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Upper Hutt Leader : May 25th 2011
43 UPPER HUTT LEADER, MAY 25, 2011 NEWS Key buildings need rubber bearings By NICHOLAS BOYACK Big shakeup: Geoff Leech, of Robinson Seismic Ltd, is expecting plenty of interest in the rubber ball-bearing system that helps buildings survive even the biggest earthquake. On screen he has a picture of the Christchurch Women's Hospital that came through the recent Christchurch earthquake unscathed. Power to resist: Transpower project director Peter Griffiths with one of 36 base isolation lead-rubber bearings that should enable the new Pole 3 north-south high-voltage direct current link building at Haywards substation to withstand a size of earthquake that statistically we're only hit with once every 2500 years. BOUNCING BACK Lead-rubber bearings have shown their effectiveness around the world in earthquake-prone areas: In 1994 in Northridge California, an earthquake measuring 6.7 struck 30 kilometres from downtown Los Angeles. The USC Teaching Hospital, protected by lead- rubber bearings, survived undamaged and remained fully functional while seven nearby hospitals were so badly damaged they had to be evacuated. In 1995 in Kobe, Japan, during an earthquake measuring 6.8, the base isolated Ministry of Post and Telecommunications computer centre survived with no damage or disruption to services while all around it buildings were damaged beyond repair. In both cases the building's acceleration (how much it shakes) was reduced by as much as a factor of five compared to the acceleration of similar buildings nearby that were not protected by lead-rubber bearings. Gracefield-based Robinson Seismic Ltd (RSL) is expecting a surge of interest in its world-renowned seis- mic isolation system. In simple terms, the system uses lead-rubber bearings that isolate structures from the ground- shaking effects of an earthquake. The system was developed by Eas- tbourne's Bill Robinson in the 1970s when he was working for Department of Scientific Industrial Research Ltd and has proved highly successful in large earthquakes in Japan and Califor- nia. Dr Robinson says the recent earthquakes in Japan and Christ- church highlight the need to use his system, as it offers protection to both buildings and their occupants. In Christchurch the only build- ing with his system in it, the Christchurch Women's Hospital, remained fully operational follow- ing both the September and Febru- ary earthquakes. Dr Robinson says seismic iso- lation devices save lives and must'' become a key part of protecting buildings when Christchurch is rebuilt. Christchurch residents may feel reluctant to live or work in multi- level buildings now. It is crucial that devices such as lead-rubber bearings are used in the reconstruction of the Christ- church CBD so that Cantabrians can go to their places of work and study with the confidence that they are as safe as possible. Base isolation is the technology that can help provide that greater level of safety and peace of mind.'' RSL manager Megan Devine says the Christchurch earthquakes were a big wake-up call to New Zealand. It has always been Wellington that has expected the big one, but she says the entire country is now better aware of the threat posed by earthquakes. In Christchurch a lot of buildings strengthened with traditional methods did not collapse but are now unusable. The strengthening allowed people to escape but the buildings were so badly damaged they have to be demolished. The Christchurch Women's Hos- pital behaved exactly as it was designed to. The bearings moved and took the force of the shake but the building was not damaged internally. In contrast, buildings around it were damaged and in some cases could not be used after- wards. Not being able to return to a building is a major disruption, and Mrs Devine hopes there is now a realisation that it is important to design buildings that can be used immediately after an earthquake. There's no excuse for this tech- nology not to be put to more exten- sive use in New Zealand. Preparedness needs to be at the forefront of our minds and base iso- lation is the most effective way to protect critical structures. We know that for every dollar spent before a disaster we save four to eight dollars in response and recov- ery costs. We need to ask whether we can afford not to base isolate apartments, hospitals and public buildings in any part of New Zea- land?'' Lead-rubber bearings currently protect Te Papa, Parliament Build- ings, the Supreme Court, the new Wellington Hospital, parts of the Hutt Hospital (including the new emergency department and operat- ing theatre block now under con- struction), as well as several privately-owned buildings in Wel- lington. Lead-rubber bearings are also under several road and rail bridges in New Zealand. The system is used more extensively overseas, particularly in Japan and Taiwan, and Mrs Devine says New Zealand needs to fall into line. It is shocking that in a country such as this in which major earthquakes are inevitable, at present only four hospitals have some level of base isolation protec- tion.'' Depending on the design of the building, it is possible to retrospectively fit the system. In Hutt City it is even be possible to use the system to protect the council building in Laings Road. The city council is looking at earthquake strengthening it, or even rebuilding on its current site, and RSL plan to talk to the council about retro-fitting their system. Mrs Devine says that in a large earthquake, it is critical that key buildings like the council, police and hospitals survive and are usable afterwards. RSL is expecting a surge of inter- est over the next few years as a result of the recent earthquakes.
May 18th 2011
June 1st 2011