## Fh rfTNmm

 Table 10.5 EC5 equations for My Rk Fastener Smooth round nails (EC5, equation (8.14)) Square nails (EC5, equation (8.14)) 0.3 fud26 (10.23) 0.45fud26 (10.24) Staples (EC5, equation (8.29)) 240d26 (10.25) Bolts (EC5, equation (8.30)) 0.3fu,kd2'6 (10.26) Dowels (EC5, 8.6.1) Smooth shank screws with a smooth shank diameter d < 6 mm Smooth shank screws with smooth shank diameter d > 6 mm As for nails As for bolts

d is the diameter of the nail, bolt, staple or dowel (in mm). For staples with rectangular sections, d is the square root of the product of the leg dimensions and for screws d is the effective diameter referred to in Table 10.3. fu is the tensile strength of the nail wire (or screw material) (in N/mm2). fuk is the characteristic tensile strength of the bolt (or screw material) (in N/mm2).

d is the diameter of the nail, bolt, staple or dowel (in mm). For staples with rectangular sections, d is the square root of the product of the leg dimensions and for screws d is the effective diameter referred to in Table 10.3. fu is the tensile strength of the nail wire (or screw material) (in N/mm2). fuk is the characteristic tensile strength of the bolt (or screw material) (in N/mm2).

The embedment is the distance the dowel depresses the timber or wood-based product. Because of the complex cellular nature of timber and wood-based products, the embedment strength is not a material property. It is a system property dependent on several factors, including the type of fastener being used. From the results of investigations by various researchers, the value derived for the characteristic embedment strength of timber and wood products, fh,k, given in EC5 when using different types of metal dowel fasteners is summarised in the following sub-sections.

10.3.3.1 Characteristic embedment strength when using nails (diameter < 8 mm)

The embedment strength varies depending on the diameter of nail being used, the types of material used in the connection, and whether or not pre-drilling is adopted. Embedment strengths for the possible variations arising in design are given in Table 10.6.

10.3.3.2 Characteristic embedment strength when using staples

The embedment strength is derived using the expressions given in Table 10.6 for nails and where the staple has a rectangular cross-section the diameter d should be taken as the square root of the product of its leg dimensions.

Fig. 10.7. Embedment strength of timber or wood-based material.
 Condition fh,k (N/mm2)
0 0