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

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

Interaction Between Tunnel Excavations and Historical Structures in Rome: A Fully Coupled Structural and Geotechnical Approach

In this paper we propose a 3D Finite Element (FE) approach to model 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

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

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

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)

Are old-old patients with major depression more likely to relapse than young-old patients during continuation treatment with escitalopram?

<p>Abstract</p> <p>Background</p> <p>Escitalopram has shown efficacy and tolerability in the prevention of relapse in elderly patients with major depressive disorder (MDD). This <it>post-hoc </it>analysis compared time to relapse for <it>young-old </it>patients (n = 197) to that for <it>old-old </it>patients (n = 108).</p> <p>Method</p> <p>Relapse prevention: after 12-weeks open-label treatment, remitters (MADRS ≤12) were randomised to double-blind treatment with escitalopram or placebo and followed over 24-weeks. Patients were outpatients with MDD from 46 European centers aged ≥75 years (<it>old-old</it>) or 65-74 years of age (<it>young-old</it>), treated with escitalopram 10-20mg/day. Efficacy was assessed using the Montgomery Åsberg Depression Rating Scale (MADRS).</p> <p>Results</p> <p>After open-label escitalopram treatment, a similar proportion of <it>young-old </it>patients (78%) and <it>old-old </it>patients (72%) achieved remission. In the analysis of time to relapse based on the Cox model (proportional hazards regression), with treatment and age group as covariates, the hazard ratio was 4.4 for placebo <it>versus </it>escitalopram (χ²-test, df = 1, χ²= 22.5, p < 0.001), whereas the effect of age was not significant, with a hazard ratio of 1.2 for <it>old-old </it>versus <it>young-old </it>(χ²-test, df = 1, χ²= 0.41, p = 0.520). Escitalopram was well tolerated in both age groups with adverse events reported by 53.1% of <it>young-old </it>patients and 58.3% of <it>old-old </it>patients. There was no significant difference in withdrawal rates due to AEs between age groups (χ²-test, χ²= 1.669, df = 1, p = 0.196).</p> <p>Conclusions</p> <p><it>Young-old </it>and <it>old-old </it>patients with MDD had comparable rates of remission after open-label escitalopram, and both age groups had much lower rates of relapse on escitalopram than on placebo.</p

Bupropion Increases Selection of High Effort Activity in Rats Tested on a Progressive Ratio/Chow Feeding Choice Procedure: Implications for Treatment of Effort-Related Motivational Symptoms

Background: Depression and related disorders are characterized by deficits in behavioral activation, exertion of effort, and other psychomotor/motivational dysfunctions. Depressed patients show alterations in effort-related decision making and a bias towards selection of low effort activities. It has been suggested that animal tests of effort-related decision making could be useful as models of motivational dysfunctions seen in psychopathology. Methods: Because clinical studies have suggested that inhibition of catecholamine uptake may be a useful strategy for treatment of effort-related motivational symptoms, the present research assessed the ability of bupropion to increase work output in rats responding on a test of effort-related decision-making (ie, a progressive ratio/chow feeding choice task). With this task, rats can choose between working for a preferred food (high-carbohydrate pellets) by lever pressing on a progressive ratio schedule vs obtaining a less preferred laboratory chow that is freely available in the chamber. Results: Bupropion (10.0–40.0 mg/kg intraperitoneal) significantly increased all measures of progressive ratio lever pressing, but decreased chow intake. These effects were greatest in animals with low baseline levels of work output on the progressive ratio schedule. Because accumbens dopamine is implicated in effort-related processes, the effects of bupropion on markers of accumbens dopamine transmission were examined. Bupropion elevated extracellular dopamine levels in accumbens core as measured by microdialysis and increased phosphorylated dopamine and cyclic-AMP related phosphoprotein 32 kDaltons (pDARPP-32) immunoreactivity in a manner consistent with D1 and D2 receptor stimulation. Conclusion: The ability of bupropion to increase exertion of effort in instrumental behavior may have implications for the pathophysiology and treatment of effort-related motivational symptoms in humans