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The Canterbury quakes prompted a comprehensive review by the NZ government of the system for managing earthquake-prone buildings (EPBs)

Councils and engineers gear up for earthquake-prone building checks – By Dave MacIntyre

Local authorities throughout New Zealand, engineers and the construction industry are starting to come to grips with the massive task of identifying which of our buildings are earthquake-prone – and creating a public register so anyone can also identify them.

It is a huge audit that will occupy councils and the industry for years as engineers and consultants identify at-risk buildings and recommend how to remedy their flaws. In the wake of the Canterbury earthquakes – and latterly Kaikoura – it has the aim of ensuring the way our buildings are managed against earthquake risk is consistent across the country. 

The Canterbury quakes prompted a comprehensive review by the NZ government which identified problems with the system for managing earthquake-prone buildings (EPBs) under the Building Act 2004. There was too much variability in local practices, poor-quality information about the number and specific location of EPBs across the country, and a lack of central government guidance.
 
What was needed was standardisation of the rules and processes that apply to identifying EPBs. Instead of a ‘one-size-fits-all’ approach, the new approach needed to prioritise geographic areas, buildings and parts of buildings that pose the greatest risk.
 

Striking a balance

From 1 July this year, the Building (Earthquake-prone Buildings) Amendment Act 2016 took effect, setting this new standard. The new legislation aims to strike a balance between protecting people from harm in an earthquake with the costs of strengthening or removing buildings and impacts on heritage.
 
When the-then Building and Housing Minister Nick Smith announced the new EPB legislation last year, he said that as a seismically-active country, we need to progressively upgrade our older building stock to reduce risk.
 
Since then, consultations have taken place to clarify how the audit will handle specific issues such as:

  • 
• Defining the level of seismic performance required for councils to determine whether a building is earthquake-prone
  • 
• Setting the criteria for the level of building work needed for seismic strengthening
  • 
• Specifying how buildings may be considered for exemptions from undertaking remedial work. 
One of the biggest issues is the methodology for how councils will identify EPBs, to allow them to make informed decisions.
 

Definitions and timeframes

So what is an earthquake-prone building? The new law defines an EPB as one that would have its ‘ultimate capacity’ exceeded in a moderate earthquake, and if the building were to collapse, the collapse would be likely to cause injury or death or damage to other property. The definition applies to parts of buildings as well as whole buildings, and takes into account a range of factors, including different levels of seismic risk around New Zealand.
 
Certain buildings are excluded from the new law, including farm buildings, stand-alone retaining walls, fences, wharves, bridges, tunnels and storage tanks. Most residential buildings will also continue to be excluded.
 
Timeframes for identification and remediation of EPBs have been set according to potential risk. New Zealand is categorised into three seismic risk areas based on the seismic hazard factor: high, medium and low.

The new system categorises New Zealand into three seismic risk areas defined using the ‘Z’ factor, a seismic hazard factor defined by 
NZS 1170.5; the highest Z factor is 0.6 (Arthur’s Pass) while the lowest is 0.13 (a number of places including Auckland, Northland and Dunedin)


Territorial authorities are required to undertake initial investigations to identify potentially earthquake-prone buildings within five, ten or 15 years (depending on the seismic risk of the area) using a risk-based methodology set by the Ministry of Business, Innovation and Employment (MBIE).

Building owners will be required to provide an engineering assessment within 12 months of their building being identified as potentially earthquake-prone. Territorial authorities will have limited discretion to extend this timeframe for up to a further 12 months – for example, where there are insufficient engineers available to undertake assessments.
 
If a building is determined to be earthquake-prone, timeframes for strengthening will be 15, 25 or 35 years dependent on seismic risk. For example, the timeframe in Christchurch, Gisborne, Napier and Wellington will be 15 years; the timeframe in Hamilton, Invercargill, Tauranga and Whanganui will be 25 years; and the timeframe in Auckland and Dunedin will be 35 years.
 
Buildings that are deemed as ‘priority’ for earlier remediation in areas of medium and high seismic risk include education buildings, emergency service facilities and certain hospital buildings. For heritage buildings, owners of earthquake-prone category 1 listed buildings, and those on the National Historic Landmarks List, will be able to apply for extensions of up to ten years.
 
Buildings that have been determined to be earthquake-prone will be recorded in a national register which is publicly available at https://www.building.govt.nz/managing-buildings/managing-earthquake-prone-buildings/epb-register
 
Owners are required to attach notices to their building, alerting the public to the degree to which it falls below the minimum standard. This will help the public better differentiate between EPBs and will motivate building owners to take remedial action.
 

Workshops

MBIE has recently delivered a series of 16 training workshops around New Zealand on the new EPB system to provide support for territorial authorities and engineers on their specific roles in the new system.
 
John Gardiner, manager determinations and assurance at MBIE, says one of the first priorities for most territorial authorities will be to identify potentially earthquake-prone buildings using the profile categories in the EPB guidance.
 
“Territorial authorities who had active policies under the previous system have already completed some of these assessments, while others may just be beginning. Authorities have also begun making entries in the new public register of earthquake-prone buildings,” he says.
 
“The register will continue to be populated as more earthquake-prone buildings are identified over the applicable timeframes for each seismic risk area.”
 

Getting stuck into the task

Councils confirm that they are getting stuck into the task, although Local Government New Zealand says that since the new methodology on how to do the assessments only took effect from July, training for some councils has only just finished.

A good example is Kapiti Coast District Council which has made assessing the seismic performance of approximately 1500 buildings in the Kapiti Coast district one of the key activities in its Future Kapiti Long Term Plan 2015–2035.
 
Kapiti Coast District Council staff make notes from their inspections – Photo courtesy of Kapiti Coast District Council


The Kapiti Coast is in a zone of high seismic activity with five known earthquake faults, and the council is preparing to assess all commercial, industrial and school buildings, residential buildings that are two or more storeys high and contain three or more household units, public halls, and buildings belonging to utilities that have a role in emergency and post-disaster response. 

These buildings will be assessed over five years between 2016 and 2020. In February last year the council engaged structural specialists from Opus and Beca to undertake the task.
 
Regulatory services group manager Kevin Currie says there were 479 assessments undertaken in the last year, exceeding the projected target of 250. “We’re currently reviewing MBIE’s new methodology, which is now mandatory, for assessing buildings, to establish our approach going forward. Transitional provisions mean that previous notifications to owners, informing them that their building is unlikely to be earthquake-prone, still stand.”
 

A head start in Christchurch

Christchurch City Council is also working hard on its EPB requirements. Robert Wright, head of building operational policy and quality improvement for the council, says that following the Christchurch earthquake in 2011, the Canterbury Earthquake Recovery Act 2011 was passed and the organisation CERA was established.
 
CERA’s functions under that act resulted in it collecting DEE (detailed engineering evaluation) reports on commercial buildings that had been affected by the earthquakes. “This information was also passed on to council by CERA which added to the information council already had on EPBs, and assisted the council to produce and maintain a register of EPBs within its district,” he explains.
 
“During this time period, council’s register contained approximately 900 properties that were identified as potentially earthquake-prone. Some of those buildings have now been demolished or repaired. Council issued Section 124 notices (under the former provisions of the Building Act) to the owners of these buildings,” he adds.
 
“As council had already identified potential EPBs and issued Section 124 notices to the owners prior to the new legislation coming into effect, this means Christchurch City Council has a head start regarding its responsibilities to manage EPBs within its district.”
 
Mr Wright says that to date, Christchurch City Council has transferred all the properties on its register (approximately 650) to the national EPB register, with another 20 properties still to be added once the owners have been issued with an EPB notice.
 
He adds that there is still work to be done regarding identifying potentially earthquake-prone buildings categorised as ‘priority buildings’, which requires a special consultative procedure. “At the moment there are no unforeseen problems and we are confident that the timeline is achievable,” he says.
 
Dave MacIntyre is an award-winning journalist who specialises in transport and infrastructure issues within New Zealand

 


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