Call for quake-resistant rebuild
Christchurch Earthquake 2011
New earthquake-resistant building technology must be used in Christchurch's rebuild to protect public safety and avoid more building failures, an international earthquake engineering expert says.
The call was backed by Acting Economic Development Minister and Forestry Minister David Carter, who said talks were under way with the Canterbury Earthquake Recovery Authority to ensure all those involved in the city's rebuild knew about the safer techniques.
Canterbury University's College of Engineering Associate Professor Dr Stefano Pampanin said the most earthquake-resistant building methods known worldwide included the precast seismic structural system (PRESSS), which used concrete, and New Zealand's timber version, prestressed laminated timber buildings (Pres-Lam).
Under the techniques, the articulated buildings flexed and rocked on their foundations in an earthquake, withstanding powerful earthquakes, like those in Christchurch last Monday, on February 22 and last September 4.
"The building shakes but it doesn't break and is quickly back in operation," said Pampanin, a member of the expert panel advising the royal commission of inquiry into Christchurch's earthquakes.
He said it was unsurprising a new city building was damaged beyond repair after last Monday's magnitude-6.3 aftershock.
Buildings constructed to current building design standards might withstand collapse, preventing loss of life, but would suffer significant damage from an earthquake of that power.
"It has performed as well as you would expect under the code. But earthquakes don't read codes.
"If you don't raise the bar, this is what you will get."
By comparison, Christchurch's only earthquake-resistant building, Southern Cross Hospital's endoscopy building, was unscathed after the three earthquakes.
Pampanin said society's expectations of building safety had outstripped current standards.
"We can give you something else now."
He believed the Government should offer incentives to encourage people to use earthquake-resistant technology.
Carter agreed all those involved with the city's rebuild needed to be aware of the technology to ensure improved safety and for economic benefits of buildings' swift return to use post- quake.
"It's vital the Government plays a role in setting the standards so buildings have higher earthquake resistance."
He backed away from offering incentives, saying it was over to owners to choose, but agreed it was a concern if new buildings collapsed with subsequent aftershocks.
"I think this technology is so good and so obvious that it shouldn't require people needing an incentive to use it. We want to spread the word around. Not enough is known about it."
The timber technology was sustainable and offered economic benefits for the forestry industry, Carter said.
Pres-Lam was developed by research consortium Structural Timber Innovation Company in New Zealand, led by Canterbury University, in a $12 million research project half-funded each by the Government and the building industry. It used New Zealand-made engineered wood, which was almost as strong as concrete.
Its demonstration building was built three years ago and tested in the university's laboratory, withstanding between 10 to 20 earthquakes stronger than that of February 22. It was rebuilt outside in the university's grounds just before February's quake, where it remained undamaged from all aftershocks.
Pampanin believed the community became complacent after the September quake because there was no loss of life and an expectation that another severe earthquake wouldn't occur for hundreds of years.
"Statistically, we should have had thousands of victims in February."
However, interest had surged in Pres-Lam since February, with many inquiries from the industry and home owners.
Top Christchurch fashion designer Barbara Lee was one person considering using the technology to rebuild her Tuam St business. She liked the option of building an earthquake-resistant building with wood after her 100-year- old Lyttelton wooden villa withstood all the big quakes.
- © Fairfax NZ News
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