IUSS Pavia

Pavia, Italy

IUSS Pavia

Pavia, Italy

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De Luca A.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Salvaterra R.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Tiengo A.,IUSS Pavia | D'Agostino D.,CNR Institute for Applied Mathematics and Information Technologies | And 3 more authors.
Astrophysics and Space Science Proceedings | Year: 2016

The EXTraS project (“Exploring the X-ray Transient and variable Sky”) will characterise the temporal behaviour of the largest ever sample of objects in the soft X-ray range (0.1–12 keV) with a complex, systematic and consistent analysis of all data collected by the European Photon Imaging Camera (EPIC) instrument onboard the ESA XMM-Newton X-ray observatory since its launch.We will search for, and characterize variability (both periodic and aperiodic) in hundreds of thousands of sources spanning more than nine orders of magnitude in time scale and six orders of magnitude in flux. We will also search for fast transients, missed by standard image analysis. Our analysis will be completed by multiwavelength characterization of new discoveries and phenomenological classification of variable sources. All results and productswill be made available to the community in a public archive, serving as a reference for a broad range of astrophysical investigations. © Springer International Publishing Switzerland 2016.


Welch D.P.,ROSE Programme | Sullivan T.J.,University of Pavia | Calvi G.M.,IUSS Pavia
Journal of Earthquake Engineering | Year: 2014

Various loss assessment methodologies have been proposed and developed over the past decades to provide risk assessment on a regional scale. There is an increasing need, however, to provide engineers with practical tools for building-specific loss assessment. Recently, progress has been made towards probabilistic loss models such as the PEER framework. However, as comprehensive probabilistic methodologies could be too complex for practicing engineers, this article presents a simplified probabilistic loss assessment methodology that builds on a direct displacement-based framework. The methodology is tested via examination of two RC frame buildings and encouragingly shows similar results to the PEER methodology. © 2014 Copyright A. S. Elnashai.


Sullivan T.J.,University of Pavia | Sullivan T.J.,European Center for Training and Research in Earthquake Engineering | Welch D.P.,UME School | Calvi G.M.,IUSS Pavia
Earthquake Engineering and Engineering Vibration | Year: 2014

The last decade or so has seen the development of refined performance-based earthquake engineering (PBEE) approaches that now provide a framework for estimation of a range of important decision variables, such as repair costs, repair time and number of casualties. This paper reviews current tools for PBEE, including the PACT software, and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore, proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed, highlighting needs for future research. To illustrate the potential of the methodology, performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework, applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations.


Zelaschi C.,IUSS Pavia | Monteiro R.,IUSS Pavia | Pinho R.,University of Pavia
COMPDYN 2015 - 5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering | Year: 2015

When carrying out loss assessment of a road network within a certain region, the characterization of the vulnerability of the existing population of bridges is one of the most relevant aspects. To such extent, in the last decades, the engineering community has recognised fragility curves as one of the fundamental and most effective tools in seismic risk assessment, correlating the probability of exceeding of specific limit states, which can instead be correlated with damage and loss, for different levels of intensity measures (IMs). The available literature mainly provides such curves as function of peak ground acceleration (PGA) or spectral acceleration (Sa), often preferred for the availability of national hazard information in terms of such parameters. However, when dealing with a bridge population of reinforced concrete bridges, Fajfar Index, peak ground velocity and root mean square velocity have been recently identified as the most promising intensity measures, in terms of efficiency, proficiency and sufficiency, notwithstanding the acceptable performance of PGA and Sa. As such, this paper intends to further extend the analysis of RC populations of bridges by providing a statistically sound comparison of analytical fragility curves based on traditional and innovative intensity measures of an extensive bridge population. Nonlinear static analyses of 3D RC bridge models are carried out. The bridge population is randomly generated using Latin Hypercube sampling in order to include geometrical variability, in addition to aleatory and epistemic uncertainties. For what concerns the seismic ground motion, a proper selection of records was performed, according to a recent selection and scaling procedure (Conditional Spectrum Method).


Milanesi R.R.,IUSS Pavia | Morandi P.,University of Pavia | Magenes G.,University of Pavia | Binici B.,Middle East Technical University
COMPDYN 2015 - 5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering | Year: 2015

Unreinforced masonry non-structural infills in RC structures are widely used in many countries. However, they are often designed with simplified methods which do not consider accurately their interaction with the structure. The limitation of their damage induced by earthquakes is of major interest for the prevention of extensive economic losses and possible threats to human lives. During the last decades several researches have been accomplished all around the world, and many different aspects have been investigated. The increasing interest on masonry infill is due to both the observation of unsatisfactory behaviour of infilled frame structures after real earthquakes and the difficulty to reach a widely scientifically recognized solution. Even if measures for the prevention of infill damage are to some extent included in modern seismic design code, an effective design procedure has not yet been achieved. The object of this study is to perform a numerical Finite Element Model simulation of a reinforced concrete frame specimen infilled with unreinforced Autoclaved Aerated Concrete masonry infill, in order to be able to study accurately the influence and the interaction of the non-structural wall to the reinforced concrete frame. A meso-modelling approach has been followed and the calibration has been performed according to the results of in-plane cyclic tests on single bay - single storey bare and infilled frames which have been carried out at the Department of Civil Engineering and Architecture of the University of Pavia [1, 3]. In order to obtain the parameters of the infill material, the numerical simulation has been performed, in first instance, with reference to tests of mechanical characterization and to inplane cyclic tests on load-bearing AAC masonry, similar to the one used for the infill [2, 3]. The model has been validated via non-linear static analyses. Moreover, the change in moment and shear demands on the RC members of the frame due to the influence of the presence of the infill as respect to the bare frame condition has also been investigated.


Calvi G.M.,IUSS Pavia | Sullivan T.J.,University of Pavia | Welch D.P.,ROSE Programme
Geotechnical, Geological and Earthquake Engineering | Year: 2014

Several performance measures are being used in modern seismic engineering applications, suggesting that seismic performance could be classified a number of ways. This paper reviews a range of performance measures currently being adopted and then proposes a new seismic performance classification framework based on expected annual losses (EAL). The motivation for an EAL-based performance framework stems from the observation that, in addition to limiting lives lost during earthquakes, changes are needed to improve the resilience of our societies, and it is proposed that increased resilience in developed countries could be achieved by limiting monetary losses. In order to set suitable preliminary values of EAL for performance classification, values of EAL reported in the literature are reviewed. Uncertainties in current EAL estimates are discussed and then an EAL-based seismic performance classification framework is proposed. The proposal is made that the EAL should be computed on a storey-by-storey basis in recognition that EAL for different storeys of a building could vary significantly and also recognizing that a single building may have multiple owners. A number of tools for the estimation of EAL are reviewed in this paper and the argument is made that simplified methods for the prediction of EAL are required as engineers transition to this new performance parameter. In order to illustrate the potential value of an EAL-based classification scheme, a three storey RC frame building is examined using a simplified displacement-based loss assessment procedure and performance classifications are made for three different retrofit options. The results show that even if only limited non-structural interventions are made to the case study, the EAL could be significantly reduced. It is also argued that overall, such a performance classification, coupled with some form of government or insurance-driven incentive scheme, may provide an effective means of reducing the risk, and increasing the resilience, of our societies. © The Author(s) 2014.


Sullivan T.J.,University of Pavia | Lago A.,IUSS Pavia
Engineering Structures | Year: 2012

In this paper a new methodology for the Direct displacement-based seismic design (DBD) of moment resisting frame (MRF) structures fitted with viscous dampers is proposed. The approach builds on previous recommendations for Direct DBD and gives the designer a simplified non-iterative means of controlling the system damping of the structures by choosing proportions of force resisted by the dampers relative to the main structure. Non-linear time-history analyses of a 9-storey case study structure fitted with linear viscous dampers illustrate that the new procedure may prove to be very useful for design. Future research should aim to better verify the approach and extend it to the use of frames possessing non-linear viscous dampers. © 2011 Elsevier Ltd.


Beigi H.A.,University of Toronto | Christopoulos C.,University of Toronto | Sullivan T.,University of Pavia | Calvi G.M.,IUSS Pavia
Journal of Structural Engineering (United States) | Year: 2014

Although soft-story mechanisms are generally undesirable for the seismic response of building structures, they provide potential benefits caused by the isolating effect they produce for the stories located above. In this paper, an approach for enhancing the seismic response of soft-story structures is proposed that takes advantage of the positive aspects of their response while mitigating the negative ones. To this end, an additional gapped-inclined brace (GIB) is introduced to reduce the impact of P-Delta effects on the displacement demands and to increase the deformation capacity of existing columns in soft stories without significantly increasing their lateral resistance. The mechanics of the proposed system are first defined, and theoretical relations and numerical models are then derived to verify the response. The cyclic behavior of a single-degree-of-freedom single-bay RC frame is then investigated numerically to illustrate the effect of the retrofitted system on the global response of a structure. The analytical results indicate that the hysteretic response of the retrofitted system is highly improved in terms of the energy dissipation and the residual deformation while not significantly increasing the overall strength of the structure. Although the equations governing the response of the system are derived for a single story, the concept is primarily intended to be applicable to multistory buildings. © 2014 American Society of Civil Engineers.


Caminiti S.P.,San Raffaele Scientific Institute | Siri C.,Parkinson Institute | Guidi L.,IUSS Pavia | Antonini A.,Irccs Hospital San Camillo | And 3 more authors.
Behavioural Neurology | Year: 2015

This fMRI study deals with the neural correlates of spatial and objects working memory (SWM and OWM) in elderly subjects (ESs) and idiopathic Parkinson's disease (IPD). Normal aging and IPD can be associated with a WM decline. In IPD population, some studies reported similar SWM and OWM deficits; others reported a greater SWM than OWM impairment. In the present fMRI research, we investigated whether compensated IPD patients and elderly subjects with comparable performance during the execution of SWM and OWM tasks would present differences in WM-related brain activations. We found that the two groups recruited a prevalent left frontoparietal network when performing the SWM task and a bilateral network during OWM task execution. More specifically, the ESs showed bilateral frontal and subcortical activations in SWM, at difference with the IPD patients who showed a strict left lateralized network, consistent with frontostriatal degeneration in IPD. The overall brain activation in the IPD group was more extended as number of voxels with respect to ESs, suggesting underlying compensatory mechanisms. In conclusion, notwithstanding comparable WM performance, the two groups showed consistencies and differences in the WM activated networks. The latter underline the compensatory processes of normal typical and pathological aging. © 2015 Silvia P. Caminiti et al.


PubMed | IUSS Pavia, San Raffaele Scientific Institute, Irccs Hospital San Camillo, Vita-Salute San Raffaele University and Parkinson Institute
Type: | Journal: Behavioural neurology | Year: 2015

This fMRI study deals with the neural correlates of spatial and objects working memory (SWM and OWM) in elderly subjects (ESs) and idiopathic Parkinsons disease (IPD). Normal aging and IPD can be associated with a WM decline. In IPD population, some studies reported similar SWM and OWM deficits; others reported a greater SWM than OWM impairment. In the present fMRI research, we investigated whether compensated IPD patients and elderly subjects with comparable performance during the execution of SWM and OWM tasks would present differences in WM-related brain activations. We found that the two groups recruited a prevalent left frontoparietal network when performing the SWM task and a bilateral network during OWM task execution. More specifically, the ESs showed bilateral frontal and subcortical activations in SWM, at difference with the IPD patients who showed a strict left lateralized network, consistent with frontostriatal degeneration in IPD. The overall brain activation in the IPD group was more extended as number of voxels with respect to ESs, suggesting underlying compensatory mechanisms. In conclusion, notwithstanding comparable WM performance, the two groups showed consistencies and differences in the WM activated networks. The latter underline the compensatory processes of normal typical and pathological aging.

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