# 8. Loading

This section defines all applied loads on the bridge structure beyond self-weight, including live loads, wind loads, and temperature effects.

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Load definitions follow AASHTO LRFD specifications. The influence surface-based live load analysis automatically determines critical vehicle positions.
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## Load Categories

| Category                                                                                                                                                                      | Description                                                  |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------ |
| [Load Geometry Definitions](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/loading-ex1-sig/load-geometry-definitions-ex1-sig) | Define surfaces for load application                         |
| [Loads](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/loading-ex1-sig/loads-ex1-sig)                                         | All load types including static, live, wind, and temperature |

## Loads Defined in This Example

| Load Type                     | Value/Description                      |
| ----------------------------- | -------------------------------------- |
| **Future Wearing Surface**    | 30 psf surface load                    |
| **Stay-in-Place Forms (SIP)** | 15 psf                                 |
| **Live Load**                 | HL-93 Design Vehicle                   |
| **Wind on Structure**         | Per AASHTO from multiple attack angles |
| **Wind on Live Load**         | Per AASHTO specifications              |
| **Temperature**               | Uniform temperature change             |

## Load Types

* **Static Loads**: Surface loads for wearing surface and SIP forms
* **Influence Surface-Based LL/BR/CE**: Live load, braking, and centrifugal effects using influence surfaces
* **Wind Loads**: Lateral loads on structure and vehicles from various directions
* **Temperature Loads**: Uniform temperature changes for thermal expansion/contraction