Oasys GSA Documentation

# Export to Oasys GSA

You are prompted to enter the name of the GWB file that is to be written. If the GWB file exists then you must choose whether to update the existing file or to overwrite with a new file.

# GSA Layer

You must select which GSA layer to export to.

  • Design Layer – GSA members are created. These will then have to be converted to elements within GSA.
  • Analysis Layer – GSA elements are created. These will then have to be checked for connectivity within GSA.

See ‘Recommended Practice’ for the pros and cons of each option.

# Entities

The option is given to export the whole model or, if a selection has been made in Revit, just the selection.

# Properties and Materials

The option is given to export all sections (and associated materials), 2D Element properties or just those that are referenced by entities that are being exported. If ‘Export all sections, 2D element properties and materials’ is selected then all Structural Columns, Structural Framing types, wall and floor types are exported.

See ‘Recommended Practice’ for information on why you might want to export all properties.

# Open GSA session

If checked then the model is opened in GSA upon completion of the export.

# Clear Log

The log is saved automatically on completion of the operation. The folder and filename of the log file is the same as the specified GWB file but with the extension RTF.

If ‘Clear Log’ is checked the log file associated with the GWB file being exported to is deleted at the start of the operation.

# Notes on the Export Operation – writing a new GWB file

  • Revit levels are written as GSA grid planes.
    • The GSA grid plane name is assigned the name of the level.
  • Revit grids are written as GSA grid lines * The GSA grid line name is assigned the name of the grid.
  • Each Revit column, beam and brace is written as GSA a member or element, depending on whether ‘design layer’ or ‘analysis layer’ is selected (see above).
    • If existing nodes are not found at the required locations then new nodes are created.
  • Each Revit Structural Floor and wall is written as a GSA 2D member.
    • A Revit Floor is deemed structural if the “Structural” option in its properties is checked.
    • A Revit Wall is considered structural if it has the “Enable Analytical Model” option checked in its properties and provided its structural usage is not “non-bearing”.
    • Walls/Floors with openings may not translate to GSA 2D members accurately. The user may require manual editing of the said members.
  • When exporting to the analysis layer, the Analytical Projection Plane is handled as follows:
    • For beams,
      1. if set to ‘Center of Beam’ the GSA element is offset downwards by half the beam depth.
      2. if set to ‘Top of Beam’ then no offset is applied.
      3. Other settings are not handled
    • For columns
      1. Only ‘Top of Column’ at the top and ‘Bottom of Column’ at the bottom are handled. No offset is applied.
      2. Revit materials associated with written columns, beams and braces are written as GSA materials.
    • The GSA material name is assigned the name of the material.
    • For steel materials:
      1. the Revit ‘Minimum Yield Stress’ is translated to the GSA ‘Yield Stress’ and
      2. the Revit ‘Minimum Tensile Strength’ is translated to the GSA ‘Ultimate Stress’.
    • For concrete materials the Revit ‘Concrete Compression’ is translated to both the GSA ‘Yield Stress’ and ‘Ultimate Stress’.
  • Revit family types associated with written columns, beams and braces are written as GSA sections.
    • GsRevit attempts to find a valid GSA section basing the section description on:
      1. the description entered in the Revit symbol ‘Type Comments’ field.
      2. the Revit symbol name.
    • The search for a matching GSA section is as follows:
      1. Is the section description an exact GSA section description?
      2. Does the section description approximate to a catalogue section name, whether with the type at the beginning or end of the name?
    • If no matching section name is found then an attempt is made to create a standard section based on the Revit symbol properties, as follows:
      1. If a depth, width and thickness are defined then a standard rectangular hollow section is created.
      2. If a depth and width are defined then a standard rectangular section is created.
    • The GSA section name is assigned the Revit section description, whether the symbol ‘Type Comment’ or symbol name.
  • Revit Floor and Wall types are written as 2D Element properties, with the same thickness and name as the Revit types. The materials associated with these types will not exported, hence the 2D element properties will carry a dummy material reference of 99.

# Notes on the Export Operation – updating an existing GWB file

For any Revit object that is handled by GsRevit (except floors and walls), the related object is searched for in the GSA model. The search is for the first occurrence of a reference to the Revit object in the GSA model, basing the search on the Revit object ID reference stored in the GSA objects.

  • If a related GSA object is found then only the data controlled by Revit for that object is updated. Extra data is not affected.
  • If a related GSA object is not found then a new object is written.
  • Other data in the GSA model is not affected by the update.
  • Please note that this does not apply to Floors and Walls and their types.

# Known Issues

  • Restraints are not handled.
  • Translational releases are not handled.
  • GSA objects that relate to deleted Revit objects are not deleted.

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