Documents for CTV fitout lost
Christchurch Earthquake 2011
Structural drawings for a fitout of the Canterbury Television building in 2000 were created by a "fresh graduate" who cannot be found today, a royal commission has been told.
Structural engineer David Falloon, principal of Falloon and Wilson, yesterday gave evidence at the inquiry into the CTV building collapse where 115 people died in the February 2011 earthquake.
Falloon's company was commissioned to provide structural drawings for two aspects of the fitout as the bottom two floors were to be tenanted by Canterbury Television. These were for the installation of a staircase from level 1 to level 2, which required a hole to be cut in the level 2 floor slab, as well as the creation of an entranceway in the southeast corner on level 1.
The design required the edges of the slab where the hole was cut to be supported by steel beams and a steel post. Falloon, who signed off the drawings, could recall only the man's first name, Chris, as he was a "short-term employee".
Falloon said he was unable to present fitout documents because they were lost in his former offices in a Victoria St building severely damaged in the quake and later demolished.
He admitted on questioning that he had assumed the documents were lost and had not made a definitive effort to find them. The company moved its offices before the February quake but it took mainly recent documents, he said. He believed the CTV fitout documents were among those left behind and destroyed in demolition.
Falloon had obtained a file on the work from the Christchurch City Council and was working from this and his memory for his evidence. He said he carried out "periodic reviews" of the work and told the council that it was done according to the plans.
Commission chairman Justice Cooper asked Falloon if he could recall what experience Chris had with multi-storey concrete buildings.
"He was, I believe, a fresh graduate," Falloon said.
BUILDING'S DAMAGE MAY HAVE BEEN UNSEEN
Little visible damage in the Canterbury Television building after the September 2010 earthquake did not mean there was no structural damage, a seismic engineering expert says.
Brendon Bradley, director of Bradley Seismic and a lecturer in civil and natural resources engineering at Canterbury University, yesterday gave evidence at the royal commission of inquiry into the CTV building failure in the February 2011 quake.
In earlier evidence, David Coatsworth, the only engineer to inspect the building after the September 2010 quake, said that if there had been structural damage there would have been visual evidence of it.
However, Bradley said ground motions in central Christchurch during that quake were "essentially equivalent" to that which structures were designed to withstand.
"The lack of observable damage in post-earthquake inspections does not imply that damage did not actually occur," he said.
Bradley referred to evidence by Professor Nigel Priestley that crack widths as small as two millimetres would be enough to fracture the mesh in the building.
This in turn could cause the floor diaphragms to disconnect from the north core - deemed likely to have happened during the February 2011 quake.
"This [damage] may not have been easily identified," Bradley said.
Despite suggestions that the CTV site was by nature particularly vulnerable to the vertical forces experienced during the February quake, it was in fact consistent with results seen in similar quakes elsewhere, he said.
Based on the evidence to date, the vertical nature of the February 2011 quake was not unique, Bradley said.
The inquiry also heard yesterday that the soil under the CTV building was "soft" in the northeast corner.
Tim Sinclair, a chartered professional engineer for Tonkin & Taylor and an expert in foundation engineering, told the hearing that soil "stiffness" was important for the resilience of the ground as well as its connection to the building above.
Sinclair contributed to a report on the soil at the CTV site for structural engineers Clark Hyland and Ashley Smith for their report on the collapse for the Department of Building and Housing.
He said the original interpretation of the soil under the CTV building in 1986 was that there was a "consistent" gravel layer of about four metres across the site, with silt below.
However, he found that in one area - the northeast quadrant - the gravel was largely "absent".
In one bore hole drilled in that area, there was only about 100mm of gravel, then silt. This meant the ground in that corner was softer.
About 13 bore holes were machine and hand-drilled on the site for the building's construction.
In areas where the gravel went down four metres, Sinclair found some bore holes did not reach the silt below. While there was no evidence of liquefaction damage to the building's foundations, it could not be ruled out, Sinclair said.
LANGUAGE SCHOOL DELEGATION FROM JAPAN VISITS TO GAIN INSIGHTS
A delegation from Japan was welcomed at the inquiry into the Canterbury Television building collapse yesterday.
Twelve of the 115 victims of the collapse in the February 2011 earthquake were students from the Toyama Language School.
The delegation included Professor Tadashi Jimbo, of the Toyama College of Foreign Languages, left; Kunio Oizuki, Vice-Mayor of Toyama; Houiti Sasaki, a member of the Toyama City Assembly; Mamoru Arisawa, a Toyama City Assembly member; and Ken Katayama, assistant director, secretary division, in Toyama.
The 12 Toyama victims had been on a three-week exchange. The group had arrived in Christchurch on February 19 last year and were staying with families around the city.
Royal commission chairman Justice Mark Cooper welcomed the group.
"We're honoured by your presence," he said.
There had been a Toyama representative at the hearings previously, but this was the first delegation.
Royal commission executive director Justine Gilliland told The Press the delegation was in Christchurch for a couple of days. "They found it very interesting. It does help give them some understanding."
- © Fairfax NZ News
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