Brittle Failure

The ductile strength of a connection subjected to a moment can only be achieved if there is no brittle failure caused by premature splitting or shearing of the timber.

In order to prevent this type of occurrence, EC5 gives minimum edge, end and spacing criteria for use with metal dowel type fasteners and connectors loaded laterally. These are to be considered as recommended minimum values and if anything larger spacings and distances should be adopted. From the EC5 requirements and adjusting as considered appropriate, Table 12.3 gives suggested criteria for the types of fasteners commonly used in moment connections.

Also, to prevent splitting in timber when using nails greater than 6 mm in diameter, pre-drilling must be used and the particular requirements for these fasteners are given in Section 10 of EC5. Pre-drilling is also necessary to allow nails to be fixed in dense timber is a requirement for nails if the characteristic density is >500 kg/m3.

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