anna d'onofrio | Università degli Studi di Napoli "Federico II" (original) (raw)

Papers by anna d'onofrio

<p>The Emilia-Romagna seismic sequence in 2012 has increased the interest among Ita... more <p>The Emilia-Romagna seismic sequence in 2012 has increased the interest among Italian researchers in predicting liquefaction under seismic shaking, and in the evaluation of damage induced to structures. A number of studies were carried out during the last decade to evaluate the liquefaction susceptibility of different areas of the Italian Peninsula. Some of these studies have been focused on the territorial analysis of Naples (Evangelista & Santucci de Magistris, 2011; Silvestri & d’Onofrio, 2014), which highlighted how saturated pyroclastic soils present along the coastal areas may be interested by liquefaction phenomenon. On such a basis, the present study aims at evaluating the liquefaction susceptibility throughout the area of three municipalities (Casamicciola, Lacco Ameno and Forio) of Ischia Island in the gulf of Naples (Italy), recently hit by a Ml 4 earthquake.  The coastal zones of these municipalities are characterised by the predominance of saturated pyroclastic granular deposits. The assessment was performed through a multi-level approach, i.e. by increasing level of complexity. First, the potentially liquefiable areas were delimited by combining in a Geographic Information System (GIS) data on the average seasonal depth of the water table (Piscopo et al. 2019) and on the lithological classification of the surface deposits (Seismic Microzonation, 2017). At some representative sites in these potentially liquefiable areas, simplified analyses were carried out using SPT-based semi-empirical methods (Idriss & Boulanger, 2014). The results of such analyses led to choose a specific site on which to perform non-linear ‘coupled’ dynamic analyses in time domain with the SCOSSA code (Tropeano et al. 2019). The results of the coupled analyses in terms of excess pore water pressure ratio (r<sub>u</sub>) then allowed the evaluation of the ‘Induced Damage Parameter’ (Chiaradonna et al. 2020), related to the free-field post-seismic volumetric consolidation settlement, which was classified as ‘moderate’ in this case. The procedure adopted may be a valid proposal for prompt evaluations of the liquefaction susceptibility, which allows to pass from a semi-qualitative assessment at a territorial scale to a quantitative assessment at the scale of a specific site.</p><p>References:</p><p>Boulanger R.W.,Idriss I.M. (2014). <em>CPT and SPT based liquefaction triggering procedures</em>. Report No. UCD/CGM-14/01, Center for Geotechnical Modeling, University of California, Davis.</p><p>Chiaradonna A.,Lirer S.,Flora A., 2020. <em>A liquefaction potential integral index based on pore pressure build-up</em>. Engineering Geology, 272, 1-13.</p><p>Evangelista L.,Santucci de Magistris F. (2011). <em>Upgrading the simplified assessment of the liquefaction susceptivity for the city of Naples, Italy</em>. Proc of the V International Conference on Earthquake Geotechnical Engineering, Santiago, 10–13 January 2011, Paper n. 8.10.</p><p>Piscopo V.,Lotti V.,Formica F.,Lana F.,Pianese L., 2019. <em>Groundwater flow in the Ischia volcanic island (Italy) and its implications for thermal water abstraction</em>. Hydrogeology Journal, 28, 1-23</p><p>Silvestri F.,d’Onofrio A. (2014). <em>Risposta sismica e stabilità dei centri abitati e infrastrutture</em>. Relazione generale I Sessione “Analisi e gestione del rischio sismico”. Atti del XXV Convegno Nazionale AGI: La Geotecnica nella difesa del territorio e delle infrastrutture dalle calamità naturali.</p><p>Tropeano G.,Chiaradonna A.,d’Onofrio A.,Silvestri F. (2019). <em>A numerical model for non-linear coupled analysis of the seismic response of liquefiable soils</em>. Computers and Geotechnics, 105(2019):211–227, doi.org/10.1016/j.compgeo.2018.09.008</p><p> </p><p> </p>

<p&amp... more <p>Semi-empirical procedures for evaluating liquefaction potential (e.g. Seed & Idriss, 1971) require the estimation of cyclic resistance ratio (CRR) and cyclic shear stress ratio (CSR). The first can be obtained using empirical relationships based on in situ tests (e.g. CPT, SPT), the latter can be expressed as function of the maximum horizontal acceleration at ground surface (a<sub>max</sub>), total and effective vertical stresses at the depth of interest (σ<sub>v0</sub>, σ’<sub>v0</sub>) and a magnitude-dependent stress reduction coefficient (r<sub>d</sub>) that accounts for the deformability of the soil column (Idriss & Boulanger, 2004). All these methods were developed referring to a moment magnitude (M<sub>w</sub>) equal to 7.5 and therefore require a magnitude scale factor (MSF) to make them suitable for different magnitude values. Usually, MSF and r<sub>d</sub> are computed with reference to the mean or modal value of M<sub>w</sub> taken from a disaggregation analysis, while a<sub>max</sub> is obtained from a seismic hazard curve, including the contribution of various combinations of magnitudes and distances (Kramer & Mayfield, 2005). Thus, there might be inconsistency between the magnitude values used to evaluate either MSF or r<sub>d</sub> and a<sub>max</sub>. To overcome this problem, Idriss (1985) suggests to directly introduce the MSF in the probabilistic hazard analysis of the seismic acceleration. In this contribution, an alternative method is proposed, by properly modifying the acceleration seismic hazard curve conventionally adopted by the code of practice on the basis the disaggregation analysis, so that i) the contribution of the different magnitudes and the associated MSF and r<sub>d</sub>-values are considered, ii) the computational effort is reduced since a CSR-hazard curve is straightforward obtained. This alternative method is used to carry out a…

E3S Web of Conferences

Clays with higher undisturbed undrained shear strengths than remoulded strengths are considered s... more Clays with higher undisturbed undrained shear strengths than remoulded strengths are considered sensitive. While the stress-strain behaviour of these clays under monotonic loading condition was widely investigated, few data are available of their behaviour under cyclic and dynamic loading conditions. This paper presents the preliminary results of an experimental program on undisturbed samples of a sensitive clay retrieved at Saint Luc de Vincennes (Quebec). In particular, the paper shows the comparison among the modulus reduction curve, G/G0 - γ and the damping ratio variation with shear strain, D - γ measured using different devices, trying to highlight the main factors influencing the observed behaviour , including sample disturbance and storing method. The tests were carried out using one torsional shear and two different cyclic simple shear devices capable of investigating from small to large shear strains. The tests were carried out by three different laboratories at the Univer...

Earthquake Spectra

The Central Italy earthquake sequence nominally began on 24 August 2016 with a M6.1 event on a no... more The Central Italy earthquake sequence nominally began on 24 August 2016 with a M6.1 event on a normal fault that produced devastating effects in the town of Amatrice and several nearby villages and hamlets. A major international response was undertaken to record the effects of this disaster, including surface faulting, ground motions, landslides, and damage patterns to structures. This work targeted the development of high-value case histories useful to future research. Subsequent events in October 2016 exacerbated the damage in previously affected areas and caused damage to new areas in the north, particularly the relatively large town of Norcia. Additional reconnaissance after a M6.5 event on 30 October 2016 documented and mapped several large landslide features and increased damage states for structures in villages and hamlets throughout the region. This paper provides an overview of the reconnaissance activities undertaken to document and map these and other effects, and highlig...

This paper presents the seismic risk assessment of L'Aquila gas distribution network in a perform... more This paper presents the seismic risk assessment of L'Aquila gas distribution network in a performance-based earthquake engineering framework. The study was structured in three basic activities: (1) seismic hazard characterization both in terms of ground motion and permanent ground deformation; (2) characterization of system's vulnerability via fragility curves available in literature; (3) performance evaluation in terms of connectivity. In the paper all issues involved in seismic risk analysis of this kind of systems are discussed with respect to a selected part of the whole network. In particular, the importance of modelling spatial correlation of ground motion and geotechnical hazard on risk assessment was investigated. Results indicate that the system performance may be underestimated when spatial correlation and ground failure are ignored. Moreover, the implications of using fragility curves for compressor stations for the reduction cabins, as suggested in literature, were also addressed, and the necessity of developing specific fragilities was pointed out.

Computers and Geotechnics

Computer-Aided Civil and Infrastructure Engineering, 30(7), 508–523, DOI: 10.1111/mice.12105, Jul 2015

The basic function of a gas distribution system, essentially composed of buried pipelines, reduct... more The basic function of a gas distribution system, essentially composed of buried pipelines, reduction stations, and demand nodes, is to deliver gas from sources to end users. The objective of the article is to discuss the evaluation of seismic risk of gas networks in compliance with the performance-based earthquake engineering framework adapted to spatially distributed systems. In particular, three issues are addressed: (1) spatial seismic hazard characterization in terms of ground shaking and permanent ground deformation; (2) analysis of system's vulnerability via fragility curves; (3) seismic performance evaluation via computer-aided simulation. As an application, the seismic risk analysis of L'Aquila (central Italy) gas distribution network, a 621-km mid- and low-pressure pipeline system was considered. The analyses were performed with reference to the mid-pressure part of the network, through an object-oriented software, specific for risk assessment of lifelines, developed by the authors. Results in terms of connectivity-based performance indicators are presented and discussed, along with a performance disaggregation analysis carried out to evaluate the contribution of the components of the system to the risk.

SOILS AND FOUNDATIONS, 1999

抄録 The experimental results reported in this paper were obtained performing monotonic, cyclic and... more 抄録 The experimental results reported in this paper were obtained performing monotonic, cyclic and dynamic torsional shear tests on a stiff Italian clay in the pre-failure stress-strain range. The experimental clearly demonstrate that the small strain values of shear stiffness ...

Geotechnical, Geological and Earthquake Engineering, 2011

On April 6, 2009 an earthquake (M L = 5.8 and M W = 6.3) stroke the city of L'Aquila with MCS Int... more On April 6, 2009 an earthquake (M L = 5.8 and M W = 6.3) stroke the city of L'Aquila with MCS Intensity I=IX and the surrounding village with I as high as XI. The earthquake was generated by a normal fault with a maximum vertical dislocation of 25 cm and hypocentral depth of about 8.8 km. The deaths were about 300, the injured were about 1500 and the damage was estimated as high as about 25 billion €. Both maximum horizontal and vertical components of the accelerations recorded in the epicentral area were close to 0.65g. The paper summarises the activities in the field of earthquake geotechnical engineering aimed to the emergency and reconstruction issues. The ground motion recorded in the epicentral area is analysed; the geotechnical properties measured by in-situ and laboratory tests before and after the earthquake are summarised; site effects are preliminarily evaluated at accelerometric stations locations and damaged villages; the outstanding cases of ground failure are finally shown.

<p>The Emilia-Romagna seismic sequence in 2012 has increased the interest among Ita... more <p>The Emilia-Romagna seismic sequence in 2012 has increased the interest among Italian researchers in predicting liquefaction under seismic shaking, and in the evaluation of damage induced to structures. A number of studies were carried out during the last decade to evaluate the liquefaction susceptibility of different areas of the Italian Peninsula. Some of these studies have been focused on the territorial analysis of Naples (Evangelista & Santucci de Magistris, 2011; Silvestri & d’Onofrio, 2014), which highlighted how saturated pyroclastic soils present along the coastal areas may be interested by liquefaction phenomenon. On such a basis, the present study aims at evaluating the liquefaction susceptibility throughout the area of three municipalities (Casamicciola, Lacco Ameno and Forio) of Ischia Island in the gulf of Naples (Italy), recently hit by a Ml 4 earthquake.  The coastal zones of these municipalities are characterised by the predominance of saturated pyroclastic granular deposits. The assessment was performed through a multi-level approach, i.e. by increasing level of complexity. First, the potentially liquefiable areas were delimited by combining in a Geographic Information System (GIS) data on the average seasonal depth of the water table (Piscopo et al. 2019) and on the lithological classification of the surface deposits (Seismic Microzonation, 2017). At some representative sites in these potentially liquefiable areas, simplified analyses were carried out using SPT-based semi-empirical methods (Idriss & Boulanger, 2014). The results of such analyses led to choose a specific site on which to perform non-linear ‘coupled’ dynamic analyses in time domain with the SCOSSA code (Tropeano et al. 2019). The results of the coupled analyses in terms of excess pore water pressure ratio (r<sub>u</sub>) then allowed the evaluation of the ‘Induced Damage Parameter’ (Chiaradonna et al. 2020), related to the free-field post-seismic volumetric consolidation settlement, which was classified as ‘moderate’ in this case. The procedure adopted may be a valid proposal for prompt evaluations of the liquefaction susceptibility, which allows to pass from a semi-qualitative assessment at a territorial scale to a quantitative assessment at the scale of a specific site.</p><p>References:</p><p>Boulanger R.W.,Idriss I.M. (2014). <em>CPT and SPT based liquefaction triggering procedures</em>. Report No. UCD/CGM-14/01, Center for Geotechnical Modeling, University of California, Davis.</p><p>Chiaradonna A.,Lirer S.,Flora A., 2020. <em>A liquefaction potential integral index based on pore pressure build-up</em>. Engineering Geology, 272, 1-13.</p><p>Evangelista L.,Santucci de Magistris F. (2011). <em>Upgrading the simplified assessment of the liquefaction susceptivity for the city of Naples, Italy</em>. Proc of the V International Conference on Earthquake Geotechnical Engineering, Santiago, 10–13 January 2011, Paper n. 8.10.</p><p>Piscopo V.,Lotti V.,Formica F.,Lana F.,Pianese L., 2019. <em>Groundwater flow in the Ischia volcanic island (Italy) and its implications for thermal water abstraction</em>. Hydrogeology Journal, 28, 1-23</p><p>Silvestri F.,d’Onofrio A. (2014). <em>Risposta sismica e stabilità dei centri abitati e infrastrutture</em>. Relazione generale I Sessione “Analisi e gestione del rischio sismico”. Atti del XXV Convegno Nazionale AGI: La Geotecnica nella difesa del territorio e delle infrastrutture dalle calamità naturali.</p><p>Tropeano G.,Chiaradonna A.,d’Onofrio A.,Silvestri F. (2019). <em>A numerical model for non-linear coupled analysis of the seismic response of liquefiable soils</em>. Computers and Geotechnics, 105(2019):211–227, doi.org/10.1016/j.compgeo.2018.09.008</p><p> </p><p> </p>

<p&amp... more <p>Semi-empirical procedures for evaluating liquefaction potential (e.g. Seed & Idriss, 1971) require the estimation of cyclic resistance ratio (CRR) and cyclic shear stress ratio (CSR). The first can be obtained using empirical relationships based on in situ tests (e.g. CPT, SPT), the latter can be expressed as function of the maximum horizontal acceleration at ground surface (a<sub>max</sub>), total and effective vertical stresses at the depth of interest (σ<sub>v0</sub>, σ’<sub>v0</sub>) and a magnitude-dependent stress reduction coefficient (r<sub>d</sub>) that accounts for the deformability of the soil column (Idriss & Boulanger, 2004). All these methods were developed referring to a moment magnitude (M<sub>w</sub>) equal to 7.5 and therefore require a magnitude scale factor (MSF) to make them suitable for different magnitude values. Usually, MSF and r<sub>d</sub> are computed with reference to the mean or modal value of M<sub>w</sub> taken from a disaggregation analysis, while a<sub>max</sub> is obtained from a seismic hazard curve, including the contribution of various combinations of magnitudes and distances (Kramer & Mayfield, 2005). Thus, there might be inconsistency between the magnitude values used to evaluate either MSF or r<sub>d</sub> and a<sub>max</sub>. To overcome this problem, Idriss (1985) suggests to directly introduce the MSF in the probabilistic hazard analysis of the seismic acceleration. In this contribution, an alternative method is proposed, by properly modifying the acceleration seismic hazard curve conventionally adopted by the code of practice on the basis the disaggregation analysis, so that i) the contribution of the different magnitudes and the associated MSF and r<sub>d</sub>-values are considered, ii) the computational effort is reduced since a CSR-hazard curve is straightforward obtained. This alternative method is used to carry out a…

E3S Web of Conferences

Clays with higher undisturbed undrained shear strengths than remoulded strengths are considered s... more Clays with higher undisturbed undrained shear strengths than remoulded strengths are considered sensitive. While the stress-strain behaviour of these clays under monotonic loading condition was widely investigated, few data are available of their behaviour under cyclic and dynamic loading conditions. This paper presents the preliminary results of an experimental program on undisturbed samples of a sensitive clay retrieved at Saint Luc de Vincennes (Quebec). In particular, the paper shows the comparison among the modulus reduction curve, G/G0 - γ and the damping ratio variation with shear strain, D - γ measured using different devices, trying to highlight the main factors influencing the observed behaviour , including sample disturbance and storing method. The tests were carried out using one torsional shear and two different cyclic simple shear devices capable of investigating from small to large shear strains. The tests were carried out by three different laboratories at the Univer...

Earthquake Spectra

The Central Italy earthquake sequence nominally began on 24 August 2016 with a M6.1 event on a no... more The Central Italy earthquake sequence nominally began on 24 August 2016 with a M6.1 event on a normal fault that produced devastating effects in the town of Amatrice and several nearby villages and hamlets. A major international response was undertaken to record the effects of this disaster, including surface faulting, ground motions, landslides, and damage patterns to structures. This work targeted the development of high-value case histories useful to future research. Subsequent events in October 2016 exacerbated the damage in previously affected areas and caused damage to new areas in the north, particularly the relatively large town of Norcia. Additional reconnaissance after a M6.5 event on 30 October 2016 documented and mapped several large landslide features and increased damage states for structures in villages and hamlets throughout the region. This paper provides an overview of the reconnaissance activities undertaken to document and map these and other effects, and highlig...

This paper presents the seismic risk assessment of L'Aquila gas distribution network in a perform... more This paper presents the seismic risk assessment of L'Aquila gas distribution network in a performance-based earthquake engineering framework. The study was structured in three basic activities: (1) seismic hazard characterization both in terms of ground motion and permanent ground deformation; (2) characterization of system's vulnerability via fragility curves available in literature; (3) performance evaluation in terms of connectivity. In the paper all issues involved in seismic risk analysis of this kind of systems are discussed with respect to a selected part of the whole network. In particular, the importance of modelling spatial correlation of ground motion and geotechnical hazard on risk assessment was investigated. Results indicate that the system performance may be underestimated when spatial correlation and ground failure are ignored. Moreover, the implications of using fragility curves for compressor stations for the reduction cabins, as suggested in literature, were also addressed, and the necessity of developing specific fragilities was pointed out.

Computers and Geotechnics

Computer-Aided Civil and Infrastructure Engineering, 30(7), 508–523, DOI: 10.1111/mice.12105, Jul 2015

The basic function of a gas distribution system, essentially composed of buried pipelines, reduct... more The basic function of a gas distribution system, essentially composed of buried pipelines, reduction stations, and demand nodes, is to deliver gas from sources to end users. The objective of the article is to discuss the evaluation of seismic risk of gas networks in compliance with the performance-based earthquake engineering framework adapted to spatially distributed systems. In particular, three issues are addressed: (1) spatial seismic hazard characterization in terms of ground shaking and permanent ground deformation; (2) analysis of system's vulnerability via fragility curves; (3) seismic performance evaluation via computer-aided simulation. As an application, the seismic risk analysis of L'Aquila (central Italy) gas distribution network, a 621-km mid- and low-pressure pipeline system was considered. The analyses were performed with reference to the mid-pressure part of the network, through an object-oriented software, specific for risk assessment of lifelines, developed by the authors. Results in terms of connectivity-based performance indicators are presented and discussed, along with a performance disaggregation analysis carried out to evaluate the contribution of the components of the system to the risk.

SOILS AND FOUNDATIONS, 1999

抄録 The experimental results reported in this paper were obtained performing monotonic, cyclic and... more 抄録 The experimental results reported in this paper were obtained performing monotonic, cyclic and dynamic torsional shear tests on a stiff Italian clay in the pre-failure stress-strain range. The experimental clearly demonstrate that the small strain values of shear stiffness ...

Geotechnical, Geological and Earthquake Engineering, 2011

On April 6, 2009 an earthquake (M L = 5.8 and M W = 6.3) stroke the city of L'Aquila with MCS Int... more On April 6, 2009 an earthquake (M L = 5.8 and M W = 6.3) stroke the city of L'Aquila with MCS Intensity I=IX and the surrounding village with I as high as XI. The earthquake was generated by a normal fault with a maximum vertical dislocation of 25 cm and hypocentral depth of about 8.8 km. The deaths were about 300, the injured were about 1500 and the damage was estimated as high as about 25 billion €. Both maximum horizontal and vertical components of the accelerations recorded in the epicentral area were close to 0.65g. The paper summarises the activities in the field of earthquake geotechnical engineering aimed to the emergency and reconstruction issues. The ground motion recorded in the epicentral area is analysed; the geotechnical properties measured by in-situ and laboratory tests before and after the earthquake are summarised; site effects are preliminarily evaluated at accelerometric stations locations and damaged villages; the outstanding cases of ground failure are finally shown.