Research Goal 1: Loss-driven design and mitigation approaches
There are still important “open” issues in the design and retrofit of structures against natural hazards. Past events have repeatedly highlighted their potential impact in terms of economic losses, casualties, and overall disruption (i.e., indirect loss). Additionally, there are several key areas in which further innovation and knowledge expansion can be made. This first research goal focuses on this from the perspective of loss-driven mitigation approaches.
Seismic Hazard
In the case of seismic design, it has become increasingly obvious that the current approach possesses several flaws both on a technical and conceptual level. This is a general statement applicable worldwide, but in the case of Europe, several particular issues arise. On the technical side, it is clear that there is still much to be learned on the behaviour and performance of existing structures to make them Eurocode-compliant, with the existing building stock in most European countries having been constructed in the post-WWII construction boom period (Crowley et al., 2020; Crowley, 2021) that predated any modern building codes based on sound seismic design principles. On a conceptual level, it is clear that even today, when structural behaviour is understood with a degree of confidence in many cases, it is still not abundantly clear what their target performance should be and how it should be ensured. This applies to structures forming a part of the built environment (e.g., residential buildings), critical infrastructures (e.g., bridge network) and industrial facilities (e.g., processing plants), which form part of RA1, RA2 and RA3 of ERIES. Hence, there is a problem with both conceptual implementations to ensure satisfactory performance and technical know-how to allow this to take place. ERIES will work through its TA activities to address both of these issues. This will be primarily through the development of necessary data for loss-based approaches. Past developments have mainly centred on US-based research, but some progress has been made on this from a European perspective. ERIES TA activity will seek to conduct research projects that can make significant contributions in this regard. This research, forming parts of RA1, RA2 and RA3 and to be conducted in the available research infrastructures, involves the detailed characterisation via experimental testing. The combination of world-class facilities and research projects make ERIES uniquely positioned to conduct world-class and cutting-edge research to address these gaps. For example, this will be done via the novel shake table system in Pavia to allow a unique way of testing and validating non-structural element damage in buildings, in addition to the diverse and complementary shaking table facilities at Lisbon, Paris, Bristol and Skopje. In addition, the unique facilities to investigate other types of damage mechanisms and potential consequences can be addressed at the laboratory facilities in Patras, Thessaloniki and the JRC’s facilities at Ispra. Specific damage mechanisms, potential repair actions and associated costs will be targeted via numerous testing campaigns throughout this network of advanced research facilities to foster the development of a database of damage and cost functions for loss-driven assessment and design that will form a next-generation approach to reducing seismic risk.
Wind Hazard
Design optimisation to prevent disruptions and minimise economic losses under wind actions is one of the major goals of the ERIES project. From the damage surveys after increasingly frequent and disruptive events, the main impacts are observed for residential and commercial/office high-rise and low-rise buildings embedded in complex historic urban environments (RA1), especially due to non-structural components damages. This is seen for slender and flexible structures, such as bridges, poles, towers and transmission lines (RA1, RA2, RA3) and for critical infrastructures, such as ports and airports where a large number of strategic activities are daily deployed (RA2), in addition to light and heavy industries (e.g., factories and production plants) (RA3). In addition, designing new facilities/equipment/tools inspired by the well-settled worldwide facilities commonly used to accurately reproduce and simulate natural disasters is crucial (RA4).
In compliance with some of the aforementioned knowledge gaps, substantial improvements in design procedure require, on the one hand, reliable models of wind flow, especially generated by non-synoptic phenomena (e.g., tornadoes and downbursts). On the other hand, they require refined analysis of the aerodynamic and aeroelastic response and damage mechanism of the structures and structural elements. The research activities of the ERIES project, offering world-class outstanding and strongly complementary experimental facilities, help users develop ground-breaking research with a strong impact on improving and optimising the structural design and reliability, and possibly reducing the maintenance and management costs.
On these grounds, the Doppler Lidar WindCube 400s available in Genova, with the capability to take free field flow measurements up to 15 km and 50m physical resolution, open new perspectives in the wind engineering sector in terms of full-scale measurements of synoptic and unsteady flows. Boundary-Layer Wind Tunnels at UNIGE (Genova, Italy), TUE (Eindhoven, The Netherlands) and CSTB (Nantes, France) allow experimental tests on structures, structural elements and urban environments models with complementary characteristics. The UNIGE facility offers high-quality atmospheric boundary layer (ABL) flow reproduction and state-of-the-art equipment for aerodynamic and aeroelastic tests on reduced scale and sectional models of structures and structural elements (RA1, RA3). Large-scale investigations (i.e., meso- and microscale) of urban environments (RA1) and critical infrastructures (RA2) can be carried out for different neutral ABL winds through the wind tunnels of TUE. The Jules Verne climatic wind tunnel of CSTB can simulate and analyse the behaviour of structures or systems (RA1, RA2, RA3) up to full scale in extreme weather events, reproducing freezing temperatures at −32°C, extreme heat at +55°C, snow, rain, ice, fog, sandstorms or dust storms, and winds up to 280 km per hour. In addition, unique advanced facilities at WU (Western Ontario, Canada) complete and extend the ERIES wind experimental capability. The 3LP Lab is a test facility equipped with an innovative pneumatic loading system using modular “pressure boxes’’ to subject a full-scale specimen house to realistic time-varying pressures and suctions over the entire exterior surface, simulating extreme environmental loading due to wind, snow, and rain. With 106 real-time controlled fans and hundreds of flow modifiers, the world’s first hexagonal wind chamber of the WindEEE Dome offers the ability to test scaled models of buildings, structures and flow fields in complex synoptic and non-synoptic wind systems, reproducing tornadoes, downbursts, complex 3D flow fields as well as atmospheric boundary layer winds at various geometric scales.
This exceptional network of advanced research facilities will boost the advancement in the knowledge of wind effects on structural and non-structural elements. Damage mechanisms, potential repair actions and associated costs will be targeted via numerous testing campaigns, to foster the development of a database of damage and cost functions for loss-driven assessment and design that will form a next-generation approach to reducing wind risk.
Geotechnical
Concerning geotechnical applications, soil-structure interaction (SSI) effects are typically neglected in the design of new structures and assessment of existing ones, based on the perception that this invariably leads to broader safety margins. This traditional approach has significant implications in evaluating losses because the seismic demand may be overestimated and the real structural behaviour could be different from that expected. The stiffness contrast between soil and structural elements is one of the most influential parameters in assessing kinematic and inertial SSI effects. During earthquakes, the differential evolution of soil and structural plasticity alters the initial stiffness contrast, making the evaluation of nonlinear SSI phenomena more complex. Very often, this aspect, and more in general the evaluation of losses, is overlooked in experimental studies on SSI because structural specimens often remain in the elastic range. One of the research goals of ERIES is to use high-end laminar soil containers on shake tables and field tests to bring both part of the system (i.e., soil and structure) into the plastic range to experimentally evaluate the beneficial or detrimental role of SSI on the assessment of direct and indirect losses.
The impact of soil-structure interaction and geohazards-related phenomena on the risk and loss of civil infrastructure will be thoroughly explored within the complementary facilities of the ERIES project. The UK National Facility for Soil-Structure Interaction in Bristol (SoFSI Lab) will serve as the TA platform to reduce the epistemic uncertainty associated with the models accounting for the way structures interact with their supporting soil. Envisaged experiments will be conducted on the two shaking tables: the 10t/6DOF and the 50t/2DOF installations in the SoFSI and EQUALS Labs, respectively. They will be applied to a wide range of critical infrastructures such as irregular buildings, curved and seismically isolated bridges (RA1), above ground and buried energy systems (e.g., offshore wind turbines, water, wastewater and natural gas pipelines) (RA2), as well as nuclear facilities (including small modular reactors, RA3) whose damage and loss due to dynamic environmental loads strongly depends on their supporting conditions. Smart materials and methods for mitigating the above effects (RA4) will also be tested at Bristol’s dual SoFSI/EQUALS facility.
Likewise, field tests at the EUROSEISTEST and EUROPROTEAS installations could provide excellent means for uncertainty reduction and knowledge expansion in geotechnics and soil-structure interaction. Free from scaling-law bias encountered in small rigs, these can serve for testing simple buildings (RA1), models of bridge piers and scaled foundations of wind turbines (RA2), or even test non-structural elements in industrial facilities (RA3). Innovative geotechnical solutions to seismic isolation and mitigation (RA4) can be tested on a field scale. Testing geotechnical seismic isolation of buildings (RA1) or critical infrastructure and industrial facilities (RA2 and RA3) can shift decision making from capability-driven to loss-driven approaches.
Finally, the possibility to combine complementary and compatible installations across different project RI will be offered as part of the geographically distributed hybrid testing (i.e., soil-structure systems that are substructured into individual numerical and slowly tested experimental modules that are coordinated remotely). It is anticipated that the loss-driven design and mitigation approaches explored in ERIES will contribute towards achieving more rational designs and thus increasing value for money.
Research Goal 2: Risk quantification and prioritisation
While the first research goal focuses on the loss-driven application of research, the second research goal focuses instead on the risk-related aspects. This involves risk quantification, management and prioritisation as part of a more general thrust towards increased resilience and robustness of society to natural hazards. As such, TA activities carried out toward this goal should be geared in a way that they are making a clear contribution toward this increase in resilience and robustness.
Seismic Hazard
For what concerns seismic risk, the increased understanding of structural dynamics and response to earthquake loading in the 1970s and 1980s (Housner, 1984) resulted in the introduction of probabilistic approaches in earthquake engineering. It was initially embraced indirectly by building codes like Eurocode 8, and the recent revision to Eurocode 8 includes a more detailed treatment. To facilitate this in a European context, much data is still needed to verify and calibrate these mathematical models that form the basis of probabilistic seismic risk analysis. The TA activities carried out in ERIES will identify gaps in the contexts covered by RA1 and RA3. This research will pave the way for a more risk-aware society and effectively exploit the new and existing experimental results to provide the data needed to form part of a next-generation set of building codes for Europe. Furthermore, seismic design, assessment and strengthening have been traditionally focused on single constructions (i.e., buildings, bridges, tunnels, including their dynamic interaction with the soil etc.) (e.g., Calvi, 2013). The next logical step has been to extend the combination to “systems of systems” (i.e., consider the interconnectivity between roads and electrical networks, hospital and healthcare systems). Some studies on this topic have been the subject of the past European project: SYNER-G: Systemic Seismic Vulnerability and Risk Assessment of Complex Urban, Utility, Lifeline Systems and Critical Facilities (Pitilakis et al., 2014). In this respect, the TA activities of ERIES will provide further support to this line of thinking and allow the development of the necessary data and tools to help develop and implement this kind of approach in practice. As anticipated, it mainly applies to the context of RA2 and RA3 and forms part of a next-generation approach to seismic risk mitigation for critical infrastructures.
Wind Hazard
The assessment and quantification of risks due to windstorms is crucial for any category of structure. This includes residential/commercial/office buildings embedded in complex urban environments (RA1), bridges connecting coastlines and crossing hilly and mountainous terrains (RA1), small and large-size vertical or/and horizontal axis wind turbines installed on buildings and nearby urban areas (RA3), critical transportation infrastructures such as railways, ports and airports (RA2) where a large number of goods and passengers move every day, as well as for strategic industrial facilities and electric transmission lines (RA3). The operational management of large wind sensitive infrastructures, including alert systems, is often governed by wind, influencing the safety of people but also the economic performance and cost-efficiency of the infrastructure (e.g., Repetto et al., 2018). Similarly, the reliable prediction of loss using rigorous, large-scale experimentation of soil-structure systems described in Research Goal 1 is expected to reduce the associated uncertainties in the definition of their risk under dynamic loads (and thus lead to higher cost in design and rehabilitation of structures). The awareness of risks that can lead to a prioritisation of interventions and to prevention of detrimental accidents is a challenging task for local authorities and municipalities. Both cost- and resilient- based planning approaches should be analysed in a probabilistic environment, considering scenarios with specified probability of occurrence, to define the best compromised solution. ERIES offers a large experimental infrastructure and technical expertise to support research of potential users from a variety of application fields, making it possible an accurate monitoring and simulation of wind flow characteristics as well as structural and infrastructural response and vulnerability at different temporal and spatial scales. The resultant open database will pave the way for an advanced systemic approach to risk assessment of buildings and infrastructures, contributing to increase the preparedness and resilience of the urban areas subjected to wind hazards.
Geotechnical
Regarding geotechnical risks, quantification, management and prioritisation are carried out without considering SSI effects, hence reliable results are obtained only when these effects are negligible. Otherwise, when SSI is detrimental the relevant risks may be underestimated while, when it is beneficial, results may be overestimated. A major goal of the proposal is to carry out experimental tests with cutting-edge soil boxes on shake tables and field tests, to refine the assessment of both seismic demand and capacity incorporating kinematic and inertial SSI, to improve the approaches to increase resilience and robustness of society to natural hazards.
Research Goal 3: Green and sustainable development
The issue of green and sustainable development is a research goal that permeates each research area and hazard addressed in ERIES. This reflects the collective action needed in order to work towards a more green and sustainable engineering sector. It must also effectively contribute towards the mitigation of the effects of climate change and improve overall energy efficiency of constructions in general.
In particular, recent research from many European countries is looking towards more integrated approaches for structural rehabilitation and bringing energy and other impacts into the discussion. For example, not just consider the impacts of earthquakes on structural behaviour but also how the energy efficiency and environmental impacts of different structural interventions may be considered and optimised. Studies such as Caruso et al. (2021) have proposed integrated frameworks to this effect and studies like Clemett et al. (2021) investigating how environmental impacts can be included in the decision-making process. These efforts represent a clear and positive step towards a greener and more sustainable environment. While such studies have outlined frameworks, they fundamentally rely on experimental evidence and data for new green and innovative solutions that can be considered in these processes. It is here that ERIES plays a key and crucial role by allowing users to carry out experimental investigations on innovative materials and technologies.
RA1 to RA3 of ERIES foresee users carrying out experimental investigations on innovative base materials and structural solutions that can be used to improve the built environment and civil infrastructure. RA4 of ERIES focuses in part on developing innovative devices that can be used to reduce losses and risks. These devices represent by themselves a unique opportunity to utilise and recycle material, and also propose new relevant innovative technologies. A typical example is the use of recycled rubber (notably shredded tyres) to develop low-cost seismic isolation devices for developing countries, or other wood- and earth-based solutions. Naturally, these innovative approaches require experimental investigation at advanced facilities before they may be considered market-ready in Europe and beyond. Some of these innovations using recycled rubber have already been pilot tested, but further research under ERIES will be undoubtedly beneficial.
Achieving net-zero carbon and resilience to the impacts of climate change represents a major challenge. A multidisciplinary approach is required to support the cross-sectoral, society-wide transformation to reduce the carbon footprint. At the same time, new engineering solutions, smart materials and construction practices that are net-zero compliant have not been thoroughly tested against the evolving natural hazards.
Focusing on renewable energy, ERIES offers contributions in the wind and solar energy sectors. TA users will be able to investigate and improve the performance of horizontal- and vertical-axis wind turbines at different scales and arrangements. Likewise, wind-tunnel tests can be carried out on photovoltaic panels to optimise the structural design of panels and arrays, ensure the best performance and minimise the risk of possible disruptions. Geotechnical applications may involve thermal piles and pile groups. Innovative micro-power plants and smart grid solutions can be explored as well.
Examples of the multidisciplinary approach also enter under the umbrella of sustainable energy development. Wind turbines are increasingly used around Europe but, in some cases, their interaction with the supporting foundation system during their regular use and also strong wind is not well-understood in some instances, which has led to failures of the turbines due to excessive tilting. The interdisciplinary nature of ERIES allows for significant progress to be made in this regard. Innovative geotechnical seismic isolation (GSI) systems aim at high-performance dynamic and geo-environmental insulation for resilient and sustainable near-zero (or net-zero) energy buildings. The scientific challenge explored in ERIES will be to improve the holistic performance and life-cycle of buildings towards a smart, safe, economical, green and sustainable design. Modern societies have augmented needs related to lower energy consumption of buildings, and to seismically safer structures, along with better environmental protection against various natural and man-made hazards. This could lead to the ultimate goal of a more resilient society and built environment. Considering these general societal and economic requirements, the need for innovative construction, foundation isolation systems is prevalent. Using their expertise in climatology, physics and aerodynamics, ERIES partners will also guide the development of key solutions for safe and comfortable urban environments, including experimental studies of the natural ventilation and pollutant dispersion in buildings and urban areas where the majority of human activities take place, as well as a solution to protect the soil from wind erosion and contrast desertification effects.