> For the complete documentation index, see [llms.txt](https://docs.enercalc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.enercalc.com/e3d-user-manual/model-entities/toc175916832/toc161394048.md).

# Membrane Nodal Resultants

Understand membrane nodal resultants and how to use them to compute shear wall pier forces and moments.

The membrane nodal resultants of a shell are concentrated forces Fx and Fy (with force units) at the four nodes of each shell element. They in effect keep each individual element in equilibrium (in-plane). They are expressed in the local coordinate system.

You may view nodal forces of selected shell elements by Quick Access Toolbar > Annotate. The membrane nodal forces may be used to compute shears, axial forces, or moments in a shear wall. For example, the following three shells represent a pier in a shear wall. Each shell is 1.5 x 1.5 ft in size. Membrane nodal resultants Fx and Fy are shown in the first and second rows respectively at each corner of the element. The shear, axial force and moment resultants on the top of the pier may be computed as follows:

![](https://560001759-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FWNe8U6EBBBdUJHdb2X9G%2Fuploads%2Fgit-blob-793eb0be92bc8ee04f0154c9eb42225e1d74711d%2FFASTFR~1_img184.png?alt=media)

![](https://560001759-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FWNe8U6EBBBdUJHdb2X9G%2Fuploads%2Fgit-blob-3061cdfd68e52148167c630c2c4113117cef7d3e%2FFASTFR~1_img258.png?alt=media)

| Fxi (kips)         | Fyi (kips)               | Xi (ft) | Fyi \* Xi (ft-kips) |
| ------------------ | ------------------------ | ------- | ------------------- |
| 1.758              | -2.284                   | -2.25   | 5.139               |
| 3.226              | 1.663                    | -0.75   | -1.24725            |
| 7.226              | -8.458                   | -0.75   | 6.3435              |
| 5.786              | 4.611                    | 0.75    | 3.45825             |
| 3.144              | -3.718                   | 0.75    | -2.7885             |
| 2.722              | 3.082                    | 2.25    | 6.9345              |
| Shear ΣFx = 23.862 | Axial Force ΣFy = -5.104 |         | Moment ΣM = 17.8395 |


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.enercalc.com/e3d-user-manual/model-entities/toc175916832/toc161394048.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.