This document summarizes the performance of masonry buildings in Christchurch during the 2010-2011 earthquake swarm. It provides an overview of the history of masonry construction in New Zealand and Christchurch. It describes the characteristics of the 2010 and 2011 earthquakes and compares the damage to different building types such as unreinforced masonry, reinforced concrete, and timber buildings. It discusses the factors that influenced building performance such as short ground shaking duration. It also summarizes the lessons learned about retrofitting technologies and the seismic vulnerability of unreinforced masonry buildings.

1. THE PERFORMANCE OF MASONRY
BUILDINGS IN THE 2010/2011
EARTHQUAKE SWARM
Jason Ingham
University of Auckland

2. The performance of masonry buildings in
the Christchurch earthquake
Jason Ingham
The University of Auckland

3. Contributors
Dmytro Dizhur Lisa Moon Charlotte Knox Hossein Derekhshan Najif Ismail
Auckland, NZ Adelaide, Australia Auckland, NZ Aurecon, NZ Auckland, NZ
Jocelyn Dickie Ilaria Senaldi Jose Centeno Joao Leite Will Cyrier
Calgary, Canada Pavia, Italy Vancouver, Canada Minho, Portugal Washington State, USA

4. History of masonry
construction in New Zealand

5. Early Construction Practice
Before 1830
1833
1860 1880

6. Early Christchurch
Both stone and clay brick masonry
Victorian Christchurch in 1885 (Coxhead 1885) Christchurch’s first ‘skyscraper’, photo
circa 1910 (Brittenden Collection 1910)

7. 1931 Hawke’s Bay earthquake
(256 deaths, 525 aftershocks in 14 days, M7.8)
Hastings Street, Napier, circa 1914 (Alexander View down Hastings Street, Napier after the
Turnbull Library). 1931 earthquake (Alexander Turnbull Library).

8. 1931 Hawke’s Bay earthquake
(earthquake followed by fire)
Looking over Napier at the buildings ruined by Ruins of the Napier Anglican Cathedral
the 1931 earthquake and the fires (Alexander after the 1931 Napier earthquake
Turnbull Library). (Alexander Turnbull Library).

9. Slow steady loss of heritage unreinforced
masonry buildings, post-1930
Alexander Turnbull Library Alexander Turnbull Library
Wellington, 1950

10. Concrete Masonry Construction flourishes,
1960-1990
1965 Warren Townhouse

11. 1975 Dawn of Capacity Design
• Ductility
• Confinement
• Plastic hinges

12. Concrete masonry construction today

13. Clay brick masonry veneer on timber
frame, residential construction

14. Number of earthquake prone URM
buildings in different regions of NZ
Estimated %NBS of URM buildings in Provinces throughout New Zealand

15. Tectonic setting

16. New Zealand’s tectonic setting
Japan
California
Taiwan
Chile
New Zealand

17. No known faults

18. 4 September 2010

19. Earthquake statistics
• Date: 04.09.2010 4:35 am (NZ Standard
time)
• Magnitude: Mw 7.1
• Focal depth: 10 km
• Maximum Intensity: MMI 8
• No direct fatalities (one heart attack)
• 1 major casualty due to falling chimney
• Largest earthquake on record to occur
within 40 km of major city and cause no
fatalities
Credit: GeoNet

20. Fault trace
• Numerous places where offset could be
measured – right lateral up to about 3 m,
with variable vertical throw (mostly < 1 m).
Credit: GNS

21. Out-of-plane URM wall failure
162 URM buildings > 10% damage

22. Parapet failures

23. 22 February 2011

24. 22 February 2011
• David Biggs overnighted in Grand Chancellor
hotel
• Jason flew from Nelson arriving 7.30 am, bags
checked on to Wellington
• Interviewed by Canterbury TV at 11.00 am
• Ken Elwood (Vancouver) in audience
• 84 attendees at afternoon seminar
• Earthquake struck at 12.51 pm

25. 22 February, 1pm. M6.3

26. Sept & Oct 2010
Earthquake Swarm
Nov & Dec 2010
Jan & Feb (15th) 2011
Feb 22nd – Mar 28, 2011

27. Evacuating the city centre
(arrived in Chch at 7.30 am, scheduled to depart at 7.30 pm)

55. Comparison

56. Comparisons
Year Event Country Magnitude Duration Depth Time Deaths
(sec) (km)
1931 Napier NZ 7.9 150 20 10.47 256
1989 Loma Prieta USA 6.9 17 18 17.54 63
1994 Northridge USA 6.7 15 19 4.31 33
2001 Nisqualle USA 6.8 10 52 10.54 0
2007 Gisborne NZ 6.8 7 44 20.55 0
2009 L’Aquila Italy 6.3 10 10 3.32 308
2010 Port-au-Prince Haiti 7.0 35 13 16.53 316,000
2010 Maule Chile 8.8 180 35 3.34 562
2010 Darfield NZ 7.1 10 10 4.35 0
2011 Christchurch NZ 6.3 7 5 12.51 181
2011 Tohoku Japan 9.0 120-180 32 14.46 25,000

57. Transect

58. Command centre Day 5 Cathedral
Day 4
During earthquake

144. Transect
• Designed to sample on a pre-determined
route
• Used for sampling biological species
• Deficiencies
– Dependent on route, and route was intentionally
selected to survey large stock of URM buildings
– Level 1 sampling, building condition judged
exclusively by appearance of street frontage
– Data is subjective

145. URM = 52%
Of URM, 48% red
Red URM = 24.8%
Some buildings worse
than appear from street
front
Say about 1 in 3 red
overall
Thanks to Quincy Ma,
Liam Wotherspoon,
Rick Henry

146. Benefits
• Immediately of interest to Christchurch City
Council
• Requested by the Historic Places Trust
• Used to provide accurate information to
media
• Used in response to a request to identify a
suite of ‘indicator buildings’

147. Inspections and indicator
buildings

148. Indicator buildings
• If these buildings exhibit damage then others
of this class need to be inspected also
• URM: Soft enough (damaged) so that it did
not take shock of comparable intensity to
cause further damage
• Other forms: Exhibiting measurable damage
that can be easily monitored

157. Concrete buildings

158. Building Performance (final death toll 181)
The Press,
12/03/2011

159. Canterbury
Television Building
Following 2010 event,
engineer’s report
recommended repair of
superficial damage but declared
building safe.

160. CTV building

161. Pyne Gould Corporation Building
(1963-1964)
PGC after 2010 event; before 2011 event PGC after 2011 event (Brian Neller)
(Weng Y Kam)

162. PGC Building

163. David was one of the last paying customers!
Grand Chancellor Hotel
• 1980s construction
• Constructed in 2 stages
• Core wall up to 7th storey
• Perimeter moment frame
above
• South face dropped 600mm
to 900mm due to failure of
wall at ground level and
columns at 7th storey

164. RC Structural Wall Buildings
Overall differential settlement of
around 300 mm
Lightly confined boundary zones

166. Clay brick masonry

167. Area surveyed

168. Other locations being inspected
1000+ clay brick masonry
500+ concrete masonry
100+ stone masonry
250+ churches
Perhaps 25% of all
heritage masonry
buildings in New Zealand

169. Is this what we should expect for
an earthquake this intense?
(1:10,000 years or 1:3.65 million days!)
CENTRAL CITY AND NZS1170 SPECTRA
CLASS D DEEP OR SOFT SOIL
Larger Horizontal Components
1.8
1.6
NZS1170 2500-yr Class D
1.4
Demand 1.2
NZS1170 500-yr Class D Deep or
Soft Soil
CHHC_MaxH_FEB
1
SA(T) (g)
0.8 CCCC_MaxH_FEB
0.6
CBGS_MaxH_FEB
0.4
Capacity REHS_MaxH_FEB
0.2
GM_Larger_FEB
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Period T(s)

170. Is this what we should expect?
• Yes. URM buildings consistently collapse in
large earthquakes
• The NZ URM building stock is analogous to
that of other European colonies. Past failures
elsewhere have relevance to NZ
• Unretrofitted URM buildings loaded to about
6 times their calculated capacity
• Why did they not all completely collapse?

171. Short duration of ground shaking
(Less than 10 seconds of string ground shaking on both occasions)
0.30
Acceleration(g)
N64E
0.15
0
-0.15 4 Sept 2010
-0.30
0 10 20 30 40 50 60
Time(s)
22 Feb 2011

172. Duration of shaking

173. Implications for elsewhere in NZ?
• The URM building stock throughout NZ is
remarkably homogeneous
• The same outcome can be expected
anywhere in NZ after a large earthquake
1. Do nothing
2. Seismic improvement
3. Demolition

174. Von Sierakowski and Co. Building
[1906] [2010]
The Von Sierakowski Building, Corner Tuam and Columbo Street (1906). The factory
was erected in 1906 and was the largest wireworks factory in the Colonies.

175. Von Sierakowski and Co. Building
[1906] [September 2010]
The September Darfield earthquake of 2010 caused out-of-plane wall failure and loss
of the parapet.

176. Von Sierakowski and Co. Building
[1906] [February 2011]
The September Darfield earthquake of 2010 caused out-of-plane wall failure and loss
of the parapet.

177. The Christchurch Cathedral
[1888] [February 2011]
The Cathedral was designed by the Englishman G.G. Scott and work began on it in
1863. The tower and spire, paid for by the Rhodes family, are complete in the
photograph but were damaged multiple times by earthquakes in 1881, 1888 which
brought down part of the top section, and again in 1901.

178. Poor quality of mortar
Many tested samples 1.0-1.5 MPa
Τ=C+µN compression strength

179. Large vertical accelerations,
short duration
Τ=c+µN
If c = 0 and
N=0?
Vertical accelerations high frequency

180. Poor quality of diaphragm timber

181. Diaphragm Extraction and Testing
Establish the properties of actual heritage diaphragms with true timber species and aged
nail connections. Test both roof and floor diaphragms

182. Awnings/canopies and anchorage failures
Failures observed at both
ends of braces

183. Pier failures
Diagonal pier failure reasonably well understood
Spandrel failure over arched windows requires more attention

184. Spandrel failures

185. Pounding damage
Widespread examples of pounding damage

186. Pounding damage

187. Out-of-plane failures
Diaphragm flexibility responsible for failure
Note the anchorages into roof diaphragm

188. Mixed Mode failure
(In-plane, Out-of-plane, corner effects)

189. Multiple events, multiple intensities,
multiple directions – fragility functions

190. Look for cavity construction,
No header bricks

191. Vulnerability of cavity construction
Documenting damage
Identifying prevalence of failure modes
Fragility functions
Performance of retrofit technologies
Repair vs demolish scenarios

192. Performance of seismic
retrofits

193. Steel strong backs generally performed well

194. Steel Frames

195. Shotcrete

196. Textile Reinforced Mortar

197. Floor Diaphragm Retrofits

199. Unsuccessful Parapet Strengthening
Wall has detached from struts

200. Unsuccessful Parapet Strengthening
(require protection at corners)

201. Failure of epoxy bonded connections

202. Churches

203. Timber frame with
masonry veneer
(18) Reinforced concrete
Timber construction
or steel structure
(16)
(20)
URM stone
(22)
URM brick Approximately 250
(24) churches

204. Damage to rubble masonry Damage to brick masonry Damage to a gable in St
construction in Holy Trinity in St Luke’s church (1859), James church (1926),
church (1872), Avonside Christchurch Riccarton
Plaster Brick Unrein. (?) concrete Stone
10 220 170 230
St James Church (1926), Riccarton; wall composition

205. Basilica
Documenting damage
System identification
Damage detection
Performance in aftershocks

206. Stone masonry

207. • Characterisation
• Remediation
techniques

210. Performance of stone masonry
buildings
Excellent success of horizontal
and vertical post-tensioning

212. Success of wall-diaphragm anchorage plates

213. Reinforced concrete masonry

214. Reinforced Concrete
Masonry Buildings

215. RCM Cavity construction

216. Rollerston Courts Cambridge Courts

223. Damage to 1 and 2 Story RCM Structures

224. Damage to 1 and 2 Story RCM Structures
4; 3% 1; 1%
None or Non-Visible
Minor
61; 47% Severe
63; 49% Failure

225. Residential, commercial

226. Conclusions
• URM – why was there not more collapses (because of low
duration)?
• Massive loss of architectural heritage “Christchurch now
has no earthquake-prone buildings”
• Clear lesson for all of NZ regarding earthquake prone
buildings. Improve or remove
• Better knowledge of URM and diaphragm materials
• Proven success of a number of retrofit technologies
• Good data on seismic performance macros URM building
stock and of churches
• RCM failures mostly attributable to poor grouting and
rebar detailing

227. As the recovery begins ...
• Futility is appearing, public lack of confidence
• Insurance companies saying that they will not
insure a strengthened URM building
• Used to be 1/3rd of 0.22. Now 2/3rd of 0.30
(strengthening requirement is now 3 times what
it was a year ago)
• “Knock them all down – its too hard to make
them safe”

228. “Is it acceptable that 2 New Zealand cities have been destroyed
by earthquakes in the past 80 years?”
Nigel Priestley at the PCEE conference