> For the complete documentation index, see [llms.txt](https://alpaca4d.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alpaca4d.gitbook.io/docs/basics/elements.md).

# Elements

Alpaca4d provides different finite element types to model 1D, 2D and 3D structural components.\
The main Grasshopper components are **Line to Beam**, **Mesh to Shell** and **Brick Element**.

## Beam elements – Force Beam Column

The **Force Beam Column** component converts Rhino curves into **Timoshenko beam elements**.

* **Usage**
  * Use beams when one dimension (length) is much larger than the cross‑section dimensions.
  * Suitable for frames, trusses, columns, beams, braces and similar members.
* **Behaviour**
  * Timoshenko formulation → includes both bending and shear deformations.
  * The cross‑section is defined separately and can be oriented using the `orientSection` input.
  * The `beamType` option allows you to release end rotations and/or forces, e.g. to create axial‑only (truss) elements.

## Beam elements – Beam With Hinges

The **Beam With Hinges** component creates a force-based beam element with **concentrated plasticity** at the element ends using `HingeRadau` integration.

* **Usage**
  * Use when yielding is expected only at the ends of a member (e.g. in moment frames under seismic loading).
  * Suitable for modelling pinned or moment-released connections by setting DOF releases at the I or J end.
* **Behaviour**
  * The interior of the element stays **linear elastic**; nonlinearity is confined to the hinge zones.
  * The hinge zones are defined by a `Release` condition and a plastic hinge length ( l\_p ).
  * Uses `HingeRadau` integration, written as an inline `forceBeamColumn` command in OpenSees.

## Shell elements – ASDShell

The **ASDShell** component converts mesh faces into **shell elements**.

* **Usage**
  * Use shells when one dimension (thickness) is much smaller than the in‑plane dimensions.
  * Typical applications: slabs, walls, plates, folded shells, roofs, tanks.
* **Behaviour**
  * Triangular faces are converted to **ASDShellT3** elements.
  * Quadrilateral faces are converted to **ASDShellQ4** elements.
  * The element thickness and material are defined through the assigned shell section.

## Brick elements – SSPbrick

The **SSPbrick** component converts hexahedral solids into **3D brick elements** (e.g. `SSPbrick` ).

* **Usage**
  * Use bricks for fully 3D stress states, such as foundations, solid walls, blocks, soil volumes, or regions with strong 3D effects.
* **Behaviour**
  * The input must be a hexahedral mesh (six‑faced solid with quadrilateral faces).
  * Creating high‑quality hex meshes can be challenging; the **MeshSeriesToBrick** utility component can help generate simple brickable volumes from a series of meshes.

In practice, you will usually **combine** these element types in the same model:\
beams for the main frame, shells for slabs and walls, and bricks for local 3D regions where needed.


---

# 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://alpaca4d.gitbook.io/docs/basics/elements.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.