February 2013
www.waterfordpress.co.nz
Constructing the Treetop walkway Page 26
Engineers decry ‘misinformation’ over structural performance Karen Phelps An “information vacuum” left after the Christchurch earthquake has resulted in misinformation about the role of engineers and how well the city’s buildings actually stood up to the quake, says an engineers’ industry organisation. The Association of Consulting Engineers of New Zealand (ACENZ) says most of the city’s buildings behaved as they were supposed to under the extreme force of the earthquake. ACENZ chief executive Kieran Shaw says while it was “acknowledged” that structural design standards of buildings built during the 1960s to 1980s period were less than those applied in later and recent years, “it is noteworthy that - other than the two well reported exceptions - most of these structures achieved their purpose of protecting life,” says Shaw. “Internationally respected New Zealand standards of design and construction prevented what could have been widespread and even more catastrophic loss of life,” he says. Shaw says the 6.3 magnitude earthquake which struck Christchurch on February 22, 2011, had several factors which meant that unexpected amounts of stress were placed on the city’s structures. Shaw says “In some locations the vertical accelerations during the earthquake were more than twice that of gravity, around 309 TJ of energy was released (equal to nearly five Hiroshima bombs) and the earthquake occurred at a depth of just six kilometres directly underneath the city. “An earthquake such as this is estimated to be a one in 2500 year event,” says Shaw. “Statisticians have also estimated that an
.... most of these structures achieved their purpose of protecting life.” earthquake of this magnitude happening from an unrecognised fault directly below a major city is an even more unlikely event – as high as one in 100,000 years.” However Shaw acknowledges that it is difficult for the general public to understand “why so many buildings have to be demolished”. “The fact that buildings need to be demolished sometimes gets interpreted as a design failure,” says Shaw. “Whereas in fact the buildings have behaved as they are supposed to and were designed to behave in absorbing the stress in these circumstances and thereby reducing the risk to the building occupants,” he says. Shaw says ACENZ has chosen to take a future leadership role to better inform the public and thereby assist in avoiding future misinformation clouding the real issues. Shaw says that following a disaster it is important to acknowledge that mistakes can be made in design and construction, that lessons must be learned and previous standards can and should be improved. He says that ACENZ hopes to take a role within the construction industry in helping to implement the findings and recommendations of the Royal Commission.
A new twist on climbing.... New Zealand adventure activity company Sheer Adventure will be promoting its new ‘Twister’ tower at international trade shows this year as it looks to build on its offshore success. The tower is the latest innovation from the Christchurch-based company whose colourful Clip ’N Climb climbing arenas have revolutionised indoor climbing. Story, page 3
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