New plans for earthquake strengthening
HAMISH RUTHERFORD AND MICHELLE COOKE
Commercial and multi-storey residential buildings in New Zealand will have to be assessed for seismic strength within five years under government recommendations in the wake of the Christchurch earthquake.
Proposals from the Ministry of Business, Innovation and Employment also cut the time that owners have to strengthen earthquake-prone buildings, from an average of 28 years, to just 15 years.
Volume 4 of the Canterbury Earthquakes Royal Commission’s findings outlines recommendations for how to handle the estimated 15,000-25,000 earthquake-prone buildings in New Zealand.
Crucially, the current threshold for earthquake-prone buildings, often referred to as 34 per cent of the new building standard, will not be raised.
Building and Construction Minister Maurice Williamson estimated that raising the standard to 67 per cent would cost more than $12 billion over the next five years. He said the recommendations were an attempt to strike a balance between ensuring safety and realistic costs.
The new measures were expected to add about $700 million to bringing New Zealand’s earthquake prone buildings up to standard, on top of the $1b cost under the current rules.
Today’s report makes 36 recommendations, many of which cover buildings with unreinforced masonry (UMR):
- Falling hazards such as chimneys and ornaments, for even single unit residential buildings, must be reinforced or dismantled.
- Local authorities could be given the power to require unreinforced masonry buildings to be strengthened within two years. It does, however, give scope for buildings such as rarely used rural churches to be allowed to be exempt.
- A new grading system, ranging from A to E, will be established to assist public knowledge of building strength.
Today’s report was the fourth of seven volumes and includes the commission’s findings on the failure of 21 buildings, and a free-standing masonry wall, which caused the deaths of 42 people in the February 22 quake.
A report on the investigation into the PGG building, where 18 people died, has already been released in earlier volumes, and the report into the CTV building where 115 people were killed, was delivered to the Governor-General last month and is expected to be made public by the end of the year.
Today’s report also makes recommendations for best practice, policy and legislation to help minimise the risks to public safety from vulnerable buildings during an earthquakes, but is not binding on the Government.
Most of those killed in the February quake, excluding those who died in the PGG or CTV buildings, were killed by falling debris when they were walking past a building, sitting in a vehicle outside a building, or had run out of a building to escape. Six people were in a neighbouring building when they were killed by falling walls or unreinforced masonry from another building and four people were killed by the building they were in.
Thirty six of the 42 deaths investigated in the report occurred within the CBD and the other six were in Christchurch suburbs.
All but one were caused by older unreinforced masonry buildings or brick or block structures.
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