Assessment needed for 158 buildings
IT SHOULD not have taken nearly two years for Government and local authorities to start looking for buildings that were as flawed as Christchurch’s CTV building, says Wellington property developer Ian Cassels.
Cassels, president of the Wellington Property Council and managing director of The Wellington Company, was commenting on the call for engineering assessments of 158 multi-storey buildings constructed between 1982 and 1995.
The Business, Innovation and Employment Ministry recently identified these buildings as possibly having the same potential weaknesses as the CTV building which collapsed in the February 2011 earthquake, killing 115 people.
Councils nationwide were alerted to the problem about a month ago and Wellington City Council has written to the owners of 65 city buildings. Three more have been identified in Porirua and Upper Hutt.
Suspect buildings were built at a time when standards allowed the use of brittle ‘‘non-ductile reinforced gravity concrete columns.’’
Cassels said the work now being called for should have been done a lot earlier.
‘‘I’m flabbergasted that we’ve waited two years to get around to looking at buildings that exhibit the same issues as the CTV building. I can’t fathom it.
‘‘I don’t think there’s an issue in Wellington as Wellington buildings are built better with more reinforcing.’’ dompost.co.nz/ commercialproperty
If a safety problem was identified in vehicles, recall notices would have gone out almost immediately, not two years later, said Cassels.
John Scarry, an engineer who has been highly critical of the building industry, said the collapse of the CTV building also related to beam-column joints.
A clause in the 1982 reinforced concrete design standard that should not have been there, given the state of knowledge at the time, meant the CTV building columns ended up with insufficient reinforcing spirals.
But concrete beam-column joints – the most highly stressed elements in the building – had absolutely no confining spirals or stirrups whatever.
‘‘There was an absolute requirement in the standard at the time that even in ‘gravity frames’ like those in the CTV building, the beam-column joints had to have stirrups, hoops or spirals strength and confinement.’
Scarry said columns could be strengthened with high strength wrapping or encasement.
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‘‘But . . . how do you wrap carbon fibre sheets around a beamcolumn joint when there are two beams in the way? One could conceive of massive confinement plates, clamped on with high strength stressed rods, etc, but it is a major undertaking, which I suspect in many cases will be overlooked,’’ said Scarry.