinforcement due to restraint being determined for the respective reinforcement direction of the surface when selecting "pure tension restraint" or "bending restraint." If you select "Depending on the defined load," there will be no constant distribution of the minimum reinforcement due to restraint.The program behavior described above is the same in RF‑CONCRETE Members and RF‑CONCRETE Surfaces (in RFEM 5), and is also applied to the CONCRETE add-on module (in RSTAB 8).
AnswerNo, this is unfortunately not possible.If the "Tension Stiffening" option is not applied for the calculation, the damage parameter ζ is either "0" for "uncracked sections" or "1" for "cracked sections." For this, see the technical article about the distribution of the damage parameter ζ under Downloads below.Nevertheless, the manual specification of ζ = 0.5, for example, is not possible.
AnswerThe concrete tensile strength fct, eff, wk = fctm × crack width factor is applied.
AnswerNo, it is unfortunately not possible.
AnswerNo, this is unfortunately not possible.The intermediate values from the calculation (for example, effective depth d applied for shear force design) are only available for the selected FE node or grid point when opening the "Design Details" dialog box. But not for all FE mesh nodes of the designed surfaces.Therefore, these intermediate values cannot be used for a graphic display on the model, but only in tables under the design details.
AnswerIn this case, the Calculation Method and the type of the 2D model are important.When using the analytical method (RF‑CONCRETE Deflect), it is possible to perform the calculation in 2D models. When using the nonlinear method (RF‑CONCRETE NL), the calculation for 2D XY (uZ/φX/φY) is not possible. In the nonlinear calculation, shrinkage is represented internally as strain load, which is not possible in this type of 2D model due to the limited degrees of freedom.Convert 2D to 3D ModelIn General Data, you can simply convert a 2D model into a 3D model. For the supports, all degrees of freedom not contained in the 2D model are fixed when converting to a 3D model (see the video).
AnswerIn Table 1.3 Surfaces, you can specify the parameters for the automatic determination of the creep coefficient and shrinkage value in the corresponding tabs. It is also possible to enter user-defined values, if necessary.
AnswerThe differences resulting from the determination of the deformation in the cracked state can have various causes. In the case of deviations, you should check the following points:
Is the same calculation method applied?
RF-CONCRETE Deflect uses the analytical analysis approach according to EN 1992‑1‑1, 7.4.3.RF-CONCRETE NL uses the physically nonlinear analysis approach.You can find more information about the calculation methods in Chapter 2.7 and Chapter 2.8 of the RF‑CONCRETE Surfaces manual.
Is the same initial structure available?
If considering the underlying structural system as equivalent, the results of the linear calculation can be considered in the best way. The linearly determined deformation of the underlying combination should be approximately equal. Possible differences in the linear deformation may be increased in the cracked state in connection with the deformation analysis.
Are the same effects taken into account?
When comparing, make sure that the same effects, such as creeping and shrinkage, are taken into account (Figure 02).
Are the same initial values available?
In connection with the deformation analysis, you should further check if the same initial values are available. In this case, a special attention has to be paid to the fact whether the applied reinforcement (Figure 03) and the lever arm or the concrete cover are the same.
If you cannot find the cause after the fundamental examination, please contact our hotline.
Yes, it is possible.For this, you can select the "Use required reinforcement for design of serviceability" check box in Window "1.4 Reinforcement," tab "Longitudinal Reinforcement."Thus, the add-on module creates the entire reinforcement required for the ultimate limit state design and/or serviceability limit state design in the reinforcement layout.In this case, the result of "Additional Reinforcement" is omitted after the calculation in the result windows in the add-on module as well as in the printout report.It is possible to combine the "Use required reinforcement for design of serviceability" option with the "Increase the required longitudinal reinforcement automatically for serviceability liimit state design" option.
The "Design Details" button is only available or can be selected if the required reinforcement has been selected from the ultimate limit state (ULS).As soon as the governing reinforcement consisting of ULS and SLS or only the SLS is shown in the result tables, the "Design Details" button is grayed out.You can select the design details for the serviceability limit state in Table 3.1 - Table 3.3.
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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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