# Frequently Asked Questions (FAQ)

#### Customer Support 24/7

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.

Receive information including news, useful tips, scheduled events, special offers, and vouchers on a regular basis.

1 - 10 of 804

Sort by:

• ### How can I create a user-defined coordinate system using the COM interface and then assign it to a nodal support?

New

004789

When programming with the COM interface, a nodal support has the ReferenceSystem and UserDefinedReferenceSystem properties. With ReferenceSystem, the type (e.g. "Rotated" or "Coordinate System") of the user-defined coordinate system and depending on which type has been selected, this type is then defined via UserDefinedReferenceSystem.

In the following example, "Coordinate system" was set as the type and a user-defined coordinate system was also created for it:

//create user-defined coordinate systemIGuideObjects iGuide = iModel.GetGuideObjects ();//delete cozy No 2UserCoordinateSystem [] csList = iGuide.GetCoordinateSystems ();if (csList.Length> 1){for (int i = 0; i <csList.Length; ++ i){if (csList [i] .No == 2){iGuide.PrepareModification ();iGuide.DeleteObjects (GuideObjectType.CoordinateSystemObject, "2");iGuide.FinishModification ();}}}//define new cozy No 2UserCoordinateSystem uCs = new UserCoordinateSystem ();uCs.Name = "test";uCs.Comment = "test";uCs.No = 2;uCs.IsValid = true;uCs.Origin.X = 1;uCs.Origin.Y = 0;uCs.Origin.Z = 1;uCs.Point1.X = 2;uCs.Point1.Y = 0;uCs.Point1.Z = 1;uCs.Point2.X = 1;uCs.Point2.Y = 1;uCs.Point2.Z = 2;//set cozy No 2iGuide.PrepareModification ();iGuide.SetCoordinateSystem (uCs);iGuide.FinishModification ();//create nodal support with user-defined cozyNodalSupport ns = new NodalSupport ();ns.SupportConstantX = -1;ns.SupportConstantY = -1;ns.SupportConstantZ = -1;ns.RestraintConstantX = -1;ns.RestraintConstantY = 0;ns.RestraintConstantZ = -1;ns.Comment = "user-defined cozy";ns.NodeList = "1";ns.ReferenceSystem = ReferenceSystemType.UserDefinedSystemType;ns.UserDefinedReferenceSystem.ObjectNo = 2;ns.UserDefinedReferenceSystem.Type = UserDefinedAxisSystemType.DefinedCoordinateSystemType;iModData.PrepareModification ();iModData.SetNodalSupport (ns);iModData.FinishModification ();

In order to create the coordinate system, the interface for the auxiliary objects is required IGuideObjects. With the DeleteObjects () function, an existing coordinate system with the number 2 is first deleted and a new one is created with SetCoordinateSystem (). Please note again the Prepare Finish Modification block in order to transfer the new element.

The nodal support is transferred via the IModelData interface, which also requires a Prepare Finish Modification block.

• ### How do I display the nodal displacements graphically?

To display the nodal displacements graphically, the setting "Nodal Displacement" in the Display Tab under Results - Deformations - Members - Nodal Displacements must be activated.

Under the Results tab, turn on Global Deformations. Then the nodes can then be highlighted and isolated by using the "Views By Selected Objects" for a better view of the nodes and displacements.

• ### I would like to perform a stability analysis of the upper flange in a long truss. What is the best way to proceed?

According to DIN EN 1993‑1‑1:2010‑12 [1], Annex BB.1.1, the buckling length may be used in the individual bracing under certain conditions. This means that in this case, the individual members, not a set of members, can be applied with the effective length factors specified in the standard.

Since this approach only considers the local failure, it is necessary to analyze the global failure of the entire structure. For this design, the set of members must have the corresponding imperfection. Under certain conditions, the design can be performed on single members, depending on the model (for example, a tower), or the set of members must be analyzed for a failure from the plane (the truss), as in the attached example.

• ### Although I have deleted the area load plane, members are still loaded. Why?

New

004779

You have generated member loads by using the Generate Member Loads from Area Loads via Plane function. You have probably only deleted one area load plane and not all the area load planes.

In our example, we have defined three individual area load planes.

There are two options to delete the area load planes. You can either delete the current area load plane or delete all area load planes.

If you only delete the current area load plane, you can still select the other two remaining area load planes in the drop-down list. You can see whether all area load planes have been deleted if the Delete All Area Load Planes button is grayed out.

• ### I perform design in RF‑/STEEL AISC for result combinations from RF‑/DYNAM Pro and get the error message "Not designable - Null value of the critical moment on the segment." What should I do?

In this case, the only solution is to increase the limit value for special cases for bending in Details, for example, from 0.01 to 0.05 (see the figure). In this way, the correspondingly small moments are not considered.

• ### The design of my connection is not possible because of an incorrect geometry input. What can I do?

The RF‑/FRAME‑JOINT Pro add-on module designs rigid bolt connections between columns and horizontal beams, and classifies these connections. The rigid bolt connections are designed with the ultimate load method according to Eurocode 3 or DIN 18800.

The dimensions of an end plate can be defined in the add-on module. However, the bolts in the extensions are only possible in the extended top.

A bolt row in the extended bottom is not provided, and therefore the error message appears.

You can check the minimum dimension under the design hints in the add-on module.

The desired geometry can be entered in the RF‑/JOINTS Steel - Rigid add-on module.

• ### How can I display the result values on surfaces in the middle of a finite element?

New

004766

The values on surfaces can be displayed in the surface grid. Please note the following points:

• Dialog box "Edit Surface," tab "Grid": Activate "User-defined" and check the distance and the grid origin, see Figure 01.

• Results navigator: Activate "Values on Surfaces," deactivate "Extreme Values," activate "In Surface Grid," see Figure 02.

• ### How can I assign a common eccentricity to several different cross-sections at once?

New

004765

This can be done by means of multiselection and the shortcut menu:

• Select the corresponding members.
• Right-click the selection, click Edit Member, see Figure 01.

• Assign the eccentricity, see Figure 02.

• ### In connection with the calculation according to Theory III. Order, I get significantly smaller deformations than when calculating according to Theory I. or II. Order. How is this possible?

When calculating according to Theory III. Order, the membrane stiffness or the axial stiffness is also considered with regard to pure bending stress. For theory I and II. Order, only the bending stiffness is taken into account for pure bending stress.
• ### After activating a layered FE mesh, the axis orientation is automatically reset to the default. How can I keep the defined axes after layering the FE mesh?

When using a layered FE mesh for solids, it is unfortunately not possible to keep the user-defined axis orientation because the layers are always in the z‑direction, and thus the axis definition is determined automatically.

As an alternative, you can use an FE mesh refinement, see the figure.

1 - 10 of 804

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.

#### First Steps

We provide hints and tips to help you get started with the main programs RFEM and RSTAB.

#### 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.

#### Your support is by far the best

“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. ”