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

Low 25-OH vitamin D levels at time of diagnosis and recurrence of ovarian cancer.

The objective of this study was to evaluate the correlation between 25-OH vitamin D and ovarian cancer as a diagnostic marker or recurrence disease marker. We studied the following: (1) 61 women without gynecologic diseases, (2) 45 women affected by benign ovarian disease, (3) 46 women with recent diagnosis of ovarian cancer, (4) 26 follow-up women with recurrent ovarian cancer, and (5) 32 follow-up women with stable ovarian cancer. The 25-OH vitamin D was quantified with LUMIPULSE® G 25-OH vitamin D on LUMIPULSE® G 1200 (Fujirebio, Japan). As a threshold value, identified by ROC curve analysis, 20.2 ng/mL (sensitivity 73.3 %, specificity 84 %) was chosen corresponding to the limit between sufficient and insufficient 25-OH vitamin D according to the WHO. Low 25-OH vitamin D levels were observed in 26 % of women without gynecologic diseases, in 80 % of women with recent diagnosis of ovarian cancer and in 24 % women affected by benign ovarian diseases (p < 0.001). The follow-up study showed an insufficient level of 25-OH vitamin D in 73 % women with recurrent ovarian cancer and in 47 % women with stable ovarian cancer (p < 0.0003). This study showed that patients with ovarian cancer are often insufficient in 25-OH vitamin D compared to women with benign ovarian diseases. The women with recurrent ovarian cancer presented more often low levels compared to women with stable ovarian cancer. This study suggests that 25-OH vitamin D, due to its antiproliferative properties, can be a good marker for ovarian cancer also

Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Numerical simulation of the heat penetration in two-plate arc welding

A mathematical model and numerical simulation of the three-dimensional and transient metal arc-welding process is presented. The heat source is considered as spatially distributed following a centered Gaussian bell, while the substract material (Al 6063) is assumed homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are also calculated through an empirical temperature dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Calculations were performed by using a finite volume code (CFX4.2TM). Computed heat penetration and weld metal area are found to be in good agreement with experimental data

Study of the transient temperature profiles induced by changes of the welding parameters during aluminium two plate arc butt-welding

The numerical study and calculation of transient temperatures developing during the arc-welding process of 6063 T5 aluminum plates is presented. The mathematical model is based on the differential energy conservation equation. The governing equation is solved via numerical simulation using the finite control volume method to obtain the three dimensional and transient temperature profiles induced during the welding process. The moving heat source is considered as represented by a centered Gaussian-Bell distribution, while the base material is assumed to be homogeneous and isotropic with temperature-dependent thermal properties. Radiation and convection are computed and introduced into the model through the boundary conditions as an empirical temperature-dependent correlation. Phase-change phenomenon is included as a discontinuity in the material specific heat. Computed results show the influence of the variation of the welding parameters such as the arc power and welding speed on the computed transient temperatures, penetration and process efficienc

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

Interactive management control via analytic hierarchy process (AHP). An empirical study in a public university hospital.

Management control in public university hospitals is a challenging task because of continuous changes due to external pressures (e.g. economic pressures, stakeholder focuses and scientific progress) and internal complexities (top management turnover, shared leadership, technological evolution, and researcher oriented mission). Interactive budgeting contributed to improving vertical and horizontal communication between hospital and stakeholders and between different organizational levels. This paper describes an application of Analytic Hierarchy Process (AHP) to enhance interactive budgeting in one of the biggest public university hospital in Italy. AHP improved budget allocation facilitating elicitation and formalization of units’ needs. Furthermore, AHP facilitated vertical communication among manager and stakeholders, as it allowed multilevel hierarchical representation of hospital needs, and horizontal communication among staff of the same hospital, as it allowed units’ need prioritization and standardization, with a scientific multi-criteria approach, without using complex mathematics. Finally, AHP allowed traceability of a complex decision making processes (as budget allocation), this aspect being of paramount importance in public sectors, where managers are called to respond to many different stakeholders about their choices

Bedaquiline in MDR/XDR-TB cases: first experience on compassionate use

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Centrifuge modelling of the behaviour of pile groups under vertical eccentric load

Annular shaped pile groups are a very common foundation layout for onshore wind turbines and other slender structures. In this study, their performance under vertical loads of moderate to high eccentricity, including moment rotation response and bearing capacity, was investigated by centrifuge testing on small scale physical models embedded in kaolin clay. To identify experimentally the capacity of the examined pile groups under different load paths, the model foundations were loaded monotonically until a clear collapse mechanism was achieved. The testing procedure and the proposed interpretation methodology can be easily adapted to load paths or pile layouts other than those considered in the current study. The experimental data can be adopted as a useful benchmark for mathematical models aimed at predicting the response of pile groups to complex load paths. The results of this testing program can also be used to assess the degree of conservatism of current methods adopted by industry for the design of piled foundations subjected to eccentric loads