# Combinations

This section defines load combinations for structural analysis and design per AASHTO LRFD specifications.

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**Navigation:** Combinations
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## Overview

Load combinations combine individual load cases with appropriate factors to evaluate structural performance under various conditions:

* **Result Extraction Cases:** Define cases for extracting analysis results
* **Design Load Combinations:** Configure limit states and load factors per AASHTO LRFD

## Sections

| Section                                                                                                                                                                        | Description                                        |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------- |
| [Result Extraction Cases](https://docs.openbrim.org/examples/concrete-bridge-examples/example-concrete-u-girder-bridge/combinations-ex1-cug/result-extraction-cases-ex1-cug)   | Define result extraction parameters                |
| [Design Load Combinations](https://docs.openbrim.org/examples/concrete-bridge-examples/example-concrete-u-girder-bridge/combinations-ex1-cug/design-load-combinations-ex1-cug) | Configure limit states and load combination tables |

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Complete all load definitions before configuring load combinations.
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