Availability and the engineering design of bolts, coach bolts, coach screws and dowels are covered in this section. Bolts, coach bolts, coach screws and dowels provide high lateral strength transmitted through shear and can act in tension.
The fasteners described in this section are:
Illustrations: Courtesy Timber Design Guide, 2007
These fasteners transmit forces through shear at one (or more) interface and develop moderately high lateral strength through an interaction of wood bearing and fastener bending.
At higher loads and deformations, a bolt may act in tension and transmit increased loads through friction and the tensile ‘rope effect’, but only if the tensile forces can be transmitted to the timber members.
This is not the case with dowels.
Bolts, coach bolts, coach screws and dowels are available throughout New Zealand from building supply stores.
There are several New Zealand manufacturers and importers. Custom made bolts and coach screws are also available.
Split-ring connectors, shear plates or tooth plate connectors (bulldog) can increase the strength of a bolted joint, however these connectorsare not readily available in New Zealand.
Bolted truss roof structure
Source: Courtesy Timber Design Guide, 2007