# Boundary Conditions

This section defines the support conditions for the superstructure, including bearing fixities and stiffness values at each support location.

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## Overview

Boundary conditions control how forces are transferred between the superstructure and substructure. They are defined at insertion points along each support line.

## Subsections

* [Bearing Fixity](https://docs.openbrim.org/examples/concrete-bridge-examples/example-prestressed-i-girder-concrete-bridge-ex1-pig/superstructure-ex1-pig/boundary-conditions-ex1-pig/bearing-fixity-ex1-pig) - Define translational and rotational fixities at each bearing location