1492488257932 - Earthquake tests on cheap, safe multi-storey building ‘promising’

Earthquake tests on cheap, safe multi-storey building ‘promising’

Canterbury University structural timber engineer Dr Minghao Li wants to find cheaper ways to build earthquake-resistant buildings.

His team, including researchers from Tongji University in China, built a replica of a four-storey building out of cheap materials and shook it to see what would happen.

With the help of a $67,000 grant from the Earthquake Commission (EQC) and funding from the Natural Science Foundation of China, Li oversaw the construction of the 8.8 metre building on a “shake table” in Shanghai, China.

“Each storey is 2.2m tall. I would say it’s two thirds [of a real building],” Li said.

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Constructing large buildings to be earthquake-resistant is expensive – structures often use imported high-grade steel and engineered timber framing.

The costs are a barrier to construction for developers looking to make a margin on sales or rental when the building is complete.

Li is using materials readily available in New Zealand: a “hybrid system” of commonly-used steel framing and light structural timber.

​”The whole idea is to try to combine timber and steel to try and make a stronger system which is able to resist large earthquakes, to try to minimise the damage for mainly multi-storey buildings, mainly for residential applications.”

The shake table simulated several earthquakes, including one with ground acceleration 1.4 times stronger than what was detected in the Christchurch Botanical Gardens during the February 2011 earthquake.

Li said the results were promising.

“We observed a very small amount of minor damage. So it definitely performed better than a timber-only solution.”

He said he hoped cheap hybrid systems could be used soon, but were “still in the research stage”.

“They are not that popular at the moment, because our building standards have not incorporated these type of systems yet.”

Case studies would be needed to determine how much money could be saved using hybrid systems, Li said.

“We’re confident that it definitely will be much cheaper than using other engineered timber products.”

Research at the university to test structural connections and the design of the hybrid concept is ongoing.

“The aim of our project is to feed the findings and outcomes of our research into ongoing and future earthquake strengthening design and builds in New Zealand, to improve building resilience, and keep people safe,” Li said.

The research is one of 15 projects that received $1 million in funding from EQC’s 2016 Biennial Grants Programme.

The programme is designed to build knowledge about New Zealand’s natural disasters. Applications for the 2018 programme open later this month.

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