Seismics and the City 18 March 2016 - Shaping Canterbury's Future Now Engineering regeneration, collaboration and innovation Applying some seismic lessons learnt to saving several heritage gems and collaborating on the Christchurch Art Gallery Base Isolation retrofit project.

1. CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT
Contributor: Grant Wilkinson
Director of Ruamoko Solutions Ltd

2. CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT
• Completed sufficiently to reopen to public on 19 December 2015
• Full gallery opening was 5 February 2016, on time and on budget
• The retrofit base isolation project cost range $20 to $25M
• It was part of a larger project that included relevelling and repairing
the Art Gallery
• The improved seismic protection of the Art Gallery means that it
will continue to attract international art exhibitions
• If Christchurch had another February 22 event, the isolated Art
Gallery will only be exposed to 20 to 25% of the damaging forces
that it was subjected to in February 2011

3. • Owner: Christchurch City Council
• Council’s Structural Engineer: Aurecon
• Design Build Contractor: Fulton Hogan
• Fulton Hogan’s Structural Engineer: Ruamoko Solutions
• Project Manager: Greenstone Group
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

4. • There are many other parties to the project including: Warren and
Mahoney, Beca, Archimedia, and Norman Disney & Young
• High level of collaboration between all parties
• Grant Wilkinson was structural design project director of the
original design and construction in 1999 to 2002
• Grant Wilkinson had previous experience with the retrofit of base
isolation to NZ Parliament Buildings, base isolating Christchurch
Women’s Hospital and Wynn Williams House in Hereford Street,
Christchurch
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

5. Clearly Defined Structural Responsibilities:
Aurecon (Council’s Engineer)
• Analysed the building superstructure above ground floor level and
selected the base isolators for the project
• Peer Reviewed by Forell / Elsesser, San Francisco
Ruamoko Solutions - through Fulton Hogan (Main Contractor)
• Designed all of the intensive strengthening and retrofit work to the
ground floor and basement levels
• Peer reviewed by Aurecon
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

6. The Structural Design Challenge:
• Where New Structural Demands < Structural Existing Capacity
• Intervention and strengthening was not required
• Where New Structural Demands > Structural Existing Capacity
• Intervention and strengthening was required
• Generated a ‘bespoke/innovative’ design as the existing geometry
and the imposed demands varied considerably between isolator
locations
• Challenging, but deeply satisfying work for us
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

7. Main Components of the Isolation Project:
• 140 Triple Pendulum Friction Sliding Isolator bearings
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

8. Main Components of the Isolation Project:
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT
VIDEO COURTESY OF EPS
CENTRE POSITION
DESIGN BASIS
EARTHQUAKE
MAXIMUM CREDIBLE EARTHQUAKE

9. Main Components of the Isolation Project:
• Basement columns were enlarged
• Basement floor was protected with plinths to the columns
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

10. Main Components of the Isolation Project:
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT
• New part basement areas were required• Ground floor slabs and beams were strengthened• Stairwells were suspended• Suspended mechanical plant room was required• Basement lift shaft was suspended• Basement walls were buttressed• Seismic movement joints were added• Carpark entry ramp rebuilt to allow + 550mm of seismic movement

11. The Art Gallery is Well Suited to Base Isolation Retrofit
• Existing basement under 90% of the isolated building
• Only 10% of new basement construction was required
• Isolators installed in the basement at underside of ground
floor
• Existing basement and ground floors are thick concrete that
weigh the building down against high ground water pressures
• Those thick floors reduced the amount of strengthening
required
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

12. Isolated Building Movement
• Building is designed to move +
550mm in all directions
• Relates to a ‘Maximum Credible
Earthquake’ with a return frequency
of once every 2500 years
• + 550mm gaps and ‘rattle space’
required
• Wide cover plates required to support
highway wheel loads while the granite
surface is to remain undamaged
CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

13. CHRISTCHURCH ART GALLERY
BASE ISOLATION RETROFIT
PROJECT

14. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower
Contributor:
Grant Wilkinson

15. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower
• Contrast in size to the Art Gallery project
• Small project that delivered great value
• Severely damaged in February 2011 quake
• Damage generally confined to the stone buttresses
• The tower benefited from the strengthening work in 2003
• The tower permanently rotated and sheared the buttresses
• In danger of collapsing onto Montreal Street in aftershocks

16. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower

17. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower

18. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower
• Stabilised with a very heavy internal steel braced frame so
that Montreal Street could be reopened for traffic
• Deconstructed and reconstructed each buttress, one at a
time, so that the tower is now supported by 4 new reinforced
concrete buttresses and arches, and has all been re-clad with
the original stone laid as a veneer
• Challenging to support the tower as each buttress was
deconstructed at a time of strong aftershocks
• The rebuilt stone exactly matches the original stonework

19. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower
The project attracted a lot of positive comment relative to the
small size of the project
• People have been genuinely surprised it survived the quakes
• Continues to provide a familiar reference point for those
approaching the city
• Looks great amongst the emerging urban landscape
• It is heritage ‘on show’ as you enter the city

20. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Jubilee Clock Tower Edmonds Clock Tower Lyttelton Cenotaph
Other recent examples of small heritage towers nursed back to
good seismic strength health by Ruamoko Solutions include:

21. HERITAGE ‘GEMS’
IN THE NEW URBAN LANDSCAPE
Banks Peninsula
War Memorial
Lyttelton Timeball Tower
(Tender Stage)
• They are all ‘punching well above their weight’ delivering
great value relative to their cost
• They are all heritage gems within the urban landscape

22. THANK YOU
ANY
QUESTIONS?
Contributor: Grant Wilkinson