Wrapping thin concrete walls with carbon-fibre straps can inexpensively “earthquake-proof” older high-rise buildings to a standard well beyond today’s building code, Toka Tū Ake EQC says.

The carbon fibre solution means walls cannot buckle, EQC-funded research demonstrated, and engineers can use the data and new technology with confidence to repair weak spots in old walls.

Many pre-1982 concrete buildings are considered a particular earthquake risk, with more than 100 multi-storey buildings in Wellington’s CBD alone below modern code.

The research delivers practical guidance to strengthen them cost-effectively, Head of Research Natalie Balfour says.

“It will also establish a consistent way of doing these fixes across New Zealand,” Dr Balfour said.

Supervisor Enrique Del Rey Castillo’s research team tested 56 different combinations of concrete, steel and carbon fibre to see when and how they would break.

“The results have even been better than we anticipated,” Mr Castillo said. “Thanks to input from people working in the industry we have delivered something that can be put to practical use right away.”

University of Auckland PhD student Victor Li says just 1% of lateral displacement can cause catastrophic collapse in older, unreinforced concrete walls due to axial failure.

“With the carbon fibre solution, the wall cannot buckle,” he said.

See a video of the testing here.