# Degree of Freedoms in a Node of a 3D Frame/Beam Element

I recently took a quiz for my Matrix Methods of Structural Analysis Class, in which I encountered the following MCQ. My answer of '6' was justified, in my opinion, by the size of the stiffness matrix for a general 3-D beam element, which is 12x12 (6 for each node). I am pretty sure I am correct but I would like confirmation on whether to approach my instructor with this. • Why are you not sure of your answer? Have you checked your notes? If you are sure then contact your instructor - easy enough to correct a question. – Solar Mike May 14 '20 at 8:12
• I have gotten lazy during online classes, so no notes. Also he hasn't introduced 3D elements yet. – ABDELTA May 17 '20 at 17:30

## 1 Answer

Six seems to be the correct answer: 3 translational DoFs $$\left(u_x\right.$$, $$u_y$$, $$\left.u_z\right)$$ and 3 rotational DoFs $$\left(\phi_x\right.$$, $$\phi_y$$, $$\left.\phi_z\right)$$

You can even have a 3D beam element with 7 degrees of freedom. The 7th is for warping