Engineers Launch New Building System To Protect Houses In A Quake

Canterbury engineers are moving forward with plans to manufacture a new base isolation system that will make Kiwi houses safer in an earthquake.

University of Canterbury postdoctoral fellow Tom Francis (right) and Civil and Natural Resources Engineering Professor Tim Sullivan (left) are keen to start manufacturing a base isolation system for residential houses. (pictured with UC Structural Engineering Laboratory Manager John Maley)

A prototype of the system was tested last year by a University of Canterbury team led by Civil and Natural Resources Engineering Professor Tim Sullivan and postdoctoral fellow Tom Francis.

It showed very promising results and with the encouragement of University of Canterbury Research and Innovation staff, the project team has now won funding from KiwiNet’s Emerging Innovator Programme.

The programme supports scientists to develop their innovations through a business-lens and take them into the world where they can make a difference. KiwiNet has also provided $40,000 in Tier 1 PreSeed Funding.

Dr Francis is using the Emerging Innovator funding to work on commercialisation of the base isolation system over the next six months, as well as designing a second prototype.

He says next year they plan to set up a company with the goal of supplying the devices to housing developers and overseeing their construction. He would take up a role as managing director of the new company.

“I’m quite driven to do this commercialisation work and starting a company would be really rewarding. It’s not something that I was expecting at the start of my research, but I’ve discovered that it’s my interest as time has gone on.”

The Emerging Innovator Programme also provides him with a mentor, experienced engineer John Cunningham, Executive Director at Ignition Partner Ltd, who is helping him work on the commercialisation process.

“I’m developing another prototype - we’re calling it a phase two system - which will have even more cost-effective construction than our original design,” Dr Francis says.

“We’re planning on talking to housing developers because we think the system will be a good selling point for new houses, making them safer for people to live in.”

He is excited about bringing the new system to market. “I was optimistic about completing a PhD that would have potential real-world benefits and after working with future stakeholders in this system, I feel positive this product will be able to be implemented.

“The testing we did of the original system using a shake table in the Structural Engineering Laboratory went even better than we expected and showed that the device we’ve created does help prevent damage to residential houses in a large earthquake.”

The base isolation system is designed to help homeowners avoid costly repairs and stressful insurance claims in the event of a major earthquake.

Testing showed that it limits building deformation, preventing damage to walls and cladding, and keeps floor and roof accelerations low which helps to protect building contents.

Last year, a mock-up room with gib lined walls was positioned on top of the newly-developed steel base isolation units, with the University of Canterbury’s shake table underneath.

The table – one of the largest in New Zealand – recreated ground movements recorded at various locations during the damaging Canterbury earthquakes as well as other strong earthquakes and a simulated Alpine Fault quake.

Results showed the base isolation units were effective and would have withstood the 2010-2011 Canterbury quakes and 2016 Kaikoura earthquakes (7.1 and 7.8 magnitude respectively), as well as an Alpine Fault scenario, without the room needing any repairs.

Professor Sullivan and Dr Francis’ goal is to keep the seismic system as low-cost as possible so it can be widely adopted by homeowners around the country, making their houses significantly safer.

“We think what we’ve come up with will prevent damage, and it doesn’t cost an arm and a leg. It also promises to reduce the disruption caused by a major quake, helping communities recover more quickly,” Professor Sullivan says.

Base isolation systems, developed to prevent or minimise damage during an earthquake, are primarily used in commercial or civic buildings in New Zealand because they are usually expensive and require specialised engineering.

The aim with the new residential system is to keep the total cost of manufacturing and installing the base isolation system to less than 5% of the total construction cost for a house.

Professor Sullivan says houses in New Zealand currently perform well in terms of saving people’s lives, but there is room for improvement in terms of preventing damage to the structure and its contents.

“Research has shown that the most upsetting thing for a lot of people wasn’t the earthquake itself, it was dealing with insurance claims, the potential loss of value for their houses, and the damage to their belongings. If we can avoid that, then I think there will be psycho-social benefits.”

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How does the new base isolation system work?

The main hurdle to overcome during the design stage for the innovative system was balancing the need for a house to be stable in high winds but also able to flex and absorb shock from an earthquake.

The system is created by installing several steel base isolation units under the concrete foundation of a house, which work in a similar way to traditional piles.

The concrete slab includes steel plates that float and slide on small round discs in the units, called ‘pucks’, allowing the house to move around in a quake and absorb the displacements and accelerations imposed by ground shaking.

The system is compatible with common building techniques for New Zealand houses and can be used under steel and timber-framed buildings or other typical structures.

It’s designed to be sustainable and easy to repair after an earthquake.

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