> 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/spliced-i-girder-bridge-workflow/construction-spig/changes-spig/bearing-fixity-change-spig.md).

# Bearing Fixity Change \[SPIG]

During construction, bearing fixities may need to change stage-by-stage. This workflow item overrides the original bearing fixity starting at the selected stage and continuing through subsequent stages.

## Superstructure Connection Change

**Stage:** Construction stage at which the new fixity definitions take effect. All subsequent stages use the new values.

**Insertion Points:** Insertion Points identifying the bearings whose fixity is being changed.

**Tx \[Fixed/Free/Stiffness]:** Longitudinal translational fixity at zero bearing rotation. For a continuous girder at least one bearing is typically fixed or given a real stiffness in Tx.

**Ty \[Fixed/Free/Stiffness]:** Transverse translational fixity.

**Tz \[Fixed/Free/Stiffness]:** Vertical translational fixity. Commonly Fixed or a high stiffness such as 1000 kip/in.

**Rx \[Fixed/Free/Stiffness]:** Torsional rotational fixity. A small Rx stiffness may be added to prevent stability issues when girders are unbraced at early stages.

**Ry \[Fixed/Free/Stiffness]:** Rotational fixity about the transverse axis — typically Free.

**Rz \[Fixed/Free/Stiffness]:** Rotational fixity about the vertical axis — typically Free.


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