Design pathways for engineering systems
NZS 4219:2009 provides two pathways to design a seismically resilient engineering system – specific design and non-specific design.
Specific design
The specific design pathway (NZS 4219:2009 section 4) allows experienced structural engineers to design the installation using standard structural engineering rationale and calculations, based on AS/NZS 1170 and the relevant materials standards. This pathway is intended to be a Verification Method that provides a means to comply with the relevant requirements of Building Code clauses.
Examples where NZS 4219:2009 stipulates specific design include:
- components connected to the building structure at more than one level without flexible joints or connections
- wall-mounted components
- floor-mounted components without a single definable centre of gravity
- brittle components
- pipes with a diameter larger than 200 mm
- steam and gas piping
- individual components that weigh more than 25 kg
- items crossing seismic gaps.
Non-specific design
The non-specific design process (NZS 4219:2009 sections 1, 2, 3 and 5 and Appendices A, B and C) provides a range of ready-made solutions for standard situations. These can be used by building systems designers who don’t have a detailed knowledge of seismic engineering. In effect, this is a self-contained Acceptable Solution that provides a means to comply with the relevant Building Code clauses.
Provided it meets the criteria set out in NZS 4219:2009, ducting and piping system restraints can be designed using a prescriptive design approach called non-specific design. (UPG Pipe Systems)
A non-specific design is not usually a generic solution, and the non-specific design process must be repeated for each building and engineering system being considered.
It may be possible, however, to develop non-project-specific solutions for commonly used components, adapt them to a particular project and verify the suitability of the solution by engaging a seismic specialist.
Examples where NZS 4219:2009 allows non-specific design include:
- typical light fitting details
- typical fan coil unit bracing details
- typical cable tray bracing
- typical duct bracing.