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Images for Seismicity; more images...

Images, eqnz.chch.2010

Quake-damaged shops on Manchester Street; aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 3 September 2010.

Images, eqnz.chch.2010

Quake-damaged shops on Manchester Street; aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 3 September 2010.

Images, eqnz.chch.2010

Car damaged by the collapse of the building parapet following the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

No traffic on Tuam Street which was in the area cordoned off following the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

This 2 storey building has been condemned after its roof collapsed during the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn there was another storey above the corner shop; aftermath of a magnitude 7.1 earthquake that struck Christchurch on 4 September 2010.

Images, eqnz.chch.2010

Cross cracks in the brick wall of St Elmo Courts apartment block at the Hereford Street / Montreal Street intersection.

Images, eqnz.chch.2010

Quake-damaged shops on Manchester Street; aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 3 September 2010.

Images, eqnz.chch.2010

Hostel along Bealey Ave with its chimney missing afetr the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Part of the parapet of this building was shaken loose by the magnitude 7.1 earthquake that hit Christchurch on 4 September 2010.

Images, eqnz.chch.2010

Part of the parapet of this building was shaken loose by the magnitude 7.1 earthquake that hit Christchurch on 4 September 2010.

Images, eqnz.chch.2010

St John the Baptist Church at Latimer Square in the aftermath of the magnitude 7.1 earthquake that struck Christchurch on 4 September 2010.

Images, eqnz.chch.2010

St John the Baptist Church at Latimer Square in the aftermath of the magnitude 7.1 earthquake that struck Christchurch on 4 September 2010.

Images, eqnz.chch.2010

This house along Bealey Ave lost its chimney stack in the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

The front and side walls of this Christchurch building had completely collapsed after being struck by the the magnitude 7,1 earthquake on 4 September 2010.

Images, eqnz.chch.2010

This hostel along Bealey Ave lost its chimney stack in the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Research papers, University of Canterbury Library

The abundance of cone penetration test (CPT) data from subsurface explorations in Christchurch and the surrounding areas provides a useful source of information for a characterization of the near surface shear wave velocity ( ) profile for the region. A portion of the investigations were conducted using seismic CPT, enabling the comparison of measured shear wave velocity with CPT data, and subsequently the evaluation of existing CPT- correlations for applicability to Canterbury-specific soils. The existing correlations are shown to be biased, generally over-predicting the observed with depth, thus demonstrating the need for a Canterbury-specific CPT- correlation.

Research papers, University of Canterbury Library

A one story, two bays, approximately half scaled, perimeter moment frame containing precastprestressed floor units was built and tested at the University of Canterbury to investigate the effect of precastprestressed floor units on the seismic performance of reinforced concrete moment resisting frame. This paper gives an overview of the experimental set up and summarizes the results obtained from the test. The results show that elongation in the beam plastic hinges is partially restrained by the prestressed floor, which increases the strength of the beams much more than that being specified in the codes around the world.

Research papers, University of Canterbury Library

This manuscript provides a critical examination of the ground motions recorded in the near-source region resulting from the 22 February 2011 Christchurch earthquake. Particular attention is given to reconciling the observed spatial distribution of ground motions in terms of physical phenomena related to source, path and site effects. The large number of near-source observed strong ground motions show clear evidence of: forward-directivity, basin generated surface waves, liquefaction and other significant nonlinear site response. The pseudo-acceleration response spectra (SA) amplitudes and significant duration of strong motions agree well with empirical prediction models, except at long vibration periods where the influence of basin-generated surface waves and nonlinear site response are significant and not adequately accounted for in empirical SA models. Pseudo-acceleration response spectra are also compared with those observed in the 4 September 2010 Darfield earthquake and routine design response spectra used in order to emphasise the amplitude of ground shaking and elucidate the importance of local geotechnical characteristics on surface ground motions. The characteristics of the observed vertical component accelerations are shown to be strongly dependent on source-to-site distance and are comparable with those from the 4 September 2010 Darfield earthquake, implying the large amplitudes observed are simply a result of many observations at close distances rather than a peculiar source effect.

Research papers, University of Canterbury Library

The aim of this report is to investigate the ductile performance of concrete tilt-up panels reinforced with cold-drawn mesh to improve the current seismic assessment procedure. The commercial impact of the project was also investigated. Engineering Advisory Group (EAG) guidelines state that a crack in a panel under face loading may be sufficient to fracture the mesh. The comments made by EAG regarding the performance of cold-drawn mesh may be interpreted as suggesting that assessment of such panels be conducted with a ductility of 1.0. Observations of tilt-up panel performance following the Christchurch earthquakes suggest that a ductility higher than μ=1.0 is likely to be appropriate for the response of panels to out-of-plane loading. An experimental test frame was designed to subject ten tilt-panel specimens to a cyclic quasi-static loading protocol. Rotation ductility, calculated from the force-displacement response from the test specimens, was found to range between 2.9 and 5.8. Correlation between tensile tests on 663L mesh, and data collected from instrumentation during testing confirmed that the mesh behaves as un-bonded over the pitch length of 150mm. Recommendation: Based on a moment-rotation assessment approach with an un-bonded length equal to the pitch of the mesh, a rotation ductility of μ=2.5 appears to be appropriate for the seismic assessment of panels reinforced with cold-drawn mesh.

Research papers, The University of Auckland Library

The Catholic Cathedral of the Blessed Sacrament is a category 1 listed heritage building constructed largely of unreinforced stone masonry, and was significantly damaged in the recent Canterbury earthquakes. The building experienced ground shaking in excess of its capacity leading to block failures and partial collapse of parts of the building, which left the building standing but still posing a significant hazard. In this paper we discuss the approach to securing the building, and the interaction of the structural, heritage and safety demands involved in a dynamic seismic risk environment. We briefly cover the types of failures observed and the behaviour of the structure, and investigate the performance of both strengthened and un-strengthened parts of the building. Seismic strengthening options are investigated at a conceptual level. We draw conclusions as to how the building performed in the earthquakes, comment on the effectiveness of the strengthening and securing work and discuss the potential seismic strengthening methods.

Research papers, The University of Auckland Library

The susceptibility of precast hollow-core floors to sustain critical damage during an earthquake is now well-recognized throughout the structural engineering community in New Zealand. The lack of shear reinforcement in these floor units is one of the primary reasons causing issues with the seismic performance of these floors. Recent research has revealed that the unreinforced webs of these floor units can crack at drift demands as low as 0.6%. Such observation indicates that potentially many of the existing building stock incorporating hollow-core flooring systems in cities of relatively high seismic activity (e.g. Wellington and Christchurch) that probably have already experienced a level of shaking higher than 0.6% drift in previous earthquakes might already have their floor units cracked. However, there is little information available to reliably quantify the residual gravity load-carrying capacity of cracked hollow-core floor units, highlighting the need to understand the post-cracking behavior of hollow-core floor units to better quantify the extent of the risk that cracked hollow-core floor units pose.

Research papers, University of Canterbury Library

The performance of conventionally designed reinforced concrete (RC) structures during the 2011 Christchurch earthquake has demonstrated that there is greater uncertainty in the seismic performance of RC components than previously understood. RC frame and wall structures in the Christchurch central business district were observed to form undesirable cracks patterns in the plastic hinge region while yield penetration either side of cracks, and into development zones, were less than theoretical predictions. The implications of this unexpected behaviour: (i) significantly less available ductility; (ii) less hysteretic energy dissipation; and (iii) the localization of peak reinforcement strains, results in considerable doubt for the residual capacity of RC structures. The significance of these consequences has prompted a review of potential sources of uncertainty in seismic experimentation with the intention to improve the current confidence level for newly designed conventional RC structures. This paper attempts to revisit the principles of RC mechanics, in particular, to consider the influence of loading history, concrete tensile strength, and reinforcement ratio on the performance of ‘real’ RC structures compared to experimental test specimens.

Research papers, University of Canterbury Library

Very little research exists on total house seismic performance. This testing programme provides stiffness and response data for five houses of varying ages including contributions of non-structural elements. These light timber framed houses in Christchurch, New Zealand had minor earthquake damage from the 2011 earthquakes and were lateral load tested on site to determine their strength and stiffness, and preliminary damage thresholds. Dynamic characteristics were also investigated. Various loading schemes were utilised including quasi-static loading above the foundation, unidirectional loading through the floor diaphragm, cyclic quasi-static loading and snapback tests. Dynamic analysis on two houses provided the seismic safety levels of post-quake houses with respect to local hazard levels. Compared with New Zealand Building Standards all the tested houses had an excess of strength, damage is a significant consideration in earthquake resilience and was observed in all of the houses. A full size house laboratory test is proposed.

Images, eqnz.chch.2010

Colombo Street closed off south of Moorhouse Ave, due to a damaged shop now deemed unstable; aftermath of a magnitude 7.1 earthquake that struck Christchurch on 4 September 2010.

Images, eqnz.chch.2010

This shop on Riccarton Road was badly damaged in the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010, and had to be demolished.

Images, eqnz.chch.2010

The quake-damaged facade of the Baptist Church at the Kilmore Street / Madras Street intersection being propped up while repairs are in progress.

Images, eqnz.chch.2010

Time stands still on the Science Museum clock tower as a poignant reminder of the moment the trembler struck Christchurch in the early hours of Saturday 4 September 2010.

Images, eqnz.chch.2010

This building on Lichfield Street lost the top floor of its facade during the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Damaged shops at the Manchester Street / Tuam Street corner; aftermath of the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.