The earthquake-induced damage to earth-retaining structures located along roadway network clearly affects the operations during the emergency and rescue phases in the immediate aftermath of a seismic ...event. The prompt estimation of the seismic vulnerability of a structure or a typological class of structures having a similar seismic behaviour is of foremost importance. In this framework, fragility curves represent an effective tool which can be adopted for quickly evaluating the seismic response of strategic structures. Aim of this study is to propose novel sets of fragility functions for earth-retaining structures, which adopt as input the Intensity Measures (IMs) best correlated to the response of the walls. First, target earth-retaining structures identified along the Italian roadway network are numerically modelled and then two-dimensional (2D) dynamic analyses carried out with reference to different geometrical features of the structure (i.e. height and shape of the walls) and configurations of the backfill. Metrics such as efficiency, practicality, proficiency, and sufficiency are assessed for different demand parameters (overall 35 IMs). The structure response is expressed in terms of horizontal displacement and rotation of the wall. Fragility functions for peak values of velocity (PGV) and acceleration (PGA) are developed. The fragility models are then applied for computing the seismic damage scenario associated to a real earthquake occurred in Central Italy in 2016. Predictive capabilities of the models are assessed by comparing surveyed damages. The proposed tools are useful in emergency management and also during preparedness phase to identify the priority actions and proper countermeasures for seismic risk mitigation.
•2D dynamic analyses of earth-retaining walls along the Italian roadway network.•Identification of the optimal intensity measures.•Development of novel fragility curves for earth-retaining walls.•Computation of seismic damage scenario associated to a real earthquake.
Soil liquefaction is a well-known ground instability phenomenon that may occur during earthquakes. This paper presents a novel catalogue of earthquake-induced manifestations of soil liquefaction ...occurred in Europe in the latest 1000 years or so. This unique digital archive, named “European interactive Catalogue of earthquake-induced soil Liquefaction phenomena” ECLiq, contains documented historical information regarding liquefaction-related phenomena (e.g. sand ejecta and boils, soil settlements and lateral spreading, ground and structural failures) triggered by seismic activity in continental Europe. It is publicly available as web-based GIS (Geographical Information System) platform at the link
http://ecliq.eucentre.it/
. Data and metadata were gathered within the time window 1117–2019 AD and include: the main seismological characteristics of the earthquake (e.g. UTC date, epicentre coordinates, magnitude, etc.), location of the site where liquefaction phenomena were documented, a description of the features of ground failure. The archive was built within the framework of LIQUEFACT, a 3.5-year research project funded under the Horizon 2020 Research and Innovation Programme. LIQUEFACT is the largest research project on the assessment and mitigation of risks associated with earthquake-induced soil liquefaction ever funded by the European Commission. Indeed, data and information have been retrieved, collected, critically reviewed and harmonized to compile a composite, homogeneous, and well-documented catalogue of earthquake-induced liquefaction occurrences in Europe. ECLiq is built as an interactive digital archive fully accessible as WebGIS and, as such, it will be useful to a broad range of stakeholders and end-users. ECLiq may help decision makers in identifying urban areas susceptible to undergo liquefaction-induced damage. Furthermore, it may also encourage the scientific community to upgrade soil liquefaction risk models.
The Internet of things concept empowered by low-cost sensor technologies and headless computers has upscaled the applicability of vibration monitoring systems in recent years. Raspberry Shake devices ...are among those systems, constituting a crowdsourcing framework and forming a worldwide seismic network of over a thousand nodes. While Raspberry Shake devices have been proven to densify seismograph arrays efficiently, their potential for structural health monitoring (SHM) is still unknown and is open to discovery. This paper presents recent findings from existing buildings located in Bucharest (Romania) equipped with Raspberry Shake 4D (RS4D) devices, whose signal recorded under multiple seismic events has been analyzed using different modal identification algorithms. The obtained results show that RS4D modules can capture the building vibration behavior despite the short-duration and low-amplitude excitation sources. Based on 15 RS4D device readings from five different multistorey buildings, the results do not indicate damage in terms of modal frequency decay. The findings of this research propose a baseline for future seismic events that can track the changes in vibration characteristics as a consequence of future strong earthquakes. In summary, this research presents multi-device, multi-testbed, and multi-algorithm evidence on the feasibility of RS4D modules as SHM instruments, which are yet to be explored in earthquake engineering.
This paper aims to investigate the seismic vulnerability of key port infrastructure components by using the outcomes of advanced numerical analysis. For the first time, to the best knowledge of the ...authors, a pile-supported wharf structure, the soil deposits where the wharf lies, and a crane typically operating on the wharf are numerically modelled as a combined system. The starting point for building the numerical model is the main components of strategic facilities at the port of Gioia Tauro (Italy), which is a strategic hub for container traffic located in one of the most seismically active regions of the Mediterranean Sea. Based on the results obtained from two-dimensional (2D) dynamic analyses, fragility curves were developed for single port components and the wharf-crane-soil system. A scenario-based seismic damage assessment was then exemplified to compare the predictions resulting from the fragility model presented in this work with the relevant data available in the literature. It turns out that, besides some inevitable variations, expected damage percentages were in general agreement. As the main contribution of this work, derived fragility curves might be adopted as an effective tool for rapid evaluation of the seismic performance of port components during the development of strategies for risk mitigation and also the emergency management in case of an earthquake.
This paper presents a multi-level methodology for near real-time seismic damage assessment of multi-story buildings, tailored to the available level of knowledge and information from sensors. The ...proposed methodology relates changes in the vibratory characteristics of a building—evaluated via alternative dynamic identification techniques—to the European Macroseismic Scale (EMS-98) damage grades. Three distinct levels of knowledge are considered for the building, with damage classification made through (i) empirical formulation based on quantitative ranges reported in the literature, (ii) analytical formulation exploiting the effective stiffness concept, and (iii) numerical modelling including a simplified equivalent single-degree-of-freedom model or a detailed finite element model of the building. The scope of the study is twofold: to construct a framework for integrating structural health monitoring into seismic damage assessment and to evaluate consistencies/discrepancies among different identification techniques and model-based and model-free approaches. The experimental data from a multi-story building subject to sequential shaking are used to demonstrate the proposed methodology and compare the effectiveness of the different approaches to damage assessment. The results show that accurate damage estimates can be achieved not only using model-driven approaches with enhanced information but also model-free alternatives with scarce information.
This paper presents a geospatial methodology for zoning the earthquake-induced soil liquefaction risk at a continental scale and set-up in a Geographic Information System (GIS) environment by ...coupling data-driven and knowledge-driven approaches. It is worth mentioning that liquefaction is a phenomenon of soil instability occurring at a very local spatial scale; thus, the mega-zonation of liquefaction risk at a continental scale is a hard facing challenge. Since the risk from natural disasters is the convolution of hazard, vulnerability, and exposure, the liquefaction risk mapping is based on the combination of geospatial explanatory variables, available at the continental scale, of the previously listed three assumed independent random variables. First, by applying a prediction model calibrated for Europe, the probability of liquefaction is mapped for the whole continent. Then, the Analytical Hierarchy Process (AHP) is adopted to identify areas that have a high risk of liquefaction, taking into account proxy data for exposure. The maps are computed for different levels of severity of ground shaking specified by three return periods (i.e., 475, 975, and 2475 years). A broad variety of stakeholders would benefit from the outcomes of this study, such as civil protection organizations, insurance and re-insurance companies, and infrastructure operators.
Liquefaction-induced surface manifestations are the result of a complex geological–geotechnical phenomenon, driven by several controlling factors. We propose a multidisciplinary methodological ...approach, involving engineering geologists, geomorphologists, sedimentologists, and geotechnical engineers, to build a 3D engineering geological model for liquefaction assessment studies. The study area is Cavezzo (Po Plain, Italy), which is a municipality hit by superficial liquefaction manifestations during the Emilia seismic crisis of May–June 2012. The site is characterized by a Holocene alluvial sequence of the floodplain, fluvial channel, and crevasse splay deposits prone to liquefaction. The integration of different geotechnical investigations, such as boreholes, CPTm, CPTu, and laboratory tests, allowed us to recognize potentially liquefiable lithological units, crucial for hazard assessment studies. The resulting 3D engineering geological model reveals a strict correlation of co-seismic surface manifestations with buried silty sands and sandy silts within the shallow 10 m in fluvial channel setting, which is capped and laterally confined by clayey and silty deposits.
Earthquake early warning (EEW) systems are used to provide timely alerts on ongoing earthquakes, which can facilitate important risk-mitigation actions before potentially damaging seismic waves reach ...target sites. A major shortcoming of existing EEW approaches is that the earthquake-related conditions for activating alerts are not generally defined according to a formal decision-support system (DSS) that accounts for possible risk-based consequences of triggering/not triggering the alarm. This paper exploits a next-generation risk-informed EEW DSS, which incorporates multi-criteria decision-making for evaluating the optimal decision. The proposed DSS integrates engineering-driven loss predictions associated with issuing/not issuing an EEW alert during an event, also considering possible system malfunctions. The DSS is demonstrated for the strategic Gioia Tauro seaport, located in a region with some of the highest seismic hazard in Italy. Real-time seismic risk analyses are conducted for various earthquake scenarios, accounting for event-parameter uncertainties that are integral to any EEW process and considering the multicomponent nature of the port as a system of interconnected elements. The results of these analyses are used as input to the proposed EEW DSS along with end-user risk preferences, to evaluate the optimal decision in each case and to define a series of risk-informed EEW warning thresholds for the port.
•The system integrates seismic risk predictions and multi-criteria decision-making.•The system identifies the optimal action (issue or not a warning) for a given event.•The optimal action can be sensitive to stakeholder risk preferences.•The optimal action can depend on the level of functionality interdependence captured.
The preliminary results are presented herein for the engineering applications of the characteristics of the ground motion induced by the May 20, 2012, Emilia earthquake. Shake maps are computed to ...provide estimates of the spatial distribution of the induced ground motion. The signals recorded at the Mirandola (MRN) station, the closest to the epicenter, have been processed to obtain acceleration, velocity and displacement response spectra. Ground-motion parameters from the MRN recordings are compared with the corresponding estimates from recent ground-motion prediction equations, and with the spectra prescribed by the current Italian Building Code for different return periods. The records from the MRN station are used to plot the particle orbit (hodogram) described by the waveform. The availability of results from geotechnical field tests that were performed at a few sites in the Municipality of Mirandola prior to this earthquake of May 2012 has allowed preliminary assessment of the ground response. The amplification effects at Mirandola are estimated using fully stochastic site-response analyses. The seismic input comprises seven actual records that are compatible with the Italian code-based spectrum that refers to a 475-year return period. The computed acceleration response spectrum and the associated dispersion are compared to the spectra calculated from the recordings of the MRN station. Good agreement is obtained for periods up to 1 s, especially for the peak ground acceleration. For the other periods, the spectral acceleration of the MRN recordings exceeds that of the computed spectra.
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