Heritage buildings 'can be made safe'

Heritage buildings can be made safe if you do your homework and understand what happens to masonry during an earthquake, Palmerston North building owners were told last night.

More than 70 people learned from information gleaned from what happened to various heritage buildings in Christchurch during the February earthquake as leading structural engineer and executive officer of the New Zealand Society for Earthquakes Win Clark showed slide after slide at Te Manawa of damage to both single and multistorey buildings.

"You have to know what happens to the walls when the masonry shakes and how the masonry will perform. Floors and ceilings have to support the masonry walls," said Mr Clark.

He said Christchurch was able to show them what worked and what didn't.

In an engineering 101 lesson, people were able to identify buildings that related closely to their own.

Mr Clark said there was a range of solutions that would be applicable to retro-fitting buildings for seismic strengthening.

New Zealand Historic Places Trust central region co-ordinator David Watt said adapting and strengthening heritage buildings was a crucial issue and there needed to be a blend between public safety and affordability.

The meeting was jointly hosted by the trust and the city council, which has been fielding calls from building owners and tenants about assessment requirements and options for strengthening buildings.

Mr Clark showed the gathering examples of where retro-fitting had worked, including a building in Lyttelton where steel bracing had been put inside the building to shore it up.

And he warned against canopies, which could give a false sense of protection.

"They don't necessarily protect pedestrians; the masonry can easily fall through canvas, or cause stronger awnings to break."

He said the information they had gleaned from Christchurch gave engineers more options.

"Once you understand the building, what it's made of and how the bricks are set and where the loadings are, once you have that data, it's not hard to know where the work needs to be done."

However, that information took time to get. He also warned against piecemeal work as it could add stress on other parts of the building and make the situation worse.

Manawatu Standard