Kaikoura quake a reminder of need for resilient design - engineer

The Christchurch and Kaikoura earthquakes have done a lot to change building owners and developers' views when it comes to designing for earthquake safety, a Wellington engineer says.

As the third anniversary of the Kaikoura earthquakes nears, people are reportedly asking for better materials and techniques that exceed what the Building Act requires.

Hamish McKenzie, principal - structures at Holmes Consulting, says the Act is predominantly aimed at reducing deaths rather than damage but it doesn't have to stop there.

"I think people have learned the need for good design, the benefits of going a bit further than the Building Act minimum and risk-to-life safety imperatives. We need to keep learning the lessons so that we continue to build better buildings for the future."

Five years after Christchurch's devastating 2011 earthquake, Kaikoura's 2016 quake struck, creating widespread business disruption in both its epicentre and Wellington.

Many businesses were forced to leave the capital's centre temporarily and buildings were unoccupied for long periods.

At least eight buildings were deemed irrepairable, including the city's BNZ building, a modern building sited on reclaimed land and which is only now being demolished.

The buildings in Wellington most affected by that quake were mid-rise buildings (6-10 storeys high) sitting on softer, more flexible soils.

While preventing death is all important, owners and insurers are now asking how buildings can also get back to normal more quickly after a major shake, McKenzie says.

Materials and structural solutions that are less vulnerable to damage and easier to repair include "base isolators," lead-rubber bearings already used by Te Papa and Parliament House.

Another option are "viscous dampers" which reduce shaking in higher, more flexible buildings, whereas the base isolators are better for low rise or squat buildings, McKenzie says.

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