Research reduces earthquake strengthening costs for schools

Associate Education Minister Nikki Kaye says ground-breaking research released today by the Ministry of Education has found timber-framed classrooms are extremely resilient to earthquakes.

“This is good news for the education budget because we will not have to spend hundreds of millions of dollars on earthquake strengthening these buildings,” Ms Kaye says.

“The research has confirmed these buildings are safe and resilient in quakes. This means that we can focus on modernising buildings to provide better learning environments.

“The Ministry advises me that timber-framed structures account for up to 90 per cent of school classroom and administration buildings.

“Timber-framed school buildings performed very well in the Canterbury earthquakes, with no major structural damage caused by ground shaking. Building damage there was caused by liquefaction, rather than shaking.

“The Ministry advises me that this led to commissioning research to find out definitively whether wooden school buildings needed earthquake upgrading, or whether they were already strong enough.

“This research confirmed that timber-framed buildings are low risk and don’t pose a significant life safety hazard in quakes. But it showed that previous models which engineers worked with didn’t accurately quantify this.

“As a result of the research engineers are conservatively assessing that the Ministry’s one and two-storey timber-framed buildings are twice as strong as previously thought.

“In terms of school buildings which are not timber-framed, outside of greater Christchurch the Ministry is looking more closely at a small group of 1900 out of a total 35,700 buildings to make more detailed engineering assessments.

“These include unreinforced masonry, multiple storey and heavy construction buildings and buildings with a large open area. Based on the individual assessments, they will be prioritised for strengthening work if required.

“In greater Christchurch the Ministry has been assessing approximately 2600 buildings as required by the Canterbury Earthquake Recovery Authority (CERA). A majority of these buildings are timber framed and CERA has agreed to a streamlined approach to the evaluation of timber framed school buildings.

“This research may have wider implications for the nation’s wooden buildings, meaning they are significantly more resilient than engineering calculations had previously suggested.”

The research – Report on Structural Testing of a Standard Classroom Block in Carterton in June 2013 -  can be found at: http://www.minedu.govt.nz/DestructiveTesting

More about the research

The Kestrel Group’s Dave Brunsdon, a top private sector structural and earthquake engineer, was appointed to head the Ministry of Education’s Engineering Strategy Group in late 2012 to co-ordinate the approach to assessments of the strength of school buildings.

The group commissioned destructive testing on a typical timber-framed classroom block, literally attempting to pull it apart using two huge trucks and cables. The massive force pulling in opposite directions was designed to place the building under stresses it would experience during an earthquake.

It was thought the building might splinter when the massive [40-50 kN] of force was applied. That’s what existing engineering models would have predicted. But what was found was there was no real damage until forces four or five times greater than the building would have been predicted to withstand were applied. At that point some windows broke. Even then, the building continued on to withstand much higher levels of loading without showing any signs of imminent collapse.

The results from this testing are being circulated in engineering circles and have been fed into the Ministry of Business, Innovation and Employment’s current review of the management of earthquake-prone buildings. It is also being fed into the New Zealand Society for Earthquake Engineering’s guidelines for the assessment of buildings.

The research was independent and externally reviewed. The test was undertaken by the Building Research Association of New Zealand (BRANZ) on behalf of the Ministry of Education.