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Images, UC QuakeStudies

A photograph of the spire of ChristChurch Cathedral sitting on the ground in Cathedral Square. The photograph is captioned by BeckerFraserPhotos, "The dry summer grass shows the passing of the seasons while the top of the spire of the ChristChurch Cathedral stays still".

Images, UC QuakeStudies

A weather-damaged Chinese lantern fallen to the ground in Victoria Square. The Chinese New Year Lantern Festival was to be held on Saturday 26 February and Sunday 27 February 2011 but was cancelled due to the earthquake. The lanterns hung in Victoria Square until they fell.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Loyal Benevolent Lodge on Canon Street. The top of the façade has crumbled, and the bricks have fallen oto the ground, taking the awning with them. Plastic fencing has been placed around the building as a cordon.

Images, UC QuakeStudies

Flowers blooming in a vacant site left by the demolition of a building at the corner of Worcester Street and Stanmore Road. A sign on the ground says 'Commemorative service here Wed 22nd Feb. Bring flowers, seedheads and symbols of memory and hope". In the background, on the wall it says 'Do not demo!'.

Images, UC QuakeStudies

A photograph of Jayne White delivering coffees to the Crack'd for Christchurch team. The team are working on their armchair artwork in a garage. In the background, mosaic flowers have been laid on the ground. A table with tea and coffee is sitting to the right.

Images, UC QuakeStudies

Damage to a house in Richmond. Bricks have fallen from a wall, and there is a visible gap between the foundation and the surrounding ground. The photographer comments, "The foundation and a section of the wall of the dining room have shifted and cracked. The dining room floor is very springy".

Images, eqnz.chch.2010

There are quite a few signs like this around Christchurch after the Quake. This is one of them. Off shot to the right is a leveled patch of ground where the owners furniture restoration shop used to be. Twitter |

Research papers, University of Canterbury Library

The purpose of this thesis is to evaluate the seismic response of the UC Physics Building based on recorded ground motions during the Canterbury earthquakes, and to use the recorded response to evaluate the efficacy of various conventional structural analysis modelling assumptions. The recorded instrument data is examined and analysed to determine how the UC Physics Building performed during the earthquake-induced ground motions. Ten of the largest earthquake events from the 2010-11 Canterbury earthquake sequence are selected in order to understand the seismic response under various levels of demand. Peak response amplitude values are found which characterise the demand from each event. Spectral analysis techniques are utilised to find the natural periods of the structure in each orthogonal direction. Significant torsional and rocking responses are also identified from the recorded ground motions. In addition, the observed building response is used to scrutinise the adequacy of NZ design code prescriptions for fundamental period, response spectra, floor acceleration and effective member stiffness. The efficacy of conventional numerical modelling assumptions for representing the UC Physics Building are examined using the observed building response. The numerical models comprise of the following: a one dimensional multi degree of freedom model, a two dimensional model along each axis of the building and a three dimensional model. Both moderate and strong ground motion records are used to examine the response and subsequently clarify the importance of linear and non-linear responses and the inclusion of base flexibility. The effects of soil-structure interaction are found to be significant in the transverse direction but not the longitudinal direction. Non-linear models predict minor in-elastic behaviour in both directions during the 4 September 2010 Mw 7.1 Darfield earthquake. The observed torsional response is found to be accurately captured by the three dimensional model by considering the interaction between the UC Physics Building and the adjacent structure. With the inclusion of adequate numerical modelling assumptions, the structural response is able to be predicted to within 10% for the majority of the earthquake events considered.

Research papers, University of Canterbury Library

Damage distribution maps from strong earthquakes and recorded data from field experiments have repeatedly shown that the ground surface topography and subsurface stratigraphy play a decisive role in shaping the ground motion characteristics at a site. Published theoretical studies qualitatively agree with observations from past seismic events and experiments; quantitatively, however, they systematically underestimate the absolute level of topographic amplification up to an order of magnitude or more in some cases. We have hypothesized in previous work that this discrepancy stems from idealizations of the geometry, material properties, and incident motion characteristics that most theoretical studies make. In this study, we perform numerical simulations of seismic wave propagation in heterogeneous media with arbitrary ground surface geometry, and compare results with high quality field recordings from a site with strong surface topography. Our goal is to explore whether high-fidelity simulations and realistic numerical models can – contrary to theoretical models – capture quantitatively the frequency and amplitude characteristics of topographic effects. For validation, we use field data from a linear array of nine portable seismometers that we deployed on Mount Pleasant and Heathcote Valley, Christchurch, New Zealand, and we compute empirical standard spectral ratios (SSR) and single-station horizontal-to-vertical spectral ratios (HVSR). The instruments recorded ambient vibrations and remote earthquakes for a period of two months (March-April 2017). We next perform two-dimensional wave propagation simulations using the explicit finite difference code FLAC. We construct our numerical model using a high-resolution (8m) Digital Elevation Map (DEM) available for the site, an estimated subsurface stratigraphy consistent with the geomorphology of the site, and soil properties estimated from in-situ and non-destructive tests. We subject the model to in-plane and out-of-plane incident motions that span a broadband frequency range (0.1-20Hz). Numerical and empirical spectral ratios from our blind prediction are found in very good quantitative agreement for stations on the slope of Mount Pleasant and on the surface of Heathcote Valley, across a wide range of frequencies that reveal the role of topography, soil amplification and basin edge focusing on the distribution of ground surface motion.

Research papers, The University of Auckland Library

The seismic performance of soil profiles with potentially liquefiable deposits is a complex phenomenon that requires a thorough understanding of the soil properties and ground motion characteristics. The limitations of simplified liquefaction assessment methods have prompted an increase in the use of non-linear dynamic analysis methods. Focusing on onedimensional site response of a soil column, this thesis validated a soil constitutive model using in-situ pore pressure measurements and then assessed the influence of input ground motion characteristics on soil column response using traditional and newly developed metrics. Pore pressure recordings during the Canterbury Earthquake Sequence (CES) in New Zealand were used to validate the PM4Sand constitutive model. Soil profile characterization was key to accurate prediction of excess pore pressure response and accounting for any densification during the CES. Response during multiple earthquakes was captured effectively and cross-layer interaction demonstrated the model capability to capture soil response at the system-level. Synthetic and observed ground motions from the Christchurch earthquake were applied to the validated soil column to quantify the performance of synthetic motions. New metrics were developed to facilitate a robust comparison to assess performance. The synthetic input motions demonstrated a slightly larger acceleration and excess pore pressure response compared to the observed input motions. The results suggest that the synthetic motions may accumulate higher excess pore pressure at a faster rate and with fewer number of cycles in the shear response. This research compares validated soil profile subject to spectrally-matched pulse and non-pulse motions, emphasizing the inclusion of pulse motions with distinctive characteristics in ground motion suites for non-linear dynamic analysis. However, spectral matching may lead to undesired alterations in pulse characteristics. Cumulative absolute velocity and significant duration significantly differed between these two groups compared to the other key characteristics and contributed considerably to the liquefaction response. Unlike the non-pulse motions, not all of the pulse motions triggered liquefaction, likely due to their shorter significant duration. Non-pulse motions developed a greater spatial extent of liquefaction triggering in the soil profile and extended to a greater depth.

Images, UC QuakeStudies

A photograph of the earthquake damage to a shop on Colombo Street. Part of the closest brick wall of the building has collapsed and the bricks have spilled onto the ground in front of the building. "No go" has been spray-painted on the footpath in the foreground of the photograph.

Images, UC QuakeStudies

A photograph of the corner of Manchester Street and Cashel Street. The site has been fenced off and there is building rubble on the ground. There is a coloured tape installation on the fence, and an image of Homer Simpson on the exposed wall of the second storey of the building.

Images, UC QuakeStudies

A photograph of the corner of Manchester Street and Cashel Street. The site has been fenced off and there is building rubble on the ground. There is a coloured tape installation on the fence, and an image of Homer Simpson on the exposed wall of the second storey of the building.

Images, UC QuakeStudies

A photograph of Cranmer Courts on the corner of Kilmore and Montreal Streets. Pieces of masonry and chimneys have been removed from the building and placed on the ground in front. Wire fencing and road cones have been placed around the building to create a cordon.

Images, UC QuakeStudies

A residential property in Bexley with an overgrown garden. Dried liquefaction silt still covers the ground. The photographer comments, "Today I took a drive around the residential area between Bexley and New Brighton. It was a stark reminder to be thankful for the situation we're in and perhaps not complain too much that our garden wall hasn't yet been rebuilt".

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "The failed column near the south-east corner of the ground floor of the Hotel Grand Chancellor. This corner of the building slumped 700mm when this column and a nearby sheer wall failed. Scaffolding was erected all around it and then sprayed with concrete to stabilise the building".

Images, UC QuakeStudies

Crack repairs on the Rendezvous Hotel in Gloucester Street. Cracks have been injected with epoxy resin using syringes. The epoxy resin leaves a peak around each hole which will be ground down to a smooth surface. The wall will then be repainted. This process actually makes the wall stronger than it was originally.

Images, UC QuakeStudies

A photograph captioned by BeckerFraserPhotos, "The failed column near the south-east corner of the ground floor of the Hotel Grand Chancellor. This corner of the building slumped 700mm when this column and a nearby sheer wall failed. Scaffolding was erected all around it and then sprayed with concrete to stabilise the building".

Images, UC QuakeStudies

The southern side of the Christ Church Cathedral with boarded up windows and damage to the roof above both of the transepts. Damaged masonry has been piled on the ground in front and one of the spires has been removed and braced with steel in the foreground.

Images, UC QuakeStudies

A sewage pumping station on Avonside Drive near the intersection with Robson Avenue has been lifted out of the ground by liquefaction. The photographer comments, "A Sunday afternoon ride to New Brighton, then back via Aranui, Wainoni, Dallington, and Richmond. Not a cheerful experience. Pumping station. Another hydraulically-lifted sewage pumping station, this time on Avonside Drive".