@article {bnh-8215, title = {Cost-effective mitigation strategy development for building related earthquake risk {\textendash} Melbourne case study}, number = {707}, year = {2021}, month = {09/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Earthquake hazard was not fully recognised in Australian building design until the mid-1990{\textquoteright}s. This oversight has resulted in a legacy of vulnerable buildings that can be readily damaged in moderate to severe Australian earthquakes. In particular, older unreinforced masonry (URM) buildings built with the architectural styles, materials and construction details used in the United Kingdom are particularly vulnerable. Australian earthquakes have highlighted the vulnerability of this building type. These events include the Adelaide Earthquake of 1954, the Meckering Earthquake of 1968, the Newcastle Earthquake of 1989 and the Kalgoorlie Earthquake of 2010, all of which damaged pre WWII masonry buildings in particular.\  Buildings of this style are present in the older centres of our major cities, and Melbourne has a very significant number of these. As shown in this research, in number nearly half of the buildings in the Melbourne central business district are of this type of construction. The damage to these buildings can greatly add to human casualties as a result of falling masonry elements. Further, the severity of damage and losses can impede the recovery of cities like Melbourne physically, economically and socially. Finally, many of these buildings have heritage value to communities that residents may want preserved.

This document reports on the final deliverable for Project A9 Cost-effective mitigation strategy development for building related earthquake risk of the Bushfire and Natural Hazards Collaborative Research Centre (CRC). It builds on the masonry component research of the University of Adelaide in this project and is a milestone for Geoscience Australia. The work follows the utilisation project entitled {\textquotedblleft}Earthquake Mitigation of WA Regional Towns: York Case Study{\textquotedblright}, that was jointly delivered by GA and the University of Adelaide. The utilisation project developed original condition and mitigated vulnerability models for six URM building types. In this project, these outcomes have been applied to the much larger Melbourne CBD exposure.

The project had the following key components:

The work required the development of the three fundamental risk elements of earthquake hazard, community exposure and building vulnerability. It also entailed the assessment of the economic loss measures associated with human injury, contents losses, rental income, commercial property leasing, and business activity. Additionally, it included the application of the semi-intangible value placed on human life to society. Each of these are described below.

Earthquake hazard

This study has drawn upon the latest understanding of the Melbourne region earthquake hazard by utilising the recently released National Seismic Hazard Assessment (NSHA 2018) (Allen et al, 2018a). The bedrock hazard from this assessment shows Melbourne to have a {\textquotedblleft}low{\textquotedblright} earthquake hazard by global standards but significant by Australian standards. The hazard is further amplified by the presence of the sediments deposited by the Yarra River.\  These soil effects increase the hazard, particularly those in the study region south of the Yarra River. The effects of soil amplification can double the severity of shaking in some areas.

Community exposure

The definition of the building assets in the study region utilised several sources. The available state government building data integrated into the National Exposure Information System (NEXIS) was accessed and supplemented by an engineering survey database developed and maintained by GA for the Australian Reinsurance Pool Corporation. This was further refined by a desktop review of all masonry buildings utilising available street level imagery. In total there were 1,543 buildings in the study region, and 687 of these were identified as URM.

The assessment of human activity was achieved by utilising research undertaken outside of this project. This research utilised a population model developed by downscaling a destination zone based telecommunication model with pedestrian counts, the Melbourne traffic control systems movement counts, and building floor area information. Using this work it was possible to define the local human exposure at the time of the scenario event, particularly those in damaged buildings and those potentially exposed to falling masonry during a rapid onset earthquake event.

Building vulnerability

The building vulnerability assessment work for the URM building stock was a direct utilisation of the six vulnerability types identified in the earlier York WA mitigation study. This included the vulnerability in present condition, and that with mitigation measures applied to the vulnerable elements. To complete the context, the vulnerability of other building types was attributed using a suite of models developed through an adaptation of US HAZUS models, reference to \ heuristically developed models from a GA facilitated UN workshop (Maqsood et al, 2014), and through heuristic adjustments by the project team. This vulnerability of non-URM buildings remained a constant in the study as mitigation of these buildings was not considered.

Economics of cost assessment

The economic assessment considered a broad range of measures. These ranged from the direct costs to property owner, building occupiers, and businesses through to health care costs and the partially intangible value placed on the loss of a human life. The aim was to provide scalable information on benefits versus cost to a range of decision makers and investors. Importantly, the measures where not comprehensive and so represent a lower bound to the actual avoided impacts mitigation achieves. For example, the cost of emergency response, clean-up and community recovery support were not considered. Neither was a macro-economic perspective developed to capture non-impacted businesses that would benefit from a stimulus in business activity such as in the construction industry, the supply of home appliances, soft furnishings and drapery. Significantly, the value of avoided heritage building loss was considered through the utilisation of metrics developed by a UWA led CRC project.

Scenario impacts and risks

The study considered a single rare earthquake scenario having an annual likelihood of 1/5,000 of causing the targeted bedrock shaking severity beneath the Melbourne CBD, or greater. This likelihoods corresponds with a 1\%, chance of this shaking severity being exceeded in the next 50 years. For the event the injuries and other losses within the scope of this study were assessed using the human exposure corresponding with 11:00am of Monday through to Thursday. The losses ranged from $737m for building damage only, through to $1.66b for the other monetary costs considered.\  The value of human life lost increased this to $3.97b. Where 25\% of the masonry building stock was retrofitted, over 30 years, these losses reduced by approximately 16\%.

The reduction in injuries if this event occurred in 30 years time was also evaluated. Serious injuries reduced by 16 and deaths by 98 persons. Urban Search and Rescue logistics would also reduce correspondingly.

In a similar manner, the long term financial risk of the Melbourne CBD study region was evaluated for building damage. It was presented as the average annualised loss for the URM building stock and for the entire study region buildings. It was also forecast 30 years into the future and the financial risk reduced by 38\% for the URM building stock and by 10\% across the entire study region buildings.

Discussion and outcomes

Earthquakes occur frequently in Australia with over 100 events greater than magnitude 3.0 (ML) recorded within the Australian continent every year by Geoscience Australia. The smaller and more frequent events are typically non-damaging, whereas the less frequent larger events can be very damaging when they occur close to a community. This plays out in the economics of strengthening older structures where the benefits of avoided building damage and contents losses through retrofit for earthquake are not a full offset for the significant costs.\  Other avoided costs associated with business losses, lost wages, health care costs, and the value placed on human life, do increase the sum significantly but are not realised by the property owner. While not all avoided costs were considered, this project indicates that the justification for retrofit based solely on a financial investment may be difficult to demonstrate for URM buildings in Melbourne.

As was also illustrated by the earlier York study, there are other considerations for the retrofit of URM buildings in the Melbourne CBD and in other older business districts in the city. If a rare earthquake occurred locally during a period of high public exposure there would be considerable loss of life. This research has shown that if a 5,000 year Return Period (RP) event (5.5 Mw) occurring on a business day approximately 100 people would die with close parallels to the 2011 Christchurch Earthquake outcome for masonry structures (42 fatalities). This may point to cheaper levels of retrofit with the objective of tying back elements that could cause casualties, rather than having the aim of avoiding economic loss.

Further, following a rare, but credible, earthquake high value heritage buildings would be lost. The research has shown that the willingness to pay by just the residents of the City of Melbourne LGA adds a notional 10\% of the total benefits of the mitigation program.

SUMMARY

The project has applied a range of retrofit measures for a suite of six URM building types developed as part of Project A9 to a very large population of URM building found in the Melbourne CBD. These measures have been demonstrated to reduce the physical vulnerability of each building. The project has also translated this vulnerability change into broader metrics that form an evidence base to inform decisions to retrofit.

The project has also demonstrated the benefit of retrofit through a virtual retrofit of a major city CBD. These benefits include reduced post event logistics for emergency management and the local government, reducing financial losses to building owners, businesses, and reducing injuries and fatalities. It has also demonstrated that retrofit reduces the long term financial cost of earthquake hazard, thereby making risk transfer through insurance uptake more affordable. Finally, it has demonstrated how valuable heritage structures can be progressively preserved for the future by protecting them from future credible earthquakes.

}, keywords = {buildings, earthquake, Melbourne, mitigation, risk, strategy}, issn = {707}, author = {Hyeuk Ryu and Martin Wehner and Jaroslav Vaculik and Valdis Juskevics and Mark Edwards and Michael Griffith and Itismita Mohanty and Stuart Butt and Neil Corby and Trevor Allen and Robert Hewison} } @article {bnh-7952, title = {Cost-effective mitigation strategy development for building related earthquake risk - final project report}, number = {657}, year = {2021}, month = {04/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

This final report contains a summary of the research undertaken by the research team from four partner institutions towards the development of an evidence base to inform decision making on the mitigation of the seismic risk posed by the most vulnerable Australian buildings subject to earthquakes.\  Without this evidence base, it is impossible to make cost-effective and economically justifiable decisions by building owners and government officials on all matters concerning seismic strengthening of existing and design of new buildings.\  While the focus of this project is on buildings, many of the project outputs will also be relevant for other Australian infrastructure such as bridges, roads and ports, while at the same time complementing other {\textquoteleft}Natural Hazards{\textquoteright} CRC project proposals for severe wind and flood.\ 

In order to achieve the overall project aim, work was undertaken on three complementary fronts to:

  1. Understand the seismic vulnerabilities of existing unreinforced masonry (URM) and limited ductile reinforced concrete (LDRC) buildings and methods to address them through seismic retrofit;
  2. Risk assessment of the building stock through development of an economic loss model with trial evaluations for a regional town (York, WA) and a metropolitan area (Melbourne); and
  3. Advance an end-user focused research utilisation project in the area of community risk reduction. This is done through an Earthquake Mitigation Case Study for the historic town of York in Western Australia.

The first of the above components was researched in the Universities of Adelaide, Melbourne, and Swinburne. This work included investigations of existing building seismic capacities and development of building specific retrofit techniques. The second area was studied by Geoscience Australia and the work includes estimating direct and indirect losses associated with building damage and benefits from seismic retrofit.\  The delivery date for the Melbourne CBD trial evaluation was delayed due to Covid-19 impacts but the revised delivery date of March 2021 has been agreed by the CRC. The last component was conducted utilizing the research findings in the two other areas in collaboration with the Western Australia Department of Fire and Emergency Services, York Shire Council and its residents.

Finally, using the new damage loss models and costings for seismically retrofitting buildings, recommendations are made for the development of seismic retrofit guidelines and policy based on the strong evidence base being developed by this CRC project team.

As a consequence, the project has been extremely successful with several end-users implementing the research outputs.\  York Shire Council has embarked on seismic retrofit of up to three buildings in the Shire as demonstrations to other building owners of the cost-effectiveness as well as helping to develop the local expertise amongst the building profession to implement these simple seismic strengthening techniques.\  The project has also resulted in a follow-on project in Western Australia to expand the building typologies from York to include three additional typologies that are common in the rest of WA.\  The retrofit strategies for all nine typologies will be made publically available through web sites.

}, keywords = {buildings, cost-effective, earthquake, mitigation, risk, strategy}, issn = {657}, author = {Michael Griffith} } @article {bnh-8130, title = {Cost-effective mitigation strategy development for flood prone buildings {\textendash} final project report}, number = {691}, year = {2021}, month = {07/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

The motivation for this project arises from the experience and observations made during the 2011 and 2013 floods in Australia, which caused widespread devastation in Queensland. Considerable costs were sustained by all levels of government and property owners to effect damage repair and enable community recovery.

A fundamental reason for this damage was inappropriate development in floodplains and a legacy of high risk building stock in flood prone areas. While the vulnerability and associated flood risk for newer construction is being addressed (moderated) by new standards (ABCB, 2012), building controls and land use planning, the vulnerability associated with existing building stock remains. This vulnerability contributes disproportionally to overall flood risk in many Australian catchments.

The Bushfire and Natural Hazards Collaborative Research Centre (CRC) project entitled Cost-effective mitigation strategy development for flood prone buildings addresses this issue and is targeted at assessing mitigation strategies to reduce the vulnerability of existing residential building stock in Australian floodplains. The project addresses the need for an evidence base to inform decision making on the mitigation of the flood risk posed by the most vulnerable Australian houses and complements parallel CRC projects for earthquake and severe wind.

The project has developed a building classification schema to categorise Australian residential buildings into a range of typical storey types. Mitigation strategies developed nationally and internationally have been reviewed. A floodproofing matrix has been developed to assess appropriate strategies for the selected storey types. All appropriate strategies have been costed for the selected storey types through the engagement of quantity surveying specialists. Vulnerability curves have been developed featuring reduced losses achieved through appropriate mitigation strategies for the five selected storey types.

Furthermore, selected building materials/systems have been tested to ascertain their resilience to floodwater exposure. These tests were aimed at addressing knowledge gaps in the areas of strength and durability of building materials during immersion.

A research utilisation project with NFRAG, AIDR and FMA as key stakeholders commenced in 2018. The project has developed generalised vulnerability functions for use by floodplain managers who may not have detailed exposure information.

In concluding the project, cost benefit analyses of mitigation options were conducted at three levels of resolution. These have added to cost versus benefit work already completed by the project team for Launceston as a utilisation project. The results are an evidence base to inform decision making by government and property owners on the mitigation of flood risk by providing information on the cost effectiveness of different mitigation strategies.

This report describes the research methods, project activities, outcomes and their potential for utilisation.

}, keywords = {buildings, Flood, mitigation, strategy}, issn = {691}, author = {Dale, K and Maqsood, T and Martin Wehner} } @article {bnh-7378, title = {Cost-effective mitigation strategy development for building related earthquake risk: annual report 2019-2020}, number = {614}, year = {2020}, month = {09/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

This annual report contains a summary of research undertaken by 4 partner institutions towards the development of cost-effective seismic retrofit methods for vulnerable Australian buildings in the 12-month period from July 2019 through June 2020.

Progress has been made in 4 complementary fronts to:

  1. understand the seismic vulnerabilities of existing unreinforced masonry (URM) and limited ductile reinforced concrete (LDRC) buildings and methods to address them through seismic retrofit
  2. risk assessment of the building stock through development of an economic loss model
  3. advance an end-user focused research utilization project in the area of community risk reduction. This is done through an Earthquake Mitigation Case Study of the historic town of York in Western Australia
  4. commencement of an End-User Utilisation Project with York Shire Council and the WA Department of Fire and Emergency Services through a Natural Disaster Resilience Program funded grant.

The first of the above components is being researched in the Universities of Adelaide, Melbourne, and Swinburne. This work includes investigation of existing building seismic capacities and development of retrofit techniques. The second area is being studied by Geoscience and the work includes estimating direct and indirect losses associated with building damage and benefits from seismic retrofit. The third component is being conducted utilizing the research findings in the two other areas in collaboration with the Western Australia Department of Fire and Emergency Services, York Shire Council and its residents. The last component only started at the end of 2019 but is extremely exciting. To date, the project team has identified several URM buildings in the York Shire to act as {\textquoteleft}exemplars{\textquoteright} for seismic retrofit. The first of these, the York Residency Museum building, has been seismically assessed, retrofit solutions recommended, local consultants (engineering and building contractors) have submitted a report and estimated costings for the rehabilitation work and Council is now in discussions with the contractor.

Finally, using the new damage loss models and costings for seismically retrofitting buildings, recommendations are made for the development of seismic retrofit guidelines and policy based on the strong evidence base being developed by this CRC project team.

}, keywords = {building, earthquake, mitigation, risk, strategy}, issn = {614}, author = {Michael Griffith} } @mastersthesis {bnh-8090, title = {Wildfire suppression {\textendash} an international analysis of operations, strategy and firefighter safety}, volume = {Doctor of Philosophy}, year = {2020}, month = {10/2020}, pages = {430}, school = {Edith Cowan University}, abstract = {

Wildfire suppression remains an inherently dangerous yet increasingly frequent task for fire services throughout Australia and the world. Each year firefighters from career and volunteer agencies respond to wildfires that impact the urban interface. When such an event occurs during a period of intense fire behaviour the conditions are often incompatible with life for persons either caught in the open or those seeking refuge in a vehicle. In order to improve firefighter safety and operational effectiveness at the rural urban interface (RUI) during landscape scale wildfires, this dissertation serves to examine critical components of wildfire response, most notably wildfire suppression strategies and tactics applied during a landscape scale wildfire event and the procedures and protective systems utilised in the event of firefighter entrapment and burnover.

The theme of the research is firefighter safety and suppression effectiveness during mega-wildfire response at the rural urban interface (RUI), also known as the wildland urban interface (WUI). Mega-wildfires are those landscape wildfires that overwhelm firefighting resources, typically generate their own localized weather systems, and require campaign style efforts lasting extended durations. Wildfire events including Margaret River (2011), and Yarloop (2016) in Western Australia, the devastating Californian and Greece wildfires (2018) and the unprecedented wildfires throughout eastern Australia in late 2019 / early 2020 meet this category. The RUI is the land where towns and cities exist alongside forest and other vegetation that supports the development of an established headfire with a quasi-steady rate of spread (RoS) across the landscape. In such instances, firefighters are called on to protect vulnerable communities and critical infrastructure from the ember storms, radiant heat and flames that accompany the head fire. In doing so, firefighters face great personal peril. If the incorrect suppression tactics or strategies are applied, or if wildfire behaviour suddenly changes, firefighter entrapment and burnover resulting in significant injury or fatality remains an all too common consequence.

The studies not only quantify the severity of the conditions firefighters encounter when attempting to protect life, property and the environment at the RUI, but also find traditional wildfire suppression strategies and tactics at the RUI need to be reexamined. Whilst the field of wildfire engineering is in its infancy, the studies suggest its development and adoption into wildfire suppression operations has the potential to improve both operational effectiveness and firefighter safety.

}, keywords = {analysis, firefighter, international, operations, safety, strategy, suppression, Wildfire}, url = {https://ro.ecu.edu.au/theses/2349/}, author = {Greg Penney} }