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Frequently Asked Questions (FAQ)
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AnswerNo, this is unfortunately not possible.The program concept of RF-CONCRETE Surfaces is designed in such a way that it is always necessary to place a reinforcement on the top and bottom layer.If necessary you can try to concentrate the individual reinforcement layers in the center of the surface. However, it is important to ensure that the individual reinforcement layers do not "touch" each other. Otherwise, an error message appears. See Figure 01.
In RF-CONCRETE Surfaces, you can use the [Info] button to display the corresponding steel stresses for each design location for the ultimate limit state (see Figure 01). A graphical display is not possible here.
For the serviceability limit state design, it is possible to display the steel stress graphically as the corresponding design can be performed (see Figure 02).
When you create a new cross-section in RFEM / RSTAB, you can select different cross-section types in the "Parametric - Massive" category. When the mouse cursor lags a button for a moment, a message appears informing you which add-on modules to dimension this cross-section (see Figure 01).
The cross-sections marked green in Figure 01 can be designed with CONCRETE and RF-CONCRETE Members. However, a "Pi cross-section, type A" is not suitable for the design with CONCRETE or RF-CONCRETE Members. However, as shown in the Info dialog box, RF-TENDON allows you to analyze the cross-section. Thus, you can select this cross-section for a member in RFEM and design it in the RF-TENDON Design add-on module.
Why can not you design all cross-sections in CONCRETE or RF-CONCRETE Members?
This is due to the available reinforcement layers for the individual cross-section types. For example, if you create and dimension a rectangular cross-section, you can find the corresponding reinforcement layer in CONCRETE TEMPLATE 1.6, that is, the possible reinforcement distribution (see Figure 02). Different reinforcement diagrams are possible for a rectangular cross-section. These reinforcement layers are required to determine the stresses and strains in the cross-section and thus the required reinforcement.
For other cross-sections such as Pi cross-sections, this information is not available in the current development state. Therefore, you can not design them with CONCRETE or RF-CONCRETE Members.
If the program DICKQ is licensed, you can create the statical structure with Pi cross-section in RFEM / RSTAB and determine the governing internal forces. In DICKQ, it would then be possible to define the cross-section, import the internal forces from RFEM / RSTAB, and to design the cross-section manually set the longitudinal reinforcement manually.
You can find more information about DICKQ at the following link: https://www.dlubal.com/en-US/products/silitary-section-electroducts/dickq
With DICKQ, you can freely define massive cross-sections.
In Table 2.1 of RF-CONCRETE Surfaces, the depth is not designable for some locations because the concrete compressive stress is too high there (see Figure 01). In this window, you can also check the design details for the result row selected in the table above by using the [Info] button. In a new window, the values show that the resistable membrane force is smaller than the design membrane force in the strut direction (see Figure 02).
The program displays a corresponding non-sensible message on all finite elements with concrete compressive stresses that are too high.
You can find the theoretical background to this design in the manual of RF-CONCRETE Surfaces, for example. You can download it using the literature link below or use the [F1] key to open the module.
In order to counteract the non-designability, it is possible to proceed as follows
- The non-desiderableness can be caused by singularities .
- As soon as the plate is not pure, the internal force size optimization may be the cause. It should be deactivated for shells and shells (Figure 3).
- It is possible that a third reinforcement direction is added (Figure 4).
- The concrete grade can be increased
- The surface thickness can be increased
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