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Frequently Asked Questions (FAQ)
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AnswerThe add-on module RF-CONCRETE Deflect is available for the calculation of state II deformations in RF-CONCRETE Surfaces.For the analytical calculation of deformations in state II, RF-CONCRETE Deflect requires a unique load situation, which is given only by using the load combinations (COs). Result combinations do not offer a clear load situation, whether additive or as an enveloped OR combination. Therefore, when applying the RC for the calculation of deformations in RF-CONCRETE Surfaces by RF-CONCRETE Deflect, you receive the mentioned error message. See Figure 01.To avoid this problem, you can simply generate load combinations (COs) instead of result combinations (RCs). If you still want to perform the ultimate limit state design with RC's, you can create a CC for each in addition to the existing RCs for which you want to calculate the deformations by means of RF-CONCRETE Deflect. See Figure 02.It is important that RF-CONCRETE Surfaces calculates the loads from the quasi-permanent design situation by default for the calculation of the deformations. See Figure 03. This means that the CO for which the deformations are to be calculated must be defined as "quasi-permanent." Alternatively, the check boxes for the settings of the design situations (see Figure 03) can be user-defined.
AnswerIt is correct that no corresponding load cases are displayed in Table 4.13 "Surfaces - Local Deformations".However, you can find them in Table 4.4 "Members - Local Deformations", for example. See Figure 01.If you now define the corresponding load cases for the max. If you want to see the deformations of an RC on a certain surface, you can integrate a member into this surface. So that this member does not influence the surface stiffness, it is recommended to For example, a very small cross-section can be used.If the member has been integrated or cross-linked correctly in the surface, the table shown in Figure 01 is obtained. Figure 02 shows the corresponding deformation in the surface component.Optionally, it is now possible to click into the row with the desired result (for example max u) to execute a right-click. In the shortcut menu, you can now use the option "Generate CO by Selected Row" which you can use to generate a CO that contains the load cases belonging to the selected value. See Figure 03.When you execute this command, you receive a CO from the RC with the corresponding load cases. See Figure 04 with the results of the generated CO and the max. Deformations in the considered field.
AnswerPlease note that in the context of the nonlinear calculation, the reinforcement is not increased automatically. A nonlinear calculation is based on an already provided reinforcement. This provided reinforcement can result, for example, from the ultimate limit state designs or a defined ground reinforcement. The reinforcement applied for the SLS designs can be displayed graphically (see Figure 2).Cause of issue:If no reinforcement results from the ULS or the basic reinforcement in some areas, the serviceability limit state design is carried out without the applied reinforcement, and very high results may result, for example in the crack width.Solution to the problem:It should be ensured that there is a reinforcement in each zone of the structure. This can be implemented by applying a basic reinforcement (see Figure 3).
AnswerThe deformations in the usability proof in STAHL EC3 are referenced by default to the displaced rod or rod set ends. This makes sense because you want to prove the local component.
See technical paper: https://www.dlubal.com/support-and-training/support/knowledge-base/001081
In the case of a result combination of load cases with the form LF1 / s + LF11 / s or up to LF31, a reference to the deformed system can lead to implausible results. The background to this is that the values of the displaced bar ends can come from independent load situations and thus a correct gauge can not be determined.The figure shows the enveloping deformation of an EK of the type (LF1 / s + LF11 / s or to LF31). The deformed bar ends each come from different load cases. Here this was simulated for comparison with LK's. The stitch determined in the middle of the staff is not meaningful to evaluate.One should work with load combinations in these cases.
AnswerNo, this possibility does not exist. Node deformations are always output in relation to the global coordinate system, regardless of whether the structure input was done using a user-defined coordinate system.Optionally, the output of local bar or area deformation results may help as needed.
AnswerIt is quite likely that the high deformations are caused by the consideration of shrinkage and the horizontal storage in the model.The shrinkage is taken into account internally on the load side as elongation, in which connection a failure due to the prevention of shrinkage is also possible. If the shrinkage is prevented by a non-displaceable horizontal bearing, forces are created which can lead to failure of the concrete and thus to a significant increase in deformation or even instability of the model.In this context, it is important that when using the nonlinear deformation calculation, the boundary conditions of the model are mapped as realistically as possible.
AnswerTo also display the desired nodal values, select the "Nodal displacements" option in the Display navigator (see figure).
AnswerFor crane runway girders that are supported laterally by a semi-rigid spring (Schlingerverband), we set Method 3 under Details under "Permitted Deformations". With this, the length for the determination of the allowable deformation is related to the inflection points of the deformed member axis.
If you want to relate the allowable deformation to the length between start and end support, you have to calculate it manually.
AnswerThe Young's modulus in the state II is not directly output in the deflect calculation.But you can switch to the result window "3.3 Point-by-Scavity Serviceability Design" and filter an FE mesh or grid point for which you want to see the design details. See Figure 01.In the table, select the result row for the "u z, local " deformation.Then, click the [i] button to display the design details for the selected point.In the design details, you can find the intermediate values for the deformation analysis, such as the moment of inertia of the cross-section in state I and state II, the distribution coefficient zeta, and the final cross-section values. See Figure 02.Since these intermediate values are always determined when you open the design details table and are always displayed and temporarily saved for that point, the intermediate values can not be displayed graphically for the designed surface.
AnswerBy default, the shear stiffenings of members are activated in the program (see Figure 1). The calculation type and defined stiffness factors (see Figure 2) also affect the calculation. However, the parameters mentioned above are often neglected in the manual calculation, which of course contributes to a result difference. If these functions are deactivated, the results are usually identical with the manual calculation.
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