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Compression perpendicular to the grain in supports

Design of compression perpendicular to the grain in supports is based on the chapter 6.1.5 of EN 1995-1-1:

The design compressive stress in the contact area perpendicular to the grain is calculated using the formula (6.4):

\sigma _{c,90,d}=\frac{F_{c,90,d}}{A_{ef}}

Final verification corresponds to the expression (6.3):

\sigma _{c,90,d} \leq k_{c,90} f_{c,90}

The following rules are used for determination of the factor k_c,90:

• The value 1.5 is used for solid timber providing that the distance from the nearest joint is longer than 2h (where h is the height of supported member).
• The value 1.75 is used for glued laminated timber providing that the distance from the nearest joint is longer than 2h (where h is the height of supported member). The length of the support shall be shorter than 400mm.
• The value 1.0 is used in other cases

Different procedures are used for certain national annexes:

SS EN 1995-1-1 (Sweden)

Following values of partial factors are used for verification of pressure perpendicular to the grain:

\gamma _{M}=1.0 ; k_{mod}=1.0

This procedure can be used in cases when increased deformations in supports have no significant impact on the system’s stability and mechanical resistance. Otherwise, the procedure according to EN 1995-1-1 shall be used.

NS EN 1995-1-1 (Norway)

Verification of pressure perpendicular to the grain is based on "Rapport 86: Compression perpendicular to the grain, a recommendation" (released by Norsk Treteknisk Institutt in February 2013).

Following values of the characteristic compressive strength perpendicular to the grain f_c,90,k are used for verification of pressure perpendicular to the grain:

The factor k_c,90 is calculated according to this table: