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Images, eqnz.chch.2010

Rolleston/Burnham, South Island, NZ It's been a busy few weeks! Was away on geology fieldtrips all the previous two weeks, then on Saturday morning 4th September 2010 at 4.35 am we got woken in Westport to a reasonable but very long earthquake. My husband was back in Christchurch at the time and texted me saying "are you ok?". I replied, "yes!"...

Research papers, University of Canterbury Library

Following the recent earthquakes in Chile (2010) and New Zealand (2010/2011), peculiar failure modes were observed in Reinforced Concrete (RC) walls. These observations have raised a global concern on the contribution of bi-directional loading to these failure mechanisms. One of the failure modes that could potentially result from bidirectional excitations is out-of-plane shear failure. In this paper an overview of the recent experimental and numerical findings regarding out-of-plane shear failure in RC walls are presented. The numerical study presents the Finite Element (FE) simulation of wall D5-6 from the Grand Chancellor Hotel that failed in shear in the out-of-plane direction in the February 2011 Christchurch earthquake. The main objective of the numerical study was to investigate the reasons for this failure mode. The experimental campaign includes the recent experiments conducted in the Structural Engineering Laboratory of the University of Canterbury. The experimental study included three rectangular slender RC walls designed based on NZS3101: 2006-A3 (2017) for three different ductility levels, namely: nominally ductile, limited ductile and ductile. The numerical results showed that high axial load combined with bi-directional loading caused the out-of-plane shear failure in wall D5-6 from the Grand Chancellor Hotel. This was also confirmed and further investigated in the experimental phase of the study.

Research papers, University of Canterbury Library

Recent field investigations were carried out to define the shear wave velocity (VS) profile and site periods across the Canterbury region, supplementing earlier efforts in urban Christchurch. Active source surface wave testing, ambient wave field (passive) and H/V spectral ratio methods were used to characterise the soil profile in the region. H/V spectral ratio peaks indicate site periods in the range of 5-7 seconds across much of the Canterbury Plains, broadly consistent with those based on a 1D velocity model for the region. Site periods decrease rapidly in the vicinity of the Canterbury foothills and the Banks Peninsula outcrops. In Christchurch, the Riccarton Gravels result in a significant mode of vibration that has a much shorter period than the site period of the entire soil column down to basement rock.

Articles, UC QuakeStudies

The previously unknown Greendale Fault ruptured to the ground surface, causing up to 5 metres horizontal and 1 metre vertical permanent offset of the ground, during the September 2010 Darfield (Canterbury) earthquake. Environment Canterbury commissioned GNS Science, with help from the University of Canterbury, to define a fault avoidance zone and to estimate the fault recurrence interval. There is little evidence for past movement on the fault in the past 16,000 years. However, because of the uncertainties involved, a conservative approach was taken and the fault has been categorised as a Recurrence Interval Class IV fault (a recurrence interval of between 5,000 and 10,000 years). A PhD study by a University of Canterbury student will work towards refining the Recurrence Interval Class over the next three years. Taking a risk-based approach, the Ministry for the Environment Active Fault Guidelines recommend that normal residential development be allowed within the fault avoidance zone for faults of this Recurrence Interval Class, but recommends restrictions for larger community buildings or facilities with post-disaster functions. The report is assisting Selwyn District Council in granting consents for rebuilding houses on or near the Greendale Fault that were damaged by permanent distortion of the ground due to the fault rupture in the September 2010 earthquake. The report provides specific recommendations for building on or close to the Greendale Fault, which are being implemented by Selwyn District Council. See Object Overview for background and usage information.