Authorities urged to quake-safe buildings

5:24 pm on 6 December 2011

An overseas expert giving evidence at an inquiry into the Canterbury earthquakes has called on authorities to act quickly to strengthen buildings.

A Royal Commission is conducting a series of hearings into the strong and devastating quakes in the Canterbury region that began on 4 September last year.

On 22 February this year, a 6.3-magnitude quake hit Christchurch killing 182 people, including more than 70 foreign nationals. Many others were injured as buildings in the central city collapsed.

The commission is hearing evidence about the collapse of the Pyne Gould Corporation building, in which 18 people were killed and dozens more injured when it pancacked in February. It was the second greatest loss of life, behind the collapse of the CTV building, that day.

After the 7.1-magnitude quake in September, structural engineers carried out four assessments of the PGC building and each time cleared it as being safe to occupy. How thorough these visual assessments were have been the subject of much discussion throughout this phase of the hearing.

On Tuesday, Bill Holmes, a structural engineer from California, told the inquiry that city and district councils need to act quickly to encourage owners to strengthen their buildings while the memory of the quakes was still fresh in their minds.

Mr Holmes said the cost of upgrading buildings was significant and while owners might be willing to meet this cost now, their willingness to do so would fade over time.

He told the hearing he was shocked at the lack of reinforcing found in girders used in the PGC building.

People were crushed after being caught between the floors. Mr Holmes said with extra strengthening, the building could have collapsed like a tee pee instead of pancaking and many lives would have been saved.

However, he said no one designs buildings capable of withstanding a quake as powerful as the one which hit the region in February.

Inspectors' work defended

The PGC building was built in the 1960s and had several critical structural weaknesses which, by 1997, had led to it being identified as being potentially earthquake-prone.

Professor Nigel Priestley, an expert in structural engineering, says if engineers had had that kind of information to hand, a more thorough assessment may have been done.

Engineers from Holmes Consulting carried out the four assessments and told the Royal Commission last week they would not have done anything differently if they were asked to carry them out again.

On Monday, their boss John Hare defended his inspectors.

Mr Hare told the commission it was important to remember that the investigation his engineers completed was only an initial assessment to look at any damage after the September quake, as opposed to a thorough evaluation of the PGC building's overall strength.

He insisted the destructive force of February's quake could not have been anticipated by the engineers.

The hearing into the collapse of the PGC building has concluded on Tuesday. The commission will resume next week and focus on the collapse of the remaining buildings in Christchurch, apart from the CTV building.