The Earthquake Commission (EQC) is celebrating a triumph
of research that has helped New Zealand homes become much
stronger and could soon become part of many current building
designs.
The engineering breakthrough stems back to
the Canterbury earthquakes when BRANZ engineer Dr Angela Liu
observed that new or architecturally-designed homes with
mixed bracing had suffered significantly more damage than
older traditionally built houses.
“You’d expect
modern homes to be stronger, so it just didn’t add up and
EQC supported me to investigate why these houses were so
badly damaged,” says Dr Liu, who examined the causes for
the substantially damaged houses by using existing testing
data and carrying out desktop studies.
The results of
her EQC-funded research identified the bracing issues and
led to formal design guidance for specifically designed
bracing systems in light timber-framed residential
buildings, which was published in 2015.
Through Dr
Liu’s perseverance in presenting her results to peers and
at conferences, the 2015 guidance gradually became the
informal compliance pathway for seismic design of houses
with specifically designed bracing systems.
EQC’s
Research Manager Dr Natalie Balfour says that the work by Dr
Liu and her BRANZ team is a great example of how engineering
research can have a real impact on the resilience of New
Zealand homes.
“This is the reason why EQC invests
in earthquake engineering research, as this science has a
tangible impact on protecting New Zealand properties and
people,” says Dr Balfour.
Dr Liu’s research is
already having wide impact across the country, resulting in
the building of stronger homes and providing greater
resilience against damage from natural hazards.
“The
2015 EQC/BRANZ guidance has had wide impact, having been
taken up by professional engineers and territorial
authorities across the country,” says Dr Liu.
“In
2020 it was also used to develop the good practice document
‘Residential Portal Frames’ published by Engineering NZ
and the Engineering General Practitioners Group. This has
further helped the industry to make use of our
guidance.”
It is also likely to feature in the NZS
3604 document that is used to design our homes and sets out
the compliance pathway for many of New Zealand’s
timber-frames buildings, which is currently in the process
of being updated.
Dr Balfour says it is rare for
research to be adopted into practice and compliance in such
a short timeframe, due to the complexities and timing in
connecting research to policy and practice.
“This is
a great result for New Zealand, and it is our goal to
continue to see natural hazard resilience embedded in all
aspects of decision-making for our communities,” Dr
Balfour
says.