		2006 NZSEE Conference
	Abstracts

Keynote Address Learning from Hawke's Bay 1931 Earthquake Performance Assessment and Retrofit Decision Making for Risk Mitigation Behaviour of Walls and Piers Understanding Reinforced Concrete Behaviour Modelling Earthquake Performance Earthquake Performance Poster Papers Design and Development

Decision Tools for Earthquake Risk Management, Including Net Present Value and Expected Utility

Warwick Smith and G.A Vignaux

The results of earthquake risk assessments should be presented in ways that will help facilitate risk management decisions. So the measures of risk that are chosen need to be those that will assist decision-makers. Annualised Loss may not be the best basis on which risk management decisions can be made. The Conditional Expected Value of the loss, defined for a suitable set of probability ranges, is a promising measure of the risk because it is similar to a scenario loss and can be readily comprehended by decision-makers. Utility Theory provides a further measure by taking account of individuals’ perceptions of the severity of losses. It can be combined with the concept of Net Present Value to give an overall measure of the risk in terms of the value judgements of the individual decision-maker. The reduction in risk that would result from proposed mitigation works can be readily assessed, so that the decision-maker who is faced with the costs of mitigation is in a position to assess the benefits.

Paper P11: [Read]

Recent Advances in Improving the Resilience of Road Networks

Brabha Brabhaharan

The Hawke’s Bay Earthquake struck in 1931, and not only did it cause devastation to the buildings in Napier, but also to the transport infrastructure. Roads were made impassable by liquefaction induced lateral spreading of embankments and also landslides.

Some recent research and studies have focussed on road networks, and how their resilience can be improved through spatial road risk assessment methods, economic analyses of risk mitigation and implementation issues in the New Zealand context. Research just concluded considers the resilience of road networks and a framework for improving the resilience by considering key parameters that are important to the community.

The resilience is represented by damage and availability of the network combined with the outage (time network is impaired). The key influences that impact on the target (desired or tolerable) level of resilience of roads are life safety, disruption, loss of access for emergency services, need for lifeline restoration, and wider economic impacts.

Target resilience levels can be set for different links in the road network, and the resilience gap can be assessed as the difference between the likely resilience in hazard events and the desired or target resilience. This will facilitate development of mitigation measures to enhance the resilience, and these can then be incorporated into the strategic asset management for the road network.

Paper P12: [Read]

Seattle Fault Scenario - A Decision-making Tool for Earthquake Risk

Gregory MacRae, Don Ballantyne, Mark Stewart and Jane Preuss

An Earthquake Engineering Research Institute (EERI) report entitled “Scenario for a magnitude 6.7 earthquake on the Seattle Fault” was released in late 2005. This report represents more than three years of effort by professionals in the Seattle region in conjunction with EERI. It was initiated to assist engineers, architects, building owners, emergency managers, government agencies, and elected officials to plan for response to such an event, and to serve as a basis for reducing earthquake risks. The scenario document describes the scenario earthquake, ground failure, possible effects on lifeline structures, transportation facilities, buildings and critical facilities as well as the economic impact. Response and recovery issues are also described. The key object of the scenario is a “call to action” for regional preparation and mitigation. The tool “HAZUS” was used to quantify some of the expected losses. This paper describes the background to the document, methods which have been used to communicate technical details to non-technical people, and the impact of the document since its recent release.

Paper P13: [Read]

Vulnerability Methods and Damage Scenario for Seismic Risk Analysis As Support to Retrofit Strategies: An European Perspective

S. Giovinazzi, S. Lagomarsino and S. Pampanin

The inherent seismic vulnerability of existing R.C. buildings, designed prior to the introduction of adequate seismic code provisions in the early/mid-1970s, has been dramatically confirmed by the catastrophic socio-economical consequences of earthquake events that have occurred worldwide in the past decade. The urgent need for the development of feasible and efficient structural mitigation strategies, and the implementation of “standardized” retrofit solutions for intervention at urban or territorial scale, has received increasing recognition and attention. Damage scenario and seismic risk analysis, along with the use of a GIS-environment to represent the results, are considered as a helpful tool to support the decision making for planning and prioritizing seismic retrofit intervention programs at large scale. In this paper, after an overview of current vulnerability methods for seismic risk or damage scenario analysis at a territorial scale, tentative suggestions for possible refinements will be provided with particular focus on the vulnerability models for pre-1970 reinforced concrete buildings. Improvements should include the possibility to account for the peculiar alternative damage limit states and collapse mechanisms observed in real earthquakes and further confirmed by recent numerical and experimental investigations. Comparative evaluation of the reduced level of expected damage after alternative retrofit solutions will be carried out and described in terms of fragility curves. A damage scenario analysis, referred to a case study area in Italy, will be provided as further exemplification of the effects of implementing a multi-level retrofit strategy approach at territorial scale.

Paper P14: [Read]