In addition to personal support, we offer resources 24/7 through our website.
Frequently Asked Questions (FAQ)
Customer Support 24/7
The list of possible diameters can be extended or modified in the modules CONCRETE, RF CONCRETE Members, or RF/CONCRETE Columns using the "Edit List of Possible Diameters" button.
The design of a column with RF‑CONCRETE Columns determines a provided reinforcement, among other things. This is displayed in Table 4.1 and illustrated in the graphics below and in the table on the right.
You can use the "Edit Reinforcement" button to change the reinforcement, if necessary. Click the button to open the "Edit Longitudinal Reinforcement" dialog box (see the image). It includes the table for the "Position of Reinforcement Bars." Here you can delete rows by selecting the row that contains the member to be removed and then clicking the button below.
If "Uniformly surrounding" is set for the reinforcement distribution, the longitudinal reinforcement can be increased or decreased by selecting the number of members in four steps.
Then, it is necessary to recalculate the design for the modified reinforcement arrangement in order to update the design ratio.
The described procedure is shown in the explanatory video.
AnswerFirst, you should set the reinforcement layout to "Uniformly surrounding" in the Reinforcement tab in Window 1.4.Then, open one of the result windows to compare the results from RF‑CONCRETE Columns and the comparative calculation (for example, 3.1 Required Reinforcement by Cross-Section). There you can check the location where the calculation deviates or where there are serious differences in the results.The first point to check would be the determination of internal forces according to the second-order analysis. These internal forces are ultimately applied for the cross-section design and may lead to different amounts of reinforcement.With this procedure, you can compare the results step by step and, if necessary, identify different calculation methods.Furthermore, it should be checked in which way the stability analysis was performed in the comparative calculation. RF‑CONCRETE Columns designs columns with the nominal curvature method according to EN 1992‑1‑1. If the comparative calculation was performed with a general nonlinear calculation, it is possible that the different results can be linked to the method of calculation.Furthermore, it should be noted that the nominal curvature method for columns in usual building construction with the slenderness λ ≤ 70 gives relatively good results. In the case of greater slenderness, however, this method becomes inefficient relatively quickly.
RF-CONCRETE Columns designs a provided reinforcement to perform a stability analysis using the method with nominal curvature.
However, the fire resistance design may require a higher basic reinforcement. For this, you can activate the "User-defined minimum and maximum longitudinal reinforcement" in the "DIN EN 1992‑1‑1" tab of Window 1.4 Reinforcement. Then, you can specify an increased basic reinforcement by clicking the [Edit] button.
Yes, it is possible, for example, if a file (calculated in version 5.23.01) is opened in an older version (such as 5.20.01).
The add-on modules for reinforced concrete structures have no backward compatibility. This means that the module entries must be deleted, depending on the version change.
For instance, this may be necessary if there is a function or a feature contained in the latest program version, which was not yet available in the older version. To avoid compatibility problems, the entries in the add-on modules are removed.
In the example, the file from version 5.23.01 is opened in version 5.20.01. In this case, the entries from RF‑CONCRETE Surfaces will be lost. If you open it in the version 5.17.01, for example, the entries from RF‑CONCRETE Members is also lost.
To avoid the problem, it is recommended to conclude a service contract and use the current version of RFEM.
AnswerThe fire resistance design is based on the temperature course from Annex A EN 1992‑1‑2.The initial values for temperature courses cannot be adjusted in the add-on modules (RF‑/CONCRETE Members and RF‑/CONCRETE Columns). The temperature curves according to Annex A EN 1992‑1‑2 are based on the following assumptions:
- The specific heat of concrete corresponds to the specifications according to EN 1992‑1‑2, 3.2.2.
- The moisture is 1.5%. For moistures greater than 1.5%, the specified temperatures are on the safe side.
- The thermal conductivity of concrete is the lower limit value mentioned in EN 1992‑1‑2, 3.3.3.
- The emissivity value of the concrete surface is 0.7.
- The convective heat-transmission coefficient is 25 W/m²K.
AnswerThe fire resistance design with RF‑/CONCRETE Columns is performed according to the simplified calculation method according to EN 1992‑1‑2 , Section 4.2. The program uses the zone method described in Annex B.2:In case of exposure to fire, the bearing capacity is reduced due to a reduction of the component's cross-section and a decrease of material strengths. The concrete zones that are directly exposed to fire and thus damaged are not taken into account for the equivalent cross-section used for the fire resistance design. The fire protection design is performed with the reduced cross-section and the reduced material properties analogous to the ultimate limit state design at normal temperature.That is: The nominal curvature method according to , Section 5.8.8, is performed with the hot materials and reduced cross-section.
AnswerYes, if you select the National Annex "DIN", the "extended zone method" according to DIN EN 1992‑1‑2, Annex B.2 is used for the fire resistance design.
AnswerIn principle, RF‑/CONCRETE Columns designs the statically required reinforcement for a buckling analysis and generates a reinforcement proposal on this basis.As an alternative to this procedure, it is also possible to specify a certain minimum reinforcement ratio before starting the calculation. You can enter this data iin Window "1.4 Reinforcement" in the tab for the selected National Annex of EN 1992‑1‑1 (for example, DIN EN 1992‑1‑1).A new reinforcement concept is defined on the basis of the entries specified here and used to perform the designs.
In principle, RF‑/CONCRETE Columns designs the statically required reinforcement for a buckling analysis and generates a reinforcement concept on this basis.
This reinforcement concept can be used to perform the fire resistance design, for example.
As an alternative to this procedure, you can also specify a certain minimum reinforcement content before starting the calculation. You can enter the data for this in Window "1.4 Reinforcement," in the tab for the respective National Annex for EN 1992‑1‑1 (for example, DIN EN 1992‑1‑1).
A new reinforcement concept is defined on the basis of the entries specified here, and used to perform the designs.
Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
Wind Simulation & Wind Load Generation
With the stand -alone program RWIND Simulation, you can simulate wind flows around simple or complex structures by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you very much for the useful information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. In the industry of structural analysis, I use several software including service contract, but your support is by far the best.”