Rivets, pins and dowels tend to be used in countries other than New Zealand. Guidance for their use is not specifically covered by New Zealand building standards, suppliers should, however, be able to provide this information. Split-ring connectors to improve bolt loads tend to no longer be used in New Zealand. Ply and nailed steel gussets are used extensively in New Zealand and detail on their design and use is covered here.
The New Zealand timber Structures Standard NZS 3603 is largely silent on the design of rivets, pins and dowels for timber.
These products are usually part of a proprietary system, so suppliers of the systems need to demonstrate the performance of these fixings comply with the New Zealand Building Code. A means for doing this is specified in appendix A of NZS 3603.
The similarity between rivets, pins and nails means that designers may be able to use the provisions of NZS 3603 to design these fixings, however, a good understanding of behaviour of the timber and the fastener, as well as reference to other sources, is recommended.
Without the benefit of nuts and washers, dowels have a lower load capacity than bolts.
The use of these systems is not extensive in New Zealand.
An annular groove is machined into both faces of the timber, centred about the centreline of the bolt. The ring is split so that it can be fitted into the circular grooves on the meeting face of each timber member.
The principle behind split-ring connectors is that the ring mobilises a larger area of timber, resulting in a higher bolt load capacity.
These products were once used in New Zealand but are unavailable at the present time. No current loading data is available.
Ply gussets have been used in New Zealand for many years as a utilitarian method of fixing timber to get a joint capable of carrying high moment loading. In particular, they are used to form portal frames.
Glulam portal frames with ply gusset joints
Photo: Courtesy Timber Design Guide, 2007.