# What is the meaning of "Shear failure in glued contact surface" in the details of the RF‑LAMINATE add-on module?

In the case of the cross-laminated timber plates that are not glued to the narrow sides, and a wall-like structural behavior, the torsion stress in the glued joints is often governing. This design is performed according to the following equation in compliance with the explanations in the literature reference below.

$\eta_x=\frac{\tau_{tor,x}}{f_{v,tor}}+\frac{\tau_x+\tau_{xz}}{f_R}=\frac{\displaystyle\frac{3\ast n_{xy}}{b(n-1)}}{f_{v,tor}}+\frac{{\displaystyle\frac{\frac{\partial n_x}{\partial x}}{n-1}}+\tau_{xz}}{f_R}\leq1$

where
• b is the board width,
• n is the number of board layers,
• nxy is the shear in the layer plane,
• $\frac{\partial n_x}{\partial x}$ is the shear of board layers,
• $\tau_{xz}$ is the shear in the thickness direction,
• fR is the rolling shear strength,
• fv,tor is the torsional shear strength.
For the y-direction, the design is similar, but with the values for the y‑direction.