Council HQ taken off earthquake concern list

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The Waitaki District Council’s main office building ended up on a government earthquake concern list but has since been removed.

As part of a national review, Building and Constuction Minister Maurice Williamson compiled a list of 14 buildings across the country where owners had been slow to have assessments made of buildings with possible non-ductile columns.

The Waitaki council’s policy and communications manager, Fraser Liggett, said an engineer’s assessment of the council HQ was made last month – three years after the minister’s initial request – and it was expected a final report would give the all clear.

“Council anticipates the report will conclude that there are no non-ductile columns present in the building.”

Asked why it took so long, council’s customers services general manager Richard Mabon said Opus made an assessment of the building in 2011, and in 2012, structural engineer Lou Robinson, of Dunedin firm Hadley & Robinson Ltd, was appointed to investigate the possibility of non-ductile columns in the building.

“Lou is a specialist in his field and the challenge is on because of others on the list (of buildings needing assessment) such as the University of Otago, and other buildings of that ilk in Dunedin.”

Mr Mabon said the council building was no longer on the minister’s list.

Mr Williamson said 176 buildings around the country with non-ductile columns were cleared, another 59 excluded from the review. However, to his knowledge, 14 building owners had not engaged an engineer to make an assessment, one of them being the Waitaki Council HQ.

In December, he threatened to name them publicly.

Mr Liggett said council advised the ministry that Mr Robinson was heavily committed elsewhere and “they were comfortable with the extended timeframes”.

Five other North Otago buildings were assessed for potential non-ductile columns and cleared.

Mr Robinson made his assessment of the council building on January 23. Last Tuesday, he wrote to council stating a three-dimensional analysis of the buildings was being made and they would soon report their findings. The council building comprises the former post office and telephone exchange structures.

“We have now reviewed in further detail the possibility that columns in the building might fail prematurely in an earthquake due to inadequate ductility. We find that unlikely to occur,” he said.

Mr Robinson added in his letter: “Under earthquake, deflections of the structure relative to the ground and differences in deflection between floors (interstorey drift) are not sufficiently large to cause distress in columns, even allowing for reduction in stiffness when the primary structure cracks.

“There is a wide margin between deflections that would be sufficiently large to cause flexural hinging in columns, distress from concrete spalling or possible shear failure, and those deflections likely to be encountered during an earthquake.”

By CHRIS TOBIN