Engineers in favour of new assessment guidelines for earthquake-prone buildings

Friday, 7 July 2017

New Zealand Society of Earthquake Engineering president Peter Smith said engineering guidelines created a more 'systematic approach'.

Engineers are welcoming new legislation they say means more consistency in the assessment of earthquake-prone buildings.

New Zealand Society of Earthquake Engineering (NZSEE) president Peter Smith said the engineering guidelines included in the legislation created a more 'systematic approach'.

IPENZ cheif executive Susan Freeman-Greene encourages building owners to do their homework on who they hire to carry out seismic assessments.

'They provide clearer definitions and more detailed guidance on ratings, which will make assessments more consistent.'

The legislation, Building (Earthquake-prone Buildings) Amendment Act 2016, came into effect July 1.

Structural Engineering Society president Paul Campbell said the previous 'red book' for seismic assessment was outdated and caused 'consistency issues'.

The Nokia House had widely variable seismic assessments after the Kaikoura earthquake.

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Building and Housing Minister Nick Smith said the date would 'trigger the timeframes for the new legal requirement to assess and upgrade buildings' when he released the consultation regulations in September last year.

Building owners are now required to provide an engineering assessment within a year of their building being identified as earthquake prone, and upgrade buildings anywhere from 7.5 years to 35 years depending on their assessed risk and location.

An earthquake-prone building typically refers to buildings that meet less than 34 per cent of the new building standard, though the classification takes into account the seismic risk of the building's location.

Under the new legislation, confirmed quake-prone buildings will also need to display a public notice.

Structural Engineering Society (SESOC) president Paul Campbell said the legislation had a 'better framework' and 'tools for assessing buildings' which would help improve building stock and increase seismic resilience.

'It also means a more consistent approach to the management of earthquake-prone buildings,' he said.

Campbell said the new legislation would encourage discussion between owners and engineers on how owners can proactively manage and improve buildings.

Following the Canterbury Earthquakes a government review identified problems with the system for managing earthquake-prone buildings under the Building Act 2004, citing too much variability in local practice, poor quality information about the number and specific location of earthquake-prone buildings across the country, and a lack of central government guidance.

Campbell said the previous 'red book' for engineer assessment was designed to enable a few engineers to do assessments on behalf of councils but after Christchurch the large demand for earthquake damage assessment gave way to consistency issues.

He said he would like to believe engineers can agree on the reason behind a rating, but the numbers may vary, so the new legislation 'closed up' any areas that were open to interpretation.

'It's very difficult to give a precise number, it's a bit like going to the doctor and asking them how long you've got to live, they're not going to say 23 days, they'll give you a range.'

Following Wellington's November 14 earthquake, the Alcatel-Lucent House, now known as the Nokia House, had diverging assessments from three structural engineering firms as to whether or not the building was earthquake-prone.

One firm reportedly rated it above 100 per cent new building standard on multiple occasions, while another said it may be less than 33 per cent NBS.

Campbell said he was not aware of lots of cases with that large a variation in seismic assessment.

The Institution of Professional Engineers New Zealand (IPENZ) chief executive Susan Freeman-Greene said, 'It's not unexpected that there will be some variation in assessment among the experts but… we would expect them to be in the same general ballpark.'

Freeman-Greene said building owners looking for engineers to do a seismic assessment should make sure the engineer has been trained on the new guidelines.

'Building owners should use Chartered Professional Engineers when commissioning seismic assessments,' she said.

'We recommend that building owners also ask engineers about their experience of that specific type of building and whether they are members of SESOC, NZSEE, or NZGS [New Zealand Geotechnical Society].'