Three 'critical factors' in CTV failure

The remains of the collapsed CTV building, which was not up to the required standard for quakes when it was constructed. Photo / Geoff Sloan

The Canterbury Television Building would have had a "much better" chance of staying intact if it had met building codes, says an engineer who worked on an inquiry into its collapse.

A long-awaited report on the Department of Building and Housing's technical investigation into the six-storey structure's collapse released today found it failed to meet construction standards when it was built.

One hundred and fifteen people - many of them foreign students - died when the building collapsed in the magnitude 6.3 quake on February 22 last year.

The report, identifies three "critical factors" in its failure - brittle columns, intense ground shaking, and the asymmetrical layout of shear walls.

It also found that concrete in many of the building's columns were significantly weaker than it should have been.

The report appears to exonerate the structural engineers who designed the building in the mid-1980s, Alan Reay Consultants.

However, the authors refused to attribute blame to the building company, which is believed to have gone out of business.

Consultant engineer Dr David Hopkins told a press conference today: "It was not part of our investigation to look at fault. What we sought to understand was the structural performance of the building and reasons for the collapse.

"If you take the low concrete strength as an example, what we looked at were the implications for the building on February 22. The reasons for the low concrete strength, if in fact it did exist, and who was responsible was not part of our investigation."

However, Dr Hopkins admitted that if building codes had been met the building would have had "a much better chance" of surviving.

"It would be a brave person that said it wouldn't," he added.

Department chief executive Katrina Bach also refused to lay blame and said many people were involved in the consent process.

"There are more factors involved than just those who signed off on the building; there's the building consenting process, the design process, those giving effect to those designs.

"I think all of those come into question in one way or another."

Police said they had received a large amount of information from the department and would consider it and take legal advice before deciding whether to investigate the possibility of criminal charges.

Canterbury TV worker Peter Brown was called to the building to help find and identify the dead.

He said some families would be angry about the report because they blamed the builders for its collapse.

"A lot of people think this would be good to lay to rest. This brings it all back into focus."

But Mr Brown said changes to building safety standards would be a positive outcome.

"You can't get people back but if you can prevent things from happening in future then that will do some good."

The report examined several possible collapse scenarios and concluded the "common factor" in all was that "one or more columns failed because of the forces placed on them by horizontal movement between floors".

The report also highlighted contributing elements to the "critical factors", including low concrete strengths.

However, it quashed claims the building suffered major damage in the quake on September 4, 2010.

It said damage reported after that event was "relatively minor" and not indicative of a building under immediate stress.

Tenants had "significant concerns" demolition work on a neighbouring building before February 22 was causing structural damage to their premises.

But the report concluded damage to the CTV building would have been "unlikely".

The results will be contestable at the Royal Commission of Inquiry into Canterbury Earthquakes hearings which will likely be heard in April.

Labour's earthquake recovery spokeswoman Lianne Dalziel said the report would have a devastating impact on the families of the 115 victims.

"It will be particularly difficult for the families of those who lost loved ones in the collapse to deal with the news that the disaster has now been referred by the Department of Building and Housing to the police.

"If something went wrong that could have been avoided, then people will want accountability, but that won't change the horror of what happened."

Earthquake Recovery Minister Gerry Brownlee acknowledged the news would be painful for the families, colleagues and friends of the 115 people who lost their lives in the building's collapse.

"Our thoughts are with them on this difficult day."

Local Government New Zealand said it supported a more stringent national standard for strengthening earthquake-prone buildings.

The Department of Building and Housing will lead research on the performance of buildings in the Canterbury earthquakes and implement necessary changes to the Building Act, Building Code, education, training and professional practices.

The department is also working with the New Zealand Geotechnical Society to review information standards.

The Government will work with Civil Defence and other experts on a review of how buildings are inspected after earthquakes to ensure there is "a common approach and understanding across New Zealand".