In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.
Frequently Asked Questions (FAQ)
Customer Support 24/7
AnswerThe reason for the different results is probably the settings of effective lengths for the stability analysis. According to the default setting, these are determined automatically in the RF‑/CONCRETE Columns add-on module. However, this method does not work for divided members, and thus no stability analysis is performed (a corresponding warning message appears).If you have entered the effective lengths manually, this only applies to a single member. In order to perform a correct stability analysis of the column as an entire structural component, it is necessary to define it as a set of members.
AnswerThis is not possible directly in RFEM, but the RF‑/STEEL EC3 add-on module allows you to create a list of steel parts. In Details of the add-on module, you can specify whether the parts list should apply to all members or only for members to be designed. Then, you can simply carry out the calculation and the parts list will be displayed. It is also possible to export the parts list to Excel and further edit it.
AnswerIn order to display the loads correctly, it is necessary to make some adjustments. In the case of an incrementally applied load, the boundary of the area load plane may only be defined in sections (by load increment). Otherwise, the load is distributed linearly over the entire area load plane.
The result display of intermediate values is generally linked to the member division property. Also, member loads defined in sections in RFEM generate further intermediate results. For example, if a member load defined in sections is distributed from the member start to the member end, the intermediate results are obtained at the member end nodes.
In the Dlubal programs, all values are stored internally based on SI units. When a user changes the units in the program to metric or imperial, SI units are still used internally and only the value displayed in the interface is modified. Therefore, all values set in the time diagram function also default to SI units unless the user clarifies an alternative unit.Let's look at a simple example shown in Figure 1 where the parameter x = 1 ft has been set in RFEM.In RF-DYNAM PRO - Forced Vibrations, the time diagram function is defined as k(t) = 1*x where 1 is the multiplier (1/ft) to convert x to a dimensionless value. You can see in Figure 2, because all values default to SI units, the Multiplier column produces values of 0.305 instead of the correct value of 1.000.In order to correct the issue, the user only needs to specify the units of the multiplier as (1/ft) in the function equation. This can be done with the formula modification k(t) = 1/1[ft]*x as shown in Figure 3. Notice the Multiplier column now shows the correct values of 1.000.In summary, when using units in the program other than SI units, coefficients or multipliers in the time diagram function should be accompanied with alternative units defined in brackets.
In order to only calculate specific load cases, load combinations, or result combinations in the same way as the "To Calculate..." command (see Figure 01), you can use the CalculateBatch method of the ICalculation interface. For the transfer, the method expects a field with the load type of Loading. This Loading includes the number of the load, and the type (for example, a load combination):Sub batch_test()' get interface from the opened model and lock the licence/programDim iModel As RFEM5.IModel3Set iModel = GetObject(, "RFEM5.Model")iModel.GetApplication.LockLicenseOn Error GoTo e' get interface for calculationDim iCalc As ICalculation2Set iCalc = iModel.GetCalculation' create array with loading typesDim loadings(3) As Loadingloadings(0).no = 1loadings(0).Type = LoadCaseTypeloadings(1).no = 4loadings(1).Type = LoadCaseTypeloadings(2).no = 4loadings(2).Type = LoadCombinationType' calculate all loadings from the array at onceiCalc.CalculateBatch loadingse: If Err.Number <> 0 Then MsgBox Err.description, , Err.SourceSet iModelData = NothingiModel.GetApplication.UnlockLicenseSet iModel = NothingEnd Sub
AnswerIn the "Edit Load Cases and Combinations" dialog box, you can specify in the bottom right of the "Combination Expressions" tab which method of analysis should be used as the basis for the generated load combinations. By default, the linear calculation according to the geometrically linear analysis is preset for load cases and the nonlinear calculation according to the second-order analysis for load combinations.Thus, you can quickly determine whether the load case or the load combination is calculated according to the geometrically linear, second-order, or large deformation analysis. The postcritical analysis option allows you to carry out the stability analysis according to the large deformation analysis with regard to the post-critical failure of the entire structure.In case the model includes cable members, the calculation according to the large deformation analysis is preset in all cases.
AnswerIf the PLATE‑BUCKLING add-on module is not opened as a stand-alone version, but via RFEM or RSTAB, it is possible to import the panels (c/t parts of a member cross-section) and the respective load cases of the RFEM or RSTAB model to PLATE‑BUCKLING (see the figure).If there are no valid cross-sections of PLATE‑BUCKLING found in the model file of RFEM/RSTAB, the option for importing the buckling panels remains inactive.
AnswerWhen using the COM interface (RF‑COM or RS‑COM), you can create a comment by using the guide object interface IGuideObjects. The following is an example program that creates a comment:Sub test_comment()' get interface from the opened model and lock the licence/programDim iModel As RFEM5.IModel3Set iModel = GetObject(, "RFEM5.Model")iModel.GetApplication.LockLicenseOn Error GoTo eDim iModelData As RFEM5.IModelData2Set iModelData = iModel.GetModelDataDim iGuiObj As RFEM5.IGuideObjectsSet iGuiObj = iModel.GetGuideObjectsDim comm As RFEM5.Comment' set frame typecomm.Frame = CircularFrameType' set reference object typecomm.ObjectType = GeneralObjectTypecomm.ObjectNo = 1' set point if GeneralObjectType is choosencomm.Point.X = 2comm.Point.Y = 4comm.Point.Z = 6' set offset from reference objectcomm.Offset.X = 0.5comm.Offset.Y = 1comm.Offset.Z = 1.5comm.Rotation = 1' set text of commentcomm.Text = "testcomment"' transfer object to programiGuiObj.PrepareModificationiGuiObj.SetComment commiGuiObj.FinishModificatione: If Err.Number <> 0 Then MsgBox Err.description, , Err.SourceSet iModelData = NothingiModel.GetApplication.UnlockLicenseSet iModel = NothingEnd SubThe selection of the reference or the element to which the comment is refferred to is defined by the type (ObjectType) first. Here, it is possible to select, for example, a member, a node or any point in space. Next, the number of the reference object is specified via ObjectNo (for example, Member 1). If you have selected a free point, it is set by Point.Finally, you can specify an offset which results from the reference object.
In RFEM and RSTAB, the simplified design from , Chapter 2.2.3, have been implemented for the automatic load combinations. This means that strictly speaking, only structures concerning the final deformation may be analyzed, in which materials with identical creep behavior occur since the creep deformations are considered in a simplified way on the load side. If the structure is a mixed structure made of wood with different creep properties or in combination with steel, the final deformations must be determined according to  Amendment to 2.2.3 as follows:
'(4) If a structure consists of structural components or components with different creep properties, the long-term deformations should be calculated according to 18.104.22.168 (1) due to the quasi-permanent combination of actions with the final values of the mean values of the corresponding elasticity, shear, and displacement modules. The final deformation ufin is then calculated by superposition of the initial deformation due to the difference of the characteristic and quasi-permanent combinations of actions with the long-term deformation.'
However, this requires a superposition of results from different load combinations, which cannot be implemented automatically in RFEM and RSTAB.If the different creep properties are to be taken into account, the load combinations must be created manually, and the stiffness must be reduced according to the creep coefficient.The procedure is described using the example of a timber-concrete composite floor presented on the Info Day 2017. Below this FAQ, you can find the link for this.
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, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you for the valuable information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”