The EC5 design requirement is that the design stress be less than or equal to the design tensile strength, i.e.:

fff,inst,t,mean,d and CTf,fin,t,mean,d < /t,d (7.41)

Km where the functions are as previously described and /t,k is the characteristic tensile strength ( /t, 0,k or /t,90,k, as appropriate) of the flange material. Strength information for timber and the commonly used wood-based structural products is given in Chapter 1. Stresses in the web

The design requirements for the web are that it must be able to support the flexural stresses that arise, that the shear stress in the web must be acceptable, and that the glued joints between the web and the flanges must be able to transfer the horizontal shear stresses at the interface.

(a) Bending stresses.

The maximum stresses due to bending will arise at the extreme fibre locations at a distance of (y1 - 0.5hf,c) or (y2 - 0.5hf,t) from the neutral axis as shown in Figure 7.7b.

The maximum design stress on the compression side of the web will be: • At the instantaneous condition,

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