> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/truss-bridge-workflow/construction-tb/arch-elements-construction-tb/arch-construction-tb.md).

# Arch Construction \[TB]

The Arch Construction workflow item activates the selected arch ribs, arch bracings, and hangers in the staged construction model. From the selected stage onward, the listed elements contribute stiffness and their own self-weight to the analysis, each scaled by its dedicated self-weight factor.

## Arch Construction

**Stage:** Select the [Construction Stage \[TB\]](/templates/truss-bridge-workflow/construction-tb/construction-stage-tb.md) at which the arch elements will be constructed. The arch, bracing, and hanger FE groups are activated from this stage onward.

**Bridge:** Select the [Bridge Alignment \[TB\]](/templates/truss-bridge-workflow/bridge-geometry-tb/bridge-alignment-tb.md) that the arch elements belong to.

**Selected Arches:** Pick the arch ribs to be constructed at this stage. Arches whose construction should start at a different stage should be placed in a separate Arch Construction object.

**Selected Arch Bracings:** Pick the arch bracings to be constructed at this stage.

**Selected Hangers:** Pick the hangers to be constructed at this stage.

**Arch Self Weight Factor:** Factor applied to the arch ribs' self-weight during this stage. A value of `1.0` applies the full self-weight; higher or lower values scale it up or down to account for fabrication / attachment weight not captured by the cross-section alone. Applied as a downward (negative Z) body-force multiplier on the selected arch FE group.

**Arch Bracing Self Weight Factor:** Factor applied to the arch bracings' self-weight during this stage, with the same meaning as the Arch factor above.

**Hanger Self Weight Factor:** Factor applied to the hangers' self-weight during this stage, with the same meaning as the Arch factor above.

**Stiffness \[No/Yes]:** Choose whether the listed arch elements, bracings, and hangers contribute stiffness to the FE model from this stage onward. In most construction scenarios this is set to **Yes** so that the elements resist load once constructed; **No** can be used when the elements are placed for weight only (e.g. during heavy-lift erection) before being fully engaged structurally.


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