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Frequently Asked Questions (FAQ)
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AnswerIf any circular cross-sections are available in a structure, they can only be designed with circumferential 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).
AnswerDistinctions in determining the deformation in the cracked state may have different causes. The following points should be checked for deviations:
Is the same calculation method used?
RF-CONCRETE Deflect uses an analytical calculation method according to EN 1992-1-1 7.4.3.RF-CONCRETE NL uses a physically nonlinear calculation method.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 original system available?
It is best to consider the results of the linear calculation if the underlying system is to be considered as equivalent. The linearly determined deformation of the underlying combination should be approximately equal. Any 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 performing a comparison, make sure that the same effects, such as Creeping and shrinkage are taken into account (Figure 02).
Are the same input values available?
Furthermore, it should be checked in connection with the deformation analysis if the same input values are available. In this case, it is important to pay attention to whether the applied reinforcement (Figure 03) and the lever arm or concrete cover are the same.
If you can not find the cause after the basic check, please contact our hotline.
AnswerNo, this is not possible.A member or a set of members is designed as a "structural component" with the model column method.This means that the longitudinal reinforcement is constant over the entire length of the structural component.The design is carried out with the governing internal forces at the governing location of the structural component (member or set of members).A stability analysis with a reinforcement graded via the column in RF-CONCRETE Members (RFEM) or CONCRETE (RSTAB) is possible via the nonlinear design for compression elements.
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.You can also find more information about the features of RF-CONCRETE Columns on the product homepage 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
2nd VEd / VRd, max
3. VEd / VRd, pIn the course of VEd / VRd, max, the inclination of the compression 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 run, the subsequent design VEd / VRd, s is not performed and the design criterion VEd / VRd, c is displayed.
Yes, it is possible.You can do this by selecting the check box under "Use Required Reinforcement for Serviceability Design" in the "Longitudinal Reinforcement" dialog box "1.4 Reinforcement".Thus, the module places the entire reinforcement that is required for the ultimate limit state design for the ultimate limit state and / or serviceability limit state into a reinforcement layer.The results output "Additional Reinforcement" is omitted after the design in the results windows in the add-on module as well as in the printout report.The option "Use Required Reinforcement for Serviceability Limit State Design" can be combined with the option "Automatically Increase Required Longitudinal Reinforcement 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.
AnswerIt is difficult to enumerate one or particular reasons for the deviations. Basically, the design in RF-CONCRETE Columns is an analytical method, the nominal curvature method according to EN 1992-1-1 5.8.8. One advantage here is that it is a standardized method and that all intermediate values of the calculation are output in the add-on module.By means of the intermediate values, it is possible to search for the cause of a deviation between 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 intermediate values from the program used for the comparison.
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.Please note, however, 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, e.g. 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.
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