Sotiris Argyroudis

Dr Sotirios Argyroudis


Research

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Research projects

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My publications

Publications

Dimitra V. Achillopoulou, Stergios A. Mitoulis, Sotirios A. Argyroudis, Ying Wang (2020)Monitoring of transport infrastructure exposed to multiple hazards: a roadmap for building resilience, In: Science of The Total Environment746141001 Elsevier

Monitoring-enhanced resilience in transport management is emerging together with the new technologies and digital data, however have not been fully explored yet. Digital technologies have the potential to provide rapid resilience assessments in a quantifiable and engineered manner for transport infrastructure, which is exposed to multiple natural and human-induced hazards and diverse loads throughout their life-cycle. Physical damage and disruption of networks and interdependent systems may cause tremendous socioeconomic impact, affecting world economies and societies. Nowadays, transport infrastructure stakeholders have shifted the requirements in risk and resilience assessment. The expectation is that risk is estimated efficiently, almost in real-time with high accuracy, aiming at maximising the functionality and minimising losses. Nevertheless, no integrated framework exists for quantifying resilience to diverse hazards, based on structural and functionality monitoring (SHFM) data, and this is the main capability gap that this paper envisages filling. Monitoring systems have been used widely in transport infrastructure and have been studied extensively in the literature. Data can facilitate prognosis of the asset condition and the functionality of the network, informing computer-based asset and traffic models, which can assist in defining actionable performance indicators, for diagnosis and for defining risk and loss expediently and accurately. Evidence exists that SHFM is an enabler of resilience. However, strategies are absent in support of monitoring-based resilience assessment in transport infrastructure management. In response to the above challenge, this paper puts forward for the first time in the international literature, a roadmap for monitoring-based quantification of resilience for transport infrastructure, based on a comprehensive review of the current state-of-the-art. It is a holistic asset management roadmap, which identifies the interactions among the design, monitoring, risk assessment and quantification of resilience to multiple hazards. Monitoring is embraced as a vital component, providing expedient feedback for recovery measures, accelerating decision-making for adaptation of changing ecosystems and built environments, utilising emerging technologies, to continuously deliver safer and resilient transport infrastructure.

Gregory McKenna, Sotirios A. Argyroudis, Mike G Winter, Stergios A. Mitoulis (2020)Multiple hazard fragility analysis for granular highway embankments: moisture ingress and scour, In: Transportation Geotechnics100431 Elsevier

Fragility functions express the probability that an asset exceeds some serviceability or limit state for a given level of environmental perturbation or other loadings, to which the asset is subjected. They are important components in the quantitative risk analysis of infrastructure exposed to natural hazards and they have typically been derived for structural assets. It is relatively difficult to derive fragility functions for geotechnical assets, such as highway or railway slopes and embankments, due to their inherent heterogeneity. In this paper, a generic granular highway embankment is modelled using the finite element method, considering various groundwater profiles and scour depths at the toe to quantify the deformation of the road surface. A probabilistic assessment of the magnitude of deformation and the groundwater level and scour depth is undertaken to derive fragility functions for the prediction of damage to assets exposed to these multiple hazards. The process of fragility function derivation is explained, uncertainty values are derived, and various regression methods are undertaken. This study is a first attempt to provide a basis for the prediction of slope deformation, and hence of damage, due to moisture ingress and scour, which can be aggravated by climate change. This can be used for the assessment of existing assets, and the design of new ones in the pursuit of more resilient transport networks, as well as for other assets such as levees, dams and other similar earthworks, with some limitations.

S.A. Argyroudis, D.V. Achillopoulou, V. Livina, S.A. Mitoulis (2021)Data-driven resilience assessment for transport infrastructure exposed to multiple hazards by integrating multiscale terrestrial and airborne monitoring systems, In: Proceedings of IABMAS 2020: 10th International conference on Bridge Maintenance, Safety and Management International Association for Bridge Maintenance and Safety

The exposure of critical transport infrastructure to natural hazards and climate change effects has severe consequences on world economies and societies and, thus, safety and resiliency of transport networks are of paramount importance. The currently available frameworks for quantitative risk and resiliencebased design and assessment have been mainly developed for bridges exposed to earthquakes. However, there is an absence of well-informed exposure, vulnerability, functionality and recovery models, which are the main components in the quantification of resilience. The present paper proposes an integrated framework for the data- driven resilience assessment of transport infrastructure exposed to multiple hazards by using multiscale monitoring data, such as terrestrial and airborne data, as well as open-access crowd data and environmental measurements. Monitoring and early warnings are expected to produce accurate and rapidly informed quantitative risk and resilience assessments for transport infrastructure and to enhance asset management. Therefore, this framework aims to facilitate stakeholders’ decision-making for daily and catastrophic events and to support adaptation and preparedness with preventive and/or retrofitting measures against multiple hazards.

Leung Fo Vincent Yuan, Sotirios A. Argyroudis, Enrico Tubaldi, Maria Pregnolato, Stergios A. Mitoulis (2019)Fragility of bridges exposed to multiple hazards and impact on transport network resilience, In: Proceedings of the 2019 Society for Earthquake and Civil Engineering Dynamics conference (SECED 2019) Society for Earthquake and Civil Engineering Dynamics (SECED)

Transportation infrastructure is a pylon for the society and economy, enabling the services and transportation of goods and people, under normal and emergency circumstances. Bridges act as bottlenecks within road and rail networks, since bridges are crunch points along the network system. Their failures due to multiple natural hazards (e.g. floods, earthquakes, tsunami or ground movements) may cause disproportionate losses, which are expected to be exacerbated due to climate change. Thus, pinpointing the vulnerabilities and quantifying bridge resilience within transportation networks is of paramount importance in the context of natural hazards. However, reliable quantification of risk and resilience of bridges is not yet available, as engineering judgment dominates quantitative assessments. This paper describes an integrated framework for the development of numerical fragility functions and the resilience assessment of bridges subjected to multiple hazards. The framework is applied to obtain the fragility of a representative bridge exposed to flood-induced scour followed by an earthquake. The resulting fragility functions are essential to evaluate direct losses due to multiple hazards, i.e. physical damage, as a means to deliver the Quantitative Risk Assessment (QRA) of the exposed bridges and networks. The framework is extended to the transport network level exposed to multiple hazards, providing a mean for allocating the resources reasonably toward efficient management and consequence analysis.

SA Argyroudis, G Nasiopoulos, N Mantadakis, SA Mitoulis (2020)Cost-based resilience assessment of bridges subjected to earthquakes, In: International Journal of Disaster Resilience in the Built Environment Emerald

Purpose Transport infrastructure resilience is of paramount importance for societies, therefore its quantification is urgently needed. A resilience assessment framework based on well-informed resilience indices is presented and applied for assessing the resilience of representative bridges exposed to earthquakes. Design/methodology/approach The framework quantifies the robustness of bridges against different seismic hazard scenarios, by utilising realistic fragility functions and the rapidity of the recovery and/or retrofitting after the occurrence of a certain degree of damage, based on realistic restoration functions. Findings Two different approaches for the modelling of the restoration tasks are examined. Both direct losses due to structural damage and indirect losses due to traffic disruption are estimated. Originality/value A new cost-based resilience index is introduced and alternative approaches for expressing the restoration strategies are examined and assessed. The results facilitate owners to enhance cost-based resilience management toward more resilient infrastructure.

Stergios A. Mitoulis, Sotirios A. Argyroudis, Rob Lamb (2019)Risk and resilience of bridgeworks exposed to hydraulic hazards, In: IABSE 2019 conference report International Association for Bridge and Structural Engineering (IABSE)

Transportation infrastructure is a pylon for the society and economy, enabling the services and transportation of goods, under normal and emergency circumstances. Bridgeworks act as bottlenecks within road and rail networks and their failures due to e.g. floods, cause disproportionate losses, which are expected to be exacerbated due to climate change. Thus, pinpointing the vulnerabilities and quantifying the resilience of bridges within transportation networks exposed to hydraulic hazards is of paramount importance. However, reliable quantification of risk and resilience of flood-critical bridges is not yet available, as there is a lot of engineering guesswork for qualitative assessments. This paper describes a new integrated framework for the resilience assessment of bridgeworks and networks subjected to hydraulic hazards such as scour, debris flow and hydraulic actions. An overview of the critical hydraulic hazards, and the evaluation of their intensity measures based on regional and site-specific approaches is provided in the paper. The framework also includes vulnerability models for bridges for the evaluation of direct losses, i.e. physical damage, as a means to deliver the quantitative risk assessment (QRA) of the exposed bridgeworks and networks. The second component of the resilience framework is the restoration and reinstatement models, which are expressed by practical restoration times and tasks. Toward this end, this paper summarises an on-going comprehensive survey, which aims to elicit knowledge from experts, in an effort to develop restoration models for bridges exposed to floods. The framework is a useful tool for allocating the resources reasonably toward efficient management and consequence analysis on a network level.

Sotirios Argyroudis, Stergios Mitoulis, Mike G. Winter, Amir M. Kaynia (2019)FRAGILITY OF CRITICAL TRANSPORTATION INFRASTRUCTURE SYSTEMS SUBJECTED TO GEO-HAZARDS, In: Proceedings 16th European Conference on Earthquake Engineering European Conference on Earthquake Engineering

his paper presents a review of the different methodologies developed for the fragility assessment of critical transportation infrastructure subjected to geotechnical and climatic hazards with emphasis placed on geotechnical effects. Existing information on fragility analysis is synthesized, along with its parameters and limitations with particular emphasis on the numerical modeling of transportation infrastructure subjected to geo-hazards. The definition of system of assets (SoA) is introduced and numerical fragility curves are developed for a representative SoA subjected to flooding and seismic excitations. The paper concludes with the opportunities for future developments of fragility analyses for systems of assets under multiple hazards considering mitigation measures and ageing effects.

S.A. Argyroudis, D.V. Achillopoulou, V. Livina, S.A. Mitoulis (2021)Data-driven resilience assessment for transport nfrastructure exposed to multiple hazards, In: Proceedings of the 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS2020) Taylor & Francis (CRC Press)

The exposure of critical transport infrastructure to natural hazards and climate change effects has severe consequences on world economies and societies and, thus, safety and resiliency of transport networks are of paramount importance. The currently available frameworks for quantitative risk and resiliencebased design and assessment have been mainly developed for bridges exposed to earthquakes. However, there is an absence of well-informed exposure, vulnerability, functionality and recovery models, which are the main components in the quantification of resilience. The present paper proposes an integrated framework for the data- driven resilience assessment of transport infrastructure exposed to multiple hazards by using multiscale monitoring data, such as terrestrial and airborne data, as well as open-access crowd data and environmental measurements. Monitoring and early warnings are expected to produce accurate and rapidly informed quantitative risk and resilience assessments for transport infrastructure and to enhance asset management. Therefore, this framework aims to facilitate stakeholders’ decision-making for daily and catastrophic events and to support adaptation and preparedness with preventive and/or retrofitting measures against multiple hazards.

Sotirios A. Argyroudis, Stergios Α. Mitoulis, Mike G. Winter, Amir M. Kaynia (2019)Fragility of transport assets exposed to multiple hazards: State-of-the-art review toward infrastructural resilience, In: Reliability Engineering & System Safety191106567pp. 1-22 Elsevier

Vulnerability is a fundamental component of risk and its understanding is important for characterising the reliability of infrastructure assets and systems and for mitigating risks. The vulnerability analysis of infrastructure exposed to natural hazards has become a key area of research due to the critical role that infrastructure plays for society and this topic has been the subject of significant advances from new data and insights following recent disasters. Transport systems, in particular, are highly vulnerable to natural hazards, and the physical damage of transport assets may cause significant disruption and socioeconomic impact. More importantly, infrastructure assets comprise Systems of Assets (SoA), i.e. a combination of interdependent assets exposed not to one, but to multiple hazards, depending on the environment within which these reside. Thus, it is of paramount importance for their reliability and safety to enable fragility analysis of SoA subjected to a sequence of hazards. In this context, and after understanding the absence of a relevant study, the aim of this paper is to review the recent advances on fragility assessment of critical transport infrastructure subject to diverse geotechnical and climatic hazards. The effects of these hazards on the main transport assets are summarised and common damage modes are described. Frequently in practice, individual fragility functions for each transport asset are employed as part of a quantitative risk analysis (QRA) of the infrastructure. A comprehensive review of the available fragility functions is provided for different hazards. Engineering advances in the development of numerical fragility functions for individual assets are discussed including soil-structure interaction, deterioration, and multiple hazard effects. The concept of SoA in diverse ecosystems is introduced, where infrastructure is classified based on (i) the road capacity and speed limits and (ii) the geomorphological and topographical conditions. A methodological framework for the development of numerical fragility functions of SoA under multiple hazards is proposed and demonstrated. The paper concludes by detailing the opportunities for future developments in the fragility analysis of transport SoA under multiple hazards, which is of paramount importance in decision-making processes around adaptation, mitigation, and recovery planning in respect of geotechnical and climatic hazards.

Sotirios Argyroudis, Stergios Mitoulis, Amir M. Kaynia, Mike G. Winter (2018)Fragility Assessment of Transportation Infrastructure Systems Subjected to Earthquakes, In: Geotechnical Earthquake Engineering and Soil Dynamics V: Numerical Modeling and Soil Structure Interactionpp. 174-183 American Society of Civil Engineers (ASCE)

This paper provides a review of the different methodologies for the fragility assessment of critical transportation infrastructure subjected to earthquake excitations with emphasis placed on geotechnical effects. Available approaches to fragility analysis are summarized, along with the main parameters and limitations. Additionally, definitions of damage are synthesized for the individual transportation assets and subsequently the definition of system of assets (SoA) is introduced. Numerical fragility curves are developed for a representative SoA subjected to seismic excitations. The paper concludes with the gaps in the area of fragility analysis and the needs for future development.

S Argyroudis, A Palaiochorinou, S Mitoulis, D Pitilakis (2016)Use of rubberised backfills for improving the seismic response of integral abutment bridges, In: Bulletin of Earthquake Engineering

Reuse of the 1.5 billion waste tyres that are produced annually is a one of the major worldwide challenges, as waste tyres are toxic and cause pollution to the environment. In recognition of this problem, this paper introduces the reuse of tyres, in the form of derived aggregates in mixtures with granulated soil materials, as previous studies indicated the potential benefits of these materials in the seismic performance of structures. The objective of the present research study is to investigate whether use of rubberised backfills benefits the seismic response of Integral Abutment Bridges (IABs) by enhancing soil-structure interaction (SSI) effects. Numerical models including typical integral abutments on surface foundation with nonlinear conventional backfill material and its alternative form as soil-rubber mixtures are analysed and their response parameters are compared. The research is conducted on the basis of parametric analysis, which aims to evaluate the influence of different rubber-soil mixtures on the dynamic response of the abutment-backfill system under various seismic excitations, accounting for dynamic soil-abutment interaction. The results provide evidence that the use of rubberised backfill leads to reductions in the backfill settlements, the horizontal displacements of the bridge deck, the residual horizontal displacements of the top of the abutment and the pressures acting on the abutment, up to 55%, 18%, 43% and 47% respectively, with respect to a conventional backfill comprising of clean sand. Considerable amount of decrease in bending moments and shear forces on the abutment wall is also observed. Therefore, rubberised backfills offer promising solution to mitigate the earthquake risk, towards economic design with minimal damage objectives for the resilience of transportation networks.

S Argyroudis, L. Hofer, M.A. Zanini, S. A. Mitoulis (2019)Resilience of critical infrastructure for multiple hazards: Case study on a highway bridge, In: ICONHIC Proceedings National Technical University of Athens

The exposure of critical infrastructure to natural hazards was proven to have severe consequences on world economies and societies. Therefore, resilience assessment of an infrastructure asset to extreme events and sequences of diverse hazards is of paramount importance for maintaining their functionality. However, the resilience assessment commonly assumes single hazards and one restoration strategy. In addition, owners and operators have different approaches for restoring their assets, depending on different factors, such as the available resources and their priorities, the importance of the asset and the level of damage. Yet, currently no integrated framework that accounts for the different strategies of restoration, and hence quantification of resilience in that respect exists. This paper proposes an integrated framework for the quantitative risk and resilience assessment of critical infrastructure, subjected to multiple natural hazards, considering the factors that reflect redundancy and resourcefulness in infrastructure, i.e., (i) the robustness to hazard actions, based on realistic fragility curves, and (ii) the rapidity of the recovery after the occurrence of damages, based on realistic restoration functions. Lastly, the paper includes an application of the proposed framework for a typical highway bridge for realistic multiple hazard scenarios and restoration strategies using a wellinformed resilience index.

Stergios Mitoulis, A Palaiochorinou, I Georgiadis, S Argyroudis (2016)Extending the application of integral frame abutment bridges in earthquake prone areas by using novel isolators of recycled materials, In: Earthquake Engineering and Structural Dynamics45(14)pp. 2283-2301 Wiley

Integral Abutment Bridges (IABs) are jointless structures without bearings or expansion joints, which require minimum or zero maintenance. The barrier to the application of longspan IABs is the interaction of the abutment with the backfill soil during the thermal expansion and contraction of the bridge deck, i.e. serviceability, or when the bridge is subjected to dynamic loads, such as earthquakes. The interaction of the bridge with the backfill leads to settlements and ratcheting of the soil behind the abutment and, as a result, the soil pressures acting on the abutment build-up in the long-term. This paper provides a solution for the aforementioned challenges, by introducing a novel isolator that is a compressible inclusion (CI) of reused tyre derived aggregates (TDA) placed between the bridge abutment and the backfill. The compressibility of typical tyre derived aggregates was measured by laboratory tests and the compressible inclusion was designed accordingly. The CI was then applied to a typical integral frame abutment model, which was subjected to static and dynamic loads representing in-service and seismic loads correspondingly. The response of both the conventional and the isolated abutment was assessed based on the settlements of the backfill, the soil pressures and the actions of the abutment. The study of the isolated abutment showed that the achieved decoupling of the abutment from the backfill soil results in significant reductions of the settlements of the backfill and of the pressures acting on the abutment. Hence, the proposed research can be of use for extending the length limits of integral frame bridges subjected to earthquake excitations

N. Makhoul, S. Argyroudis (2019)Tools for Resilience Assessment: Developments, Limitations and Future Needs, In: ICONHIC Proceedings National Technical University of Athens

Diverse natural and manmade disasters are becoming more frequent inflicting severe consequences to the environment, societies, economies and critical infrastructure. Therefore, it is of paramount importance to sustain the functionality and operability of critical infrastructure during and after the hazard event, minimize the direct and indirect losses and mitigate the consequences in the aftermath of a disaster. In the last few years, the need to develop risk analysis and risk management tools was emerged, toward facilitating stakeholders’ decision-making, adaptation and preparedness against diverse hazards for enhancing the resilience of cities, infrastructure and societies. Those tools were either newly developed or built on existing loss assessment platforms. In addition to the modules and functions for loss assessments, such as hazard, fragility, damage assessment, visualization and reporting of the results, some of the tools embedded modules for recovery, decision-making and risk mitigation to facilitate resilience assessments whenever feasible. The range of modules is wide, including identification of likely failures and performance of structural and infrastructure systems, recovery of loss of functionality and preparation of recovery plans for disaster events. Thus, resilience assessment tools are becoming more sophisticated, aiming to assist engineers, decision makers and planners to perform a resilience-based design or/and assessment of individual buildings, critical infrastructure and cities, and in this way to withstand and recover from catastrophic events. In this paper, a review of on-market available tools is presented, and then developments, limitations and future needs are discussed.

S Argyroudis, S Mitoulis, G Nasiopoulos, N Mantadakis, D Mantadakis (2019)Resilience of bridges subjected to earthquakes: A case study on a portfolio of road bridges, In: ICONHIC Proceedings National Technical University of Athens

Transportation infrastructure resilience is of paramount importance for societies and economies, therefore its quantification is urgently needed. Infrastructure assets and networks should be robust, i.e. they should have the ability to absorb the actions of natural hazards with minimal loss of functionality and thus should be designed to have redundancy for providing alternatives for damaged components. In addition, resilience enhancement requires the availability of resources and prioritization of goals, for rapid restoration of the affected assets functionality at an acceptable level. Hence, owners and operators would be benefited in the decision-making process from quantifications of resilience that account for different seismic events, the type and extent of expected damage, and the time of restoration. This paper is an application that takes into account the abovementioned factors in the resilience assessment of representative bridges in Thessaloniki, Greece, exposed to earthquakes. In particular, this application quantifies the robustness of bridges against different seismic hazard scenarios, by utilizing realistic fragility curves and the rapidity of the recovery and/or retrofitting after the occurrence of a certain degree of damage, based on realistic restoration functions. Two different approaches for the modelling of the restoration tasks are examined. Resilience assessment is based on a well-informed resilience index, which is a function of the time-variant functionality of the infrastructure over the restoration time for these scenarios. The results of this research are expected to facilitate owners to enhance decision-making and risk management toward more resilient infrastructure.

S. Argyroudis, M. G. Winter, S. Mitoulis (2019)Transport infrastructure ecosystems and their vulnerability to geohazards, In: Proceedings of the XVII ECSMGE-2019: Geotechnical Engineering foundation of the future IOS Press

Transport infrastructure resilience and risk assessment is typically based on the assessment of individual assets rather than the entire system. We introduce the concept of the infrastructure System of Assets (SoA), or ecosystem, referring to non-urban roads, illustrate the individual elements of the system, and the geotechnical and climatic hazards to which it is subject. The infrastructure is classified based on: (i) the road capacity and speed limits and (ii) the geomorphological and topographical conditions. This classification covers the majority of non-urban networks, exposed to hazards such as earthquakes, floods, landslides (including slides, debris flow and rock fall), extreme temperatures and shrink/swell phenomena. This approach forms the basis for an integrated assessment of the fragility of the SoA rather than the individual elements. Numerical fragility curves are introduced, to articulate the vulnerability of the SoA, to various geohazards and a case study is presented for a bridge exposed to multiple hazards. This framework can contribute to future developments in the resilience management of the transportation network in respect of geotechnical and climatic hazards.

Sotirios Argyroudis, Stergios Mitoulis, Lorenzo Hofer, Mariano Angelo Zanini, Enrico Tubaldi, Dan M. Frangopol (2020)Resilience assessment framework for critical infrastructure in a multi-hazard environment: case study on transport assets, In: Science of the Total Environment714 Elsevier

The exposure of critical infrastructure to natural and human-induced hazards has severe consequences on world economies and societies. Therefore, resilience assessment of infrastructure assets to extreme events and sequences of diverse hazards is of paramount importance for maintaining their functionality. Yet, the resilience assessment commonly assumes single hazards and ignores alternative approaches and decisions in the restoration strategy. It has now been established that infrastructure owners and operators consider different factors in their restoration strategies depending on the available resources and their priorities, the importance ofof multiple hazards and their impacts, the different strategies of restoration, 29 and hence the quantification of resilience in that respect exists and this is an acknowledged gap that needs urgently filling. This paper provides, for the first time in the literature, a classification of multiple hazard sequences considering their nature and impacts. Subsequently, a novel framework for the quantitative resilience assessment of critical infrastructure, subjected to multiple hazards is proposed, considering the vulnerability of the assets to hazard actions, and the rapidity of the damage recovery, including the temporal variability of the hazards. The study puts forward a well-informed asset resilience index, which accounts for the full, partial or no restoration of asset damage between the subsequent hazard occurrences. The proposed framework is then applied on a typical highway bridge, which is exposed to realistic multiple hazard scenarios, considering pragmatic restoration strategies. The case study concludes that there is a significant effect of the occurrence time of the second hazard on the resilience index and a considerable error when using simple superimposition of resilience indices from different hazards, even when they are independent in terms of occurrence. This potentially concerns all critical infrastructure assets and, hence, this paper provides useful insights for the resilience-based design and management of infrastructure throughout their lifetime, leading to cost savings and improved services. The paper concludes with a demonstration of the importance of the framework and how this can be utilised to estimate the resilience of networks to provide a quantification of the resilience at a regional and country scale.

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