“Base isolating the Christchurch Art Gallery has been fundamental for restoring its primary business and reputation to exhibit and protect priceless works of art worthy of an international stage,” says Stephen Hogg, Aurecon Building Expertise Leader.
“It is the first base isolation retrofit project in New Zealand to use triple pendulum double concave sliding isolators and the design team overcame many geometrical and structural complexities to deliver a complete solution.”
After the devastating 6.3 magnitude Christchurch earthquake on 22 February 2011, the Christchurch Art Gallery which is considered as the city’s largest and most iconic public building, suffered earthquake damage and foundation settlement of 150 millimetres across the building.
To redevelop the community’s central city sites and buildings, the Christchurch City Council conceptualized a recovery plan that will bring back life and excitement into the community.
As an approved consultant of the Christchurch City Council, Aurecon was commissioned to undertake the largest re-levelling project in the southern hemisphere - lifting the Christchurch Art Gallery back to level position. In a step toward recovery, the project aimed to re-level, repair and strengthen the building to protect it from similar earthquakes and to provide a high level of content protection to ensure the preservation of its art collections.
The client brief required the building to be re-levelled then strengthened as well as to provide a significantly reduced risk of damage to the building and its contents for future years.
The challenge for Aurecon was to execute the project while the building continues to house the priceless artworks in storage and to maintain a constant temperature and humidity as well as prevent the ingress of dust.
As a solution, Aurecon used a Jacking off Grout (JOG) technique called the ‘Keyhole Surgery’ provided by Uretek and The Chemical Grouting Company of Japan. The process was done by creating 124 cement columns four metres in diameter underneath the Christchurch Art Gallery which enabled the building to be lifted and levelled. The base isolation retrofit, on the other hand, was applied to strengthen the building and reduce the earthquake forces within the building to provide a high degree of seismic protection to precious art collections inside.
Friction pendulum bearings were added into the basement to minimise intrusion to the structure. This type of base isolation helped reduce seismic forces in the building by 75 per cent.
The Christchurch Art Gallery with its highly improved structure and improved seismic risk, meets the highest international standards for housing art collections. With the application of the Keyhole Surgery that has never been used in New Zealand, Christchurch’s most iconic public building has boosted its strength and resiliency, providing the perfect shelter for its priceless artworks.
The structural engineering services provided by Aurecon eliminated the need to undertake significant construction works within the Christchurch Art Gallery, and allowed significant amount of savings in relocating the on-site stored artwork.
After closing down since the earthquake, the Christchurch Art Gallery re-opened in December 2015.
The client, Jenny Harper, Director of the Christchurch Art Gallery, is immensely proud of the work Aurecon has undertaken.
“It’s very, very important in a community that’s been rocked by something as major as we have to have our cultural facilities maintained and open. It doesn’t feel like a city without an art gallery.
Having the art gallery base isolated gives us confidence into the future. It took a bit longer for it to be base isolated but we knew that that was worth it because we need to have a sure future. Once a city like ours is designated an earthquake zone and people remember that it’s had earthquakes, then you essentially need to provide potential lenders with a “gold plated” engineering certificate.”