# Example C-1 · Bridge pier spread footing

Bridge pier spread footing. Example C-1 of Kimmerling (2002) solved in Rischio and compared with the source's answers.

SourceManual

Kimmerling, R. E. (2002). Geotechnical Engineering Circular No. 6: Shallow Foundations (FHWA-IF-02-054). Federal Highway Administration. Example C-1, p. C-13 to C-30.

ID `fhwa-gec-6-c-1`

[Open in the studio](https://studio.rischio.io/examples/fhwa-gec-6-c-1?utm_source=rischio.io&utm_medium=website&utm_content=docs-example) A copy, in your account [Open the PDF](https://rosap.ntl.bts.gov/view/dot/40555/dot_40555_DS1.pdf)

Rischio isn't affiliated with the source's authors or publishers. If you hold its rights and want this example removed, write to [hello@rischio.io](mailto:hello@rischio.io).

The model, as the editor draws it. In the source: Figure C1-1, p. C-13.

## Source vs Rischio

|  | Source | Rischio | Difference |
| --- | --- | --- | --- |
| Factored pressure on the effective area, q | 475 kPa | 475 kPa | +0.1 % |
| Eccentricity along the width, ey | 0.033 m | 0.033 m | −0.1 % |
| Eccentricity along the length, ez | 0.117 m | 0.117 m | −0.1 % |

The example, worked to AASHTO LRFD 1998, checks the eccentricity only under the minimum load factors, without the live load, and those are the values shown. Rischio checks every Strength I combination: the minimum dead load factor with the live load gives a larger eccentricity along the width, 0.104 m.

## How it's calculated

-   [Method and assumptions → What the engine does, and what it assumes.](https://rischio.io/docs/shallow-foundation/theory/)
-   [Equations → Every step of the calculation, in order.](https://rischio.io/docs/shallow-foundation/equations/)
-   [Inputs → Every field of the model, with its units.](https://rischio.io/docs/shallow-foundation/inputs/)

---

Source: https://rischio.io/docs/examples/fhwa-gec-6-c-1/