Rupture directivity and its potential frequency dependence is an open issue in the seismological ... more Rupture directivity and its potential frequency dependence is an open issue in the seismological community, especially for small-to-moderate earthquake. Directivity itself is the focusing of the radiated seismic wave energy due to the rupture propagation along the direction of the fault.In this research, we calibrate a non-ergodic ground motion model for the ordinates of the 5% acceleration response spectra (computation interval 0.04-2 sec) and we analyse, earthquake by earthquake, the azimuthal dependence of the aleatory component, i.e. the residual terms corrected for systematic source, site and path contributions. The final aim is the calibration of a prediction model including directivity effects that can be used for engineering purposes such as seismic hazard assessment and shaking scenarios generation.The study area is the Central Italy, which was affected by several seismic sequences in the last 20 years, occurred on normal fault systems. The dataset we used is composed by al...
We investigated the temporal variation of the spectral decay parameter κ before and after two mai... more We investigated the temporal variation of the spectral decay parameter κ before and after two main earthquakes that occurred in the central Italy region, namely the Amatrice (Mw 6.0) of 24 August 2016 and the Norcia (Mw 6.5) of 30 October 2016 earthquakes. For this analysis, we used seismograms from the central Italy dense seismic array stations, and earthquakes located at hypocenter distances r < 80 km, having magnitudes Mw 3.4–6.5. The dataset consists of 393 events recorded at 92 stations. We estimated, for both earthquake sequences, average functions κ˜(r) that describe the distance dependence of κ along the S-wave source-station paths using acceleration spectra from foreshocks, mainshock, and aftershocks. We observed that there was a regional attenuation drop within approximately two months after the Amatrice earthquake. Then, κ˜(r) tends to return toward the attenuation values observed before the occurrence of the main event, namely to the values of κ˜(r) obtained from the ...
We propose a new fully nonergodic ground motion model for Central Italy, which is one of the most... more We propose a new fully nonergodic ground motion model for Central Italy, which is one of the most sampled areas in the world after the occurrence of the last seismic sequences of 2009 and 2016–2017. The model predicts 69 ordinates of the Fourier Amplitude Spectrum in the magnitude range 3.2–6.5 and is constrained on a dense set of seismological and geophysical parameters (i.e. stress-drop $$\Delta \sigma$$ Δ σ , shear-wave velocity in the uppermost 30 m, VS,30 and high-frequency attenuation parameter at source $${\kappa }_{source}$$ κ source and site $${\kappa }_{0}$$ κ 0 ) made available from a non-parametric generalized inversion technique (GIT). The aim of this work is to capture the underlying physics of ground motion related to different source energy levels, as well as to the crustal and geological structure of the region, thus providing less uncertain predictions. Calibration is performed using a stepwise regression approach which has the advantage of taking a more complex fu...
ITACA is the ITalian ACcelerometric Archive of waveforms recorded by the National Accelerometric ... more ITACA is the ITalian ACcelerometric Archive of waveforms recorded by the National Accelerometric Network (RAN, Rete Accelerometrica Nazionale), operated by the Italian Civil Protection Department - Presidency of the Council of Ministers (DPC), the National Seismic Network (RSN, Rete Sismica Nazionale), operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), and regional and international networks operated by various providers. ITACA 3.1 contains more than 45,000 waveforms of 1,946 seismic events with magnitude greater than 3.0 occurred in the time frame 1972-2019 and recorded by about 1,450 recording stations, including about 30,000 waveforms manually processed by specialists. ITACA runs on software based upon open source projects: PostgreSQL (database system), Python (database management and user authentication), and AngularJS (website design). The ITACA3.1 database enables the association of multiple information related to the same object; for instance, a recording ...
Earthquake Engineering & Structural Dynamics, 2020
This paper provides a new methodological framework to generate empirical ground shaking scenarios... more This paper provides a new methodological framework to generate empirical ground shaking scenarios, designed for engineering applications and civil protection planning. The methodology is useful both to reconstruct the ground motion pattern of past events and to generate future shaking scenarios, in regions where strong‐motion datasets from multiple events and multiple stations are available. The proposed methodology combines (1) an ad‐hoc nonergodic ground motion model (GMM) with (2) a spatial correlation model for the source region‐, site‐, and path‐systematic residual terms, and (3) a model of the remaining aleatory error to take into account for directivity effects. The associated variability is a function of the type of scenario generated (bedrock or site, past or future event) and it is minimal for source areas where several events have occurred and for sites where recordings are available. In order to develop the region‐specific fully nonergodic GMM and to compute robust estimation of the residual terms, the approach is calibrated on a highly dense dataset compiled for the area of central Italy. Example tests demonstrate the validity of the approach, which allows to simulate acceleration response spectra at unsampled sites, as well as to capture peculiar physical features of ground motion patterns in the region. The proposed approach could be usefully adopted for data‐driven simulations of ground shaking maps, as alternative or complementary tool to physic‐based and stochastic‐based approaches.
The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains veri- fied and ... more The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains veri- fied and reliable metadata and intensity measures of manually processed waveforms included in the ESM database. The flatfile has been developed within the Seismology The- matic Core Service of EPOS-IP (European Plate Observing System Implementation Phase) and it is disseminated throughout a web portal (http://esm.mi.ingv.it/flatfile-2018/flatfile. php) for research and technical purposes. The adopted criteria for flatfile compilation aim to collect strong motion data and related metadata in a uniform, updated, traceable and quality-checked way to develop Ground Motion Models (GMMs) for Probabilistic Seismic Hazard Assessment (PSHA) and engineering applications. In this paper, we present the characteristics of ESM flatfile in terms of recording, event and station distributions, and we discuss the most relevant features of the Intensity Measures (IMs) of engineering interest included in the table. ...
Isolated bridge is described by a simple two degree of freedom (TDoF) BoucWen hysteretic model, ... more Isolated bridge is described by a simple two degree of freedom (TDoF) BoucWen hysteretic model, which has been introduced for its intrinsic ability in reproducing a wide range of real devices behavior. With the aim of taking into consideration intrinsic stochastic nature of seismic ...
One of the most widely adopted and studied strategies for vibration control both in civil and in ... more One of the most widely adopted and studied strategies for vibration control both in civil and in mechanical engineering is based on the use of tuned mass dampers (TMD) devices. Many conventional optimization criteria of mechanical parameters have been proposed, based on different ...
The primary objective of the present study is to explore a new definition of seismic response spe... more The primary objective of the present study is to explore a new definition of seismic response spectrum, where the uncertainty, that strongly affects the system and excitation parameters, is treated by fuzzy random theory. The proposed work is based on a simultaneous ...
Computational Methods in Stochastic Dynamics, 2010
Abstract Earthquake-induced ground-motion may be realistically described as random processes that... more Abstract Earthquake-induced ground-motion may be realistically described as random processes that are intrinsically non-stationary in both amplitude and fre-quency content. In order to take into account the finite duration and the amplitude non-stationarity of earthquake-induced ...
Near-source strong-moton flatfile SD (called NESS-Sdebasco) is a parametric table related to worl... more Near-source strong-moton flatfile SD (called NESS-Sdebasco) is a parametric table related to world earthquakes containing high-quality metadata and intensity measures (IMs) based on displacement of engineering interest. The table collects 5% damping spectral displacement ordinates and permanent displacement (fling step) along with the corresponding event and station metadata. The accelerometric recordings contained in the table (about 600 near-source three-component waveforms) are processed uniformly according to the eBASCO (Extended Baseline Correction) processing scheme, applied to remove the baseline of recordings by means of a piece-wise linear detrending of the velocity time-histories. Differently from standard processing schemes used to process NESS2 strong-motion data (10.13127/ness.2), eBASCO does not apply any filter that changes the low frequency content of the signal, allowing to determine the velocity pulses and the and the offset at the end of the displacement trace.
Pitting corrosion of the steel bars is a process that strongly jeopardizes the durability of rein... more Pitting corrosion of the steel bars is a process that strongly jeopardizes the durability of reinforced concrete structures exposed to chlorides. This is a problem widely studied in order to evaluate structural lifetime. Nevertheless, the proper treatment of the noteworthy sources of uncertainty, that affect the numerical values of geometrical and mechanical structural parameters, is still an open question. Such properties, in fact, cannot be considered as deterministic quantities. In many real problems, very few uncertain data are available and new non-probabilistic procedures need to be defined to perform lifetime estimation. In the present study, parameters are modelled using fuzzy set theory and a time-dependent fuzzy safety factor is defined in order to indicate how the critical chloride front is distant from the bars. Moreover, the study provides a more proper mathematical analysis of chloride penetration into concrete and an improved calibrating procedure to estimate sampling...
This study explores the ameliorative effects of rubber particles on some properties of concrete. ... more This study explores the ameliorative effects of rubber particles on some properties of concrete. The used rubber scraps are obtained from a mechanical trituration process of postused tires from motor vehicles and trucks. They have long been investigated for resource reutilization as an aggregate in concrete resulting in the ‗Rubcrete mix‘, which can be conveniently used in various applications with promising effects. Rubcrete provides a final product with good mechanical properties and also represents an effective and inexpensive way of recycling the discarded tires. The aim of this work is to present the results of an experimental investigation conducted to identify the optimal types and quantities of aggregates in concrete mixtures for engineering applications. Some of the examined characteristics include: density of rubber aggregates, workability, air entrapment and compressive strength. Three types of rubber particles (ash rubber, crumb rubber and tire chips) have been used in t...
Bulletin of the Seismological Society of America, 2021
In this article, we implement a new approach to calibrate ground-motion models (GMMs) characteriz... more In this article, we implement a new approach to calibrate ground-motion models (GMMs) characterized by spatially varying coefficients, using the calibration dataset of an existing GMM for crustal events in Italy. The model is developed in the methodological framework of the multisource geographically weighted regression (MS-GWR, Caramenti et al., 2020), which extends the theory of multiple linear regression to the case with model coefficients that are spatially varying, thus allowing for capturing the multiple sources of nonstationarity in ground motion related to event and station locations. In this way, we reach the aim of regionalizing the ground motion in Italy by specializing the model in a nonergodic framework. Such an attempt at regionalization also addresses the purpose of capturing the regional effects in the modeling, which is needed for the Italian country, where ground-motion properties vary significantly across space. Because the proposed model relies on the italian GMM...
Rupture directivity and its potential frequency dependence is an open issue in the seismological ... more Rupture directivity and its potential frequency dependence is an open issue in the seismological community, especially for small-to-moderate earthquake. Directivity itself is the focusing of the radiated seismic wave energy due to the rupture propagation along the direction of the fault.In this research, we calibrate a non-ergodic ground motion model for the ordinates of the 5% acceleration response spectra (computation interval 0.04-2 sec) and we analyse, earthquake by earthquake, the azimuthal dependence of the aleatory component, i.e. the residual terms corrected for systematic source, site and path contributions. The final aim is the calibration of a prediction model including directivity effects that can be used for engineering purposes such as seismic hazard assessment and shaking scenarios generation.The study area is the Central Italy, which was affected by several seismic sequences in the last 20 years, occurred on normal fault systems. The dataset we used is composed by al...
We investigated the temporal variation of the spectral decay parameter κ before and after two mai... more We investigated the temporal variation of the spectral decay parameter κ before and after two main earthquakes that occurred in the central Italy region, namely the Amatrice (Mw 6.0) of 24 August 2016 and the Norcia (Mw 6.5) of 30 October 2016 earthquakes. For this analysis, we used seismograms from the central Italy dense seismic array stations, and earthquakes located at hypocenter distances r < 80 km, having magnitudes Mw 3.4–6.5. The dataset consists of 393 events recorded at 92 stations. We estimated, for both earthquake sequences, average functions κ˜(r) that describe the distance dependence of κ along the S-wave source-station paths using acceleration spectra from foreshocks, mainshock, and aftershocks. We observed that there was a regional attenuation drop within approximately two months after the Amatrice earthquake. Then, κ˜(r) tends to return toward the attenuation values observed before the occurrence of the main event, namely to the values of κ˜(r) obtained from the ...
We propose a new fully nonergodic ground motion model for Central Italy, which is one of the most... more We propose a new fully nonergodic ground motion model for Central Italy, which is one of the most sampled areas in the world after the occurrence of the last seismic sequences of 2009 and 2016–2017. The model predicts 69 ordinates of the Fourier Amplitude Spectrum in the magnitude range 3.2–6.5 and is constrained on a dense set of seismological and geophysical parameters (i.e. stress-drop $$\Delta \sigma$$ Δ σ , shear-wave velocity in the uppermost 30 m, VS,30 and high-frequency attenuation parameter at source $${\kappa }_{source}$$ κ source and site $${\kappa }_{0}$$ κ 0 ) made available from a non-parametric generalized inversion technique (GIT). The aim of this work is to capture the underlying physics of ground motion related to different source energy levels, as well as to the crustal and geological structure of the region, thus providing less uncertain predictions. Calibration is performed using a stepwise regression approach which has the advantage of taking a more complex fu...
ITACA is the ITalian ACcelerometric Archive of waveforms recorded by the National Accelerometric ... more ITACA is the ITalian ACcelerometric Archive of waveforms recorded by the National Accelerometric Network (RAN, Rete Accelerometrica Nazionale), operated by the Italian Civil Protection Department - Presidency of the Council of Ministers (DPC), the National Seismic Network (RSN, Rete Sismica Nazionale), operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), and regional and international networks operated by various providers. ITACA 3.1 contains more than 45,000 waveforms of 1,946 seismic events with magnitude greater than 3.0 occurred in the time frame 1972-2019 and recorded by about 1,450 recording stations, including about 30,000 waveforms manually processed by specialists. ITACA runs on software based upon open source projects: PostgreSQL (database system), Python (database management and user authentication), and AngularJS (website design). The ITACA3.1 database enables the association of multiple information related to the same object; for instance, a recording ...
Earthquake Engineering & Structural Dynamics, 2020
This paper provides a new methodological framework to generate empirical ground shaking scenarios... more This paper provides a new methodological framework to generate empirical ground shaking scenarios, designed for engineering applications and civil protection planning. The methodology is useful both to reconstruct the ground motion pattern of past events and to generate future shaking scenarios, in regions where strong‐motion datasets from multiple events and multiple stations are available. The proposed methodology combines (1) an ad‐hoc nonergodic ground motion model (GMM) with (2) a spatial correlation model for the source region‐, site‐, and path‐systematic residual terms, and (3) a model of the remaining aleatory error to take into account for directivity effects. The associated variability is a function of the type of scenario generated (bedrock or site, past or future event) and it is minimal for source areas where several events have occurred and for sites where recordings are available. In order to develop the region‐specific fully nonergodic GMM and to compute robust estimation of the residual terms, the approach is calibrated on a highly dense dataset compiled for the area of central Italy. Example tests demonstrate the validity of the approach, which allows to simulate acceleration response spectra at unsampled sites, as well as to capture peculiar physical features of ground motion patterns in the region. The proposed approach could be usefully adopted for data‐driven simulations of ground shaking maps, as alternative or complementary tool to physic‐based and stochastic‐based approaches.
The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains veri- fied and ... more The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains veri- fied and reliable metadata and intensity measures of manually processed waveforms included in the ESM database. The flatfile has been developed within the Seismology The- matic Core Service of EPOS-IP (European Plate Observing System Implementation Phase) and it is disseminated throughout a web portal (http://esm.mi.ingv.it/flatfile-2018/flatfile. php) for research and technical purposes. The adopted criteria for flatfile compilation aim to collect strong motion data and related metadata in a uniform, updated, traceable and quality-checked way to develop Ground Motion Models (GMMs) for Probabilistic Seismic Hazard Assessment (PSHA) and engineering applications. In this paper, we present the characteristics of ESM flatfile in terms of recording, event and station distributions, and we discuss the most relevant features of the Intensity Measures (IMs) of engineering interest included in the table. ...
Isolated bridge is described by a simple two degree of freedom (TDoF) BoucWen hysteretic model, ... more Isolated bridge is described by a simple two degree of freedom (TDoF) BoucWen hysteretic model, which has been introduced for its intrinsic ability in reproducing a wide range of real devices behavior. With the aim of taking into consideration intrinsic stochastic nature of seismic ...
One of the most widely adopted and studied strategies for vibration control both in civil and in ... more One of the most widely adopted and studied strategies for vibration control both in civil and in mechanical engineering is based on the use of tuned mass dampers (TMD) devices. Many conventional optimization criteria of mechanical parameters have been proposed, based on different ...
The primary objective of the present study is to explore a new definition of seismic response spe... more The primary objective of the present study is to explore a new definition of seismic response spectrum, where the uncertainty, that strongly affects the system and excitation parameters, is treated by fuzzy random theory. The proposed work is based on a simultaneous ...
Computational Methods in Stochastic Dynamics, 2010
Abstract Earthquake-induced ground-motion may be realistically described as random processes that... more Abstract Earthquake-induced ground-motion may be realistically described as random processes that are intrinsically non-stationary in both amplitude and fre-quency content. In order to take into account the finite duration and the amplitude non-stationarity of earthquake-induced ...
Near-source strong-moton flatfile SD (called NESS-Sdebasco) is a parametric table related to worl... more Near-source strong-moton flatfile SD (called NESS-Sdebasco) is a parametric table related to world earthquakes containing high-quality metadata and intensity measures (IMs) based on displacement of engineering interest. The table collects 5% damping spectral displacement ordinates and permanent displacement (fling step) along with the corresponding event and station metadata. The accelerometric recordings contained in the table (about 600 near-source three-component waveforms) are processed uniformly according to the eBASCO (Extended Baseline Correction) processing scheme, applied to remove the baseline of recordings by means of a piece-wise linear detrending of the velocity time-histories. Differently from standard processing schemes used to process NESS2 strong-motion data (10.13127/ness.2), eBASCO does not apply any filter that changes the low frequency content of the signal, allowing to determine the velocity pulses and the and the offset at the end of the displacement trace.
Pitting corrosion of the steel bars is a process that strongly jeopardizes the durability of rein... more Pitting corrosion of the steel bars is a process that strongly jeopardizes the durability of reinforced concrete structures exposed to chlorides. This is a problem widely studied in order to evaluate structural lifetime. Nevertheless, the proper treatment of the noteworthy sources of uncertainty, that affect the numerical values of geometrical and mechanical structural parameters, is still an open question. Such properties, in fact, cannot be considered as deterministic quantities. In many real problems, very few uncertain data are available and new non-probabilistic procedures need to be defined to perform lifetime estimation. In the present study, parameters are modelled using fuzzy set theory and a time-dependent fuzzy safety factor is defined in order to indicate how the critical chloride front is distant from the bars. Moreover, the study provides a more proper mathematical analysis of chloride penetration into concrete and an improved calibrating procedure to estimate sampling...
This study explores the ameliorative effects of rubber particles on some properties of concrete. ... more This study explores the ameliorative effects of rubber particles on some properties of concrete. The used rubber scraps are obtained from a mechanical trituration process of postused tires from motor vehicles and trucks. They have long been investigated for resource reutilization as an aggregate in concrete resulting in the ‗Rubcrete mix‘, which can be conveniently used in various applications with promising effects. Rubcrete provides a final product with good mechanical properties and also represents an effective and inexpensive way of recycling the discarded tires. The aim of this work is to present the results of an experimental investigation conducted to identify the optimal types and quantities of aggregates in concrete mixtures for engineering applications. Some of the examined characteristics include: density of rubber aggregates, workability, air entrapment and compressive strength. Three types of rubber particles (ash rubber, crumb rubber and tire chips) have been used in t...
Bulletin of the Seismological Society of America, 2021
In this article, we implement a new approach to calibrate ground-motion models (GMMs) characteriz... more In this article, we implement a new approach to calibrate ground-motion models (GMMs) characterized by spatially varying coefficients, using the calibration dataset of an existing GMM for crustal events in Italy. The model is developed in the methodological framework of the multisource geographically weighted regression (MS-GWR, Caramenti et al., 2020), which extends the theory of multiple linear regression to the case with model coefficients that are spatially varying, thus allowing for capturing the multiple sources of nonstationarity in ground motion related to event and station locations. In this way, we reach the aim of regionalizing the ground motion in Italy by specializing the model in a nonergodic framework. Such an attempt at regionalization also addresses the purpose of capturing the regional effects in the modeling, which is needed for the Italian country, where ground-motion properties vary significantly across space. Because the proposed model relies on the italian GMM...
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Papers by Sara Sgobba