1619x
003351
2019-07-30

Question

Why is the shear stiffness reduced to 10% in the RF‑LAMINATE add-on module as well as for the orthotropic material model in RFEM for the shear modulus Gyz? I think the shear stiffness in the shear plane Gxy would have to be reduced here?


Answer:
The reduction of the shear stiffness is caused by the fact that the fibers perpendicular to each other have a very small stiffness and a low strength. For this reason, the rolling shear strength of CLT panels is also very small.

For cross-laminated timber plates, glued sideboards are assumed on boards. The boards are applied in the longitudinal direction along the x‑axis of the coordinate system (Image 02). For the shear stresses in Image 02, the shear stress τyz is thus opposed to the rolling shear strength.

The same applies to the shear stiffnesses. In the direction of the minor axis (yz-plane), the stiffness of the individual boards is considerably smaller than in the direction of the principal axis (xz‑plane) and larger than in the xy‑plane. The coordinate system shown in Image 02 should be placed on the boards in Image 03.