> 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/brick.md).

# Brick

The **brick** is a 3D solid hexahedral element based on the OpenSees `SSPbrick` formulation — *Stabilized Single Point*. One integration point plus a stabilization term, which keeps it free of the shear locking that a fully integrated 8-node brick suffers from in bending, and cheap with it.

Use it for volumetric behaviour: foundations, cores, massive walls, blocks, soil volumes.

## 🔧 Grasshopper component

`SSP Brick (Alpaca4d)` — **Alpaca4d ▸ 02\_Element**

Constructs one brick element from one hexahedral mesh.

### Inputs

| Name     | Nick       | Type     | Default               | Description                                                                                                                     |
| -------- | ---------- | -------- | --------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
| Mesh     | `Mesh`     | Mesh     | —                     | Hexahedral mesh with **8 vertices**, in `m`. Passed through `CleanHexahedron` to put the corners in the order OpenSees expects. |
| Material | `Material` | Material | —                     | An [nD material](/docs/basics/materials/nd.md). Uniaxial materials are not accepted.                                            |
| Colour   | `Colour`   | Colour   | Alpaca4d brick colour | Display colour in the Rhino viewport.                                                                                           |

### Outputs

| Name    | Nick      | Type    | Description                                                             |
| ------- | --------- | ------- | ----------------------------------------------------------------------- |
| Element | `Element` | Element | Brick element, to be connected to [Assemble](/docs/basics/assemble.md). |

{% hint style="info" %}
One component makes **one** element. To build a solid region, graft a list of hexahedral meshes into the component — [Mesh Series to Brick](/docs/basics/utility/mesh-series-to-brick.md) and [Mesh Loft](/docs/basics/utility/mesh-loft.md) exist to produce them.
{% endhint %}

## 📈 When to use it

**Use it when**

* You need a full 3D stress state — confinement, triaxial behaviour, contact with soil or massive concrete.
* The region cannot be represented accurately by beams or shells.
* You are studying stress concentrations inside a body.

**Do not use it when**

* The body is thin compared to its in-plane dimensions → use [Shell](/docs/basics/elements/shell.md).
* The behaviour is bending-dominated and member-like → use [ForceBeamColumn](/docs/basics/elements/force-beam-column.md).
* Your geometry only meshes into tetrahedra → use [Four Node Tetrahedron](/docs/basics/elements/four-node-tetrahedron.md).

## 🔗 Relation to OpenSees

```tcl
element SSPbrick $eleTag $n1 $n2 $n3 $n4 $n5 $n6 $n7 $n8 $matTag $bx $by $bz
```

* The 8 mesh vertices map to `$n1 … $n8`.
* `$matTag` is the **Material** input.
* The body forces `$bx $by $bz` are not exposed by the component and are left at the OpenSees default. Self-weight is applied instead as equivalent nodal loads by [Gravity Load](/docs/basics/loads/gravity.md).

Note that a brick node has **3 DOF**, not 6. A brick sharing a node with a beam or shell therefore transfers force but no moment.