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Frequently Asked Questions (FAQ)
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First, the ribbed plate should not be modeled with the classic rib member from RFEM, but with an eccentric beam member that is arranged on the bottom surface of the actual plate. Rib members cannot be calculated with RF-CONCRETE NL with regard to deformations.
The eccentric beam is then designed in RF‑CONCRETE Members. In the "Serviceability Limit State" tab of Window 1.1, you can activate the "Nonlinear calculation.". In the detailed settings for the nonlinear calculation, you can activate the export of stiffness from the nonlinear calculation.
In the example presented here, the stiffness is exported "individually" for each LC calculated in RF‑CONCRETE Members. You can find more information about the options "Individual" and "Consistent for reference load" under the link below.
After the calculation in RF‑CONCRETE Members, the exported stiffnesses of the calculated COs are available in RFEM, where you can activate them in the respective COs for a new calculation of internal forces. To do this, activate the extra options of the respective CO. In the "Extra Options" tab, you can then activate the stiffness exported from the RF‑CONCRETE Members add-on module for a new determination of internal forces.
After recalculating the internal forces of the COs in RFEM (taking into account the exported stiffness from RF‑CONCRETE Members), you can apply them for design in RF‑CONCRETE Surfaces.
The following figure shows the deformations of the ribbed plate in RF‑CONCRETE Surfaces, taking into account the stiffness in cracked state from the design in RF‑CONCRETE Members.
In comparison to Figure 03, the linear-elastic stiffness in uncracked state (state I) was applied in Figure 04 for the eccentric beam.
Notes on the procedure described above:
- In this case, the calculation was performed in RF‑CONCRETE Members first, and the resulting stiffness was exported. This approach was selected because it was assumed that the eccentric rectangular cross-section will proceed to the cracked state (state II) first.
- The procedure shown "only" describes one iteration and is therefore only an "approximation" since an uncracked plate was assumed for the calculation of the eccentric rectangular cross-section.
- The shrinkage effect is applied as an external load in the NL calculation in RF‑CONCRETE Members. This means that, for example, an unsymmetric reinforcement would result in an additional curvature, even if the cross-section remained in the uncracked state. When calculating the plate in RF‑CONCRETE Surfaces, this effect of shrinkage on the member cross-section is not taken into account anymore.
In the design modules of RFEM or RSTAB, you can define "Provided Basic Reinforcement" and perform a nonlinear calculation in the ultimate limit state for this reinforcement.
As a result, you obtain the utilization ratio from the nonlinear calculation assuming the provided longitudinal reinforcement.
The nonlinear calculation is already included in the CONCRETE add-on module for RSTAB. In RFEM, the RF‑CONCRETE NL add-on module is required.
As an alternative to the rectangular cross-section, there is also a "rotated unsymmetric floor beam," which can be created as a cross-section by using the cross-section library.
Subsequently, this cross-section can also be designed in RF‑CONCRETE Members or CONCRETE.
AnswerIn principle, RF‑/CONCRETE Columns designs the statically required reinforcement for a buckling analysis and generates a reinforcement proposal on this basis.As an alternative to this procedure, it is also possible to specify a certain minimum reinforcement ratio before starting the calculation. The input for this can be found in the '1.4 Reinforcement' mask in the register regarding the selected National Annex of EN 1992-1-1 (e. g. DIN EN 1992-1-1).A new reinforcement concept is defined based on the entries specified here and used to perform the designs.
In RF‑PUNCH Pro, a primary and secondary load is determined when introducing a compression and tensile force at a point of punching shear (for example, a column). For example, this may be the case when calculating a result combination (RC) that results from a previous dynamic analysis with RF‑/DYNAM Pro.
In this case, the tensile and compressive forces may occur at the connection of a column to a slab. The add-on module analyzes both "punching directions" individually and displays them as "primary load" and "secondary load."
In principle, RF‑/CONCRETE Columns designs the statically required reinforcement for a buckling analysis and generates a reinforcement concept on this basis.
This reinforcement concept can be used to perform the fire resistance design, for example.
As an alternative to this procedure, you can also specify a certain minimum reinforcement content before starting the calculation. You can enter the data for this in Window "1.4 Reinforcement," in the tab for the respective National Annex for EN 1992‑1‑1 (for example, DIN EN 1992‑1‑1).
A new reinforcement concept is defined on the basis of the entries specified here, and used to perform the designs.
In RF‑CONCRETE Surfaces, the compression reinforcement is calculated as well.
The note "compression reinforcement" is displayed in the design details for the respective reinforcement layer.
AnswerThe partial safety factors for reinforced concrete design can be edited in Window 1.6 "Reinforcement" in the corresponding tab for the selected National Annex (for example, DIN EN 1992‑1‑1).If required, you can also reset these values to the default value.In a similar way, this also applies to the add-on modules RF‑CONCRETE Surfaces and RF‑/CONCRETE Columns.
AnswerOpen Window 1.4 Reinforcement and clear the "All" checkbox. Then select the surfaces numerically or in graphics by using the arrow icon.
A solid must always be completely closed. To clarify the problem, imagine filling the solid with a liquid. The liquid must not escape from the solid at any point.
The attached video shows how to easily and effeciently insert the missing surfaces.
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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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