Fears over CTV may have been 'nerves'
Christchurch Earthquake 2011
"Liveliness" reported by tenants of the Canterbury Television building after earthquakes in 2010 may have been due to their own nerves, an inquiry has heard.
Structural engineer Clark Hyland told the Canterbury earthquakes royal commission today that accounts of increased shaking from people who worked in the building after the September and Boxing Day quakes in 2010 could have been biased by their state of mind.
"Liveliness is an interesting topic," he said.
"People are sensitive, I think. It's well-recognised when in designing guidelines for floor vibrations for a building, people who are a bit tense are more perceptive to floor vibration."
The CTV building was "well-spanned", Hyland said, and open areas heightened the sense of "floor vibration".
"Those spans in open plan areas [you would get] some level of discomfort to people in those rooms,'' he said.
"In areas where there are partitions across those areas ... it is less likely."
Hyland and fellow structural engineer Ashley Smith investigated the CTV building's collapse, which killed 115 people, for the Department of Building and Housing (DBH).
Witnesses have testified to increased movement in the building after the 2010 quakes.
CTV receptionist Maryanne Jackson last month told the commission she did not feel safe working there after the September 2010 quake.
An internal staircase would "shake badly, moving in and out" during a tremor, she said, and she made a habit of running outside in large aftershocks.
Relationship Services counsellor Liz Cammock said that after the September quake a nearby demolition made the CTV building vibrate.
The building felt "hollow", she said.
Hyland interviewed Jo-Ann Vivian, another Relationship Services counsellor, as part of his investigation.
Vivian last week gave evidence that she asked the Christchurch City Council to inspect the building as she was concerned cracks in the columns "might indicate structural damage".
She felt a "sense of relief" when building manager John Drew assured her it had been assessed after the Boxing Day 2010 quake.
Evidence on the DBH investigation will continue this week.
Engineer accused of being 'close-minded'
Hyland had earlier been accused of not being interested in "any alternative proposition" for the cause of the disaster.
Hyland and Smith's report, released in January, pointed to the building's failure to bend sufficiently during the quake and the poor strength and layout of key shear walls.
The building did not meet 1986 building standards, it concluded, but the report was dismissed as "technically inadequate" by Alan Reay, director of Alan Reay Consultants Ltd (ARCL), which designed the building.
At the hearing this afternoon, counsel for ARCL Hugh Rennie, QC, pressed Hyland on an October 2011 email exchange with fellow DBH investigation panel member Rob Jury.
Rennie said Hyland appeared to dismiss a possible cause of collapse cited by Jury after being put forward by the deputy chairman of the investigation panel, Nigel Priestley.
He quoted an email from Jury to Priestley and Hyland: "I also believe that it's likely as [Priestley has] suggested that the slab could have been cracked in the [September 4, 2010, quake] and possible that it had cracks adjacent to the wall prior to September."
Hyland said that scenario was analysed "quite vigorously", despite Rennie quoting an email response sent by the engineer less than 90 minutes later in which he was "stunned that [Jury] should rely on his instincts regardless of what the evidence showed".
"We treated that [scenario] with respect and we applied the analysis to it," Hyland told the commission.
"The evidence was that there wasn't any cracking in the slab adjacent to the north core. If you look at the evidence of the people who were in level 4, none of them mentioned cracking in the lift-lobby area, where you would expect this cracking to occur."
The DBH report found the collapse was largely because of concrete column failure rather than damage to a concrete slab attached to the north shear wall.
In a tense exchange, Rennie accused Hyland of being close-minded: "I think you had a settled view by October that [the cause of collapse] was a column failure and you weren't interested in any alternative proposition."
"I don't believe that's what's been shown, sir," Hyland said.
Hyland and Smith will continue to give evidence this afternoon.
Jury is the next witness scheduled to appear before the commission.
Building 'would have collapsed'
The CTV building would have collapsed during the February 2011 earthquake even if it had not sustained previous quake damage, the inquiry heard earlier today.
Hyland and Smith told the Canterbury earthquakes royal commission today that damage from earlier quakes was minor.
"In the assumptions that we were making in the analysis at the time, we did not see significant structural failures that would continue across into February," Smith said.
"The results we got from the separate analysis for February, assuming an undamaged state at the start of that analysis, indicated failure, so regardless of whether we had some damage prior to that or not, we felt it would still indicate failure."
Hyland said the "very little damage" sustained in previous quakes meant a sequence analysis - an investigation of the cumulative effects of all quakes up to February 22 - was not warranted.
"In normal engineering terms, you would say this building was largely undamaged,'' he said.
''There was one column that had a crack in it ... That was deemed to be insignificant and not necessary for repair.
''There wasn't any observed damage to the ... wall on the west side. There was apparently one fine crack on the base of the south wall.
"From an analysis point of view, that is not enough damage to even consider the sequence effects."
CTV did not meet building standards
Key connections in the CTV building lacked "toughness and ductility" and did not meet building standards at the time it was built, Smith earlier told the inquiry.
Hyland and Smith's report for the Department of Building and Housing, released in January this year, pointed to the building's failure to bend sufficiently during the quake and the poor strength and layout of key shear walls.
The building did not meet 1986 building standards, it concluded.
Smith told the commission that the building's design load - how much force it could endure from earthquake shaking - "didn't seem to conform to standards of the time".
Dragbars - links intended to provide a strong connection between columns in the building and the north shear core - lacked "toughness and ductility", he said.
"[They] were installed in levels 4 to 6 ... and in my opinion [they] could not be relied upon to sustain the ultimate response of the structure,'' he said.
"If they installed them at all levels, the design loads that we understood they designed them for didn't seem to conform to the standard of the time."
The north shear core, a key support wall that included the elevator shaft, was the only part of the building to remain standing in the February quake.
Smith said a report after the September 4, 2010, quake showed structural damage was "relatively minor", but some "key areas" were not looked at.
"[It] was not indicative of a building under immediate stress or having significantly impaired resistance to earthquake shaking,'' he said.
"Some key areas, including diaphragm tensions to the north core and column bases, were not inspected, and a photograph recently provided by Peter Higgins [who inspected the building in early February 2011] was an indication of damage to the connection between a column and the north core."
The report's findings were not universally accepted on its release.
Alan Reay, director of Alan Reay Consultants Ltd (ARCL), which designed the building, dismissed it as "technically inadequate".
''ARCL is extremely disappointed with the process the DBH has followed and the subsequent conclusions in the reports. It has not carried out the investigations it should have," he said.
''Some of the assumptions made in the reports are highly questionable. As a consequence, the report's findings are not conclusive. In fact, in many areas they may be flawed.
''I have huge empathy for the families waiting for answers, but these reports are technically inadequate.
''We owe it to the families of those who died in the CTV building to conduct a robust and thorough investigation using the best technologies and methodologies available. This has not occurred."
Reay is scheduled to appear before the commission on Thursday.
During his opening remarks on the CTV building, counsel assisting the commission Stephen Mills, QC, said the design was done principally by structural engineer David Harding, "but with some involvement by Dr [Alan] Reay and the extent of that involvement seems likely to be a matter of dispute between Dr Reay and David Harding".
Harding would reject Reay's claims he worked only three and a half hours on the CTV project, Mills said.
- © Fairfax NZ News
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