School classrooms – tougher than you think!

The after-effects of the Canterbury earthquakes are still being felt around the country in a range of different ways. For the Ministry of Education, this has involved a major effort to understand the seismic performance of its existing buildings.

The vast majority of the Ministry’s building stock is timber framed low-rise construction, with most of these being constructed prior to modern structural design codes.

It is challenging for structural engineers to evaluate the seismic performance of timber framed buildings. Many of these buildings feature elements such as fully glazed facades that have little quantifiable strength, often leading to low assessment ratings. However from a structural perspective, it has been a common view amongst engineers that these buildings pose little safety concern.

Since its establishment in November 2012, under Dave’s leadership the Ministry’s Engineering Strategy Group has systematically worked through a series of inter-related activities aimed at providing engineers with more realistic and consistent methods of assessing the seismic performance of timber framed buildings. These activities have included:

• Reviewing the application of Importance Levels to school buildings
• Production of guidance for the engineering assessment of timber framed buildings
• Detailed reviews of standard timber framed classroom blocks
• Destructive testing of a typical timber framed classroom block (undertaken by BRANZ in June 2013)

The structural testing of a standard classroom block typical of the 1960s and 1970s has confirmed what many engineers previously suspected – that the traditional style of classroom block has many times the strength previously calculated, is definitely not earthquake prone, and doesn’t need strengthening.

The results are also likely to apply to other standard classroom blocks, and therefore will lead to significant savings for the Ministry of Education as they will no longer need to seismically strengthen buildings that don’t actually require it.

The wider importance of this work is that the results can also be applied to many other timber framed buildings across New Zealand. The results are being fed into an update of the New Zealand Society for Earthquake Engineering’s national guidelines for assessing the seismic performance of existing buildings.

Please contact Dave if you would like more information about this work.