How safe are the capital's office buildings?

How safe are the capital's office buildings? The low earthquake rating of Greater Wellington Regional Council's office block raises serious questions about the safety of many other relatively modern Wellington high rise buildings, says structural engineer Adam Thornton. "The implications on the building structure are serious and could lead to a potential failure of the piles, gravity structure, severe damage of the shear wall foundations and unpredictable behaviour of the seismic resisting system. The piles were described as very lightly reinforced and did not appear to have the load capacity to adhere to current codes. There was less reinforcement and stiffness above the fifth level than on lower levels and there was an uneven mass distribution through the building. The 10-storey tower and its five-storey annex were too near to each other - just 80 millimetres - and in the event of a major earthquake there was potential for severe pounding damage as they crashed against each other. Shear walls - designed to brace the buildings against lateral forces - were brittle and liable to crack and lose their strength because they lacked sufficient reinforcing. Hollow core concrete flooring, used in a lot of commercial buildings in the 1980s, were fragile and liable to fail as the building flexed in a major quake. Ceiling tiles were liable to fall and bring down fire sprinklers. The pre-cast concrete cladding panels were also identified as a hazard. "If we felt the building was unsafe we would make that recommendation [to vacate it] but the there are lots of buildings in the city like that. The consultants estimated that strengthening the Greater Wellington building to 40 per cent of new building standard would cost $5. The cheaper option was deemed imprudent because it was unlikely to meet new minimum standards that could result from the Royal Commission on the Canterbury earthquakes. And Greater Wellington chief executive David Benham said the $32. Council development manager Murray Kennedy said the building's earthquake status was not the only problem. Options for moving were now being considered and a report would be prepared for council by September. Finding alternative office space could be hard. The way they were fixed to the building exterior did not make enough allowance for the building to flex in a moderate quake. "But to be honest we just don't know because the target of our assessments across the city have been pre-1975 buildings and we're not at the end of that. 5m. The way the pre-cast concrete stairs were fixed meant they would be subject to very high forces as the building moved in a quake. A lot of attention had been given to older unreinforced masonry buildings "but we really need to address these modern brittle buildings", he said. Many were now rated at 50-60 per cent of code and tended to be worse when built on the softer Te Aro flat soils and better on The Terrace. The fact this building now rated at only 30 per cent suggested it was not built to the codes that applied at the time. Wellington City Council earthquake resilience manager Neville Brown also believed many other buildings of that era would have similar faults. How safe are the capital's office buildings? Trade News selected by Local Linkup on 03/06/2012