324 results for Ingham, Jason

  • Nonlinear finite element modelling of unreinforced masonry walls with openings subjected to in-plane shear

    Allen, C; Masia, M; Page, A; Griffith, M; Ingham, Jason (2017)

    Conference item
    The University of Auckland Library

    This paper presents a numerical investigation into the behaviour of unreinforced clay brick masonry walls with window and door type openings, subjected to in-plane loads. Nonlinear finite element simulations of full scale walls experimentally tested at The University of Newcastle have been undertaken using the commercial finite element analysis software TNO DIANA. In this study, both continuum (total strain fixed-crack) and simplified micro-model (crack-shear-crush) nonlinear finite element modelling strategies have been employed and key parameters including force versus displacement curves, failure modes, and damage patterns have been compared to experimental results.

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  • Empirical Damage Relationships and Benefit-Cost Analysis for Seismic Retrofit of URM Buildings

    Paxton, B; Elwood, Kenneth; Ingham, Jason (2017-08)

    Journal article
    The University of Auckland Library

    Benefit-cost analyses for seismic retrofit of unreinforced masonry (URM) buildings in downtown Victoria, British Columbia, Canada were undertaken, considering the seismic hazard, building value, occupant/pedestrian exposure, a variety of strengthening measures, and local construction costs. The analyses are underpinned by building motion-damage relationships developed based on observed damage in past earthquakes in California and New Zealand. The considered upgrading measures ranged from parapet bracing to comprehensive seismic upgrades consistent with local practices. Parapet bracing and other partial retrofits were shown to have favorable benefit-cost ratios and thus be strong candidate measures for risk mitigation programs. Full upgrades were shown to have less favorable benefit-cost ratios. While applied to Victoria, the generality of the methodology and the use of observed damage data from California and New Zealand make the findings of this study particularly relevant for similar locations throughout the Pacific Northwest and abroad.

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  • Effect of boundary conditions and other factors on URM wall out-of-plane behaviour: Design demands, predicted capacity, and in situ proof test results

    Walsh, KQ; Dizhur, Dmytro; Giongo, I; Derakhshan, H; Ingham, Jason (2017-04)

    Journal article
    The University of Auckland Library

    Unreinforced masonry (URM) building construction is prominent in the form of loadbearing, partition, and infill walls. Significant out-of-plane (OOP) failures of URM walls often occur during moderate and severe earthquake shaking and such walls are often identified in structural engineering assessments as being amongst the most vulnerable elements to OOP demands, especially earthquakes. For undamaged, in situ wall conditions where material properties are known and boundary conditions reflect idealised conditions assumed in analytical predictive models, these predictive models are easily applied, although the accuracy of the model outputs may still not be well understood. Furthermore, when in situ conditions do not reflect idealised conditions assumed in analytical predictive models, engineers are often uncertain as to which analytical models and inputs are most appropriately applied. Hence, experimental and analytical campaigns were undertaken to provide specific examples for structural engineering practitioners assessing the OOP seismic behaviour of URM walls. A total of nineteen experimental proof tests were performed in situ in six different buildings. The considered wall configurations represented a variety of geometries, boundary conditions, pre-test damage states, and material properties. It was observed that twoway OOP flexure as compared to one-way vertical OOP flexure, can substantially improve the OOP load-carrying capacity of tested infill walls, and that the boundary restraints and presumed "arching??? action in walls bounded by the building frame can greatly increase the OOP capacity of URM walls. The effects of simulated in-plane damage on the OOP capacity of a URM infill wall was also investigated, and the damage was found to reduce out-of-plane strength by up to 40%. The experimental results were compared to predictive results for eighteen of the tests. The average ratio and associated coefficient of variation (CV) of predicted strengths to measured strengths were determined to be 0.84 (CV 0.56) and 0.93 (CV 0.25) for the "unbounded??? and ???bounded??? wall conditions, respectively.

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  • Securing solutions for face-loaded clay brick URM walls

    Dizhur, Dmytro; Giaretton, M; Crowe, K; Cleaver, T; Ingham, Jason (2017)

    Conference item
    The University of Auckland Library

    Out-of-plane failures induced by earthquake loads are one of the most critical deficiencies of clay brick unreinforced masonry (URM) buildings. Despite a number of seismic improvement techniques having been previously investigated and applied, there is a significant lack of experimentally validated solutions that consider the viability of these interventions in terms of overall associated cost and practicality, and impact on the building tenants, aesthetics and heritage building fabric. The main objectives of the research presented herein were to develop and validate seismic securing techniques for URM walls that satisfied the above conditions, in consultation with industry representatives. Shake-table testing of three full-scale double-leaf solid clay brick URM walls was undertaken. Wall specimens were H3300 ?? W1200 ?? T220 mm and closely simulated in-situ conditions. The vertical timber framing that is typically a nonstructural support of the inner wall lining was used as part of the retrofit solution and was fixed to the wall with steel brackets and mechanical screw-ties in order to form a strong-back. Posttensioning was also investigated as a second form of retrofit intervention. Wall and retrofit construction details, test set-up, observed crack-patterns, peak ground acceleration (PGA), wall acceleration and displacement profiles at failure, and quantification of the improvement in seismic capacity associated with use of the proposed retrofit techniques are presented herein.

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  • Damage observations following the MW 7.8 2016 Kaikoura earthquake

    Dizhur, Dmytro; Giaretton, M; Ingham, Jason (2017-06-12)

    Conference item
    The University of Auckland Library

    On 14 November 2016 a magnitude Mw 7.8 earthquake struck the upper South Island of New Zealand with effects also being observed in the capital city, Wellington. The affected area has low population density but is the largest wine production region in New Zealand and also hosts the main national highway and railway routes connecting the country???s three largest cities of Auckland, Wellington and Christchurch, with Marlborough Port in Picton providing connection between the South and North Islands. These transport facilities sustained substantial earthquake related damage, causing major disruptions. Thousands of landslides and multiple new faults were counted in the area. The winery facilities and a large number of commercial buildings and building components (including brick masonry veneers, historic masonry construction, and chimneys), sustained damage due to the strong vertical and horizontal acceleration. Presented herein are field observations undertaken the day immediately after the earthquake, with the aim to document earthquake damage and assess access to the affected area.

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  • Comparison between predicted URM wall out-of-plane strength based capacity and in situ proof test results

    Walsh, K; Dizhur, Dmytro; Giongo, I; Derakhshan, H; Ingham, Jason (2017-06-05)

    Conference item
    The University of Auckland Library

    Unreinforced masonry (URM) building construction is prominent in the form of load-bearing, partition, and infill walls. Significant out-of-plane (OOP) failures of URM walls often occur during moderate and severe earthquake shaking and such walls are often identified in structural engineering assessments as being amongst the most vulnerable elements to OOP demands, especially earthquakes. For undamaged, in situ wall conditions where material properties are known and boundary conditions reflect idealised conditions assumed in analytical predictive models, these predictive models are easily applied, although the accuracy of the model outputs may still not be well understood. Furthermore, when in situ conditions do not reflect idealised conditions assumed in analytical predictive models, engineers are often uncertain as to which analytical models and inputs are most appropriately applied. Hence, an analytical campaign was undertaken to provide specific examples for structural engineering practitioners assessing the OOP seismic behaviour of URM walls, and the predictive results reported herein were compared to previously reported experimental results of eighteen tests on existing URM walls performed in situ. The considered wall configurations represented a variety of geometries, boundary conditions, pre-test damage states, and material properties. The average ratio and associated coefficient of variation (CV) of predicted strengths to measured strengths were determined to be 0.84 (CV 0.56) and 0.93 (CV 0.25) for the ???unbounded??? and ???bounded??? wall conditions, respectively, and corresponding recommendations for analytical assessment were made for practicing engineers.

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  • Empirical vulnerability assessment of reinforced concrete frame with masonry infill buildings in the Canterbury earthquake sequence

    Fikri, R; Dizhur, Dmytro; Ingham, Jason (2017)

    Conference item
    The University of Auckland Library

    During the 2010/2011 Canterbury earthquakes, Reinforced Concrete Frame with Masonry Infill (RCFMI) buildings were subjected to significant lateral loads. A survey conducted by Christchurch City Council (CCC) and the Canterbury Earthquake Recovery Authority (CERA) documented 10,777 damaged buildings, which included building characteristics (building address, the number of storeys, the year of construction, and building use) and post-earthquake damage observations (building safety information, observed damage, level of damage, and current state of the buildings). This data was merged into the Canterbury Earthquake Building Assessment (CEBA) database and was utilised to generate empirical fragility curves using the lognormal distribution method. The proposed fragility curves were expected to provide a reliable estimation of the mean vulnerability for commercial RCFMI buildings in the region.

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  • Unbonded Tendon Stresses in Post-Tensioned Concrete Walls at Nominal Flexural Strength

    Henry, Richard; SRITHARAN, S; Ingham, Jason (2012)

    Journal article
    The University of Auckland Library

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  • Exemplar seismic retrofits of Christchurch URM buildings

    Abeling, Shannon; Misnon, A; Dizhur, Dmytro; Ingham, Jason (2017-04-27)

    Conference item
    The University of Auckland Library

    Case study unreinforced masonry (URM) buildings that were seismically retrofitted prior to the 2010/11 Canterbury earthquake sequence and exhibited successful performance during these earthquakes are presented herein. Selected buildings were divided into the following categories based on size and complexity: (1) simple, single storey box type buildings (i.e. electrical substations), (2) common and simple commercial buildings, and (3) large and complex clay brick and stone URM buildings. The retrofitted case study URM buildings were evaluated based on overall structural seismic performance as well as the categories of initial seismic design, heritage preservation, architectural appeal, and cost. Detailed observations of 4 representative case study buildings and a summary of findings are reported herein.

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  • Nonlinear parametric analysis of reinforced concrete coupled walls

    Pir, A; Ingham, Jason; Henry, Richard (2017-04-27)

    Conference item
    The University of Auckland Library

    Reinforced concrete coupled wall systems can be designed to perform as an effective seismic load resisting system with high levels of energy dissipation. However, during the 2010/2011 Canterbury earthquakes, several coupled walls were found to have not conformed to the inelastic mechanism intended by current concrete design standards. The current NZS 3101 design philosophy for coupled walls follows the capacity design approached, and strength assessment of structural elements is an essential requirement of this method. Following recommendations made by the Canterbury Earthquakes Royal Commission, the draft amendment 3 to NZS 3101:2006 included provisions to account for the axial restraint of the floor when estimating the over-strength of coupling beams. A finite element model was developed to capture the non-linear cyclic response of coupled walls systems and verified against existing experimental results. The model was used to conduct a parametric study to benchmark the effect of the floor systems on the seismic response of coupled walls typical of that built in New Zealand. The key parameters investigated included the wall, coupling beam, and floor dimensions, as well as reinforcement ratios in the wall piers and coupling beams, and foundation beam designs. The results obtained from this parametric study illustrated the increase in the shear capacity and reduction in the axial elongation of coupling beams due to interaction between the floor system and coupled walls, leading to considerable change in the coupling ratio and inelastic response of the wall system.

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  • Timber strong-backs as a cost-effective seismic retrofit method for URM buildings

    Giaretton, M; Ingham, Jason; Dizhur, Dmytro (2017-04-27)

    Conference item
    The University of Auckland Library

    Out-of-plane failures induced by earthquake loads are one of the most critical deficiencies of clay brick unreinforced masonry (URM) buildings. Despite a number of seismic improvement techniques having been previously investigated and applied, there is a significant lack of experimentally validated solutions that consider the viability of these interventions in terms of overall associated cost and practicality, and impact on the building tenants, aesthetics and heritage building fabric. The main objectives of the research presented herein were to develop and validate seismic securing techniques for URM walls that satisfied the above conditions, in consultation with industry representatives. Full-scale shake-table testing of two cavity and three double-leaf solid clay brick URM walls was undertaken. The vertical timber framing that is typically a non-structural support of the inner wall lining was used as part of the retrofit solution and was fixed to the wall with steel brackets and mechanical screw-ties in order to form a strong-back. Wall and retrofit construction details, test set-up, observed crack-patterns, peak ground acceleration (PGA), wall acceleration and displacement profiles at failure, and quantification of the improvement in seismic capacity associated with use of the proposed retrofit technique are presented herein.

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  • In-plane testing of precast concrete wall panels with grout sleeves

    Seifi, Pouya; Henry, Richard; Ingham, Jason (2017-04-27)

    Conference item
    The University of Auckland Library

    Grouted connections are widely used to connect precast concrete wall panels to their foundations. Various forms of grouted inserts are utilised in different countries to provide a splice between the wall panel and the connection reinforcement. A commonly used coupler insert in New Zealand is grouted sleeve inserts. This type of inserts has a threaded portion on top of the insert to connect the panel reinforcement and a tube-shaped part for positioning and anchoring connection reinforcement using cementitious grout. The two concerns associated with this type of connections are thread slip and reinforcement pull-out from the grout when the inserted reinforcement is subjected to cyclic loads. Thread slip affects the panel stiffness and reduces the connection integrity, and reinforcement pull-out is an undesirable failure mode. In order to evaluate the force-displacement behaviour of connections with grouted sleeve connectors, two full-scale experiments were conducted with one wall panel being reinforced with a single layer of vertical reinforcing and the other wall panel being doubly reinforced. The geometry and detailing of the wall panels was based on a previously conducted review of over 4000 constructed precast concrete wall panels. The specimens were subjected to reverse in-plane cycle loads until failure of either the connection or the wall panel. The results of the experiments are discussed in this article.

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  • Evaluating designs on existing buildings using heritage evaluation framework

    Partington, D; Dizhur, Dmytro; Ingham, Jason; Egbelakin, T (2017-04-27)

    Conference item
    The University of Auckland Library

    New Zealand owes a significant portion of its unique culture to its built heritage. While design provisions introduced into New Zealand attempt to encourage the preservation of heritage buildings, due to the high cost of remediation coupled with a short deadline for completion, many earthquake prone buildings (EPBs) are ultimately being demolished. The Heritage Evaluation Framework (HEF) is a new multi-disciplinary decision-making tool that aims to guide proposed seismic retrofit designs by gathering inputs from all parties involved in a project and using them to evaluate a particular design against client???s expectations. This research aims to analyse the performance of the HEF in relation to its potential to evaluate the appropriateness of proposed strengthening designs on EPBs. Testing of the framework was conducted via interviews, site walkthroughs and regular meetings with the teams and clients of two live heritage retrofit projects. Results were then presented back to the project members where appropriate adjustments to the design could then be achieved for the following design. Results show that the HEF is reasonably capable of analysing conceptual designs and able to give useful feedback whilst encouraging early collaboration to each project???s design team.

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  • In-Situ Testing of a Post Tensioned Seismically Retrofitted Full Scale Unreinforced Masonry Chimney

    McCauley, J; Ingham, Jason; Dizhur, Dmytro (2017-04-27)

    Conference item
    The University of Auckland Library

    Unreinforced masonry (URM) domestic chimneys are highly vulnerable and potentially earthquake prone building elements that represent a hazard to life inside and outside the buildings that they are located on. In addition, past New Zealand earthquakes have resulted in a large number of insurance claims relating to the damage associated with URM chimney failures. As part of ongoing research to establish a database of New Zealand URM chimneys, a statistical survey was conducted in Dunedin and Auckland. Key details and findings are provided from the 910 surveyed chimneys. Currently there is limited experimental research that has been undertaken on cost-effective retrofit techniques that increase the seismic resilience of domestic URM chimneys. In order to increase the pool of knowledge, a post-tensioned (PT) retrofit was experimentally field tested on an old full-scale URM chimney. Findings specific to the tested URM chimney showed a 2.6 times increase in the capacity of the retrofitted URM chimney.

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  • Seismic restraints for clay brick URM parapets validated using shake-table testing

    Dizhur, Dmytro; Giaretton, M; Ingham, Jason (2017-01-09)

    Conference item
    The University of Auckland Library

    Unrestrained unreinforced clay brick masonry (URM) parapets are found atop of a large number of vintage URM buildings. Parapets are typically cantilevered wall structural elements that form decorative and ornamental features of the building facades or in case of building side parapets, form a fire barrier. Parapets are considered to be the most vulnerable element that is prone to out-of-plane collapse when subjected to earthquake induced shaking. Due to the elevated location and the extent of the parapets above the main street frontage and main building entrances, unrestrained parapets represent a major risk to passers-by or building occupiers trying to escape from the building during an earthquake. Numerous observations made following recent earthquakes suggested that URM parapets that were previously secured performed below expectations. Subsequently, a comprehensive shake-table campaign was undertaken on 13 full-scale solid clay brick URM parapets, nine of those where then retrofitted and subjected again to dynamic loading. The objective of the study reported herein was to conduct an experimental investigation and develop generic industry-accepted proof-tested retrofit solutions for securing of URM parapets, including steel brace, timber brace, vertical strong-backs and post-tensioning. Results and observations from the experimental study are presented herein.

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  • Force based model for straight FRP anchors exhibiting fibre rupture failure mode

    Del Rey Castillo, Enrique; Griffith, MC; Ingham, Jason (2016-12-14)

    Conference item
    The University of Auckland Library

    The use of Fibre Reinforced Polymer (FRP) materials as Externally Bonded Reinforcements (EBR) is an established technique for structural improvement of existing buildings. Nevertheless the technique features disadvantages, and premature FRP-to-concrete debonding has been commonly highlighted as one of the main problems, together with the difficulty to fully wrap the structural element when the structure presents complex geometries. FRP straight anchors are used to transfer the forces from the FRP sheet into the structural element, eliminating these two problems, but a comprehensive design method for FRP anchors has not yet been established despite the increased use and research on FRP anchors. An extensive experimental programme has been carried out as part of an on-going research project with the ultimate goal being the development of a design methodology to enable engineers to efficiently and reliably design FRP anchors. The influence of a number of parameters on the capacity of straight FRP anchors has been investigated in the research, but only the anchor size and the fanning angle of the fan portion are reported here. The model that defines the relationship between anchor size, fanning angle and the capacity of the anchor exhibiting fibre rupture is described.

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  • Seismic behaviour of metal duct connections in precast concrete panels

    Seifi, Pouya; Henry, Richard; Ingham, Jason (2017-01-09)

    Conference item
    The University of Auckland Library

    The seismic performance of grouted connections between precast concrete panels was questioned in New Zealand following the 2010/2011 Canterbury earthquakes. Inadequate connection detailing contributed to the failure of some panel connections, and recommendations for more robust detailing of grouted metal duct connections were published by the Structural Engineering Society of New Zealand. In the research reported here a set of experimental tests was conducted in order to evaluate the seismic behaviour of both previously used detailing and of currently-recommended detailing of precast concrete walls with grouted metal duct connections. A total of seven full-scale precast concrete walls were subjected to reverse cyclic in-plane lateral loading. The geometry and reinforcement detailing of the walls was based on a review of over 4800 constructed precast concrete panels in order to test realistic panel detailing. Various parameters such as the wall thickness, aspect ratio, axial load, number of layers of reinforcement, and the use of transverse reinforcement around the connections were included in the experimental programme. The tests confirmed that in-plane wall response was dominated by connection behaviour, with significant rocking at the wall-to-foundation interface. Failure was typically controlled by fracture of the vertical reinforcement at the connection. The existing connections performed adequately when subjected to in-plane cyclic loads, but performance was found to diminish as the axial load and the wall dimensions increased. The use of transverse confinement reinforcement around the grouted metal ducts was observed to improve the robustness of the reinforcement splice at large lateral drifts.

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  • Investigation of equivalent frame modelling for seismic analysis of unreinforced masonry buildings with flexible diaphragms

    Nakamura, Y; Derakhshan, H; Sheikh, H; Griffith, MC; Ingham, Jason (2016-12-06)

    Conference item
    The University of Auckland Library

    A case study was conducted to investigate the applicability of equivalent frame modelling for the nonlinear time-history analysis of unreinforced masonry buildings with flexible diaphragms. The dynamic responses calculated from the equivalent frame models were compared against shake table test results of a full-scale two-storey stone masonry building. The investigated modelling approach reflected the simplifications commonly assumed for the global analysis of buildings; namely, considering the diaphragms to behave elastically and neglecting the stiffness and strength contributions of the out-of-plane responding walls. The sensitivity of the analysis to different idealisations of the equivalent frame and diaphragm stiffness values were also investigated. Discussions are provided on the accuracies and limitations of the investigated modelling approach, which may serve as a useful guidance for practical application.

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  • Pull-Out Behavior of Adhesive Connections in Unreinforced Masonry Walls

    Dizhur, Dmytro; Schultz, A; Ingham, Jason (2016-11)

    Journal article
    The University of Auckland Library

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the initial reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand, earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e., anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation, and the use of metal mesh sleeves. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5?? to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a summary of the performed experimental program and test results, and a proposed pull-out capacity relationship for adhesive anchors installed into multi-leaf clay brick masonry are presented herein.

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  • Statistical seismic vulnerability of New Zealand unreinforced masonry churches

    Marotta, A; Sorrentino, L; Liberatore, D; Ingham, Jason (2016-09-13)

    Conference item
    The University of Auckland Library

    During the 2010???2011 Canterbury earthquake sequence, extensive damage occurred to New Zealand historical and architectural heritage, and particularly to unreinforced stone and clay brick masonry churches. Of 309 unreinforced masonry churches identified nationwide, a sample of 80 buildings belonging to the affected region was studied and their performance analysed statistically. Structural behaviour of religious buildings was described in terms of mechanisms affecting the so-called macro-elements, being portions of the building behaving more or less independently. Discrete local damage levels were correlated with macroseismic shaking intensity through Damage Probability Matrices. Multiple-linear regressions were also considered, accounting for additional modifiers increasing/reducing the vulnerability of the macro-elements. Results show the relevance of the proposed multiple-linear regression models for the national heritage of churches and the advisability of extending mechanism-based regressions to other countries besides New Zealand.

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