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Frequently Asked Questions (FAQ)
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The selection in the '1.3 Surfaces' input dialog box within the 'Limitation of Crack Widths' tab has a direct influence on the kc factor for the analytical calculation of the minimum reinforcement As,min for absorbing effects due to restraint according to Equation (7.1), DIN EN 1992-1- 1, 7.3.2.If 'Centrical Restraint' is selected, a kc value = 1.0 is applied in equation (7.1). When applying 'Bending Restraint', the module sets the kc factor strictly to 0.4.If ‘Depending on Defined Load’ is selected, the program interpolates the kc value element by element depending on the stress distribution in the cross-section using the defined load.This results in a constant distribution of the minimum reinforcement from restraint being determined for the respective reinforcement direction of the surface when ‘Centrical Restraint’ or ‘Bending restraint’ is selected. If you select 'Depending on Defined Load', no constant distribution of the minimum reinforcement is resulting from restraint.The program behavior described above is identical in RF-CONCRETE Members and RF-CONCRETE Surfaces (in RFEM 5) and also applies to the CONCRETE add-on module (in RSTAB 8).
AnswerPlease deactivate the 'Indirect Calculation' by means of the steelbar diameter 'limit ds' or the steelbar distance 'lim sl'.The calculation of crack widths smaller than 0.20 mm is only possible via the direct calculation according to EN 1992-1-1, 7.3.4.
Whether or not you see the selection in the Results navigator depends on the settings for the serviceability limit state design.In the settings for the serviceability limit state design, you can find the option 'Increase Required Longitudinal Reinforcement Automatically for Serviceability Limit State Design'.Only if the automatic increase of the longitudinal reinforcement has been activated is the 'Limit States' entry available in the Results navigator.
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 results tables, the "Design Details" button is grayed out.You can select the design details for the serviceability limit state in Tables 3.1 - 3.3.
AnswerThe deduction of the precamber in the serviceability limit state design is actually not regulated in steel structures. After numerous customer requests, we have adopted this in accordance with the TIMBER or CONCRETE add-on module. However, according to the standard specification, this value should only be considered in the quasi-permanent design combination.This does not apply to the characteristic and frequent design situation. Thus, as soon as the design situation in the add-on module is adjusted accordingly (see figure), the applied precamber is also subtracted from the resulting deformation.
When checking the deformation value, for example, as a result of the deformation analysis in STEEL EC3, it is necessary to subtract nodal deformations from the total deformation shown in RSTAB (see Figure 01): the deformation value in the centre of the member represents the total deformation of the component (the deformation of nodes plus the deformation of the component).
If the deformation is set as relative to the 'undeformed system' in Details of the serviceability limit state design in the add-on module (see Figure 02), the maximum deformation including nodal deformations (the deformation value displayed in RFEM/RSTAB) is used.
In order to calculate the deformations in cracked state in RF‑CONCRETE Surfaces, it is necessary to select at least one load case or combination in the "Serviceability Limit State" tab in Window "1.1 General Data" (see Figure 01).
In the lower part of the window, specify whether the method of check should be "Analytical" or "Nonlinear."
- If "Analytical..." is selected, it is necessary to activate the "Deflection with RF‑CONCRETE Deflect" option in the detailed settings (see Figure 02).
- If "Nonlinear..." is selected, the design of deformations can also be found under the detailed settings. The "deformation" is activated here by default (see Figure 03).
This depends on the selected settings in the navigator: for the ultimate limit state and the serviceability limit state design, it is possible to select the "limit state" in the Results navigator, whose required reinforcement is to be displayed.
The following settings are possible (see the figure):
- ULS / SLS governing (the envelope of "ULS/SLS")
AnswerUnfortunately, it is not possible with the analytical method. However, you can display members as surfaces and then carry out the deformation in RF-CONCRETE Deflect. As an alternative, it is possible to obtain an approximate image of the deformation in cracked sections (state II) in RF-CONCRETE NL via stifness export for combined structures as well.
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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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