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NZ changes quake codes

Debate about whether at risk buildings should be retrofitted or demolished.

Christchurch_quake

Design deficient: Collapsed Christchurch television centre

The New Zealand government plans to demolish any earthquake- prone building that has not been seismically retrofitted within the next 15 years.

The decision follows the publication of damning recommendations by a Royal Commission into the Christchurch earthquake.

The Ministry of Business, Innovation and Employment (MBIE) has launched a new consultation exercise that would require all local authorities to assess earthquake- prone buildings within five years and give owners a further 10 to strengthen or demolish noncompliant structures.

The changes have come about after the Royal Commission into February 2011’s magnitude 6.3 Christchurch earthquake identified flaws in the country’s earthquake- prone buildings policy. The quake killed 185 people and devastated much of the city.

“The destructive earthquakes in Canterbury [the administrative area that includes Christchurch] have highlighted the need to review and improve our system for dealing with earthquakeprone buildings in New Zealand,” said New Zealand construction minister Maurice Williamson.

Last year’s earthquake produced ground movements up to 10 times greater than previously anticipated. It exposed the country’s irregular approach to building upgrades (NCE 3 March 2011).

Under existing proposals dating from 2004, the timescale for structural assessment and remediation is up to 28 years - with approaches to identifying vulnerable buildings differing across the country’s 66 local authorities.

There are up to 25,000 buildings at risk from earthquake damage in New Zealand - 13% of the country’s total building stock. They will require strengthening or demolition, according to MBIE.

Under new proposals central government will lead efforts to bring buildings up to a standard that meets 34% of the seismic loading requirements for new buildings, overseeing the work of individual local authorities.

Institution of Professional Engineers New Zealand deputy chief executive Nikki Crawford welcomed the universal approach, but warned the plans will be “contentious”.

“There is very variable practice between local authorities,” she said. “The Royal Commission and government recognised there needs to be much more consistency between local authorities.”

But Crawford said engineers were divided on whether improving buildings to 34% of code is the right approach.

“Some engineers say the new building code is not relevant [to older buildings] because it is not a reliable measure of how strong the building is,” she said.

“It’s going to have a huge impact. The implications of the policy will be dramatic, and it is contentious.”

Williamson agreed the changes “could have significant economic implications” for owners of at risk buildings.

Consultation on the new proposals will close in February.

 

Collapsed TV studios ‘badly designed’ - report

The CTV building that collapsed killing 115 people in Christchurch, New Zealand during last year’s earthquake was badly designed and should have never been issued with a permit.

The Canterbury Earthquakes Royal Commission into causes of building failure during the earthquake was released this week, and included a detailed analysis of the CTV building failure.

New Zealand prime minister John Key said the report “makes for grim and sobering reading”.

“It concludes the engineering design of the CTV building was deficient in a number of respects,” said Key.

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