The way forward? – Views from the Bay

A new building in Nelson gives us a glimpse of what many buildings in Christchurch might look like in a decade or two, when reconstruction has brought the CBD back from the dead. It’s a new, super-strong, sustainable, multi-story building made from wood.

Here’s why I got interested in this building. Last week I had my first piece published in a local magazine, “Wild Tomato”. The topic was earthquakes, what’s the situation here in Nelson? It was a lot of fun. In fact, I spent so much time on the research that I think my pay rate ended up at about half the minimum wage. Still, I have lots of material for this blog.

One of the issues in writing the story was how to deal with the safety of buildings. There are quite a few death traps around town, some of them quite photogenic. Trouble is, I didn’t want the magazine to be sued by irate owners. Anyway, there has been so much coverage of collapsed buildings in Christchurch that we all have a pretty good idea of what’s dangerous and what’s not.

I thought of one of our heritage buildings that is very close to my heart, the Nelson School of Music.

It has had a lot of strengthening work done on it so that it is no longer considered “earthquake prone”. Even though more work is planned, I feel quite comfortable in it. But they have their music festival starting this month. The last thing they want is a magazine article with the word “earthquake” in the title and a picture of their building on the page. People won’t bother to read the fine print. So that building was out.

I decided to approach the question from the opposite end. We have a new building at the Polytechnic (NMIT). It is an outstanding example of an extremely strong, earthquake-resistant structure. And the really neat thing is its environmental footprint. It is built largely from sustainably grown materials sourced from within a radius of 100 km from Nelson. It is the first of its kind in the world, using a technique called “pre-stressed laminated veneer lumber”.

From the outside it looks much like any other building.

Inside it looks (and smells) very different.

Laminated veneer lumber, or LVL, is made from thin 3 mm strips of pine glued together. The process enables very large pieces to be formed. We have a major producer here in Nelson, Nelson Pine Industries. While LVL has been around for a while, the way it is used in this building was a first. The joints are designed to move in an earthquake, held together by tensioned steel ropes. They’re called “rocking joints” (so I guess they’d be ideal for nightclubs and bars?)

To dampen down the movement, the building has “energy dissipaters”. These heavy steel pieces are designed to be twisted and bent, soaking up energy in the process. Then they can be replaced once the earthquake is over.

I managed to persuade Murray Sturgeon, the managing director of Nelson Pine Industries, to hug one of the columns. It wasn’t very difficult, he’s a real enthusiast and very proud of his product.

A lot of the design ideas have come from Canterbury University. Professor Andy Buchanan (along with a lot of other staff and students) has been doing some fantastic work on timber design. I believe their research results are going to prove extremely important for Christchurch as the rebuilding gets underway.

By the way, this construction has another benefit which at first seems counter-intuitive: timber has an excellent fire rating. Of course we know that steel doesn’t burn. The problem with steel however is that, if it gets hot enough, it loses a lot of its strength. That’s why steel beams and columns have to be protected with some kind of insulation. Timber, on the other hand, burns relatively slowly and actually retains its strength a lot longer.

One last picture before I give you some links:

links:

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