Engineers' inspections of Christchurch's tallest building, the Hotel Grand Chancellor, after the September 4 2010 earthquake showed damage was superficial and further structural damage was unlikely, engineers said today.
Structural engineer Gary Haverland, who inspected the tower building after the September shake, was giving evidence at the Royal Commission of Inquiry hearing today into the partial collapse of the hotel on February 22.
The 16-year-old hotel suffered significant structural damage in the magnitude 6.3 quake, leaving it teetering on a lean, but no-one died or was seriously injured in the building.
Mr Haverland carried out a level 2 rapid assessment of the hotel on September 5, which had already been given a green placard by the city council.
He said: "It was a visual inspection of the interior of the hotel. We were looking for immediate structural and safety hazards. A rapid 2 is concerned with ensuring public safety.''
During the four-hour inspection, hotel manager Steve Martin showed him damage at the hotel he was concerned about. Mr Haverland concluded that most of the damage was superficial.
He noticed cracks in some of the jib boarding, but did not think there was any damage behind the linings.
"The cracks were not extensive enough to suggest the building had been compromised. From what we saw we thought the building had not gone through a substantial amount of movement.''
But he also said one set of stairs, at the base of level 15, had appeared to move 10 to 15mm in the quake. A wall at the top of the car park had also appeared to move about 20mm.
Mr Haverland said the building was ``expected to maintain structural integrity'' as it was concrete and had ``performed very well'' in the September quake.
He said he had not been expecting an aftershock of such a great magnitude as the February quake, and had not thought any further inspection of the hotel was needed.
``I thought it was highly unlikely that any further damage would occur as a result of a less severe aftershock.''
Yesterday, engineering experts concluded the hotel partially collapsed because a ``vulnerable'' shear wall failed in the quake and sunk by nearly a metre. The failure of this wall caused staircases in the hotel to collapse.
Mr Haverland said he had looked at the wall during his inspection in September but saw no evidence of damage. He had not seen structural plans of the building, so did not know at the time that it was a shear wall.
He did not look at other shear walls or columns for damage.
The shear wall supported a disproportionately large load due to late planning changes in the design of the building plan. When the hotel was being built it was decided that Tattersalls Lane, next to the Grand Chancellor, would be kept as a right of way _ meaning the wall had to be moved.
Giving evidence this morning, structural engineer William Holmes said that if the wall had been placed in its original position it may not have failed in the earthquake.
He said: ``It certainly would have had a better performance.''
The slim wall also lacked reinforcement, which Mr Holmes said was probably due to the fact architects did not want a large wall taking up space in the hotel lobby.
``Unfortunately we engineers work with architects and sometimes they want us to do things which we probably shouldn't do.''
The hearing is expected to wrap up today, with the hotel's general manager Steve Martin and a representative from the city council giving evidence this afternoon.
Among the issues the commission will consider is whether the hotel complied with earthquake-risk and other best practice requirements, why the building failed, whether the building had been identified as earthquake-prone previously, and the effectiveness of inspections carried out on the building following the September 4 earthquake.