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Research Report 078 Seismic testing and behaviour of a 1936-designed reinforced-concrete bridge

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

The laboratory testing and inelastic computer analysis are described for a 1936-designed bridge which is typical of many of the older, reinforced-concrete, multi-span bridges in New Zealand. The structure has plain-round (undeformed) reinforcing bars and anchorage details, shear strength, and column-transverse reinforcement that are potentially deficient. Despite the suspected seismic deficiencies, the testing and analysis of the bridge show that its seismic performance will be good. The results indicate that (a) seismic retrofitting for the subject bridge is not warranted, (b) code criteria applicable to the design of new structures, with deformed reinforcing, can be overly conservative when used for the assessment of existing structures, and (c) plain-round reinforcing bars under seismic forces suffer extensive bond deterioration resulting in pinched hysteretic response which, for earthquakes with strong pulses, can lead to greater seismic damage.

Research Report 077 Seismic evaluation and retrofit technology for bridges

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

Despite recent progress by the structural engineering profession in addressing bridge seismic risks, several areas exist where improvements in bridge evaluation and retrofit practices are needed. This report reviews the common seismic deficiencies of bridges, procedures and criteria for the seismic evaluation of bridges, and the engineering techniques which have been used, up to 1996, for retrofitting bridge seismic deficiencies. Information on seismic deficiencies, retrofit techniques, and related research has been summarised in tabular form. The review indicates several areas where effective retrofit techniques have been established, and other areas where improved procedures or further research are needed. Seismic upgrade measures proposed for Thorndon bridge, Wellington City, New Zealand, including an innovative retrofit of superstructure linkages, illustrate the benefits of a capacity-design approach to seismic evaluation and retrofitting. Keywords: Bridges, capacity design, earthquakes, New Zealand, retrofitting, seismic evaluation, structural engineering, Thorndon bridge

Research Report 134 Risk assessment techniques for optimising slope-failure preventative maintenance programmes

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

A North American method for establishing an optimised slope-failure preventive maintenance programme for use by roading authorities has been identified and trialed by way of a case study, to determine its application to New Zealand roads. The method requires a knowledge of the slope instability, and accident and maintenance history affecting the site. This information can be used to quantify the risk to road users from adverse slope instability affects, and to identify and cost a range of preventative maintenance programmes which could be implemented to mitigate the risk. A study was carried out in 1997–98 on a length of State HIghway 73 (Christchurch to Arthur's Pass) to verify the suitability of the method for New Zealand roads.

Research Report 135 A risk assessment procedure for optimising slope-failure preventative maintenance programmes

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

A methodology has been developed, based on a study carried out in 1998–99, to assist in selecting optimum slope-failure preventive maintenance programmes for highways. The existing risk to road users from slope instability is first quantified, then the effectiveness of maintenance programmes in reducing the risk to road users is determined and the mitigated risks quantified. The risks are expressed in economic terms and the implementation costs associated with each programme are incorporated into the analysis. The technique allows for the consideration of uncertainty in various input parameters (both geotechnical and economic). Monte Carlo simulation allows analysis outputs to be expressed in terms of probability distributions. The uncertainty associated with the analysis outcome may therefore be quantified, leading to better informed decision-making and prioritisation of expenditure. A Microsoft Excel 97 file has been developed to allow the technique to be applied to a range of slope stability situations.

Research Report 208 Progressive underslip stabilisation using gravel columns

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

This report presents the findings of the monitoring programme undertaken by GHD at Snake Hill (SH1 RP 144/11. 34), a road slip site which was stabilised using graded gravel column drains. Monitoring of pore water pressures was undertaken using piezometers, inclinometers were monitored to determine deformation, and computer simulated back analysis was undertaken. This report discusses the results of the monitoring programme, and asserts that the column drains have provided effective positive subsurface drainage to the failure planes, resulting in the stabilisation of the site. It also discusses the typical cost of methods for the stabilisation of deep-seated road failures driven by high pore water pressures, and finds that column drains are comparatively cost-effective. Keywords: underslip stabilisation, graded gravel column drains, high pore water pressure, inclinometer, piezometer, deep-seated road failure, cost effectiveness, Snake Hill, SH1

Research Report 272 Standardisation of design flows for coastal catchments in New Zealand

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

As one of the outputs from the Transfund research project Standardisation of Design Flows and Debris Control Intake Structures, the purpose of this report is to provide further information for the bridge and culvert designer on hydrological approaches that are appropriate to the estimation of design flows in low-lying coastal catchments. Keywords: catchment, coastal, debris control, design flow, hydrology, New Zealand, residential zone, roads, rural zone, transport, urban, urbanisation

Research report 415 Case studies and best-practice guidelines for risk management on road networks

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

The requirements of the 2002 Local Government Act have led to a greater emphasis on local authorities having a holistic approach to risk management. However, it is widely considered that compared with other disciplines, the practical application of risk management is still lacking in the area of transportation. This research project aimed to establish a comprehensive yet simple best-practice guideline for risk management in the transport area. This was achieved through a literature review and a pilot study across nine representative transport authorities throughout New Zealand in November 2008. These guidelines provide the minimum requirements of an integrated risk framework, and also describe in detail ways to overcome some practical obstacles to the effective use of the risk management process.

Research Report 222 Natural hazard risk management for road networks: part II: implementation strategies

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

Road networks are lifelines for the community and are essential for the economic and social well-being of New Zealand. Significant natural hazard events can cause widespread damage to transportation networks, leading to significant repair costs to road controlling authorities, access difficulties for emergency services and disruption to road users and the community at large. To improve the resilience of the road network to natural hazards, risk management is required. This report, part II of a research study, develops methods of implementing natural hazard risk management at five levels: national, regional, local network, emergency management and project development. The responsibility for implementation is discussed, together with the need for an integrated approach between the five levels. Project risk evaluation is illustrated through examples of risk economic analysis at project and link levels. Road funding policies have a significant influence on risk management.

Research Report 382 Using risk analysis to assess treatments for frost and ice

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

The comparative effects on skid resistance of the two commonly used treatments for frost and ice on New Zealand roads, mineral grit and the anti-icing/de-icing agent calcium magnesium acetate (CMA), were examined through an on-road test programme. This involved locked-wheel braking tests on selected test sites under a variety of conditions using an instrumented car. Tests were conducted for various treatments, including dry (no treatment), wet, application of grit and application of CMA. Road surface types included fine and coarse chipseal, open-graded porous asphalt, asphaltic concrete and slurry seal. Comparisons of skid resistance were made between the different surfaces and different road surface treatments. Additional laboratory tests were conducted to assess the comparative variation of skid resistance with time following treatment. Typical traffic levels were also obtained for the test sites.

Research Report 147 Security of New Zealand's strategic roading system

Published: | Category: Natural hazard risk management , Research programme , Research & reports | Audience: General

The reliable operation of New Zealand's road network is critical to both its economic success and its social development. Disruption to some parts of the network may therefore have a large negative impact on these. The report outlines a systematic 'desktop' approach which, by reviewing the importance of individual links in the network, and the actual risk of travel disruption. it then identifies which sections of New Zealand's Road Network should be accorded priority in either reducing the risk of disruption or accommodating the disruption better within the network, and recommends some developments to Transfund's Project evaluation manual to address disruption and service issues. Keywords: road network, strategic network, risk analysis, network security, lifelines, travel disruption
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