What does the stiffness reduction factors k33 and k88 used in RF-LAMINATE refer to?

Answer

These factors reduce the torsional stiffness D33 as well as the shear stiffness D88 of the corresponding stiffness matrix elements of a surface. Since cross-laminated timber is generally not laminated at the narrow side, it is also not possible to transfer shear stresses to narrow sides of a timber. Thus, the stiffness would be overvalued in this case. For this reason, the stiffness must be reduced accordingly.

Some manufacturers have already informed us about these values when transmitting the layer structures. These result from internal analysis. An explanation for determining the correction factors is presented in [1]. The analysis of this work has also been involved in the Austrian Annex to EN 1995-1-1 [2] . The result is shown in Figure 02. The ratio of board width (a) to board thickness (ti) can be taken from the corresponding authorization.

Keywords

Torsion stiffness Shear stiffness D33 D88 K33 K88

Reference

[1]   Gregor Silly: Numerische Studien zur Drill- und Schubsteifigkeit von Brettsperrholz (BSP). Technische Universität Graz: 2010
[2]   Eurocode 5: Bemessung und Konstruktion von Holzbauten - Teil 1-1: Allgemeines - Allgemeine Regeln und Regeln für den Hochbau - Nationale Festlegungen zur Umsetzung der OENORM EN 1995-1-1, nationale Erläuterungen und nationale Ergänzungen; ÖNORM B 1995-1-1:2015-06-15

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