## Question

**What is the difference between the member force Mxx per unit length of a plate element and the node member force Mx?**

## Answer

**The member force Mxx per unit length of a plate element is the bending moment per unit length in the x-axis of the element coordinate system, and the node member force Mx is the torsional moment that rotates the x-axis of the element coordinate system at the node of the plate element.**

As shown in Image-1, the member force at each node has axial force components Fx, Fy, and Fz and moment components Mx and My.

Mx is the torsional moment that rotates the element coordinate system x-axis, and My is the torsional moment that rotates the element coordinate system y-axis.

As shown in Image-2, the Mxx of a plate element is the bending moment in the x-axis of the element coordinate system per unit length (width) of the y-axis.

Therefore, when placing rebar parallel to the x-axis of the element coordinate system, a member force of Mxx can be applied.

※ The output of element internal forces follows the element coordinate system, with arrows pointing in the positive direction.

(a) Internal force at nodes of rectangular elements

(b) Internal forces at nodes of triangular elements

[Image- 1] Member Force at each node of a plate element

[Image-2] Member force per unit length of plate element