Impact on loss/risk assessments of inter-model variability in vulnerability analysis

Fragility curves (FCs) constitute an emerging tool for the seismic risk assessment of all elements at risk. They express the probability of a structure being damaged beyond a specific damage state for a given seismic input motion parameter, incorporating the most important sources of uncertainties, that is, seismic demand, capacity and definition of damage states. Nevertheless, the implementation of FCs in loss/risk assessments introduces other important sources of uncertainty, related to the usually limited knowledge about the elements at risk (e.g., inventory, typology). In this paper, within a Bayesian framework, it is developed a general methodology to combine into a single model (Bayesian combined model, BCM) the information provided by multiple FC models, weighting them according to their credibility/ applicability, and independent past data. This combination enables to efficiently capture inter-model variability (IMV) and to propagate it into risk/loss assessments, allowing the treatment of a large spectrum of vulnerability-related uncertainties, usually neglected. As case study, FCs for shallow tunnels in alluvial deposits, when subjected to transversal seismic loading, are developed with two conventional procedures, based on a quasi-static numerical approach. Noteworthy, loss/risk assessments resulting from such conventional methods show significant unexpected differences. Conventional fragilities are then combined in a Bayesian framework, in which also probability values are treated as random variables, characterized by their probability density functions. The results show that BCM efficiently projects the whole variability of input models into risk/loss estimations. This demonstrates that BCM is a suitable framework to treat IMV in vulnerability assessments, in a straightforward and explicit manner

Restoration models of flood resilient bridges: survey data

© 2021 The Athor(s). The purpose of this survey is to define the restoration tasks after hydraulic-induced damage and/or loss of functionality of bridges. This includes the duration and sequence of restoration tasks, idle times, cost, and traffic/functionality loss for specified damage levels of given bridge components. The potential use of this data is the generation of sets of restoration and reinstatements functions for quantifying the resilience of bridges exposed to hydraulic hazards, i.e. scour, debris accumulation and hydraulic forces (Mitoulis et al. 2021). The data are expected to inform boroughs, county councils, road and rail owners and stakeholders by providing valuable information for managing efficiently their assets prior to and after catastrophic events on the basis of resilience. The survey was based on a questionnaire answered by experts on bridge and infrastructure engineering.European Commission H2020-Marie Skłodowska-Curie Research Grants Scheme MSCA-IF-2016 (grant agreement No 746298: TRANSRISK-Vulnerability and risk assessment of transportation systems of assets exposed to geo-hazards)

Sustainability and climate resilience metrics and trade-offs in transport infrastructure asset recovery

Copyright © 2023 The Author(s). Climate change exacerbates natural hazards and continuously challenges the performance of critical infrastructure. Thus, climate resilience and sustainable adaptation of infrastructure are of paramount importance. This paper puts forward a novel framework and metrics for optimising sustainability (Greenhouse Gas emissions - GHG), climate resilience (restoration time), and cost. The framework aims to facilitate decision-making by operators and stakeholders and communicate actionable trade-offs between these principles. It describes approaches for quantifying ex-ante adaptation and ex-post recovery from the lenses of sustainability and resilience using relevant metrics. This paper concludes with an application of the framework on a bridge, where normalised metrics are integrated into one unique index (ISRC), which can be used in the recovery prioritisation for portfolios of similar assets. The optimisation program includes a bridge recovery, while reducing GHG emissions. The impact of climate change on the sustainability and resilience indexes is examined and the results show how the optimum solutions are adversely affected by different climate projections. In all scenarios examined, more sustainable solutions leading to reduced GHG emissions (tCO2e) are the optimum solutions when weighing resilience and cost. Based on the case study analysed in this paper, the low carbon restoration strategy resulted in up to 50% higher ISRC, which can justify investments for low GHG adaptation strategies in transport assets.The authors received funding by the UK Research and Innovation (UKRI) under the UK government’s Horizon Europe funding guarantee [grant agreement No: 101086413, EP/Y003586/1, EP/Y00986X/1, EP/X037665/1]. This is the funding guarantee for the European Union HORIZON-MSCA-2021-SE-01 [grant agreement No: 101086413] ReCharged - Climate-aware Resilience for Sustainable Critical and interdependent Infrastructure Systems enhanced by emerging Digital Technologies. The first author would also like to acknowledge funding by the UK Research and Innovation (UKRI) under the UK government’s Horizon Europe funding guarantee [grant agreement No: 10062091]. This is the funding guarantee for the European Union HORIZON-MISS-2021-CLIMA-02 [grant agreement No: 101093939] RISKADAPT - Asset-level modelling of risks in the face of climate-induced extreme events and adaptation

Systemic seismic vulnerability and risk assessment of urban infrastructure and utility systems

The seismic vulnerability and risk assessment of infrastructure and utility systems are essential to prevent or mitigate sufficiently the negative consequences, implement resilience management strategies, and recover efficiently after a major earthquake. In a complex urban environment, having multiple interacting and interdependent infrastructures becomes even more important. Earthquake hazards not only affect a single asset, but also their impact is much greater because of the inter- and intra-dependences among various infrastructure, utility systems, and lifelines. Therefore, we urgently need efficient tools to quantify and assess the systemic vulnerability and risk of urban infrastructure and utility systems. This is a challenging topic that is nowadays receiving more attention from the research community, the industry domain, and the policymakers. This paper aims to review the available modelling approaches and tools for the seismic risk analysis of interconnected systems, including advantages and limitations. It focuses in particular on the European funded SYNER-G project that encompasses interdependencies, delivers a holistic methodology, and implements a comprehensive framework based on the Object-Oriented Modelling paradigm. The capacities of the SYNER-G framework are illustrated through a selected application regarding the seismic risk analysis of interconnected infrastructure and utility systems in the city of Thessaloniki, Greece. Among other aspects, the paper discusses hazard modelling issues of the two common approaches, the probabilistic and the scenario-based procedure and illustrates in a specific example the impact of mitigation strategies, based on their effect on the performance of the interconnected systems and the overall loss reduction. The integration of interdependencies into the risk analysis and resilience strategies facilitates a better understanding of critical infrastructure operation and enables well-informed proactive and reactive decision-making and efficient disaster risk management, by infrastructure owners and operators, insurance companies, consulting agencies, and local authorities.The present work has been done in the framework of grant agreement No. 813137 funded by the European Commission ITN-Marie Sklodowska-Curie URBASIS-EU project. Also, we would like to acknowledge all the contributors to the SYNER-G project that was funded from the European Community’s 7th Framework Program under grant No. 244061

Multi-hazard fragility assessment of bridges: Methodology and case study application

Reliability of road systems and their critical components exposed to multiple natural hazards is on the frontline of engineering research during the last three decades since potential damage of infrastructure is strongly related to important direct and indirect economic losses. In this context, the research project INFRARES (www.infrares.gr) aims at delivering a comprehensive methodology towards a more efficient risk and resilience assessment of roadway networks in Greece subjected to various natural hazards. In this context, an analytical framework for the fragility assessment of bridges subjected to independent and/or multiple subsequent natural hazards, is proposed herein and applied to a case study bridge. The proposed methodology includes the estimation of seismic and flood fragility and the development of multihazard fragility curves. The proposed approach considers multiple structural components for the development of fragility curves, which are generated based on case-specific estimation of limit state thresholds accounting for multiple failure modes and SSI effects. A probabilistic framework is introduced to account for the uncertainties in the demand and capacity in case of single hazards, which is then extended for multiple -separate and/or subsequent- hazards, highlighting the effect of cumulative damage on the fragility assessment. The proposed methodology is applied to a case study bridge in Greece, considering multiple hazards, separate in time (i.e. two subsequent flood events). The results in terms of flood fragility curves are discussed with a view to evaluate the effect of damage accumulation in multiple hazard analysis; the probability of damage was found to drastically increase for all limit states considered

Recent Advances in Seismic Vulnerability Assessment of Tunnels and Underground Structures

Tunnels and underground structures are constructed at an increasing rate in seismic prone areas to facilitate expanding transportation needs. The importance of these types of structures in modern societies, as well as the significant downtimes associated with seismically induced damage on them, led to an increasing interest of the scientific community and practitioners on the vulnerability assessment of this infrastructure against seismic hazard. Various methodologies have been recently proposed to estimate the vulnerability of bored tunnels in rock or alluvial and cut and cover or underground structures, e.g., subways, in alluvial, against ground seismic shaking and earthquake induced ground failures. This paper discusses critical aspects of these methodologies, based on a thorough review of relevant state-of-the art, carried out in the frame of research project INFRARES (www.infrares.gr). Emphasis is placed on the numerical tools employed to estimate analytically the fragility of examined structures in relevant studies, the constitutive models used to simulate the seismic response of ground and structures, the determination of the capacity of examined structures, the selection of appropriate seismic intensity measures, methods used to develop rational probabilistic seismic demand models, the estimation of uncertainties related to seismic vulnerability of underground structures, as well as the methods for selecting fragility functions from existing ones in assessment studies of actual case studies. Through the discussion, acknowledged gaps in the literature are highlighted and topics calling for further investigation are presented. In addition, an up-to-date database of available fragility functions for tunnels and underground structures developed within INFRARES is presented

On the effects of salient parameters for an efficient probabilistic seismic loss assessment of tunnels in alluvial soils

Copyright © 2022 The Author(s). Tunnels are critical infrastructure for the sustainable development of urban areas worldwide, especially for modern metropolises. This study investigates the effects of salient parameters, such as the soil conditions, tunnel burial depth, tunnel construction quality, and aging phenomena of the lining, on the direct seismic losses of circular tunnels in alluvial deposits when exposed to ground seismic shaking. For this purpose, a practical approach is employed to probabilistically assess the direct losses of single tunnel segment with unit length, as well as of tunnel elements representative of the Shanghai Metro Lines 1 and 10, assuming various levels of seismic intensity. The findings of this study can serve as the basis for decision-making, seismic loss, and risk management based on the principles of infrastructure resilience.National Natural Science Foundation of China (Grants No. 52108381, 51978517, 52090082); National Key R&D Program (Grant No. 2021YFF0502200); China Postdoctoral Science Foundation (Grants No. 2022T150484, 2021M702491)

A probabilistic approach to evaluate the seismic loss of metro tunnels in Shanghai City

Copyright © 2023 The Author(s). Tunnels are crucial lifeline components in the mega cities. This work studies the direct seismic cost of metro tunnels subjected to earthquake events. The degree of tunnel damage and the corresponding direct seismic loss is derived considering various tunnel burial depths. The developed framework is then applied in the metro tunnels located in Shanghai city, China. Specifically, the direct seismic loss of one tunnel ring and the whole Metro Line 10 under different hazard scenario is estimated. Results highlight the significant function of tunnel buried depths towards more efficient seismic loss assessment. The findings of this study constitute useful elements in seismic loss management in terms of lifeline resilience.National Natural Science Foundation of China (Grant No. 52108381, 52090082), Shanghai Science and Technology Committee Program (Grant No. 21DZ1200601, 20DZ1201404), and China Postdoctoral Science Foundation (Grant No. 2022T150484, 2021M702491

Conflict-resilience framework for critical infrastructure peacebuilding

Apart from security issues, war-torn societies and countries face immense challenges in rebuilding damaged critical infrastructure. Existing post-conflict recovery frameworks mainly focus on social impacts and mitigation. Also, existing frameworks for resilience to natural hazards are mainly based on design and intervention, yet, they are not fit for post-conflict infrastructure recovery for a number of reasons explained in this paper. Post-conflict peacebuilding can be enhanced when resilience by assessment (RBA) is employed, using standoff observations that include data from disparate remote-sensing sources, e.g. public satellite imagery, forensics and crowdsourcing, collected during the conflict. This paper discusses why conflicts and warfare require a new framework for achieving post-conflict infrastructure resilience. It then introduces a novel post-conflict framework that includes different scales of resilience with a focus on asset and regional resilience. It considers different levels of knowledge, with a focus on standoff observations and data-driven assessments to facilitate prioritisation during reconstruction. The framework is then applied to the transport network of the area west of Kyiv, Ukraine to demonstrate how resilience by assessment can support decision-makers, such as governments and multilateral financial institutions, to address infrastructure needs and accelerate financial and humanitarian assistance, absorb shocks and maximise infrastructure recovery after conflict

Indirect structural health monitoring (iSHM) of transport infrastructure in the digital age

Workshop reportCopyright © Joint Research Centre (European Commission). The existing European motorway infrastructure network is prone to ageing and subject to natural events (e.g. climate change) and hazards (e.g. earthquakes), necessitating immediate actions for its maintenance and safety. Within this context, the structural health monitoring (SHM) framework allows a quantitative assessment of the structural integrity, serviceability and performance, facilitating better-informed decisions for the management of the existing infrastructure. The European Commission Joint Research Centre (JRC) established the exploratory research project MITICA (Monitoring Transport Infrastructures with Connected and Automated vehicles) to investigate the opportunity to use novel methods for infrastructure motoring, aiming at the efficient maintenance of the European aging road infrastructure. This report summarizes the discussion and the outcomes of a workshop held at the JRC in Ispra (Italy) on June 6-7 2022, as part of the MITICA project. Considering the EU priority “A Europe fit for the digital age”, the workshop was dedicated to SHM and its application to civil infrastructure, focusing on innovative indirect structural health monitoring (iSHM) approaches that rely on the vehicle-bridge interaction and the deployment of sensor-equipped vehicles for the monitoring of the existing bridge infrastructure. The report aims to become a reference document in the area of iSHM using passing vehicles, for both scholars and policy makers