@article {bnh-8016, title = {Enhancing resilience of critical road structures: bridges, culvers and floodways under natural hazards {\textendash} final project report}, number = {671}, year = {2021}, month = {05/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Bridges, culverts and floodways are lifeline road structures and part of road networks, which have a significant role in ensuring resilience of a community before, during and after a natural disaster. Historical data demonstrates that the failure of road structures can have catastrophic consequences on a community affected by disaster due to the impact on evacuation and post disaster recovery.\  The main objective of the project is to understand the vulnerability of critical road structures: bridges, culverts and floodways under natural hazards of flood, bush fire and earthquakes. Once the level of vulnerability is established, the evaluation of importance of the structures for prioritization for hardening is important for decision making by road authorities.

The project funded by the BNH CRC addressed the above gap in knowledge through a comprehensive research program undertaken in collaboration with three research partners and six end user partners. In the first stage of the project, major failure scenarios and the consequences of failure were identified as a precursor for a focused research program on vulnerability modelling and prioritization of road structures under natural hazards. The research conducted included assessment of vulnerability of road bridges under flood, bush fire and earthquakes and floodways and culverts under flood. Further, three approaches were used to identify the consequences of failure of road structures under natural hazards: economic impact on the closure of structures on the community, prioritization of structures using analytical techniques and post disaster social, economic and environmental impacts of failure of road structures.

Major findings of the research include identification of the levels of hazard exposure which could lead to failure of structures and the other parameters affecting failure. Further, methods of modeling road structures under different loading regimes has been developed with case studies of typical structures. New design approaches for building back better have been proposed for floodway structures based on parametric analysis of typical types of floodways.

Major findings of the analysis of bridges under flood loading include (a) the current design process in the design standards for log and object impact are unconservative and rigorous analysis is recommended (b) when the flood velocity is over 4 m/s and the flood level reaches the soffit of the bridge deck, the failure probability of the bridge decks are very high. (c) particle size near the bridge pier foundations have a significant impact on the scour of bridge piers and placement of irregular shaped crushed rock at river-bed level can reduce the scour failure. Research conducted on impact of bush fires on composite structures indicated that the shear failure of the web of the girders is the major failure mode. Under earthquake loading, a major finding is that in the areas where peak ground acceleration is over 0.08g, girder bridges could have a high failure probability and a risk mitigation strategy is essential.

Three different tools are developed for determining the impact of failure of road structures considering economic as well as social, environmental and economic impacts.

A major utilisation outcome of the project is a resilient floodway design guide, published in collaboration with the Institution of Public Works Engineers Australia (Qld) (IPWEAQ). A utilisation project is currently in progress jointly funded by the IPWEAQ and BNH CRC. The guide has been reviewed by the IPWEAQ and is currently being revised by the researchers to enable uptake by local council Engineers. An asset management and vulnerability modeling tool for bridges has been developed for the DoT Victoria (formerly known as VicRoads) where the bridges prone to significant damage are highlighted in a GIS map of the road network.

There are two different models developed to evaluate the consequences of the failure of road structures: first considering economic impact of detour required and a second model capturing post disaster social environmental and economic impact of failure of road structures. The first tool has been incorporated into the vulnerability modeling GIS platform developed for \ the DoT, Victoria.

In addition to the above deliverables in the BNH CRC project, two subsidiary projects were undertaken to understand the effect of cyclonic events on bridge structures and also resilience of timber bridges under natural disasters.

The research team is working with the end users to socialize the vulnerability modeling and decision-making tools developed to enable optimized decision making to enhance resilience of road structures under natural hazards. This is currently being continued with direct funding from the DoT, Victoria.

}, keywords = {Bridge, critical, culvert, enhancing, Floodway, Natural hazards, resilience, road, structure}, issn = {671}, author = {Sujeeva Setunge and Priyan Mendis and Karu Karunasena and Kevin Zhang and Dilanthi Amaratunga and Weena Lokuge and Nilupa Herath and Long Shi and Hessam Mohseni and Huu Tran and Kanishka Atapattu} } @article {bnh-7907, title = {High-Resolution Estimates of Fire Severity - An Evaluation of UAS Image and LiDAR Mapping Approaches on a Sedgeland Forest Boundary in Tasmania, Australia }, journal = {Fire}, volume = {4}, year = {2021}, month = {03/2021}, chapter = {14}, abstract = {

With an increase in the frequency and severity of wildfires across the globe and resultant changes to long-established fire regimes, the mapping of fire severity is a vital part of monitoring ecosystem resilience and recovery. The emergence of unoccupied aircraft systems (UAS) and compact sensors (RGB and LiDAR) provide new opportunities to map fire severity. This paper conducts a comparison of metrics derived from UAS Light Detecting and Ranging (LiDAR) point clouds and UAS image based products to classify fire severity. A workflow which derives novel metrics describing vegetation structure and fire severity from UAS remote sensing data is developed that fully utilises the vegetation information available in both data sources. UAS imagery and LiDAR data were captured pre- and post-fire over a 300 m by 300 m study area in Tasmania, Australia. The study area featured a vegetation gradient from sedgeland vegetation (e.g., button grass 0.2m) to forest (e.g., Eucalyptus obliqua and Eucalyptus globulus 50m). To classify the vegetation and fire severity, a comprehensive set of variables describing structural, textural and spectral characteristics were gathered using UAS images and UAS LiDAR datasets. A recursive feature elimination process was used to highlight the subsets of variables to be included in random forest classifiers. The classifier was then used to map vegetation and severity across the study area. The results indicate that UAS LiDAR provided similar overall accuracy to UAS image and combined (UAS LiDAR and UAS image predictor values) data streams to classify vegetation (UAS image: 80.6\%; UAS LiDAR: 78.9\%; and Combined: 83.1\%) and severity in areas of forest (UAS image: 76.6\%, UAS LiDAR: 74.5\%; and Combined: 78.5\%) and areas of sedgeland (UAS image: 72.4\%; UAS LiDAR: 75.2\%; and Combined: 76.6\%). These results indicate that UAS SfM and LiDAR point clouds can be used to assess fire severity at very high spatial resolutio

}, keywords = {3D remote sensing, drone, fire severity, fuel structure, Lidar, photogrammetry, RPAS, structure, UAS, vegetation}, doi = {https://doi.org/10.3390/fire4010014}, url = {https://www.mdpi.com/2571-6255/4/1/14/htm}, author = {Samuel Hillman and Bryan Hally and Luke Wallace and Darren Turner and Arko Lucieer and Karin Reinke and Simon Jones} } @article {bnh-5620, title = {Analysis of design standards and applied loads on road structures under extreme events}, number = {480}, year = {2019}, month = {06/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

This is the fourth report for the Bushfire and Natural Hazards CRC project B8, entitled {\textquoteleft}Enhancing the Resilience of Critical Road Infrastructure: bridges, culverts and flood-ways under natural hazards{\textquoteright}. The work presented here addresses milestone 3.2.2 {\textquotedblleft}Analysis of design standards completed{\textquotedblright} and 3.2.3 {\textquotedblleft}Draft report 4{\textendash} Loads applied on structures under extreme events (flood, earthquake, fire){\textquotedblright}, which are due on 30 December 2015. Thus, this draft report will be reviewed and refined through the input of the external stakeholders, in particular Queensland Department of Transport and Main Roads (DTMR), VicRoads, RMS (NSW) and the Lockyer Valley Regional Council (LVRC).
The following draft report presents an analysis of relevant design codes in regards to bridges, culverts and flood-ways design considerations under natural hazards (earthquake, flood and bushfire). Although effort has been made to include major design codes, the main focus of the practice code analysis has been Australian codes, major American codes and European codes. Section 5 also discusses the strengthening methods for reinforced concrete members under natural hazards.

}, keywords = {applied loads, engineering, extreme weather, resilience, structure}, issn = {480}, author = {Sujeeva Setunge and Chun Qing Li and Darryn McEvoy and Kevin Zhang and Jane Mullett and Hessam Mohseni and Priyan Mendis and Tuan Ngo and Nilupa Herath and Karu Karunasena and Weena Lokuge and Buddhi Wahalathantri and Dilanthi Amaratunga} } @conference {bnh-6406, title = {Simulations of radiation heat flux on a structure from a fire in an idealised shrubland }, booktitle = {Bushfire and Natural Hazards CRC Research Day AFAC19}, year = {2019}, month = {12/2019}, address = {Melbourne}, abstract = {

Wildland-urban interface areas are growing rapidly. Building standards are required to ensure that the structures built in fire prone areas are resilient to fire. Australian Standard AS 3959 was developed to prescribe construction requirements for houses in bushfire prone areas. The model in AS 3959 is applied to estimate the Bushfire Attack Level (BAL) that is expected on a structure during the nominally worst-case bushfire scenario that the house can experience. Once the BAL is based on the fuel and terrain near the structure, and determines the construction requirements for the structure. AS 3959 is based upon a view-factor model of radiant heat flux, which estimates the level of heat flux expected at the structure.

}, keywords = {building standards, Fire, heat flux, structure, Wildland-urban interface}, url = {https://knowledge.aidr.org.au/resources/australian-journal-of-emergency-management-monograph-series/}, author = {Khalid Moinuddin and Duncan Sutherland} }