This article was translated by Google Translator View original text

What is the risk in RF-LAMINATE with the stiffness reduction factors k 33 and k 88 ?


These factors reduce the torsional stiffness D 33 as well as the shear stiffness D 88 of the corresponding elements of the stiffness matrix of a surface. Since cross-laminated timber is generally not laminated on the narrow side, it is also not possible to transfer shear stresses on the board's narrow sides. Thus, the stiffness would be overestimated in this case. For this reason, the stiffness must be reduced accordingly.

Some manufacturers have already informed us of these values when transferring the layer structures. These result from internal analyzes. An explanation of how to determine the correction factors is presented in [1] . The investigations of this work have also been introduced 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 found in the corresponding approval.


Torsion stiffness Shear stiffness D33 D88 K33 K88


[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

Contact us

Contact to Dlubal

Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

+49 9673 9203 0

RFEM Other

Add-on Module

Deflection analysis and stress design of laminate and sandwich surfaces

Price of First License
1,120.00 USD