Dlubal RFEM 5 & RSTAB 8 – Line Load with Influence Width

Dlubal RFEM 5 & RSTAB 8 - Line Load with Influence Width

Dlubal RFEM 5 & RSTAB 8 – Line Load with Influence Width

By Andreas Niemeier, Dlubal Software

In addition to manually entering values, you can enter line loads in the “Member Load” dialog box using the “Multilayer Composition” function. It is a library which contains compositions of several layers for applying loads. You can freely specify the layer structure using the parameters of description, thickness, density or surface load and comment for each layer.

After selecting a library entry, the program transfers all surface loads added together from previously defined layers and calculates them with regard to a user-defined influence width in a line load.

In addition to the current layer models of roof and wall structures, this function is also applicable for live loads described in standards. For this, it is necessary to create a library entry for each load category. Then, you can select the entries for load application and apply them to members using the influence width.

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Dlubal RFEM 5 & RSTAB 8 – User-Defined Factors for Shear Joint Design in RF-/CONCRETE (Members)

Dlubal RFEM 5 & RSTAB 8 - User-Defined Factors for Shear Joint Design in RF-/CONCRETE (Members)

Dlubal RFEM 5 & RSTAB 8 – User-Defined Factors for Shear Joint Design in RF-/CONCRETE (Members)

By Alexander Meierhofer, Dlubal Software

The shear resistance design value of a joint depends mainly on the formation or the roughness of the connection. When determining the ultimate limit state, this is considered by both factors µ (friction) and c (adhesion percentage of contact area of the composite concrete).

RF-/CONCRETE (Members) requires the selection of the shear joint formation available in Window 1.6, “Shear Joint” tab. There are the surface categories “Very smooth”, “Smooth”, “Rough” and “Indented” available for selection. Depending on the selected surface, the factors entered according to the standard are used for mu and c.

It is also possible to use user-defined factors for the shear resistance calculation, if necessary. In this case, copy the National Annex used and define the factors in the copy under Section 6.2.5. After selecting the modified NA copy, the user-defined connection factors are displayed in the drop-down menu in Window 1.6 and used for the shear joint design.

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Dlubal RFEM 5 – Activation of RF-FORM-FINDING

Dlubal RFEM 5 - Activation of RF-FORM-FINDING

Dlubal RFEM 5 – Activation of RF-FORM-FINDING

By Sandy Matula, Dlubal Software

The RF-FORM-FINDING add-on module can be activated in the “Edit Model – General Data” window, “Options” tab. By activating the module, a new RF-FORM-FINDING load case is created and an additional menu appears in the main program, allowing for the definition of prestress conditions for membrane and cable elements.

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Dlubal RFEM 5 & RSTAB 8 – Input Errors of Objects in Project Navigator

Dlubal RFEM 5 & RSTAB 8 - Input Errors of Objects in Project Navigator

Dlubal RFEM 5 & RSTAB 8 – Input Errors of Objects in Project Navigator

By Ulrich Lex, Dlubal Software

When modeling structural systems or loads, input errors or faulty objects may occur due to subsequent modifications, displacements and adjustments in the model.

These faulty objects are marked red in the Data navigator. “Info on Input Errors” in the submenu (right-click the faulty object) displays comments to existing errors. Therefore, the errors can be fixed very easily.

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Dlubal RFEM 5 & RSTAB 8 – Calculation Diagrams

Dlubal RFEM 5 & RSTAB 8 - Calculation Diagrams

Dlubal RFEM 5 & RSTAB 8 – Calculation Diagrams

By Adrian Langhammer, Dlubal Software

To record and display a relation between various calculation results, it is possible to use the calculation diagrams. You can create and display them using the “Calculation Parameters” dialog box available under “Calculation” -> “Calculation Parameters”.

You can create a diagram as follows:
1. Create a new diagram.
2. Select a load case or combination for which the diagram is to be displayed.
3. Set the result type for the vertical and horizontal axis.

Once the calculation has finished and results are available, the diagrams are displayed. In some situations, you can activate the function of incrementally increasing loading when creating calculation diagrams. For more information, see:
https://www.dlubal.com/blog/16780/dlubal-rfem-5-load-increment-new-options

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Dlubal RFEM 5 & RSTAB 8 – Selecting in Plane

Dlubal RFEM 5 & RSTAB 8 - Selecting in Plane

Dlubal RFEM 5 & RSTAB 8 – Selecting in Plane

By Paul Kieloch, Dlubal Software

In RFEM and RSTAB, there are several ways to select a part of the structural model for further processing. The most frequently used selection option is certainly the “selection using window”. Depending on the size of a structure, the simultaneous selection of several areas of the structure using this option may be time-consuming since the unwanted model parts are selected as well.

In this case, you can use the “Select in Plane” option. Thus, you can quickly select and further edit the structural elements lying in a specific plane (for example hall frames or platform levels). You can find this function under “Edit” -> “Select” -> “In Plane”.

In RSTAB, you can select nodes and lines, in RFEM surfaces and members in addition. The plane from which the elements are to be selected can be defined by “3 Nodes” or by “Polygonal boundary”. The “3 Nodes” option allows you to select three nodes of the structure of three grid points of the current work plane in order to define the desired plane. The example figure shows three nodes of the structure selected. When selecting grid points, please note that the currently adjusted work plane lies in the plane desired for selection. If necessary, you can adjust this by setting a new work plane or grid origin.

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Dlubal RFEM 5 & RSTAB 8 – Specifics of Using Tension Members 2

Dlubal RFEM 5 & RSTAB 8 - Specifics of Using Tension Members 2

Dlubal RFEM 5 & RSTAB 8 – Specifics of Using Tension Members 2

By Sebastian Hawranke, Dlubal Software

The previous post on this topic describes instabilities that may occur when using tension members. The example shown refers primarily to wall stiffening. Now, instability error messages can also refer to nodes within the range of supports. Especially truss girders and support trusses are susceptible to this. So what causes the instability here?

A major part of tension members fails due to shortening of the upper chord in the case of solely vertical loads. This leads to a significant increase in the effective length about the minor axis (see picture). In the case of truss girders, lateral restraint of hinged posts or diagonals leads again to a significant increase in the effective length.

An initial prestress of roof bracing is not always helpful, since there are big compressive strains of truss girders due to the relatively small chord and high compression forces. Therefore, the “Failing members to be removed individually during successive iteration” option under the “Global Calculation Parameters” tab seems to be the best option for trusses as well.

By the way: RF-STABILITY and RSBUCK allow for determination and graphical representation of buckling loads and buckling shapes. With this, instability causes can be recognized easily.

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Dlubal RFEM 5 & RSTAB 8 – Displaying Results of Members

Dlubal RFEM 5 & RSTAB 8 - Displaying Results of Members

Dlubal RFEM 5 & RSTAB 8 – Displaying Results of Members

By Walter Fröhlich, Dlubal Software

In the work window of RFEM and RSTAB, there are four display modes available for results of members. They can be selected in the Display Navigator under “Results” -> “Members”.

1. “Two-Colored” (default): Internal forces and design ratios are displayed as variable diagrams.
2. “With Diagram”: The same as above, but displayed as multicolored diagram in order to quickly find the extreme values.
3. “Without Diagram”: Colored results on a wireframe model, result values are displayed in small text boxes for each member.
4. “Cross-sections”: Colored results on a rendered cross-section, result values are displayed in the result panel.

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Dlubal RFEM 5 & RSTAB 8 – Retaining Existing Results of RF-/DYNAM Pro

Dlubal RFEM 5 & RSTAB 8 - Retaining Existing Results of RF-/DYNAM Pro

Dlubal RFEM 5 & RSTAB 8 – Retaining Existing Results of RF-/DYNAM Pro

By Stefan Frenzel, Dlubal Software

In RF-/DYNAM Pro, it is now possible to keep existing results. For example, if you work with several dynamic load cases, you can calculate or modify the individual dynamic load cases while retaining the unchanged results of the other dynamic load cases.

This may reduce the computation time since it is no longer necessary to recalculate all dynamic load cases after every change. The module displays a dynamic load case in color as soon as the results of it are available. In addition, you can delete the result of a dynamic load case separately using the shortcut menu.

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Dlubal RFEM 5 & RSTAB 8 – Parametrization of Frequently Recurring Systems

Dlubal RFEM 5 & RSTAB 8 - Parametrization of Frequently Recurring Systems

Dlubal RFEM 5 & RSTAB 8 – Parametrization of Frequently Recurring Systems

By Andreas Hörold, Dlubal Software

Many projects share similar geometry and loading. To save time when performing the structural analysis, it can be useful to parametrize the structural models. Parametrization of such systems is possible with the finite element program RFEM and the structural beam analysis program RSTAB. It is possible to parametrize variables such as lengths, angles, masses, loads, cross-sections, etc.

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