It’s been a long road, but Wellington is coming forward strongly after the November 2016 earthquakes. The city, its buildings and the people who own and upgrade them are coming out of the upgrade process better, with more proactive building owners and specialists who are better informed, more knowledgeable, and altogether better equipped to make Wellington’s buildings stronger and more marketable.
One such specialist company is consulting engineering firm Silvester Clark, which has been involved in many upgrade projects including the Central Fire Station, the Backbencher building, 186 Willis Street, 276 Lambton Quay, 268 Oriental Parade, The Basin Reserve Museum Stand – and many more.
Love Your Workspace talked to Silvester Clark Managing Director Scott Miller and Wellington Regional Manager Ignatius Black on the work they are doing, the changes happening across Wellington, the four main factors that underpin them, and the positive impacts they are seeing in the market.
Scott Miller says that the city-wide approach being taken to structural and seismic engineering has taken on board many learnings from Christchurch. These lessons have been absorbed by building owners, occupiers and suppliers alike as they work to build value back into buildings and increase value through strengthening – all underpinned by a number of fundamental factors.
Factor 1: A far better understanding of how buildings respond to earthquakes.
“Right across the industry we’re seeing a steep change in learning after Christchurch and Kaikoura,” says Miller. “This has led to a raft of new recommendations and changes to standards that are ongoing, a continual learning experience for everyone. There is now much more attention to detail, and uniformity in approach, which is a really positive thing.”
Developments in software and technology are enabling a much higher degree of 3D dynamic assessment of a building says Ignatius Black, leading to pushover assessments and getting much more out of building design. “Pushover analysis technology enables us to model a building in a computer, and then put a known earthquake through the model, with the increased detail maximising the existing building strength. This allows us to hone in on problem areas, find the weakest links, and then rectify them. This leads directly to better design and strengthening, and creates many benefits for buildings and clients, including reduced costs and less disruption.”
Wellington Central Fire Station – strengthened as importance level 4 building with concrete shear walls and ground anchors.
Factor 2: New methods of strengthening.
New building methods - such as base isolation, buckling restrained braces (BRBs) and viscous dampers - are coming to the fore, says Miller. “We currently have two buildings with BRBs on site, which are becoming more mainstream as an economical solution. There has also been a greater use of low-damage technologies such as base isolation. In places like Japan, base isolation has been common for a number of years. In New Zealand we invented it; it has been considered uneconomical, but that view is changing. There has been a definite flip since Christchurch.”
Factor 3: Increasing number of peer reviews.
This is a major factor driving time and cost reductions, says Black. “A peer review is a more productive process. The peer reviewer is often involved early and gets a good understanding of the design approach. With a Council review, there is not an opportunity for this, and the overall review process tends to take longer. A peer review really speeds up and smooths out the consent process. It is also a good thing for all involved to have another set of educated eyes looking at designs.”
Factor 4: Increased focus on seismic restraint of non-structural components.
Services, ceilings and partition walls are often costly casualties of an earthquake, says Miller. “After the 2013 earthquake many buildings were structurally okay but their services were not, and it can cost far more overall to repair them if not done well.” Citing the BNZ building at Harbour Quays, Miller says many proactive owners are now saving money by spending on services restraint. “Buildings are designed for one in 500-year events, but if you haven’t designed your services accordingly you could get a lot of damage internally with low levels of shaking and no damage to the building structure.
“Restraining services will mitigate damage to services and fitouts in seismic events, which will save on costly repairs and require less down-time for repairs, increase safety and increase potential insurance premium benefits.”
The Backbencher – strengthened with concrete shear walls, steel cross bracing to floor/roof diaphragms, and out of plane strengthening to brick walls.
So, how is Wellington coming out of this a better place?
All of this work and knowledge is already benefiting the city, says Miller. “We appreciate that owners have been going through pain to strengthen their buildings, but when they come out the other end their buildings are setting themselves apart in terms of rental rates.
“Ultimately what we’re seeing is a better understanding, leading to safer buildings and less potential damage during events. We’re also seeing new buildings designed to a higher standard, and an overall improvement in the building stock over time. It’s a good feeling knowing you’re making a positive difference to the city landscape.”
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