Assembly types and assembly hierarchy

Tekla Structures
2023
Tekla Structures

Assembly types and assembly hierarchy

Before you start to build up the assemblies in the model, consider the needed assembly structure, how it needs to be composed, and how is affects the drawings and reports. There are several methods how the assembly structure can be formed, depending on the needed structure.

Method Assembly type More information

Bolt or weld parts to an existing assembly as secondary parts.

Basic assembly

Use bolts and welds to create and connect assemblies and sub-assemblies

Add parts to an existing assembly a secondary parts.

Basic assembly

Add parts to an existing assembly

Bolt or weld assemblies to an existing assembly as sub-assemblies.

Nested assembly

Use bolts and welds to create and connect assemblies and sub-assemblies

Add parts or assemblies to an existing assembly as sub-assemblies.

Nested assembly

Create nested assemblies

Join existing assemblies together without adding any loose parts.

Nested assembly

Join existing assemblies
Tip:

To easily check the structure and hierarchy of an assembly, use the Assembly tree viewer tool from Tekla Warehouse.

Assembly types

Single-part assembly and basic assembly

A single-part assembly consists of one single part. When a part is modeled, Tekla Structures automatically creates an assembly for it.

A basic assembly consists of a main part with secondary parts, and the assembly is on one assembly level.

Tekla Structures creates basic assemblies when you:

  • Use workshop bolts or workshop welds to manually connect parts together.

  • Apply a component that automatically creates workshop welds or workshop bolts.

  • Use the Add to assembly command to add parts to an existing assembly as secondary parts.

The main part in an assembly has other parts welded or bolted to it, or added with the Add to assembly command. By default, the main part is not welded or bolted to any other parts. You can change the main part if needed.

Nested assembly

A nested assembly consists of a parent assembly and sub-assemblies which are on the lower assembly levels in the assembly hierarchy.

Tekla Structures creates a nested assembly when you:

Another type of a nested assembly is created when you join existing assemblies as sub-assemblies. The sub-assemblies are on the same assembly level.

Use the Join as sub-assemblies command to join existing assemblies together. You can add assemblies as sub-assemblies, but not any loose parts (parts or items).

Note:

Sub-assemblies in a nested assembly retain their own assembly information and main part. You can define the properties separately for the sub-assemblies and the parent assembly.

To select assemblies in different assembly hierarchy levels, place the mouse pointer on any part in the assembly, press Shift and scroll up or down with the middle mouse button.

How to check the assembly hierarchy in a nested assembly

You can work on any level of a nested assembly, from single parts and bolts, through the sub-assemblies, up to the highest level of the nested assembly.

The active selection switch defines on which level you start and toward which direction you move in the assembly hierarchy. The status bar shows the level of the assembly hierarchy you are on.

The assembly on the highest hierarchy level gets the number 0, and the assemblies or objects inside an assembly lower in the hierarchy get the number 1, 2, and so on. You can continue to level 9.

  • When the Select assemblies selection switch is active:

    Start from the assemblies on the highest level, move to their sub-assemblies, and finally select single parts, bolts, and so on.

    To shift to a specific level in an assembly, place the mouse pointer on any part in the assembly, press Shift and scroll up with the middle mouse button to highlight the objects on the lower levels in assembly hierarchy, level by level.

  • When the Select objects in assemblies selection switch is active:

    Start from single objects and move to higher levels of nested assemblies.

    To shift to a specific level in an assembly, place the mouse pointer on any part in the assembly, press Shift and scroll up with the middle mouse button to highlight the objects on the higher levels in assembly hierarchy.

The blue highlighting box indicates the assembly that you can select.

The assembly hierarchy in nested assemblies affects drawings and reports. Report and drawing templates need to be made with similar hierarchy as the assembly hierarchy in the model to output the data from the correct assembly levels.

You can create separate drawings and reports of the sub-assemblies and the nested assembly, and still produce dimensions, marks, fabrication information, and so on for all the assembly levels.

For more information how to work with the assembly hierarchy, watch the Working with multi-level assemblies video.

Assembly examples

Column corbel

A column corbel is fabricated in one workshop, and then attached to the column in another workshop. Model the corbel as a sub-assembly of the column. Then create an assembly drawing for each workshop: one assembly drawing showing how the corbel is welded together, another assembly drawing showing how the corbel and the other parts are welded to the column.

(1) Drawing 1, Workshop 1

(2) Drawing 2, Workshop 2

Complex truss

Model the halves of a complex truss as assemblies. Create assembly drawings for the workshop to fabricate the truss halves. Then create another assembly drawing showing how the halves should be joined on site.

Built-up profile

In a frame of built-up columns and beams, each built-up profile can be a sub-assembly. You can create an assembly drawing showing the entire frame, and separate drawings showing how the columns and beams are constructed.

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