A different way of thinking about seismic risk

Hare, John

doi:10.5459/bnzsee.52.3.141-149

Cited by 4 publications

(9 citation statements)

References 3 publications

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“…Many building codes and risk-targeted hazard studies consider the design of buildings as independent entities. In contrast, society often judges building codes on the performance of communities and there is motivation among engineers to consider the performance of communities (Hare, 2019). Furthermore, the concentration of many buildings can result in risk aggregation which leads to expected but unintended consequences.…”

Section: Risk-targeted Hazard: Previous Studiesmentioning

confidence: 99%

Risk-targeted hazard for seismic design in New Zealand considering individual and societal risk targets

et al. 2023

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The promotion of risk-targeted hazard as the basis of seismic design internationally has increased over the past decade. Risk-targeted hazard estimates are derived through convolution of hazard curves with representative fragility functions and provide a means to target uniform risk across a region. Using risk targets also enables performance objectives of building codes that are consistent with other life risks and can include societal input into the expected performance of structures. Current design procedures using a uniform-hazard spectrum are unable to provide equal risk across the country due to variation in the shapes of hazard curves in different locations and uncertainty in structural response. In this article a framework is proposed, which can be used with national seismic hazard models, to produce risk-targeted hazard spectra for seismic design. This study extends the risk-targeted hazard framework through full quantification of epistemic uncertainty in seismic hazard and includes multiple risk targets for individual and societal risk at the building and city scales. The article describes a framework that can be used to adjust current seismic design force levels in New Zealand standards to target uniform seismic risk for buildings considering both the performance of individual buildings and the performance of cities.

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Section: Risk-targeted Hazard: Previous Studiesmentioning

confidence: 99%

Risk-targeted hazard for seismic design in New Zealand considering individual and societal risk targets

et al. 2023

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“…Current publicized approaches to seismic performance decision-making do not provide a sufficiently nuanced assessment of buildings to ensure that investment or disinvestment decisions are effectively balancing life safety and service provision. Without a sound approach to decision-making, significant investment in seismic building upgrades could be made with limited payback or limited understanding of the value of the investment (Hare, 2019). There is little literature that currently addresses this challenge, and there are many large public and private sector organizations with broad property portfolios in seismically active zones that are facing these decisions.…”

Section: Introductionmentioning

confidence: 99%

“…While %NBS may appear at face value a straightforward concept, the complexities of seismic events and the nuances of structural design mean that the link between %NBS, building performance, and life safety risk is not always linear. Earthquakes have a range of different ground-shaking effects and %NBS will not predict how the building will perform in a particular earthquake (Hare, 2019). Percent NBS does not predict seismic performance from one earthquake to the next (Hare, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Seismic repair and retrofit prioritization framework

Brown¹,

Seville²,

Horsfall³

et al. 2022

Earthquake Spectra

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The 2010–2011 Canterbury earthquake sequence caused significant damage to the Canterbury District Health Board (CDHB) building stock. The extent of damage, post-earthquake changes to the seismic code, new legislation around earthquake-prone buildings, and ongoing changes to clinical service requirements created a challenging decision-making environment for capital works repair and retrofit. In this article, we present a framework designed to assess the seismic resilience of buildings from a holistic perspective and to determine appropriate levels of seismic retrofit. The framework design ensures that decisions are driven by building criticality in the context of a healthcare system. It helps users to balance life safety risk and the demands of delivering critical clinical services day to day: resulting in safe facilities that provide effective health services under a range of future conditions. Pilot application of the framework enabled the reprioritization of significant capital toward buildings that provide the most life safety and health service resilience benefits in the long term. The process and resulting framework from this project is applicable to a wider range of building owners navigating seismic retrofit decision-making and the emerging movement toward functional recovery–based building regulation.

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“…In light of the extensive building damage resulting in high financial loss in recent earthquakes, practicing engineers and researchers in New Zealand have been advocating a revision of the current design approach to improve the performance of new structures in future earthquakes [2][3][4][5]. As a result, large proportion of buildings constructed in the last decade (including those built to replace earthquake-damaged buildings) have shied away from the traditional damage-friendly ductile structural systems and, instead, adopted one of the new and emerging structural systems claimed to be "low-damage".…”

mentioning

confidence: 99%

Hybrid posttensioned rocking (HPR) frame buildings: Low-damage vs low-loss paradox

Dhakal

2021

BNZSEE

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The 2010-11 Canterbury Earthquake Sequence inflicted seismic losses worth more than $40B, which is about 25% of the GDP of New Zealand (as per 2011 data). More than 80% of these losses were insured, which comprised of more than $10B covered by the Earthquake Commission (a New Zealand crown entity providing insurance to residential property owners) and more than $22B (comprising of roughly equal split between domestic and commercial claims) by private insurers [1]. The scale of financial impact has been perceived to be disproportionately large given the building regulatory regime in New Zealand is relatively stringent and the earthquakes and aftershocks were of moderate magnitude. As it is well known that some of the major faults spread in the Wellington region and the subduction boundary passing through the centre of New Zealand can generate much bigger earthquakes (upwards of magnitude 8), people are left pondering whether New Zealand is able to cope with the financial impact of larger earthquakes. This fearful realisation gradually led to people being dissatisfied with merely life-safe buildings and demanding more resilient buildings that meet the objectives of performance based design; i.e. suffer less damage, incur less loss, and can remain functional after earthquakes. In light of the extensive building damage resulting in high financial loss in recent earthquakes, practicing engineers and researchers in New Zealand have been advocating for revising the current design approach to improve performance of new structures and infrastructure in future earthquakes [2-5]. As a result, large proportion of buildings constructed in the last decade (including those built to replace earthquake-damaged buildings) have shied away from the traditional damage-friendly ductile structural systems and instead adopted one of the new and emerging structural systems claimed to be “low-damage”. In many cases, the adopted structural systems are not covered by existing design standards and are approved as alternate solutions through expert peer review. The “low-damage” attribute of most structural systems has been validated by component (or sub-assembly) level experimental tests, but their interactions with other building components and implications of their use in buildings have not been rigorously scrutinised. Hence, the rushed adoption of some of these systems in buildings can surprise the engineering community in future earthquakes with mismatch between the expected and real performances of the buildings; akin to what New Zealand engineering fraternity is currently going through due to realisation of poor seismic performance of precast hollow-core flooring system that has been widely used in New Zealand buildings without rigorous scrutiny. One such “low-damage” structural system is precast post-tensioned rocking frames with supplemental energy dissipaters. This paper summarises the development of this structural system, critically reviews the literature reporting the seismic performance of this system, and qualitatively evaluates system-level implications of its use in buildings. This paper is intended to better inform engineers of the likely seismic performance of buildings with this structural system so that they can optimise its benefits by giving due consideration to its effect on other building components.

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A different way of thinking about seismic risk

Cited by 4 publications

References 3 publications

Risk-targeted hazard for seismic design in New Zealand considering individual and societal risk targets

Risk-targeted hazard for seismic design in New Zealand considering individual and societal risk targets

Seismic repair and retrofit prioritization framework

Hybrid posttensioned rocking (HPR) frame buildings: Low-damage vs low-loss paradox

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