# B21E

2D Displacement Based Bernoulli Beam With End Moment Release

* Number of Nodes: 2
* Number of DoFs: 3 (Translation, Translation, Rotation)
* DoF Label: U1, U2, UR3

## Syntax

```
element B21EL (1) (2) (3) (4) [5] [6]
element B21EH (1) (2) (3) (4) [5] [6]
# (1) int, unique element tag
# (2) int, node i
# (3) int, node j
# (4) int, section tag
# [5] int, number of integration points, default: 6
# [6] bool string, nonlinear geometry switch, default: false
```

## Remarks

1. The Lobatto integration is used by default. The number of integration points ranges from 3 to 20.
2. To use the corotational formulation for nonlinearity, please turn on the switch.
3. To release end moment at node `(2)`, use element `B21EL` in which `L` stands for low.
4. To release end moment at node `(3)`, use element `B21EH` in which `H` stands for high.
5. Analysts shall ensure the node with moment released must be connected to other elements that has in-plane rotational DoF.
6. Local iterations are performed to achieve a tolerance of `1E-13`.
7. Since additional rotation is involved to achieve a pinned connection, visualisation is not available.
8. Unlike 3D beam elements, there is no need to attach an `orientation` to 2D beam elements.


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