This is a basic single-node spring element with translational and rotational stiffness. Forces generated from these elements are included in the total reaction

Degrees of Freedom

The one-node spring contains six degrees-of-freedom (DoFs):

1. x-translation
2. y-translation
3. z-translation
4. rotation about x
5. rotation about y
6. rotation about z

The local stiffness matrix is formulated with the following degree-of-freedom order:

$\begin{bmatrix}u & v & w & \theta_{x} & \theta_{y} & \theta_{z} \end{bmatrix}$

Where:

$u=$ x-translation at node

$v=$ y-translation at node

$w=$ z-translation at node

$\theta_{x}=$ rotation about x at node

$\theta_{y}=$ rotation about y at node

$\theta_{z}=$ rotation about z at node

Stiffness Matrix Formulation

The stiffness matrix is formulated in global coordinates, as the stiffness inputs are in global coordinates.