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Loess and loess-derived soils in the Akaroa harbour area of New Zealand are typically unsaturated and vulnerable to shallow landsliding during rainfall events. In this paper, the water retention properties and unsaturated shear strength of these materials are characterised using laboratory testing and long-term field instrumentation. Because the pore size distribution of the loess is fractal, the laboratory-derived soil-water characteristic curve is described mathematically using a series of power-law relationships. The same soil-water characteristic curve applies to both recompacted and intact loess when suction is normalised by the air entry value. Stress–strain behaviours of the recompacted and intact loess exhibit significant differences, however. The unique microstructure of the intact loess contributes to its larger shear strength. Long-term field instrumentation data, including suction and volumetric water content, indicate that the hydraulic state of in situ loess remained on a scanning curve for the duration of the monitoring period, despite the occurrence of significant wetting events. This, in combination with triaxial test results, allows the contribution of suction to unsaturated shear strength to be quantified. Temporal variations in suction's contribution to strength confirms seasonal variability in unsaturated shear strength and thus slope stability. [ABSTRACT FROM AUTHOR]

Public infrastructure is an interdependent system of actors, organisations, assets, services, the society it serves, and the context of each and their whole. This complexity presents research challenges for those focused at the system level, not the least that there is limited research in whole-of-system working for public infrastructure administration and the public sector more generally. Although the available literature appears unified in calling for a probing, pluralist approach, there are few examples of how to approach complex systems in practice. This paper derives from a research programme on the strategic intent and management of infrastructure systems. That programme used the New Zealand land transport system as its focus; nonetheless, it should have wider application given the shared issues being faced within infrastructure practice and matters of sustainability, resilience and system fitness more generally. By melding methods, the action research methodology is aimed at assisting researchers of complex systems and/or problems in gaining more fulsome insights and evidence to support theory. Accordingly, the methodology contributes to the understanding of how to approach infrastructure systems from a research perspective. It offers a road map, a means of sense-making and socialising the issues found at the whole-of-system level and a systemic diagnostic tool. [ABSTRACT FROM AUTHOR]

Infrastructure forms an enduring and evolving system of services, assets, projects and networks. This paper presents an overview of research into the misalignment between the strategic intent and the management of those systems. The research draws from experiences across infrastructure sectors and countries to frame the problem and then uses central and local government transportation organisations from New Zealand to explore the problem in more detail. Although infrastructure does not often fail catastrophically, there is an inability to deliver appropriate and relevant infrastructure outcomes fully over the long term. This paper presents the cross-case analysis of three detailed studies that explored this issue through three different lenses by investigating three key life-cycle/organisational transitions at the system rather than at the project level. The research has identified a pressing need for 'system stewardship' to address the increased specialisation and siloed operation within current practice. This boundary spanning function/culture is needed to deliver not only 'joined-up thinking', but also organisational learning and the ongoing transformation of the complexed asset–service–organisational–contextual system in response to ongoing change. [ABSTRACT FROM AUTHOR]

The complexity of advanced constitutive models often dictates that their capabilities are only demonstrated in the context of model testing under controlled conditions. In the case of earthquake engineering and liquefaction in particular, this restriction is magnified by the difficulties in measuring field behaviour under seismic loading. In this paper, the well-documented case of the Canterbury earthquake sequence in New Zealand, for which extensive field and laboratory data are available, is utilised to demonstrate the accuracy of a bounding surface plasticity model in fully coupled finite-element analyses. A strong motion station with manifestation of liquefaction and the second highest peak vertical ground acceleration during the 22 February 2011 Mw 6·2 seismic event is modelled. An empirical assessment predicted no liquefaction for this station, making this an interesting case for rigorous numerical modelling. The calibration of the model aims at capturing both the laboratory tests and the field measurements in a consistent manner. The characterisation of the ground conditions is presented, while, to specify the bedrock motion, the records of two stations without liquefaction are de-convolved and scaled to account for wave attenuation with distance. The numerical predictions are compared to both the horizontal and vertical acceleration records and other field observations, showing a remarkable agreement, also demonstrating that the high vertical accelerations can be attributed to compressional resonance. The results provide further insights into the underperformance of the simplified procedure. [ABSTRACT FROM AUTHOR]

State Highway 16 (SH16) is a motorway of significant strategic importance, connecting central Auckland to the city's western suburbs and beyond. It carries an average of 90 000 vehicles per day and runs through an environmentally sensitive coastal marine reserve. Two bridges on the route – Whau River Bridge and Causeway Bridge – were rehabilitated due to extensive chloride contamination as a result of exposure to the marine environment. This paper offers a holistic review of the inspection, durability assessment and design processes, and discusses construction, operation and maintenance details. The durability assessment considered deterioration mathematical modelling with regard to service life extensions of 25 and 50 years. A hybrid corrosion protection (HCP) system was selected as the preferred corrosion management solution. The system operates in two phases, initially energised using low-voltage direct current power to arrest ongoing corrosion and thereafter in galvanic mode to provide corrosion prevention. A structural health monitoring system was also designed and installed to offer long-term performance monitoring. The HCP system minimised physical works on site, negated the requirement for extensive replacement of chloride-contaminated concrete, allowed work to take place around the natural tide cycles and offers long-term protection. This is the first HCP system designed and installed in New Zealand and is believed to be the first of its kind for prestressed concrete in tidal waters. [ABSTRACT FROM AUTHOR]

The Auckland Harbour Bridge (Auckland, New Zealand), built in 1959 and widened in 1969, has approximately 125 000 m2 of external steel surfaces that have previously been maintained using a 'spot repair and overcoat' approach. This has been carried out since 1998 under a performance-specified maintenance contract using moisture-cured urethane coatings. In 2017, the Auckland Harbour Bridge Alliance embarked on a study to review the existing coatings maintenance regime and investigate alternative maintenance strategies. This paper summarises the findings of this investigation, from which a 40-year coatings maintenance plan was developed using net present value life-cycle cost analysis of zone painting. The maintenance plan was developed to achieve the lowest whole-of-life cost while meeting environmental protection requirements. [ABSTRACT FROM AUTHOR]

On 14 November 2016, the Mason River Bridge in North Canterbury, New Zealand, was rocked by one of the most complex and violent earthquakes ever recorded. This resulted in significant plastic hinging at the base of the pier columns. To avoid major costly repairs and strengthening, an innovative hardness and material testing technique was employed to determine the damage to reinforcement and residual capacity of the plastic hinges. This technique was developed for damaged buildings following the 2010 and 2011 Christchurch earthquakes, and is the first known example of its use for an earthquake-damaged bridge. Coupled with detailed non-linear time history analysis of the structure, this testing and analysis allowed the bridge's current and future seismic performance to be determined and helped justify the use of more conventional repairs, with major strengthening and seismic retrofit being avoided. This paper discusses the earthquake damage observed, the seismic performance of the structure, the advantages and disadvantages of the innovative material testing techniques, maintenance and repairs to the bridge and the expected performance of the repaired columns [ABSTRACT FROM AUTHOR]

The design and implementation of integral and semi-integral bridges has grown in prominence in New Zealand practice over the last two decades, and bridge designers in the country refer to the New Zealand Transport Agency (NZTA) Bridge Manual for design guidance. However, several issues related to the design and construction of integral bridges were identified as requiring either further investigation or clearer guidance for local design practice. These included non-seismic effects such as concrete creep, shrinkage and temperature, seismic effects and geotechnical issues including soil–structure interaction. Particularly, it was noted that there are no well-established earthquake design procedures for bridges with integral abutments and that the topic of soil–structure interaction required further guidance. NZTA research report 577, published in November 2015, was developed to sit alongside the Bridge Manual and provide local engineers with the necessary guidance for the design of integral bridges, including a description of the issues that need consideration to ensure excellent long-term performance. Report 577 also contains details of a review of the performance of numerous existing integral bridges in both New Zealand and California that have been subject to strong seismic events. This paper discusses the key issues for consideration in the design of integral bridges in non-seismic and seismic regions and the key recommendations for addressing these issues, and also provides examples of documented performance of some integral bridges in New Zealand. [ABSTRACT FROM AUTHOR]

During bridge design and assessment, effects of thermal actions are accounted for by means of a uniform temperature variation and temperature difference components. The uniform temperature variations cause changes in length and width of the structure, whereas the temperature difference components primarily cause curvatures and internal stresses. The effects of these strains on the superstructure depend on the structure's articulation and restraint. Design profiles used to model the temperature difference components vary between design codes, which can have a significant effect on the induced curvatures. Thermal data findings obtained from a comprehensive, year-long monitoring programme on Waterloo Bridge in London are examined, which allows comparison of these various models with performance data. The design thermal model in BS EN 1991-1-5 is examined, supplemented by the models from the Aashto and New Zealand codes. The measured uniform bridge temperature generally fell within the stipulated limits of BS EN 1991-1-5; however, at low temperatures the minimum deck temperature may be lower than the design relationship provided. The resultant moments implied from the measured vertical profiles: significantly exceed the worst-case values predicted by the UK model; exceed the Aashto model at different bridge sections; and do not exceed the New Zealand model. [ABSTRACT FROM AUTHOR]

Round tables discussing the resilience of critical infrastructure systems held in the UK, the USA and New Zealand have provided insight into how organisations are changing the basis of planning and investment decisions to enhance resilience. The events convened stakeholders to explore how resilience is embraced in their sectors and to identify how to advance practice. The overarching premise was to convene a diverse group who would not typically have an opportunity to engage with each other, to share their perspectives on putting resilience thinking into practice. The round tables identified that early-adopting organisations are implementing approaches to decision making that embrace resilience thinking, but such approaches are not yet embedded in common practice across organisations that are responsible for planning and managing critical infrastructure. The findings emphasise that multi-agency coordination and collaboration is required to advance resilience thinking in professional practice and to move beyond traditional risk-based paradigms. Governance and policy interventions will help encourage cross-sector information sharing and enforce responsibility and transparency surrounding exposure to potential shocks and stresses. It is recommended that such interventions could expand on principles and practice in existing emergency-management efforts, on the basis that such efforts are founded on coordinating various groups. [ABSTRACT FROM AUTHOR]

After drought conditions were experienced across New Zealand in 2019, Watercare determined that the 175 million litres per day (MLD) upgrade to the Waikato River to Redoubt Reservoir (R2R) project should be increased in capacity by including a 50 MLD water treatment plant (WTP) on the Waikato River at a remote location 60 km south of Auckland, New Zealand. Required for urgent drought mitigation, the WTP was designed and commissioned within 12 months, enabling water delivery to Auckland by southern hemisphere Winter 2021. As a conventional pump station could not have been constructed at this remote site within the timeframe, a floating pump station was developed utilising modular Linkflote pontoons to support the equipment, gangways for services and access and tubular piles for restraint. With principal issues of constructability and short programme, the superstructure design incorporated a steel spreader frame to distribute relatively high, concentrated loads over the Linkflote pontoon system. [ABSTRACT FROM AUTHOR]

In the present study, a novel experimental programme is conducted to evaluate the compression and shear behaviour of cob wallettes reinforced with bamboo and steel mesh. Three major categories of wallettes were prepared comprising at least three samples for each type for both compression and shear tests. The first category comprises four types of samples: unstabilised, unreinforced cob wallettes (USURCWs), cement-stabilised cob wallettes (CSCWs), coir-fibre-reinforced cob wallettes (CFRCWs) and straw-fibre-reinforced cob wallettes (SFRCWs). In the second and third categories, similar sample types as included in the first category were reinforced with bamboo and steel mesh, respectively. Five per cent fibres and 10% cement (by dry mass of soil) was added to the respective dry soil mixes followed by addition of 33.7% water and thorough mixing. Test results showed that the addition of fibre, cement and bamboo or steel reinforcement prevents brittle failure. Fibre-reinforced samples showed improvement in compressive and shear load capacity by about 5 to 33% and 78 to 107%, respectively, with respect to the USURCWs. Both fibre and cement stabilisation enhance the deformable property of wallettes compared to unreinforced ones. Overall, steel reinforcement exhibited higher load capacity, strength and deformability as compared to bamboo-reinforced samples and samples without bamboo or steel reinforcement. Compressive and shear strength results obtained satisfy the design requirement prescribed in the 1998 New Zealand standard NZS 4297, with the exception of USURCWs and USURCWs reinforced with bamboo mesh. [ABSTRACT FROM AUTHOR]

To study the effect of slenderness ratio on the ultimate bearing capacity of UHPC (ultra-high performance concrete)-encased concrete-filled steel tubular (UC-CFST) columns, a total of nine specimens under axial compression were tested. A finite element model, considering the effects of material nonlinearity and interaction between concrete and steel tube, was developed. A full-range analysis was carried out on the typical load–deformation response of the UC-CFST medium-long columns. The experimental and numerical analysis results showed that with the increase in slenderness ratio, the deformation capacity of the UC-CFST columns increased, the ultimate bearing capacity decreased, and the failure mode changed from exceedance of compressive strength to loss of stability. The internal forces and stress distributions at the mid-height section of the columns at different stages were also investigated. Finally, the applicability of various methods for calculating the ultimate bearing capacity of ordinary concrete-encased CFST (OC-CFST) columns to UC-CFST columns was discussed, including the methods recommended by Chinese standard T/CECS 188-2019, European standard Eurocode 4, Australian/New Zealand joint standard AS/NZS 5100.6 : 2017 and American standard ANSI/AISC 360-16. It was found that the method recommended in AS/NZS 5100.6 : 2017 was suitable for calculating the ultimate bearing capacity of UC-CFST medium-long columns. [ABSTRACT FROM AUTHOR]

Recent earthquakes have highlighted the need for safe and efficient construction of earthquake-resilient structures. Meanwhile, helical piles are gaining popularity as a foundation not only for new construction, but also retrofitted structures, owing to their advantages over conventional driven pile alternatives. In addition, several structures supported by helical piles in New Zealand sustained minimal damage during the Christchurch earthquake, proving that helical piles can be a suitable foundation option in highly seismic areas. However, there is a knowledge gap concerning their seismic performance. Therefore, the current study investigates the performance of helical piles through a full-scale shaking table test programme – the inaugural large-scale seismic testing programme performed on helical piles. The experimental set-up involved installing ten steel piles with different configurations and pile head masses in dry sand enclosed in a laminar shear box mounted on the Network for Earthquake Engineering Simulation at University of California, San Diego (NEES/UCSD) large high-performance outdoor shaking table (LHPOST). The loading scheme consisted of white noise and two earthquake time histories with varying intensity and frequency content. The experimental results are presented in terms of the natural frequency and response of test piles (peak deflections). The effects of loading frequency and intensity and the pile's geometrical configuration and installation method were evaluated. [ABSTRACT FROM AUTHOR]

Following the extensive use of sustainability rating tools for buildings, similar tools for civil infrastructure have emerged. This study presents four industry-based infrastructure sustainability rating tools – Ceequal, Envision, Infrastructure Sustainability and Greenroads – and analyses how they assess and recognise performance. While other studies have examined the content and coverage of such tools, this study focuses on tool application – assessing a significant New Zealand-based state highway project by using each tool and comparing the results. The study explores biases within the tools and examines how each tool assesses and rewards projects and encourages project teams. The results show clear differences in the scores and award levels achieved from the same project practices and outcomes, thus encouraging infrastructure owners and tool users to challenge rating tool benchmarks and labels for sustainability. These findings highlight the dangers of direct comparisons across rating tools and the need for greater transparency in project-level sustainability reporting. [ABSTRACT FROM AUTHOR]

Infrastructure is presenting some significant global challenges. One issue is that, while it is often seen as performing well, it tends to do so against only against limited terms of reference and short-term objectives. The available literature suggests that, to date, performance has largely been approached from the point of view of a project, or through addressing latent failures arising from specific sources of shock or failure. In contrast, the literature is sparse in which these matters are examined from the perspective of service-led delivery at the system level (the system comprising assets, projects and networks each at different stages of their life cycle and variously affecting one another as they develop, then age). Yet this is arguably the level relevant to, and the reality of, much of the realm of day-to-day public infrastructure management. This apparent gap in infrastructure research has been explored through a series of interviews that looked at different levels in organisations, sectors and countries. These interviews test the presumption that a problem therefore exists, and sought to identify some of the factors involved. In so doing, this research highlights an issue with the alignment between infrastructure governance and day-to-day operations, specifically the feedforward/feedback mechanisms that span the governance/operational interface. [ABSTRACT FROM AUTHOR]

This study set out to demonstrate the feasibility and usefulness of a series of pedestrian counts, including counting the subset of pedestrians who use visibly identifiable mobility aids. The resulting proportion of mobility aid users can then be used as a proxy measure of relative accessibility for each count site. The study acknowledges the diversity of disability, and the count is not intended to capture all people who identify as having disability of any kind. It was estimated from Statistics New Zealand data that approximately 3% of New Zealand's adult population uses a mobility aid for travel at any particular time. This figure includes those identifying as having permanent disability, as well as an estimate to account for those not included in this figure, namely children, people who do not identify as having a disability but nevertheless use a mobility aid, and those with temporary disability requiring use of a mobility aid. The study identified opportunities to use the tool to remove gaps in the delivery of accessible transportation, across all parts of its system from policy and planning, through design, construction and monitoring. Its widespread promotion will support more objective measurement of inclusion, to inform best-practice infrastructure investment for all. [ABSTRACT FROM AUTHOR]