Revit Interface: Export

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Figure 01 - Export Menu: General Settings

Figure 02 - Export Menu: Structural Settings

Figure 03 - Dlubal Parameters

Technical Article

001455 21 June 2017 Technical Article René Flori Import / Export & BIM RFEM RSTAB Building Information Modeling (BIM)

BIM is often used when it comes to data management in civil engineering. The individual disciplines of architecture, structural design, construction, and structural monitoring are coming closer together. Building Information Modeling makes this possible.

Dlubal Software provides a wide range of formats for data exchange. The following article explains the details of the interface with Autodesk Revit and, particularly the export settings.

General

If Revit is installed in addition to RFEM or RSTAB, the direct interface is available in Revit as a plugin. All settings for data exchange can be done in the Revit interface. Since RFEM and RSTAB are based on the object-oriented building model and Revit on the parametric building model, the objects' intelligence won't get lost when exchanging data. This means that you will get an equivalent object for every column, wall or beam in Revit and RFEM/RSTAB, not only a collection of lines or surfaces.

Export Menu (Data Transfer from Revit to RFEM/RSTAB)

Figure 01 - Export Menu: General Settings

Z-Direction
Here you define the orientation of the global Z-axis in an RFEM file. In architecture, this axis is usually oriented upwards as a building is built from bottom to top. In structural engineering, structures are calculated from top to bottom similarly to the load transfer so the orientation of the global Z-axis is downwards.

RFEM/RSTAB
'Create new structure': It is not necessary to run RFEM/RSTAB when starting the export. The interface runs the corresponding Dlubal Software application automatically and creates a new structure with the same name as the Revit structure.
'Overwrite existing model': The data of a model opened in RFEM/RSTAB is overwritten with the Revit data during the export. If no model is opened, the interface creates a new structure.
'Update existing structure': During the export, the existing RFEM/RSTAB data are checked. New elements are added. If some components were removed in Revit after the previous export, you can also remove those objects in RFEM/RSTAB by selecting 'Remove absent objects'. If the model has already been adjusted in RFEM/RSTAB, you can prevent updating member end releases in RFEM/RSTAB by selecting the 'Do not overwrite member releases' check box.
If a Revit user does not have the RFEM/RSTAB license, it is possible to export the RFEM/RSTAB data in a file using the 'Export to file' option.

Objects to Transfer
The 'Only selected objects' option allows you to export the objects selected in Revit to RFEM/RSTAB separately from a complex model. In Revit, it is common to work with various views. This allows you to compile the relevant components in a special view and transfer them to Dlubal Software by using the 'Only visible objects' option.

Options
The 'Apply member/surface eccentricities' option transfers the offsets defined in Revit as member or surface eccentricities to RFEM/RSTAB.
If you select the 'Export release of type fixed' option, RFEM/RSTAB creates member end releases without a degree of freedom for those members that have no releases defined in Revit.
The 'Updated objects to partial view' option allows you to easily follow the modifications of a structure in RFEM/RSTAB. The option is especially useful when working with a global model.
'Connect lines/members' connects the lines or members that cross each other. In this way, a mechanically connected system is generated, which can be calculated. However, this may be related to model changes, which make it more difficult to align a model with Revit afterwards.
If you use the 'Rigid and analytical links as member of type "Rigid"' option, rigid members with freely definable member end releases are created in RFEM/RSTAB.
'Use cross-section/material name from "Dlubal name" parameter': In the case of user-defined Dlubal parameters defined for the material and cross-section names, these will be used during the data exchange.

Figure 02 - Export Menu: Structural Settings

Structural Data
The data exchange can be limited to the model and/or load data. This is useful when loads are defined in a program and not supported by the other application.

Apply loads
'Self-weight in the LC': The automatic calculation of the self-weight (not possible in Revit at the moment) can be assigned to a specific load case in a Dlubal Software program.
Using 'Export load combinations of type "Combination" as', you can define whether to generate a load combination or an 'enveloping' result combination. A load combination of the 'casing' type in Revit is always transferred to RFEM/RSTAB as a result combination.

Converting isolated/wall foundations
Isolated or wall foundations can optionally be converted in RFEM as hinged nodal and line supports or as surfaces with elastic foundation. In RFEM/RSTAB, there are no foundation objects as structural engineers usually use simple supports instead. Spring stiffnesses of the surfaces with elastic foundations are preset and must be adjusted in RFEM/RSTAB.

Figure 03 - Dlubal Parameters

Dlubal Parameters
Dlubal parameters allow you to provide the Revit objects with additional information so they can then be transferred to RFEM/RSTAB. The following is currently possible:

Defining the 'Without Tension' Dlubal element type for masonry calculation in the case of walls in Revit
Generating surface supports in RFEM surfaces also for floor slabs in Revit
Defining material and cross-section mapping directly for the material or cross-section in Revit
Defining the 'Truss' member type
Defining the 'Tension' member type
Having the option of user-defined renaming of the parameter names, depending on the language

Click the [Start] button to either add or remove the parameters to the Revit project.