According to EN 1995-1-1 §6.1.7 (1)P the shear check implies:
with
- the design shear stress
- the design shear strength (= a material property)
From any course on mechanics, you can find that the maximal shear stress in a rectangular section equals:
Combining both equations gives:
or
The area of a rectangular section equals :
Yet EN 1995-1-1: 2004/A1:2008 §6.1.7 (2) states that the effective width = should be used instead of the width to take the influence of cracks into account. for solid and glued laminated timber, for all other wood based products.