Bushfire-prone Areas Research Articles

Why do people relocate to bushfire-prone areas in Australia

Bushfires account for 40% of fatalities associated with declared disasters in Australia. A significant proportion of these fatalities occur closer to forested areas because over 90% of the recorded locations for the deaths were within 100 metres of bushland areas. Despite this, there has been an increase in people relocating to now-considered high-risk bushfire areas. This paper considers why people live in bushfire-prone areas particularly following Australia’s 2019–20 catastrophic summer bushfires. The study used a qualitative approach and conducted 30 semi-structured interviews with people living in the southeast part of New South Wales; a region hardest hit during the 2019–20 summer bushfire season. The interviews identified 7 reasons, as given by the participants, concerning why they thought people continued to move near bushland. The reasons were a quest for a ‘tree change’, proximity to family, location beauty, place attachment, work-related needs, property affordability and partner-related factors. These reasons were categorised into internal and external factors. This study serves as a useful reference when creating ways to encourage early self-evacuation and, ultimately, to reduce injuries and fatalities. These findings are not exhaustive and do not represent the entirety of New South Wales nor Australia or other countries. However, they represent a sample of lived experience by participants. Future studies might cover wider areas and include great numbers of participants and so garner diverse opinions about locations where people live and the hazard experienced.

Investigating factors underlying why householders remain in at-risk areas during bushfire disaster in Australia

Although most homes lack design and construction features to withstand bushfires, there is a growing trend of householders relocating to bushfire-prone areas. Notably, many bushfire-related fatalities have occurred within proximity, specifically within 100 m of bushland. Therefore, this paper explores the factors that drive householders to remain in at-risk areas, despite the imminent threat of bushfires. Thirty semi-structured interviews were conducted with participants residing in the southeastern region of New South Wales (NSW). The interviews were recorded, transcribed using Otter.AI, and subjected to thematic analysis using NVivo 12 Pro. The findings shed light on why certain householders decided to stay on their properties during the catastrophic 2019/2020 bushfires. Upon analysis, we uncovered thirty-six distinct factors that underlie householders’ choices to remain during bushfires. These factors were categorized into nine groups: protection-related, attitude-related, information-related, operation-related, road-related, shelter-related, finance-related, health-related, and rebuilding-related factors. The study underscores the importance of understanding gender-based differences and pet ownership in bushfire evacuation decisions, emphasizing the need for tailored communication strategies. These findings hold several important implications for research and practice regarding early self-evacuation from bushfires.

Incentives for self-evacuation: A panacea for bushfire fatalities in the Australian bushfire-prone areas

Recurring bushfire disasters have shaped the Australian landscape for over 110 years. Despite this, there has been a rise in the migration of residents into bushfire-prone areas, resulting in increased fatalities. This study investigated incentives that could encourage householders to self-evacuate from bushfire-prone areas during bushfires to address this issue. An inductive approach was adopted, utilizing thirty semi-structured interviews with participants in the southeastern part of New South Wales because the region was the most severely affected during the 2019/2020 Black Summer bushfires. The study found that about 41% of residents needed to be aware of existing incentives. In addition, we identified 13 potential incentives that could encourage early self-evacuation during bushfires. These incentives include information and communication, adequacy of resourcing rural fire service, bushfire education programmes, vegetation management, emergency accommodation, financial assistance, access roads availability, security and property protection, affordable insurance coverage, alternative power supply, property preparation assistance, return access to the property, and improved development approval procedures. The findings provided valuable insights into the incentives that could influence householders’ decisions to self-evacuate during bushfires. The recommendations were based on these findings, suggesting that future studies consider a broader range of participants and geographical areas to enhance the generalizability of findings. The outcomes can be a valuable reference for policymakers and emergency agencies to develop and implement strategies to encourage early self-evacuation during bushfires, thus reducing fatalities.

Pull-out capacities of screw connections in thin steel battens exposed to bushfire conditions

External building envelopes made of cold-formed steel (CFS) claddings are commonly used in bushfire prone areas due to their non-combustible properties. However, their designs should ensure safety under the combined action of enhanced wind suction loading and elevated temperatures experienced during bushfires. Although numerous studies have investigated the critical pull-out failures in CFS batten screw connections under wind suction loading at ambient temperature, the pull-out failure behaviour of batten screw connections under bushfire conditions has not been investigated. The main objective of this study is to examine the pull-out failure mechanisms and capacities of screw connections in CFS battens under wind suction loading at elevated temperatures. Two hundred and sixteen small-scale tests were conducted on CFS battens made of three commonly used thicknesses and both high (G550) and low (G300) strength steels. Tests were conducted at six different temperatures using three types of screw fasteners to investigate the critical localised pull-out failures of batten screw connections. The results of these tests were utilised to develop applicable design equations and capacity reduction factors for the pull-out capacities of batten screw connections under the combined action of wind suction loading and elevated temperatures. The findings of this study will help design and build structures safely in bushfire-prone regions.

An advanced observer-based nonlinear model predictive controller design for distribution networks in bushfire prone areas

An advanced observer-based nonlinear model predictive controller design for distribution networks in bushfire prone areas

Detection of Faulty Feeders and Phases in Resonant Grounded Power Distribution Networks for Bushfire Prone Areas Using Measurements From Existing Field Devices

Detection of Faulty Feeders and Phases in Resonant Grounded Power Distribution Networks for Bushfire Prone Areas Using Measurements From Existing Field Devices

Heat Transfer Analysis of Full-Scale Safe Rooms Exposed to Bushfire Conditions

Sheltering in place is identified as an accepted behaviour during disasters while safe rooms are purpose-built buildings used for sheltering or storage of valuables under these circumstances. However, ensuring the integrity of safe rooms in bushfires is complex and challenging due to many factors. This study aims to advance the understanding of the bushfire fire heat transfer in steel framed bushfire safe rooms using a numerical modelling approach. Both small-scale models of individual external walls and full-scale models of safe rooms were developed and validated using the results of an experimental study of a full-scale safe room. Then the study was extended to address the identified challenges in the design of safe rooms influenced by the factors such as, the fire exposed area, internal compartment arrangement, location of the safe room in the bushfire-prone areas, and the external environmental temperatures during summer on the tenability requirements. The results of this study provide considerable details of the performance of above-ground bushfire safe rooms detached from the associated dwelling under realistic fire conditions. They showed that the integrity of the doors is very important and that having multiple internal compartments is favourable for the bushfire performance of safe rooms. This study shows that safe rooms can be constructed using available building materials to satisfy the bushfire heat transfer requirements and provides conditions for their usage. Furthermore, the modelling methods emphasise their applicability to evaluate safe rooms and modular buildings in bushfire and building fire related scenarios.

Bushfire performance of native Australian wood species

This paper describes fire safety experiments on Australian native timber samples with a special focus on their use in bushfire-prone areas. Nine species were assessed through testing in a cone calorimeter, thermogravimetric analysis and differential scanning calorimetry (DSC). The effects of density, moisture content and chemical extractives content were evaluated. Marked differences in ignition times were found, possibly due to variations in density across species, as well as the chemical extractives content. Analysis of the heat flow through DSC indicated that the type of extractives can influence the fire safety performance and that this aspect of wood properties merits further study. One additional species was identified as a suitable candidate for bushfire-resisting species in the Australian bushfire context.

Advances on fault detection techniques for resonant grounded power distribution networks in bushfire prone areas: Identification of faulty feeders, faulty phases, faulty sections, and fault locations

Advances on fault detection techniques for resonant grounded power distribution networks in bushfire prone areas: Identification of faulty feeders, faulty phases, faulty sections, and fault locations

Bushfire Resistance of Lightweight Masonry Blocks Made with Diatomite Aggregate

‘Diatomite’ is a naturally occurring soft material that contains fossilized skeletal remains of diatoms. It is lightweight, and the porous structure of the aggregate possesses low thermal conductivity. This study was aimed at developing masonry (i.e., cement) blocks using diatomite aggregate and assessing their suitability for use in bushfire shelters and external walls of buildings in bushfire-prone areas. First, the chemical and physical properties of mix components (i.e., cement, sand, and diatomite aggregate) were determined. Then masonry block cement mixes including a cement-sand (i.e., standard) and three different cement-diatomite (i.e., diatomite) mixes were developed by absolute volume method. The properties of fresh mixes; slump and fresh density and properties of hardened mixes; density, compressive strength, and water absorption were investigated, while bushfire and building fire resistance of developed masonry blocks were examined by exposing them to the standard fire curve for 30 min and three hours, respectively. The obtained results from this experimental study showed that diatomite mixes have a negative correlation between the amount of diatomite aggregate and the density and compressive strength, while a positive correlation for water absorption and bushfire and building fire resistance. All the developed diatomite blocks are ultralightweight, loadbearing, and have three hours of building fire resistance. Further, the obtained results were compared with those of the standard and two other previously developed lightweight masonry blocks/mixes using expanded perlite and pumice aggregates. In comparison to the standard and other diatomite, expanded perlite, and pumice blocks, blocks made with 60% of diatomite aggregate are recommended for use in bushfire shelters and other buildings in bushfire-prone areas.

Bushfire resistance of external light steel wall systems lined with fibre cement boards

Bushfires/wildfires have become a widespread and frequent occurrence in many parts of the world. With the adverse effects of climate change and the increasing population in the Bushland Urban Interface (BUI)/Wildland Urban Interface (WUI), ensuring adequate bushfire resistance of buildings in bushfire-prone areas has become very important. Improving the safety and integrity of the external building envelope is identified as a solution to minimise the bushfire related building damage and losses. This paper presents the details of bushfire resistance experiments conducted on external Light gauge Steel Framed (LSF) wall systems and the results. These LSF wall systems were externally lined with fibre cement boards and exposed to both bushfire radiant heat and flame zone fire conditions under indoor and outdoor test conditions. The results have shown that the rapid increment of the heat flux led to sudden explosive failure of the wall system whereas the gradual increment of the heat flux resulted in a progressive failure. This study has highlighted the importance of external cladding integrity and thermal shock resistance of building elements to enhance the bushfire resistance of buildings.

Control of arc suppression devices for reducing powerline bushfires in resonant grounded power distribution networks using global terminal sliding mode controller

AbstractThis paper proposes a global terminal‐sliding mode controller (GT‐SMC) to compensate powerline bushfires due to electric faults in power distribution networks using arc suppression devices (ASDs). A GT‐sliding surface along with a new quick reaching law is used to design the controller. The major control objective is to compensate the fault current caused by single line‐to‐ground (SLG) faults to a value that cannot ignite fires in bushfire prone areas. A T‐type residual current compensator inverter within an ASD is controlled to achieve the goal. An integral‐sliding mode controller (I‐SMC) is also designed using a conventional reaching law for comparing the performance. Simulations studies and processor‐in‐loop implementations are carried out to investigate the ability of the GT‐SMC over an I‐SMC over a range of fault impedance scenarios. Dynamic properties of the voltage and current due to SLG faults along with the current injection by the ASD are analyzed against the standard criteria, to be followed to get rid of powerline bushfires. Results under different operating scenarios indicate that both controllers are capable to maintain standard criteria for preventing powerline bushfires though the GT‐SMC is proven to exhibit superior transient responses to that of the I‐SMC and integral backstepping controller.

A hybrid sliding mode control scheme for rapid earth fault current limiters in compensated distribution networks in bushfire prone areas

AbstractA hybrid sliding mode controller is proposed for rapid earth fault current limiters (REFCLs) used in resonant grounded power distribution networks to self‐extinguish powerline bushfires where the concepts of the proportional integral (PI) action and nonsingular fast terminal sliding surface (NFTSS) are combined together to utilize the benefits of both schemes. A hybrid sliding surface is designed for obtaining the control input so that the fault current compensation is achieved by the residual current compensation (RCC) inverter used within a REFCL to a value that the fire does not ignite. The inclusion of an integral action along with the NFTSS helps to significantly reduce the chattering effect. Furthermore, a continuous function is introduced within the proposed scheme to replace the discontinuous signum function. The switches for the RCC inverter are controlled by deriving control actions from the Lyapunov stability theory applied on the hybrid PI‐NFTSS. The performance of the proposed controller is compared with a nonsingular fast terminal sliding mode controller. For this reason, this paper also includes the design process of nonsingular fast terminal sliding mode controller which is designed using only the NFTSS. Simulations under different scenarios having different fault resistances clearly depict the superiority of the proposed scheme over the nonsingular fast terminal sliding mode controller and an existing integral sliding mode controller in terms of maintaining transient responses.

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

A comprehensive review of control techniques for compensating the fault current in resonant grounded distribution networks: From the perspective of mitigating powerline bushfires

Powerline faults are responsible for major bushfires around the world where arcs provoked from ground faults are common causes for igniting such fires. The grounding techniques (mainly resonant grounding) used in distribution substations and arc suppression devices play a crucial role for compensating fault currents in order to extinguish arcs so that the likelihoods of powerline bushfires are significantly reduced. Though passive arc suppression devices (e.g. Petersen coils) are extensively used for compensating the reactive component of the fault current, the active component of this current is still large enough to ignite the fire in bushfire prone areas for which active arc suppression devices are recently used. These active arc suppression devices incorporate residual current compensation inverters and the full compensation of the fault current rely on the control scheme of these inverters. This paper comprehensively reviews different control schemes that are used for compensating the fault current in resonant grounded power distribution systems. The existing control schemes are discussed in terms of the model used during the controller design process, loop structures, control block diagrams, and performance analysis frameworks (i.e. the type of fault impedances). It is worth mentioning that faults on resonant grounded power distribution networks exhibit the characteristics of high impedance faults and it important to consider this aspect for performance analysis of the control scheme. This paper also covers a brief overview of different grounding techniques used for mitigating fault currents and finally, the challenges with the existing controllers are identified in terms of extinguishing powerline bushfires. The comprehensive review motivates and guides future research activities on developing more efficient fault compensation techniques.

Understanding the intention to stay and defend during a bushfire: An application of virtual reality to improve awareness of predictors associated with behavioural response

Encouraging residents of bushfire-prone areas to make wise protective action decisions in response to bushfire threats is a challenging task. Despite the emphasis on early evacuation as the safest option, there are circumstances when staying and defending a property is a rational decision. Using the protective action decision model (PADM), this study aimed to: (1) increase understanding of the relative importance of bushfire risk perception, protective action perception, and stakeholder perception in predicting the intention to ‘stay and defend’ and (2) analyse the effect of a virtual reality (VR) intervention on these factors among South Australian residents (n = 299). Prior to the VR intervention, participants were grouped into three cohorts of ‘stay and defend’, ‘leave early’ and ‘wait and see’ based on their preferred protective action on a day forecast as a day of severe fire danger. The participants who either indicated they would ‘stay and defend’ or ‘wait and see’ experienced the intervention which challenged their capacity to ‘stay and defend’ using a virtual bushfire threat. Structural equation modelling (SEM) analysis of data showed that protective action perception was the strongest predictor of the intention to stay and defend for all cohorts. Self-efficacy was found to have a mediating role between risk perception and the intention to stay and defend. For those intending to ‘stay and defend’, stakeholder perception was not a significant predictor, however, its importance amongst all three groups significantly increased after exposure to the virtual bushfire experience. Understanding the differences in the decision-making process of the three cohorts and the way they were influenced by the virtual scenario provides valuable insights that could contribute to the design of more effective bushfire risk communication strategies.

Bushfire-Resistant Lightweight Masonry Blocks with Expanded Perlite Aggregate

During bushfires, one of the building elements that is directly exposed to embers, radiant heat and direct flames is the “wall” element. This study investigated the feasibility of using expanded perlite aggregate in masonry (i.e., cement) blocks to enhance their bushfire resistant characteristics. The chemical, physical, and thermal properties of expanded perlite aggregate were determined first and then masonry block cement mixes were developed by replacing sand in the conventional mix with expanded perlite aggregate by volume at different percentages (100, 80, 60, and 40%). The properties of fresh and hardened cement mixes (slump, density, compressive strength, and water absorption) were measured. The developed masonry blocks were exposed to Bushfire Flame Zone conditions (i.e., 20–842 °C) and the standard fire curve for three hours (i.e., 20–1110 °C) to assess their resistance to bushfires and building fires, respectively. The properties of Cement–Expanded Perlite mixes were compared with those of the standard Cement–Sand mix. The test results showed that the use of perlite aggregate reduced the workability, density, and compressive strength of the cement mix while increasing the water absorption and fire resistance level. All the developed perlite blocks were lightweight and had three hours of fire resistance level (-/180/180). When exposed to bushfire flame zone conditions, the blocks made with 100, 80, and 60% perlite satisfied the maximum ambient surface temperature limit. Of these, masonry blocks made with 60% perlite aggregate are the most suitable for use in external walls of bushfire shelters and residential and commercial buildings in bushfire-prone areas.

An integral backstepping controller design for compensated distribution networks with rapid earth fault current limiters in bushfire prone areas

AbstractThis paper presents a nonlinear integral backstepping controller (I‐BSC) design scheme for a T‐type residual current compensation (RCC) inverter used in compensated distribution networks with rapid earth fault current limiters (REFCLs). The major control task for the proposed scheme is to reduce the fault current to a value suitable for the mitigation of powerline bushfires due to single phase‐to‐ground faults in compensated distribution networks. The key distinct feature of the proposed I‐BSC over the traditional backstepping controller (T‐BSC) is that it introduces an integral action for analyzing the dynamic of the tracking error which minimizes its steady‐state value and ensures better dynamic performance. In order to prove the global asymptotic stability of the RCC inverter with the proposed integral backstepping controller (I‐BSC), the Lyapunov function‐based theory is used. Finally, the performance of the I‐BSC is analyzed on the MATLAB/Simulink environment and compared with a T‐BSC. The performance of both I‐ and T‐BSCs is assessed in terms of transient behaviors of the injected current to the neutral, fault current, and line‐to‐ground voltage of the faulty phase to ensure the standard operational criteria for self‐extinguishing powerline bushfires. Simulation results clearly demonstrate that both controllers fulfill operational standards for REFCL‐compensated networks though the I‐BSC archives better transient behaviors while comparing with the T‐BSC. Results from the processor‐in‐loop (PIL) validations are also included to further justify the applicability of the newly proposed scheme in the real‐time environment.

Fire performance of timber: review for use in wildland-urban interfaces

Abstract Wood is increasingly viewed as a more environmentally sustainable material owing to its low embodied energy, workability, and renewability, but its two major drawbacks are susceptibility to biological degradation and fire. Biodegradation is typically addressed through effective designs to exclude moisture or, where that is not possible, the use of either naturally durable or chemically protected timber. Naturally durable timbers are widely used globally while preservative treatments are increasingly used to protect less durable timbers. These practices have markedly extended the use and service life of timber in harsher environments. However, these treatments do not improve the fire performance of the timber and there is increasing interest in the use of fire resistive coatings or impregnation with fire retardants to allow use in bushfire prone areas. This review provides background on the problems associated with increased building and construction in the wildland-urban interface. It summarizes the codes, standards and state of the art practices needed for adequate fire safety in timber construction.

A nonlinear model predictive controller design for residual current compensation inverters in rapid earth fault current limiters to mitigate powerline bushfires

This paper presents a nonlinear model predictive control scheme for residual current compensation inverters in rapid earth fault current limiters to inject appropriate current to the neutral so that the fault current is compensated in distribution networks. The proposed nonlinear model predictive controller is designed to limit the fault current within a level that powerline bushfires do not ignite due to single line-to-ground faults on power distribution systems in bushfire prone areas. The nonlinear model predictive controller is designed for a T-type residual current compensation inverter in rapid earth fault current limiters based on its dynamical model where the control objective is to inject current for compensating the fault current. The control law for the residual current compensation inverter is obtained by solving an optimal control problem while using the concept of the receding horizon control scheme. The performance of the controller is evaluated through standard software-based computer and processor-in-loop simulations where results are benchmarked against backstepping and sliding mode controllers in terms of compensating both faulty phase voltage and fault current.