Nails in structures designed to Eurocode 5 can be ‘smooth’ (which in practice means smooth round nails), ‘square’ (usually square twisted nails which are frequently used for joist hangers and other light gauge metal-work) or ‘threaded’ (normally termed ‘ringed shank’ and favoured for flooring).
Smooth nails have less withdrawal resistance than the other ‘improved nails’, and their calculated resistance to lateral loading may also be less.
Where nails have to resist axial loading it is recommended that improved nails be specified. The axial withdrawal resistance of particular products must be determined by test. In the absence of test data conservative calculations methods are proposed by Eurocode 5.
This unit outlined the use of nails in timber connections, looking at sizes and other limitations. Performances of improved nails were compared to that of smooth nails through Eurocode 5 expressions. Penetration limit requirements for different types of nails were presented with minimum timber thicknesses specified to prevent splitting failures.