Soil-structure interaction for the seismic design of the Messina Strait Bridge

This paper illustrates an approach to the study of the seismic soil–structure interaction that was developed at the verification stage of the design of the Messina Strait Bridge in order to validate its seismic behaviour. It consisted of a series of two-dimensional, plane strain numerical analyses on models that included, in addition to the embedded foundation elements, a simplified structural description of the bridge towers: simplified structural models were specifically designed to reproduce the first vibrations modes of the towers, that were deemed to have the most significant influence on the system's dynamic response. Non-linear dynamic analyses were carried out in the time domain, studying the effects of two different natural records, each characterised by three orthogonal components of the soil motion. In the first part of the paper, essential information is provided about the foundations layout, the main properties of the foundation soil resulting from the in situ and laboratory investigation, and the assessment of the liquefaction potential. Then, the numerical models are discussed in some detail, with an emphasis on the modelling of the soil and of the structural elements. For sake of conciseness, details are provided only for one of the two shores. The results obtained with the present approach shed some light on the complex coupling between the soil's and the structure's behaviour, evidencing the significant role that the embedded, massive foundations of the bridge play in the dynamic response of the system. The computed time-histories of the displacements of the foundation elements are used to assess the seismic performance of the bridge

The crossing of the historical centre of Roma by the new underground line C: a study of soil-structure interaction for historical buildings

This work deals with the soil structure-interaction problems posed by the construction of the third line of Roma underground (Line C), which, in its central stretch, crosses the historical centre of the city with significant interferences with the archaeological and monumental heritage. The paper describes the methodological approach developed to evaluate the effects of tunnelling on the existing monuments and historical buildings, starting from a careful geotechnical and structural characterisation and including the development of reliable geotechnical and structural models. Experts in several disciplines were committed to this multidisciplinary work, ranging from geologists to geotechnical and structural engineers, archaeologists, and professionals working in the field of conservation and restoration of works of art and monuments. The study of the interaction between the construction activities and the built environment was carried out following procedures of increasing level of complexity, from green field analyses, in which the stiffness of the existing buildings was neglected, to full soil-structure interaction analyses, performed in both two- and three-dimensional conditions, accounting for the stiffness of existing buildings and considering possible long-term effects. The paper illustrates the main aspects of this procedure, using the example case studies of the Basilica di Massenzio and of the building of the Amministrazione Doria Pamphili

Predicting the seismic behaviour of the foundations of the Messina Strait Bridge

This paper presents some of the geotechnical studies carried out for the seismic design of the one-span suspension bridge across the Messina Strait, that is to connect Sicily with mainland Italy. These studies included advanced geotechnical characterisation, through in situ and laboratory tests, estimate of site stability involving both liquefaction analysis and submerged slope stability, evaluation of soil-foundation stiffness for spectral analysis of the superstructure, 3D FE static calculations, evaluation of anchor block performance under seismic conditions, and full dynamic analyses of the soil-structure interaction. The paper summarises the main results obtained from the geotechnical characterisation of the foundation soils, reports the approach adopted for evaluating the seismic performance of the anchor blocks through a modified Newmark-type calculation, and presents the study of the soil-structure interaction carried out through a series of two-dimensional, plane strain numerical analyses. In these analyses, in addition to the embedded foundation elements, the models included a simplified structural description of the bridge towers specifically designed to reproduce their first vibrations modes, that were deemed to have the most significant influence on the system's dynamic response. The illustration is limited to the foundation systems of the bridge located on the Sicily shore

A simplified procedure for the evaluation of the seismic performance of bridge piers on caisson foundations

In this paper, a simplified procedure for the evaluation of the seismic performance of bridge piers founded on caissons subjected to strong ground motions is outlined. To this end, the up-per-bound semi-empirical relationships proposed in [1] are considered for the estimation of the seismic performance, expressed in terms of the maximum and permanent values of the deck drift ratio attained during and at the end of the seismic event. These drifts were related to the period ratio Teq/T0 between the fundamental periods of the deck-pier-caisson-soil sys-tem and of the soil column in free-field conditions. The deck drift and the period ratios were extracted from the results of an extensive parametric study, where 14 different systems were subjected to 6 real high-intensity seismic records. In the parametric study, 3D dynamic anal-yses were performed with the Finite Element Method in the time domain, in terms of effective stresses but assuming undrained conditions and adopting an elastic-plastic constitutive model to reproduce the irreversible soil behaviour under cyclic loading. As 3D dynamic numerical analyses are not expected to become an every-day design tool, the period ratios Teq/T0 are evaluated through empirical and analytical relationships available in the literature as well and then compared with the ratios obtained from the parametric study, to assess the possibil-ity of using simplified relationships while still getting a reliable estimate of the deck drift ra-tio. It is shown that these relationships can be profitably adopted provided that a fair estimate of the equivalent shear wave velocity, depending on the intensity of the seismic inputs, is used

Assessment of Tunneling Induced Damage on Historical Constructions Through a Fully Coupled Structural and Geotechnical Approach

The development of urban mobility implies the construction of tunnels, often interacting with valuable historical structures. It is thus necessary to develop rational and reliable procedures to estimate the potential excavation-induced damage, dealing with complex soil-structure interaction problems. Classical approaches are often characterised by relatively simple schematisations for either one or both components of the problem, as, for example, springs for the soil or equivalent plates for the structure. Such simplified assumptions prove to be appropriate for simple soil-foundation cases, while show several limitations when tackling more complex problems, as those involving the excavation in the vicinity or beneath historical masonry structure. In such cases, the need for reliable prediction of the potential damage on surface structures induced by construction activities justifies the adoption of advanced numerical approaches. These need to be based on realistic constitutive assumptions for both soils and masonry elements and require the definition of the three-dimensional geometry as well as an accurate modelling schematisation of the excavation process. In this paper a 3D Finite Element approach is proposed to model in detail the excavation of twin tunnels, accounting for the strongly non-linear soil behaviour, interacting with monumental masonry structures, carefully modelling their geometry and non-linear anisotropic mechanical behaviour. The work focuses on a specific case-study related to the ongoing construction of the line C of Rome underground

La mitigazione degli effetti indotti dallo scavo di gallerie mediante l’uso di barriere preinstallate: il caso della linea C della metropolitana di Roma

La rete di trasporti pubblici della città di Roma è attualmente in via di potenziamento con la costruzione della terza linea della metropolitana, la linea C. Questa sottopassa il centro storico della città con significative interferenze con monumenti ed edifici esistenti di inestimabile valore storico e artistico. Ciò ha determinato l’adozione di particolari misure di salvaguardia per prevenire danni ai manufatti più vulnerabili. A tale scopo, per verificare l’efficienza di barriere preinstallate per la riduzione degli effetti indotti dallo scavo di gallerie, è stato predisposto un campo prova con una barriera costituita da una fila di pali accostati nel tratto di linea tra le stazioni di Amba Aradam e San Giovanni, vicino a una sezione di monitoraggio di campo libero. In questa nota sono mostrati i dati di monitoraggio registrati nella sezione di campo libero e in quella in cui è presente la barriera. Le misure in sito sono state quindi interpretate con un’analisi a ritroso svolta con il metodo degli elementi finiti, utilizzando tre procedure 2D di simulazione dello scavo della galleria

Indici di prestazione sismica per le dighe in terra

I dati disponibili in letteratura mostrano che lo spostamento verticale della cresta delle dighe in terra può essere assunto come indice rappresentativo della prestazione sismica complessiva della diga e del più ampio sistema di cui essa fa parte. Tale parametro è infatti ben correlato al livello di danno indotto da un evento sismico e all’eventuale superamento di una condizione limite che configura la perdita di funzionalità della diga o dell’impianto. In questo articolo è stato esaminato un ampio insieme di dati di letteratura, relativi ai danni indotti da eventi sismici su varie tipologie di dighe, per individuare diverse classi di danno e le possi-bili condizioni limite raggiunte dalla diga o dall’impianto. Le distribuzioni dei valori dello spostamento verti-cale della cresta, corrispondenti a ognuna delle classi di danno esaminate, sono poi state utilizzate per indivi-duare valori di soglia che configurano l’insorgere di un dato stato limite

Conditioned task-set competition:Neural mechanisms of emotional interference in depression

Depression has been associated with increased response times at the incongruent, neutral, and negative-word trials of the classical and emotional Stroop tasks (Epp et al., 2012). Response time slow-down effects at incongruent and negative-word trials of the Stroop tasks were reported to correlate with depressive severity, indicating strong relevance of the effects to the symptomatology. The current study proposes a novel integrative computational model of neural mechanisms of both the classical and the emotional Stroop effects, drawing on the previous prominent theoretical explanations of performance at the classical Stroop task (Cohen et al., 1990; Herd et al., 2006), and in addition suggesting that negative emotional words represent conditioned stimuli for future negative outcomes. The model is shown to explain the classical Stroop effect and the slow (between-trial) emotional Stroop effect with biologically-plausible mechanisms, providing an advantage over the previous theoretical accounts (Matthews and Harley, 1996; Wyble et al., 2008). Simulation results suggested a candidate mechanism responsible for the pattern of depressive performance at the classical and the emotional Stroop tasks. Hyperactivity of the amygdala, together with increased inhibitory influence of the amygdala over dopaminergic neurotransmission, could be at the origin of the performance deficits

Rehabilitative treatment of patients with covid-19 infection: The p.a.r.m.a. evidence based clinical practice protocol

Background: The impact of the SARS-CoV-2 on the National Health System (NHS) required a reorganization of the various levels of care, which also involved the rehabilitation reality. Aim of the work: A clinical practice review of the literature was conducted to provide operational-rehabilitation guidelines adapt-ed to the local reality and to the recent corporate reorganization in the context of the COVID-19 emergency. Methods: A practice review of the available scientific evidence was regularly conducted from the start of the COVID-19 pandemic to periodically update the clinical practice guidelines. Articles that met the following inclusion criteria were included: studies conducted on human adult subjects with COVID-19 infection, un-dergoing rehabilitation in any hospitalization setting. Results: The results of this clinical practice update were periodically discussed with colleagues and collaborators in a multi-professional team, in order to guarantee a good clinical practice protocol, named P.A.R.M.A. Conclusions: The P.A.R.M.A. protocol is the result of a periodic review literature update, which has allowed us to take charge of patients affected by COVID-19 ac-cording to the most up-to-date clinical evidences, guaranteeing a shared and uniform treatment within a local reality in an era of health emergency. (www.actabiomedica.it)