CTV building catastrophe: a catalogue of tragic failure

By Rebecca Macfie In Letter from Christchurch

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Christchurch earthquake - CTV building

photo Geoff Sloan

The Canterbury Television building twisted, tilted towards the east, jolted, and then pancaked down. The collapse was complete within 10 to 20 seconds of the start of the February 22, 2011 earthquake. Shortly after, fire took hold that burned for several days.

The failure of the CTV building took 115 lives.

The Canterbury Earthquake Royal Commission’s report on the building’s collapse was released today. Here are the key points:

  • The CCC’s consenting officer, Graeme Tapper, identified deficiencies in the building’s design, but it is likely he was directed to approve it after the principal of the engineering design company, Alan Reay, convinced Tapper’s boss that his concerns were unfounded.
  • The Alan Reay employee who did the design and signed off the drawings, David Harding, had never designed a multi-storey building of this type before, and was not competent for the task although he believed at the time that he was.
  • Alan Reay did not check Harding’s design.
  • Reay convinced the CCC’s building engineer, Bryan Bluck (Tapper’s boss) that the design was satisfactory despite knowing little about the structural details and not having reviewed any of the structural drawings prior to the permit being issued.

There were also deficiencies in the construction of the building, the commission concludes:

  • The foreman on the job was not properly guided by the construction manager, Gerald Shirtcliff (who has been revealed to have faked his engineering credentials and stolen another man’s identity).
  • One notable construction defect was a lack of “roughening” of construction joints between precast and in situ concrete, which should have been visible to the supervising engineer if he was doing regular inspections, as well as to the foreman and construction manager.
  • A five-month period elapsed during construction without CCC  inspections.

When the building was put up for sale in 1990, engineer John Hare of Holmes Consulting did a pre-purchase inspection and found non-compliant connections between the floors and the north wall. This was reported to Alan Reay Consultants. Reay’s firm installed some remedial features, but no building consent was sought for these and the firm did not carry out its own full review of the building.

After the September 2010 earthquake, the building was inspected by the CCC and by the building owners’ consultant and deemed safe for continued occupancy. After the December 26, 2010 quake it received only a “level 1” assessment, and was again green-stickered. The building manager did not consider it necessary to undertake a more detailed assessment.

The commission identifies four critical design failures that contributed to the building’s catastrophic collapse:

  • The failure to adequately design the beam-column joint zones;
  • The failure to provide adequate strength between the floors and the north wall complex;
  • Inadequate confinement of the columns;
  • The failure to identify clearly the need to roughen the interface between the ends of the precast beams and the in situ concrete in the beams.

For more on the EQ Royal Commission’s findings, click here.

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