The Canterbury earthquakes illustrated the potential for large financial losses ($16B of $40B total) and multi-year disruption to Aotearoa New Zealand’s residential sector, with significant implications on mental health and the disaster insurance market. This programme will tackle the problem of resilient housing – including effective engineering and technological solutions, land-use planning, improved insurance processes and frameworks, effective legislation, and communication and engagement strategies.
The Canterbury earthquakes caused widespread damage and losses to residential buildings, and significant community disruption. Despite this, few changes have taken place to reduce the vulnerability of residential buildings. There is an urgent need to improve the resilience of the residential sector, particularly given New Zealand’s acceleration in construction of new houses. To do this we need to understand how to effectively reduce damage to residential housing in earthquakes through engineering practice, and address any contributing societal components (e.g. planning, policy, beliefs and actions). This project focusses on identifying the nature of key challenges to residential resilience in an earthquake context (i.e. legal, land-use planning, insurance, engineering and technology, and societal issues) for improving residential resilience, and creating Thriving Residential Communities.
The research aims to achieve the objectives of the Thriving Residential Communities theme through the activities described below:
1. Legal Frameworks and Planning for Thriving Residential Communities
(Natalie Baird, John Hopkins, Wendy Saunders)
Recent events such as the 2010-11 Canterbury earthquake sequence and 2016 Kaikōura earthquake have brought to attention issues related to recovery processes, and have highlighted that certain legal circumstances can affect the resilience of communities to earthquakes. In IP2, research will look to understand how legal frameworks contribute to creating earthquake resilient communities, and will identify tools to support this. This will include consideration of the legal mechanisms to improve choices of more resilient new housing solutions or voluntary retrofitting, as well as the complex legal issues that arise with the development of medium density housing solutions. As land-use planning is a key component in new development, this aspect will also be considered in our research.
2. Earthquake Insurance for Residential Communities
(Ilan Noy, John Hopkins, Tim Sullivan)
Earthquake insurance of housing is widespread in New Zealand, a fact that helped mitigate the economic impact of recent earthquakes in New Zealand. However, questions have been raised as to whether the insurance model currently adopted in New Zealand is the most appropriate. It may be possible that certain insurance models could be used to incentivize the adoption of more resilient housing solutions and part of the research will consider an experiment on insurance incentives, to get insight into how big these need to be in order to change behaviour. There may also be a potential tension between what the insurers, the insured, and the government might want to achieve in such a system and thus understanding these tradeoffs/tensions, especially in a system where part of the risk is insured by the government (the EQC, and not the private insurers), would also be a very useful investigation. Finally, the traditional wording of insurance policies that endeavor to restore a building to the “as-new” condition has been the cause for demolition of buildings that might otherwise have been considered reparable. Research into alternative insurance policy wordings would need to consider the potential implications for the insurance industry, the engineering community and also within the legal system.
3. Understanding and reducing the vulnerability of the existing housing stock
(Angela Liu, David Carradine, Rajesh Dhakal, Catalina Miranda, Charlotte Toma, Julia Becker)
Recent earthquakes in New Zealand has generated an extensive amount of data on the vulnerability of our housing stock. However, this vulnerability could be quantified better so that potential improvements and changes to building and design procedures can be properly quantified. Thus, IP2 will look to undertake analytical studies and draw from the results of parallel investigations (such as that being undertaken by Tonkin and Taylor for EQC) to quantify the vulnerability of different types of traditional housing systems. Research is also planned on the public expectations of existing residential housing and performance (see below), with the objective of identifying effective means of increasing retrofitting. The research will also look to support research into hill-side housing, which has been identified as having potential issues with torsion and could be most at need of retrofit.
4. Seismic Performance Expectations
(Julia Becker, Catalina Miranda, Charlotte Brown, Kakati Royal, Tim Sullivan)
Current research is revealing that residents expect their houses to perform well in a future seismic event, despite many houses not necessarily being structurally sound (e.g. having poorly secured foundations). This is a concern as much of today’s housing stock will be subject to the earthquakes of the future. This research will explore the reasons why there are gaps between expectations of performance and actual likely performance in an earthquake. We will look at ways of addressing such gaps, so that residents gain a more realistic understanding of the current status of their house, and are motivated to retrofit their houses (McClure et al., 2015; McCrae et al., 2017) in ways that meet performance expectations. We will also consider communities, who may be disadvantaged and have limited control over retrofitting (e.g. are renters, or are of limited socio-economic means). We will explore mechanisms that can support residential retrofitting across the spectrum (e.g. from provision of information through to specialist support). There will be a focus on understanding what Thriving Residential Communities means from a Māori perspective, and how this can be facilitated. We will link with other research that investigates expectations of performance (e.g. expectations of functional recovery via QuakeCoRE IP1, EQC projects), and will hold a workshop to share research approaches and findings on performance expectations.
5. Resilient Infrastructure for Residential Communities
(Liam Wotherspoon, Richard Mowll)
The Canterbury earthquake sequence caused widespread damage to infrastructure that took considerable time to restore in some regions. In IP2 research will continue to develop tools and methodologies for more resilient infrastructure and strategies to communicate and identify acceptable post-earthquake service levels. Identification of such levels prior to an event, will aid with planning for more resilient infrastructure before an event and aid response and recovery, contributing to thriving residential communities. The research will benefit from aligned research in the Built Environment Theme of the Resilience to Natures Challenge.
6 Develop engineering and technological solutions to effectively reduce damage and losses for new and existing buildings, with a focus on:
6.1 Foundation Systems
(Gabriele Chiaro, Greg MacRae, Tim Sullivan, Maxim Millen)
Recognizing the large damage and disruption the Canterbury earthquakes caused because of poor site and foundation systems, the geotechnical engineering research will aim to (i) Critically review and improve existing post-earthquake self-levelling foundation systems and (ii) Develop innovative foundation systems that are cost-effective and are characterized by good post-earthquake reparability. Funding in the first year will contribute towards experimental testing costs associated with “eco-rubber geotechnical seismic-isolation (ERGSI) foundation systems” (Chiaro, et al., 2019). Following the initial experimental work, the proposed project focuses on the evaluation of the field performance of a large-scale structure supported on ERGSI foundation and the validation of a numerical model for parametric analysis to inform the development of a refined performance-based design framework for implementation by engineering practitioners.
Additionally, new research will be initiated aimed at developing low-cost resilient foundation systems for lightweight houses on soils that may not be deemed “good ground” and/or TC3 land (prone to liquefaction).
6.2 Low-damage systems for traditional housing
(Tim Sullivan, Tom Francis, James Lim, Krishanu Roy, Charles Clifton, Pouya Lofti Rad, Greg MacRae)
While existing New Zealand houses are generally characterised with good life-safety performance, damage and repairs were extensive in the Canterbury earthquake sequence. Consequently, in Flagship 4 of QuakeCoRE I, work was initiated on the development of low-cost base-isolation systems for housing that would significantly reduce the vulnerability of traditional single-dwelling housing. Funding will co-fund a post-doc for Tom Francis in order to assist in transitioning the knowledge generated into practice. In addition, the University of Auckland has been helping develop light-gauge steel framed housing solutions (Yeow et al, 2018) that promise high seismic resilience and research will aim to identify the fragility of this housing system, also quantifying better the performance of this type of housing observed in previous earthquakes. Further research is planned in IP2 of QuakeCoRE II to generally develop the relevant findings from QuakeCoRE I to arrive at products and design procedures that are ready for implementation and begin improve the resilience of New Zealand’s building stock. Part of this research will look at the development of engineering solutions and technologies while another part will look at identifying the factors that either discourage or encourage the uptake of more resilient housing solutions.
6.3 Resilient medium-density housing solutions
(Rajesh Dhakal, David Carradine, Angela Liu)
Medium density housing is expected to increase in coming years, given the current housing shortage in New Zealand. Research in IP2 plans to develop seismically resilient solutions for medium density housing that fulfil multiple performance criteria, including environmental sustainability, durability, thermal performance and construction speed. This will include consideration of timber, steel and pre-cast concrete (including modular) medium density housing solutions. Furthermore, it is well understood that residential buildings contain an increased number of non-structural partition walls and special linings (e.g. tiled surfaces) that present a challenge from a post-earthquake seismic resilience point of view. Thus, IP2 will look to link up with the Ministry of Business Innovation and Employment (MBIE) Building Innovation Partnership (BIP) programme to advance the understanding and resilience of non-structural elements (Sullivan et al., 2018) in medium density housing systems.
Programme Leaders: Tim Sullivan, Julia Becker
Researchers: Esther Aigwi, Natalie Baird, Charlotte Brown, David Carradine, Gabriele Chiaro, Charles Clifton, Rajesh Dhakal, Tom Francis, Lesley Gray, John Hopkins, Emma Hudson-Doyle, James Lim, Angela Liu, Pouya Lofti Rad, Greg MacRae, Maxim Millen, Catalina Miranda, Richard Mowll, Ilan Noy, Krishanu Roy, Kakati Royal, Wendy Saunders, Charlotte Toma, Liam Wotherspoon, Pouyan Zarnani