Faults in CTV building known 20 years ago
Twenty years ago a group of engineers realised the Canterbury Television building did not meet construction standards.
And yesterday, their boss voiced his surprise to the Canterbury earthquakes royal commission at just how non-compliant the building was.
Holmes Consulting Group (HCG) was employed to examine the CTV building for a potential buyer in 1990.
Engineer John Hare found the connections between the building's floors and key support wall were not strong enough.
He picked up the fault "fairly quickly", he said, and quoted his 1990 report to the Canterbury earthquakes royal commission:
"The building would effectively separate from the shear walls well before the shear walls themselves reached their full design strength”.
Hare's then boss, Grant Wilkinson, told the commission he shared the concerns, but was surprised the young engineer had found any fault at all.
"This particular building was brand new, so we were going into [the pre-purchase inspection] expecting that it should comply."
Hare advised the company that designed the building, Alan Reay Consultants (ARCL), of his concerns and drew up draft strengthening plans that costed the “potentially expensive remedial work” at $14,000.
Soon after this the potential buyer, Canterbury Regional Council, pulled out and HCG was ordered to stop work.
ARCL continued with the remedial work itself, but only installed ties to strengthen the floor-wall connections on the top three levels. Hare's draft recommended ties on all five levels above the ground floor.
“The [ARCL] remedial detail . . . differed in several ways,” he said.
“I would not have agreed to the ARC remedial detail had I been consulted about it at the time.”
Hare told the commission he had discussed the installation of ties with ARCL engineer Geoff Banks after HCG's involvement had ended.
Banks raised the possibility of not needing ties on five levels, Hare said, but he would have been “reluctant to agree” to that.
“I would have said that the absence of a tie meant that a tie should have been put in there, so I would have been reluctant to agree to any transfer of load.
“It would have been just as easy in my view to put a tie in.”
Later calculations, done by ARCL in October 1991 when they did the remedial work, appeared to have been for this purpose, Hare said.
"It [appears they] were carried out by [ARCL] to check whether loads . . . can be transferred to [other walls].”
However, Hare agreed with Banks' counsel Helen Smith's contention that his views on ARCL's work were clouded by hindsight:
“It's difficult when giving your evidence to devoid yourself from the 22 years of knowledge and experience that we all now have in design, isn't it?” Smith asked.
“I agree with that,” Hare replied.
It was hard to compare the two designs 22 years later, Hare said, as his own was just a draft and ARCL's was more detailed.
“I was asked to comment [on ARCL's remedial work] by the commission and have done so,” he said.
ARCL engineer Geoff Banks and principal Alan Reay will give evidence at the commission today.
INQUEST TO FOCUS ON SIX DEATHS
The inquest into the CTV building deaths will resume at the end of October.
Coroner Gordon Matenga will conduct the inquest into the deaths of all who died in the CTV building, with the emphasis on six victims who initially survived the collapse but could not be rescued.
The hearing will resume in Christchurch on October 29 and run for two weeks, then reconvene for a final week at the beginning of December.
Last year the inquest looked at the circumstances surrounding all the deaths. The hearing was adjourned in September, pending further investigation, but no finding has yet been released.
"The inquest will focus on the circumstances around the six tragic deaths of those who were known to have been alive for a period of time after the building collapsed but were unable to be rescued," Matenga said.
"It will not look at any of the matters currently subject to the royal commission of inquiry into the collapse of the building."
A meeting will be held on September 7 to allow survivors and families of victims to informally discuss the inquest. Counsel assisting the coroner will attend to answer questions and explain the process.
Letters advising of the meeting were sent last week.