Construction stages and design stages

Tekla Structural Designer
Modified: 12 Mar 2024
2024
Tekla Structural Designer

Construction stages and design stages

Construction stages

Floor levels (specifically, levels marked as floors) denote potential construction stages. Default construction stages are automatically created so that members in a floor level or attached to that level from below form an individual construction stage. You can reassign members between stages if required.

Each construction stage is assigned a stage duration (in weeks).

When the staged construction analysis is performed, each construction stage is analyzed sequentially for the Staged Construction combination only.

Stresses that develop in one construction stage become “Locked-in stresses” that are input to the following stage. At the end of the construction stages there is a set of “Locked-in stresses” that are carried through to the design stages.

Design stages

Design stages only come in to play after the end of construction, (so they don't have stage durations).

Any model can potentially have up to five design stages, each having its own set of stiffness modification factors. The design stages are:
  • Persistent Loading - Strength

  • Persistent Loading - Service

  • Transient Loading - Strength

  • Transient Loading - Service

  • Seismic Loading

When the staged construction analysis and design is performed, the Gravity, Lateral and Seismic combinations are automatically assigned to a design stage according to loadcase types contained within the combination. For example, any combination including wind will be considered transient and will be analyzed using properties appropriate to the "Transient Loading - Strength" and "Transient Loading - Service" design stages.

Load combination assignment:

The rules for the assignment are as follows:

  1. IF a combination includes any seismic case it is assigned to the Seismic Loading design stage.

  2. ELSE IF a combination includes any of the following cases it considered as Transient Loading:

    • Wind

    • Snow

    • MLL

    • Temperature

  3. ELSE the combination is considered as Persistent Loading

  4. The Strength (ULS) and Service (SLS) variants of the combination are then separated as appropriate.

The Gravity, Lateral and Seismic combinations are then designed accordingly, (the Staged Construction combination is not designed).

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