SUMMARY AND CONCLUSIONS:

Project Masonry will result in the creation of a unique database which can be used by the

public, recording the progression of damage to and characteristics of Christchurch’s many

masonry buildings. The database will allow researchers to see the frequency of different

damage modes, and to look for trends in building types and damage types. It will enable the

team to develop fragility curves and scrutinise the performance and effectiveness of different

retrofit techniques. Although the database is not complete preliminary results have been

widely reported, and already it has been shown that buildings must be strengthened to at least

67% of the code requirements for new buildings in order to significantly reduce the

likelihood of suffering major damage.

Lisa M. Moon, Dmytro Dizhur, Jason M. Ingham & Michael C. GriffithLink from: https://researchspace.auckland.ac.nz/bitstream/handle/2292/19768/22_MOON_AEES_2012_Paper.pdf?sequence=2 Following the Christchurch earthquake of 22 February 2011 a number of researchers weresent to Christchurch, New Zealand to document the damage to masonry buildings as part of“Project Masonry”. Coordinated by the Universities of Auckland and Adelaide, researcherscame from Australia, New Zealand, Canada, Italy, Portugal and the US. The types ofmasonry investigated were unreinforced clay brick masonry, unreinforced stone masonry,reinforced concrete masonry, residential masonry veneer and churches; masonry infill wasnot part of this study.This paper focuses on the progress of the unreinforced masonry (URM) component of ProjectMasonry. To date the research team has completed raw data collection on over 600 URMbuildings in the Christchurch area. The results from this study will be extremely relevant toAustralian cities since URM buildings in New Zealand are similar to those in Australia.Since the M 7.1 Darfield earthquake on 4 September 2010 the region around Christchurch,New Zealand, has been subjected to over 10,000 earthquakes on previously unknown faultlines. The most catastrophic of these was the M 6.3 earthquake on 22 February 2011, whichoccurred close to the CBD. Furthermore, between September 2010 and August 2012 theregion was shaken by about 50 earthquakes M 5.0 and above. Figure 1 shows the location ofthe 4 September 2010 and 22 February 2011 earthquakes and the location of all aftershocksM 3.0 or greater up to 11 July 2012. Figure 2 shows the magnitudes of all earthquakes from4 September 2010 until August 2012. The peak ground accelerations induced in Christchurchdue to the Darfield Earthquake were approximately equal to those of the design levelearthquake, and the only visible shaking damage in the city was sustained by the mostvulnerable known building type: URM buildings. On 22 February, despite the smallerearthquake magnitude, the accelerations induced in the CBD were up to three times greaterthan designed for and while all buildings types sustained some damage from this earthquake,URM buildings again suffered the most damage.Christchurch was famous for its many heritage and URM, buildings, so following the 22February earthquake researchers were dispatched to Christchurch to document the damage toURM buildings. Later, researchers were also sent to focus study reinforced concrete masonry(RCM), residential masonry veneer, churches, and stone masonry.2011 marked the end of a long term study by the University of Auckland into the seismicassessment and retrofit of URM buildings in New Zealand, which also included a study onthe standard typologies for URM buildings around the country (Retrofit Solutions, 2011). Thestudy showed that the types of URM buildings around the country were of similar styles andages, and that the building stock was relatively homogenous (Russell & Ingham, 2010). TheURM buildings in Christchurch can therefore be considered representative of those acrossNew Zealand, and therefore their seismic performance during the Christchurch Earthquakesequence is typical of how all New Zealand URM buildings would respond seismically. Insome cases Christchurch URM buildings had also previously received various levels andforms of seismic retrofit. Therefore, studying the failure modes of these buildings and theeffectiveness of retrofits can help predict what would happen to URM buildings in other NewZealand cities and how retrofits are likely to perform.Engineers from the Universities of Auckland and Adelaide spent time in Christchurchstudying the damage to URM buildings following the 4 September 2010 earthquake, and thishas been reported by Dizhur et al (2010), Griffith et al (2010) and Ingham & Griffith (2011a).This meant that not only were the team familiar with the Christchurch URM building stockbut that they also had a record of damage to these buildings from before the 22 Februaryearthquake and could therefore better understand what additional damage was caused by theFebruary earthquake. Figure 3 shows an example of progressive damage to a URM buildingin Christchurch. Figure 3 (a) shows the building fenced off after the 2010 Darfieldearthquake; Figure 3 (b) shows the same building five months later with part of the parapetfallen and the front wall braced on the left; and Figure 3 (c), taken four days after the 22February earthquake and six days after Figure 3 (b), shows the loss of the front parapet andout-of-plane failures of upper walls.