Objective to reduce cost, comply with code
Engineers had their hands "smacked'' if they put anything into a building design that was not absolutely necessary, a royal commission has heard.
Structural engineer David Harding is giving evidence at a royal commission hearing into the collapse of the CTV building, which claimed 115 lives, during the February 2011 earthquake.
Harding prepared the detailed design of the building in 1986 while employed by Alan Reay Consultants.
He told the commission there was no tolerance from developers at that time for "conservative" design; for example, including additional steel reinforcing that meant the building more than met the building code.
You would "get your hand smacked" if you put in unnecessary reinforcement, he said.
"If you couldn't justify it being in the building, you had to leave it out.''
The main reason for this was cost, he said.
"The objective was always to reduce the cost where possible, while still complying with the code."
Earlier, Harding told the commission that before the CTV design he had worked on only single and two-storey buildings.
He spent the five years before designing the CTV building mainly working on roading projects for the Waimakariri District Council.
Harding said he relied on Reay for guidance on the CTV building design.
He said he was told by Reay that the client wanted the building to look like the Contours building in Durham St.
Because of Harding's inexperience with multi-storey buildings, Reay gave him calculations for Landsborough House at 287 Durham St to use as a template.
Harding was also tasked with using a modelling programme called Etabs to test the CTV design, even though he had never used it before.
The Etabs programme was designed to test how well a building would withstand vertical loadings such as in an earthquake.
Harding said Reay had a strong hand in all the projects undertaken by the company, and was aware he had not used Etabs before.
Reay would have contact with the clients and the architect, prepare preliminary calculations and decide where the major structural elements would go.
Harding would be shown the preliminary drawings and would then do the structural calculations, which he then gave to the draughtsmen so they could complete their drawings.
In earlier evidence, Reay said that he accepted his firm would be responsible for the CTV building failure were any shortcomings found in Harding's work.
Architect may be required
The architect who designed the CTV building may be required to appear before a royal commission for cross-examination this week.
Alun Wilkie submitted a written statement to the inquiry, which was read this morning.
Wilkie said in his evidence that he had no involvement in the structural design of the CTV building as this was solely up to engineers.
He had only architectural drawings for the building. Files relating to design and construction of the building had "long since been destroyed".
Wilkie said the architectural design of the building was a "standard developer's office building".
It was "very much in the mould of what developers constructed in that period".
It was rectangular, with each floor a repeat, open plan with toilets, lifts and stairwells grouped together.
Wilkie said he had no involvement in the observation of any structural work.
The seismic performance of a building was "always'' up to the structural engineer.
He could not recall ever going to the CTV site while the building was being constructed.
"Suffice to say, to the best of my recollection, I cannot recall having any concerns about any aspect of the contractor's work,'' he aid.
Before the design of the CTV building, Wilkie had not worked with Alan Reay consulting engineers.
Assisting counsel Stephen Mills, QC, said Wilkie had been overseas but could still be required to appear at the hearing for questioning.
"If it has to be arranged, it will be arranged,'' he said.
Structural engineers and draughtsmen employed by Alan Reay will also give evidence this week, as well as Reay himself.
Later in the week, the widow of Graeme Tapper, who was involved in checking and issuing a building permit for the CTV building in 1986, will give evidence.
The commission has until November 12 to complete its work.