Repair of earthquake damage is a critical component to the recovery after an earthquake disaster. After recent events, the time to return the commercial and industrial building stock to functionality has been hindered by the lack of understanding of residual capacity and repair. This programme will identify time-to-functionality targets and repairable building solutions, thus providing the underlying science to support the development of the world’s first functional recovery-based seismic design standard.
Inter-Disciplinary Programme 1 will promote functional recovery and develop solutions to maintain and restore building function following a large earthquake. Factors such as economic, societal, and sustainability drivers for more resilient buildings will be investigated and linked to low-damage design concepts and risk-targeted design for functionality.
The research will also investigate technical requirements to restore function and associated expectations and timeframes for repair in a post-earthquake environment.
This programme will investigate drivers for uptake of increased post-earthquake functionality and the wide-ranging motivation for, and consequences of, improved functional recovery. Specific technical, economic, and societal challenges to develop evidence-based guidance on functional recovery will be identified.
Overall, this programme will support and promote increased societal resilience through greater uptake of low-damage building designs and guidance on the repair of buildings that suffer damage during a large earthquake.
1) Drivers for Change:
Considering the significant fundamental shift suggested from a purely life-safety focus to considering design for functional recovery, there is a need to define and substantiate the drivers for change. Such evidence base will be needed by policy makers in order to justify building regulations and guidelines. The drivers will be explored from three perspectives: economy, sustainability, and societal expectations.
1a – Economic Drivers for Change: (Cardwell, Filippova) A disaster, earthquake or otherwise, results in a drop in economic activity, followed by a recovery period. A move toward functional recovery in building design is expected to lead to a smaller drop in economic activity and a faster recovery period. This project seeks to quantify these changes in economic activity and hence the overall economic benefits of targeting building designs based on functional recovery objectives.
1b – Sustainability Drivers for Change: (Toma, Chang-Richards) As New Zealand moves toward a zero-carbon economy, the construction sector must adapt. This time of change provides an opportunity to assess the impact of current seismic design standards on the environment in light of a major earthquake. This project will seek to define how functional recovery design targets can lead to fewer building demolitions, less construction waste following earthquakes and during reconstruction, and longer life cycle of buildings.
1c – Societal expectations: (Brown, Becker) Building codes serve the people who use, own, and operate buildings, hence, any fundamental changes in performance objectives need to be linked to societal expectations of building performance. This project, closely linked the EQC-funded Resilient Buildings Project, will seek to assess the expectations of building performance across a range of earthquake intensities. This project will also be linked with project 4b which explores the expectations of time frames for return to function for different building owners and tenants.
2) Maintaining Functionality:
The optimal outcome would enable near-immediate occupancy of buildings after a damaging earthquake, facilitating community resilience and rapid recovery. Such performance objectives might initially be applied to high importance-level structures or those with long-term institutional tenants with additional motivation for building resilience, before becoming more widespread. While specific drivers and social/economic factors which influence adoption of low-damage designs will be investigated within projects 1a-c, there is also a need for robust technical guidance to ensure that low-damage structural designs achieve their intended performance goals. This objective will test, analyse, and optimise Low-Damage Design Guidance and extend the methodology to a Risk-Targeted Design process.
2a – Low-Damage Design: (Rodgers, Henry) This objective will examine, test, and modify existing low-damage design guidance to assess whether this guidance provides the intended objectives to maintain functionality, enable rapid re-occupancy and support more resilient building design. Research will focus upon assessment of maintaining functionality, seek to improve and optimise guidance, as well as identify cases where designs might meet the definitions, but not the intent of the guidelines.
2b – Risk-Targeted Design for Functionality: (Stephens, Horspool, Hulsey) Risk-targeted design has recently been proposed to select design levels to ensure buildings do not exceed an acceptable annual fatality risk (Horspool et al 2021). Such concepts can be extended to be framed in terms of risk of losing functionality. With a focus on identifying non-structural components most likely to cause significant impact on functionality, this project will seek to define a framework for assessing the probability of losing functionality.
2c – Seismic Performance of Non-structural Elements: (Dhakal, Sullivan) Maintenance of functionality is often governed by the seismic performance of non-structural elements (NSE) and their interaction with the structural system. Identification of performance of existing NSE is critical to understanding the expected functionality of current designs, while development of new low-damage NSE will be critical to providing functionality for strong earthquakes.
2d – Ensuring Resilience: (MacRae, Rodgers) This project aims to define how low-damage construction will increase the “degree of confidence” (i.e. reduce the epistemic uncertainty) in our measures of loss, while also accounting for aleatory uncertainty. The project aligns with the ongoing ROBUST collaboration between QuakeCoRE and ILEE. The project will include workshops with practitioners to seek to overcome barriers to low-damage technology implementation.
3) Repaired Buildings:
It is not economical or realistic to design all buildings to maintain functionality in the whole range of earthquake intensities possible in NZ urban regions; however, buildings can be designed to facilitate repair and return to function. This objective seeks to understand societal views of repaired buildings (e.g. loss of trust or value) and identify engineering criteria for when a building is repairable.
3a – Building user views of repaired buildings: (Becker, Filippova) One rationale provided for demolition of lightly-damaged buildings after recent earthquakes has been the perception that tenants will not want to live or work in a repaired building (Marquis et al 2018). This project seeks to better understand the perceptions of building users and owners of repaired buildings, what drives these perceptions, and what can be done to build confidence in the performance of buildings repaired after strong earthquakes. This project is closely tied to project 1c and 4b, including a shared PhD student between project 3a and 4b.
3b – Component limits for repairability: (Hogan, Lopocaro) Current design standards provide material strain (or curvature) limits to ensure structural components will be able to perform as intended at the ultimate limit state. Such limits may or may not ensure repairability of the structural components. With an initial focus on reinforced concrete components, this project will seek to define material strain limits which provide a high probability of repairability and identify component detailing changes which will enhance the repairability of conventional construction in New Zealand. A particular emphasis is placed on relatively simple means of repair which enable earlier return to function.
4) Timeframes for restoration of function:
Post-earthquake recovery models can be used as decision support tools for both pre- and post-event building restoration planning. However, due to the complexities around data availability and requirements and interplays between socio-economic factors, there have been few opportunities to quantify the timeframes for restoring buildings to functional recovery. This objective seeks to understand those complexities that influence the timeframe of functional recovery.
4a – Relating functionality timeframes to building occupancies: (Boston, Chang-Richards) Different functionality timeframes will lead to different decisions on building occupancy, and associated effects of those decisions. This project seeks to use fragility curves of buildings to evaluate the criticality of both structural and non-structural building systems for achieving functional recovery; and then formulate a stochastic model by establishing relationships between functionality timeframes and building occupancies over time.
4b – Expectations of restoration timeframes: (Filippova, Ying) The lack of tools and data to aid in repair-demolish decision-making offers plausible explanation regarding the key impediments to successful building restoration decisions (Ying et al., 2016). This project seeks to establish an expectation continuum of building owners/users around the restoration timeframes and how these expectations can be better managed and factored in when identifying acceptable functional recovery timeframes. This project is closely tied to project 1c and 3a, including a shared PhD student between project 3a and 4b.
4c – Timeframes for repair in post-earthquake environment: (Chang-Richards, Cardwell) External constraints such as engineering and construction capability and stakeholder requirements are widely associated with the ability for attaining achievable and acceptable timeframes for buildings to restore functions (Chang-Richards et al., 2017). This project seeks to develop data-driven repair time models by using multivariate logistic regression to quantify the parameters that drive the step changes in functional recovery timeframes for multi-storey buildings
Programme Leaders: Alice Chang-Richards, Geoff Rodgers
Researchers: Megan Boston, Dave Brunsdon, Robert Cardwell, Ken Elwood, Helen Ferner, Anne Hulsey, Reza Jafarzadeh, Giuseppe Loporcaro, Max Stephens, Charlotte Toma, Priya Vishnu, Fei Ying