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Frequently Asked Questions (FAQ)
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AnswerThis may be related to the curtailment of the provided reinforcement.If no curtailment is activated, a uniform reinforcement is designed across the entire structure (Figure 01).
The curtailment of the reinforcement can be activated in the "Longitudinal Reinforcement" tab of the add-on module (Figure 02).
After activating the curtailment, you can define a number of zones. The higher the number of zones is, the more precisely the provided reinforcement can follow the distribution of the required reinforcement (Figure 03).
Yes, the CONCRETE for RSTAB 8 module also includes the nonlinear reinforced concrete design. Thus, you can activate the "Nonlinear design (state II)" in the "Ultimate Limit State" tab.
In the detail settings for the nonlinear design, you can select the "General design method for members subjected to compression according to the second-order analysis".
It is important that you define the imperfections in RSTAB and apply load curves (CO) according to the second-order analysis for the design, no result combinations (RC)!
Note on RFEM 5:
In RFEM 5, the same procedure is possible in RF-CONCRETE Members. However, the add-on module RF-CONCRETE NL in RFEM is required for the non-linear reinforced concrete design.
AnswerIf any circular cross-sections are available in a structure, they can only be designed with peripheral reinforcement (Figure 01). This is due to the fact that there is no "top" and "bottom" for a circular cross-section.Only one reinforcement layout can be defined for each reinforcement group in RF-CONCRETE Members. If the circular cross-section and the rectangular cross-section are designed together, only the circumferential reinforcement can be used for all cross-sections.To avoid this restriction, you have to define another or separate reinforcement group (Figure 02).
AnswerDifferences resulting from the determination of the deformation in the cracked state can have different causes. The following points should be checked for deviations:
Is the same calculation method applied?
RF-CONCRETE Deflect uses an analytical analysis approach according to EN 1992-1-1 7.4.3.RF-CONCRETE NL uses a physically nonlinear analysis approach.More detailed information about the calculation methods can be found, for example, in the RF-CONCRETE Surfaces Guide in chapter 2.7 and 2.8.
Is the same initial structure available?
The results of the linear calculation provide the best tool for consideration if the underlying system should be taken for equivalent. The linearly determined deformation of the underlying combination should be approximately equal. Etwaige Unterschiede bei der linearen Verformung können sich im Zusammenhang mit der Verformungsberechnung im gerissenen Zustand potenzieren.
Werden die gleichen Effekte berücksichtigt?
Bei einem Vergleich ist darauf zu achten, dass gleiche Effekte, wie z.B. Kriechen und Schwinden berücksichtigt werden (Bild 02).
Sind gleiche Eingangswerte vorhanden?
Des Weiteren wäre im Zusammenhang mit der Verformungsberechnung zu prüfen, ob gleiche Eingangswerte vorhanden sind. Hier ist vor allem darauf zu achten, ob die angesetzte Bewehrung (Bild 03) und der Hebelarm beziehungsweise die Betondeckung gleich ist.
Sollten Sie die Ursache nach der grundlegenden Prüfung nicht finden können, wenden Sie sich bitte an unsere Hotline.
Yes, it is possible.You can do this by selecting the checkbox next to 'Use Required Reinforcement for Design of Serviceability' in the input dialog box '1.4 Reinforcement', 'Longitudinal Reinforcement' tab.Thus, the module places the entire reinforcement required for the ultimate limit state design and/or serviceability limit state design in the reinforcement layout.The results output 'Additional Reinforcement' is omitted after designing in the results windows in the add-on module as well as in the printout report.The option "Use Required Reinforcement for Design of Serviceability" can be combined with the option 'Increase Required Longitudinal Reinforcement Automatically for Serviceability Limit State Design'.
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.
AnswerYes, it is possible.A structural model can be provided with a pile foundation in RFEM.Thus, the influence of the foundation stiffness on the actual structure can be simulated very well.However, please note that Dlubal Software currently offers no solutions for the design of pile foundations.This also means that the pile resistance must be known to the user in advance. It cannot be calculated in RFEM e.g. by defining a soil structure.The piles can be designed as beams, for example, by means of a circular cross-section.The resistance of the piles can be realized by inserting a member elastic foundation or nodal support at the pile end.Subsequently, the design of the beam could be carried out in the RF-CONCRETE Members add-on module. However, please note that RF-CONCRETE Members only implements the standards relevant for structural engineering. For example DIN EN 1992-1-1.
AnswerThe outputs of surfaces in RFEM refer to averaged internal forces. The design in RF-CONCRETE Surfaces is based exclusively on the internal forces, which have been averaged within a surface. Smoothing is not performed across the supported line. In this context, the shear force distribution shown in Figure 01 may occur.
When using the automatic arrangement of the reinforcement, make sure that, in addition to the basic reinforcement, additional reinforcement is applied, if applicable, for the serviceability limit state designs. The default setting in the add-on module is such that the required reinforcement from the ultimate limit state is also applied for the SLS.
You can select the reinforcement that is applied for the SLS in 'Additional Reinforcement for Serviceability State Design'. The Info button explains the individual options (Figure 02).
The reinforcement applied for the designs can be reproduced via the function 'Selected Reinforcement for SLS Check' (Figure 03).
AnswerThe situation could be caused by the following conditions:
- Reinforcement layers are virtually adjacent to each other in the centroidal axis of the surface
- A smaller rebar diameter has been selected
- The cross-section is completely drawn, which means that there is no neutral axis depth.
In this case, the smallest distance between the reinforcement layers is applied as a lever arm. If it is close to zero, the lever arm is also applied close to zero.
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