Working with Files

This guide covers how to save and open models, import reference files, and export to IFC.

Saving Your Model

Press Ctrl+S or go to File → Save As to download your model as a .calculus file.

The file contains everything about your model:

• All structural objects (beams, plates, bolts, welds, rebar, grids, annotations)
• All catalog data (profiles, materials, bolt assemblies, rebar grades)
• Analytical model definitions
• Saved views

The file name defaults to the model name. You can rename the model by clicking on the name in the top-left corner.

TIP

Your model is also automatically saved in your browser. If you close the tab and come back later, your model will still be there. However, clearing your browser data will erase this autosave — always download a .calculus file for safekeeping.

Opening a Model

Press Ctrl+O or go to File → Open to load a file. You can also drag and drop files directly into the Calculus window.

Loading a .calculus model

When you open a .calculus file, the objects are merged into your current model:

• Objects with new IDs are added
• Objects with IDs that already exist in your model are skipped (no duplicates)

This merging behavior lets you combine parts from multiple models. If you want to start fresh, use File → Clear Model first to empty the workspace.

What happens to catalogs when you open a file

The catalogs from the opened file are merged with your existing catalogs using the same deduplication logic. This means your model always accumulates catalog data from imported files — you won't lose profiles or materials.

Importing Reference Models

Reference models are external 3D files that appear as non-editable overlays in your workspace. They're useful for coordination — for example, viewing an architect's building model while you design the steel structure.

Supported reference formats

Format	Extension	Description
IFC	.ifc	Industry Foundation Classes — BIM models from other engineering software
glTF Binary	.glb	Efficient 3D interchange format
glTF	.gltf	Text-based 3D format
PLY	.ply	Point cloud and mesh format (e.g., from 3D scanning)

How to import a reference

1. Go to File → Open (or Ctrl+O) and select the file, or drag and drop it into the window
2. The reference model appears in the viewport
3. Use the Models tab in the sidebar to:
   • Adjust position — Move or rotate the reference to align with your model
   • Toggle visibility — Show or hide the reference
   • Delete — Remove the reference from the model

Reference models are stored locally in your browser (up to 300 MB per file). They won't be included when you save a .calculus file — they're only for visual coordination.

Exporting to IFC

Calculus exports to IFC 4x3, the latest version of the Industry Foundation Classes standard used for BIM data exchange.

How to export

1. Go to File → Export IFC 4x3
2. Choose:
   • Export all — Exports every object in the model
   • Export selected — Exports only the objects you have selected
3. The IFC file is downloaded to your computer

What gets exported

Calculus object	IFC entity
Beams and columns	IfcBeam
Plates	IfcPlate
Bolts	IfcMechanicalFastener
Reinforcement bars	IfcReinforcingBar
Cut parts	IfcVoidingFeature

You can open the exported IFC file in any BIM software that supports IFC (Tekla Structures, Revit, Solibri, BIMcollab, etc.).

Clearing the Model

Go to File → Clear Model to remove all objects from the workspace. This action asks for confirmation before proceeding and cannot be undone (the undo history is also cleared).

Tekla Structures Integration

Calculus includes a companion desktop plugin called CalculusTeklaLink that connects Calculus with Tekla Structures:

• Export from Tekla — Convert a Tekla Structures model to a .calculus file
• Import into Tekla — Load a .calculus model into Tekla Structures
• Profile and bolt mapping — Automatically maps between Tekla and Calculus naming conventions

The plugin is distributed as a Tekla Extension Package (.tsep) file that you install into Tekla Structures.

File Format Reference

Native files

Extension	Description
.calculus	Complete structural model (objects, catalogs, settings)
.profileCatalog	Profile library (steel sections, custom shapes)
.materialCatalog	Material library
.boltCatalog	Bolt assembly library
.rebarCatalog	Rebar grade library

Import/export formats

Extension	Import	Export	Notes
.ifc	As reference overlay	Full IFC 4x3 export	Standard BIM exchange format
.glb / .gltf	As reference overlay	—	3D visualization format
.ply	As reference overlay	—	Point cloud / mesh format

File size limit

The maximum supported file size for import is 300 MB.