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Essentials

Essentials​

These are the essential FEM-Design modelling steps needed for PREFAB to read your model correctly and find equilibrium.

Edge-connections​

For PREFAB, it's important to apply edge-connections on all edges interacting with other elements. If they aren't applied, PREFAB can't read the forces and will most likely not be able to find equilibrium.

Edge-connections applied on all edges interacting with other elements

You can apply the edge-connection in the Default connections tab. Define your desired connections and save the setup as a preset.

Default connections tab on a Plane wall

End-point behavior​

This is a finite element technical necessity. To ensure correct results for edge-connection forces, always apply separated end-point behavior. This is visually represented by small dots at the edge of the edge-connection. If they aren't separated, PREFAB will in many cases warn about equilibrium errors.

Separated end-point behavior shown as small dots at a wall corner

They can be applied in the Default connections tab and saved to the setup with the correct edge-connection types.

End point behaviour set to Separated for both Start and End

Point-connections​

For PREFAB to get the correct information about the interaction between bar elements (both columns and bars), it's important to apply point-connections.

Point-connection between a bar element and a shell

Apply them by setting the desired possibilities of interaction. Define the wall as the Master object, and place the second point on top of the master (if you can't see the tool, set the user interface to Full).

Point connection dialog and toolbar

Minimum edge-division number​

To help ensure good results from FEM-Design, and thereby improve the quality of the data imported to PREFAB, apply a minimum of 3 divisions on the finite elements at all edges.

Wall edges with too few divisions compared to a correctly divided wall

You can manually adjust the division number of edges in the Finite elements tab, or go to the settings menu and change the minimum to a default of 3 – this is the recommended method.

Settings > Calculation > Mesh > Elements, with the lowest minimum division number for edge connection set to 3

Storey​

To help with the overview, 3D navigation and exporting options, storeys need to be applied to the model.

Storeys applied to a multi-storey building model

Apply these using the Storeys tool, and the edit in table option.

Storeys tool and table dialog

Axis​

To help with the overview, 3D navigation and exporting options, axes need to be applied to the model.

Axes applied to a multi-storey building model

Apply these by using the Axis tool and draw them in the appropriate places. For any walls not placed on an axis plane, a custom axis will be created by PREFAB, named after the closest existing axis.

Axis toolbar and Axis dialog

Assign loads to structure​

To avoid ambiguous loads being applied to an undesired element, use the assign to structure option for your loads. It's important for all loads placed at the intersection between structural elements, but in general it's recommended to always use it. In some cases it's not necessary, i.e. surface loads on covers.

Load not assigned to structure versus a load correctly assigned to the Core wall

To assign loads to the structure, you can activate the function when defining them – remember you need to first select the structural element before you define the load.

Assign to structure toggle on the Line load toolbar

For any loads already defined, you can use the Assign loads to structure tool.

Assign load to structure tool


Last update: 2026-09-18