Australia is not known for its frequency of earthquakes and seismic events; we are not resting on a fault or tectonic plate like California, New Zealand or Japan, however major seismic events can and do occur. Many remember the Magnitude 5.6 1989 Newcastle earthquake which displaced 1,000 people, saw 300 buildings demolished, and caused 13 fatalities. According to Geoscience Australia, stronger earthquakes can occur on the mainland. Australia’s highest Magnitude earthquake was recorded in Tennant Creek, NT with a magnitude of 6.6.
Though Australia has a standard for structural design actions about earthquakes (AS 1170.4-2007), it does not have a thorough remit for anchor design or non-structural parts such as aluminium partitioning systems.
The AS1170.4-2007 contains broad and useful calculations on load bearing for seismic events on non-structural building elements.
Under seismic load, the performance of non-structural building elements may place occupants at risk of injury through collapse, ruptured plumbing, or exposed electrical wires or equipment. Secondary effects such as repair costs and lost productivity for commercial or industrial settings are also significant.
Designing non-structural building elements for earthquake forces to the standard may not be adequate for seismic bracing.
Since there is no comprehensive standard for seismic bracing or anchoring, engineers tend to ignore or gloss over specific seismic anchoring. This may be due to a perception of added expense and a lack of enforcement.
The National Construction Code (NCC) requires all buildings to comply AS1170.4 focusing on section 8 of the standard. Additional design requirements also apply to homes and structures with higher Hazard Zone factors.
According to the Master Builders’ Association of Queensland, “engineers, architects, designers, building certifiers, manufacturers, installers, and builders all share responsibility to comply with the Earthquake Standard.”
Seismic bracing has always been in the building code although rarely thought necessary in Australia to enforce it. Bracing doesn’t require much more effort to install and ensures that damage would be more readily contained if a seismic event occurred.
By contrast, the NCC in Australia is more lenient, requiring 50% of the weight to be restrained. New Zealand, they would have required 200-300% of the weight to be restrained in order to prevent much of the destruction seen in Christchurch.
When it comes to installing aluminium partitions, it is essential to refer to a structural engineer as they can run the calculations of required seismic bracing load according to hazard zone factors and the importance level of the building (according to the NCC, based on the level of occupancy.) Section 8 calculations should not be taken as a “one calculation fits all” solution.
A structural engineer is required to ascertain if your partitioning and wall system requires seismic bracing and ensures your system is safe in the remote – but still possible – chance of a seismic event causing damage to your property.