By Annabelle Tukia
A structural engineer called in to assist at the scene of the collapsed CTV building says he believes the fire that burned in the rubble for days was started by one of six cars crushed under the building.
Graham Frost took 30 samples from what was left of the building, knowing they'd be crucial in future investigations - today he told the Royal Commission what he found.
When Mr Frost arrived at the CTV site at the request of urban search and rescue, concerns were quickly raised about the strength of the building's concrete, particularly in the floor slabs and columns.
"That's why four samples of floor slabs were taken," he says.
Rob Heywood, a forensic engineer at the site reiterated those concerns - he compared the concrete columns holding the building up to sticks of chalk, and as excavators shifted the concrete it crumbled.
“I observed the concrete turned in to rubble much quicker than I would have expected,” he says.
Mr Frost also said six burnt-out vehicles found in a garage on the ground level could provide some explanation for the fire that raged in the rubble for days.
“I think it’s possible that the fire may have started in these vehicles and providing a fuel source for sometime.”
Mr Frost says he identified three possibilities for what initiated the buildings collapse and told counsel assisting Stephen Mills what he believed was the most likely cause.
“My leaning would be towards the beam column joints and the lack of strength in those points how easily those wings could have broken off and I think how little capacity remained once those had gone.”
Tomorrow the engineers who assessed the building after the first quake in September 2010, will take the stand.
3 News