1,721,091 research outputs found
Navigating the Virtual Realm of Hate: Analysis of Policies Combating Online Hate Speech in the Italian-European Context
No full textThe aim of this article is to conduct an in-depth analysis of the effectiveness of policies to counter online hate speech on social platforms. This analysis is approached through an interdisciplinary approach that combines sociological and legal perspectives to provide a non-partisan understanding of the phenomenon. The research consists of two phases: the first phase provides a general framework for the subject under examination, attempting to clearly delineate - on a definitional level - hate speech, emphasising its growing relevance in contemporary social dynamics; the second phase, focuses on an examination of the European value and regulatory framework, with particular reference to the civil law remedies that can be used in the Italian legal system to counteract the spread of online hate speech. This methodology makes it possible to identify the countervailing tools to which private individuals can resort in order to meet the requirements of justice and fairness. In this sense, the article aims to offer a broad overview of the subject matter, providing a contribution to the academic debate and to the understanding of the challenges related to the fight against online hate speech on social networks
Ho's theorem in global-local mode interaction of pin-jointed bar structures
No full textThis paper is focused on the interaction phenomena among a global critical mode and some local Eulerian critical modes in pin-jointed structures. These phenomena are framed within Koiter's theory of elastic instability, by an asymptotic reduction into cubic systems. The aim is to present an algorithm for the appraisal of the lowest critical load characterizing the structure under the effect of small imperfections. First of all, the Ho's theorem, concerning the definition of the most dangerous imperfection, is presented and discussed. Then, a FEM code aimed at the determination of the most dangerous shape for the imperfection, and at performing the related sensitivity analysis, is implemented, by superimposing a proper FE beam model (able to model Eulerian instability) to a non-linear FE model for spatial pin-jointed structures. Some numerical results having a practical interest are presented and discussed. (c) 2005 Elsevier Ltd. All rights reserved
Seismic assessment of a RC case study building using the simple lateral mechanism analysis, SLaMA, method
No full textThe seismic assessment of an existing structure is a complex procedure. In the evaluation of the structural capacity, difficulties arise in the definition of the lateral resisting members, in the estimation of the lateral capacity from component to system level. The identification of the local and global mechanisms, depending on the hierarchy of strength at subassembly level, is a challenging task. Nowadays, advanced numerical analysis procedures, implemented in user-friendly commercial software, are commonly adopted in the current practice to overcome the difficulties in the use of non-linear analyses. Nevertheless, their accuracy strongly depends on the ability of the numerical model to capture all the probable failure mechanisms. To help the user in the assessment of the probable failure mechanism and to have a first estimation of the building lateral capacity, the Simple Lateral Mechanism Analysis (SLaMA) method has been recently developed and included in the NZSEE 2016 guidelines. SLaMA is a simple and reliable "by-hand" tool to derive the local and global mechanism of a structural system and the corresponding capacity curve. This paper deals with the application of the SLaMA to an existing RC building severely damaged during the Christchurch earthquake (2011, New Zealand). The lateral capacity of four 2D resisting systems was assessed following the SLaMA method. The results of a refined nonlinear numerical model were used to assess the accuracy and reliability of SLaMA. The good match confirmed that SLaMA can be a useful and simple tool to have a first estimation of the building lateral response. It allows to identify the main structural weaknesses driving the user to the development of more refined nonlinear models
Non-Linear Dynamic Analysis of Masonry Towers under Natural Accelerograms Accounting for Soil-Structure Interaction
No full textThe object of the paper is the influence of the soil-structure interaction on the dynamic response of masonry towers, for which a high level of stress is involved already in the static field. The relevant deformations and displacements at the base of the tower suggest that a significant volume of ground is engaged into the overall dynamic response, both as a participating mass and as a potential carrier of energy dissipation. In order to investigate this aspect and assess the sensitivity of the dynamic response of the soil-structure system to different soil characteristics, the non linear dynamic response of a case study is analysed, by including in the model a significant volume of foundation soil and considering two different ground types. The numerical model is based on a specific Rigid Body and Springs approach, in which the structure is idealized as a mechanism made of rigid elements connected each to the other by axial and shear springs. The nonlinear behaviour is lumped into the springs assigning proper constitutive laws able to model the significant inelastic aspects of the constitutive behaviour and the meso-scale damage mechanisms with a moderate computational effort. Two types of foundation soil have been considered in order to perform the dynamical analysis accounting for the soil-structure interaction: rock and deposits of compact gravel. For both models, non-linear dynamic analyses have been performed adopting natural records having different characteristics (with regard to the frequency content; distance from the epicentre and type of soil). Some interesting considerations are derived from this comparative study about a problem that is very actual for those who deal with non linear dynamics of structures, but yet is not much explore
Effects of “reinforced” infilled frames on existing RC buildings
No full textThis paper presents some considerations about the role of strengthening interventions involving the solidarization of the infill panels to the RC frame on the seismic retrofitting of existing buildings. Within this context, an appraisal of the actual resulting displacement capacity and of possible alteration induced on the global collapse mechanism and on is provided. Nowadays, it is well-established that infill panels contribute in increasing the overall in-plane resistance to horizontal actions within a variable range of the displacement intervals before they start to degrade. Anyway, in most cases there is also an effect of significant alteration of the overall seismic behaviour and collapse mode, which should be properly taken into account. With reference to a real case study concerning a school building (which was part of a wide vulnerability assessment investigation performed in the Province of Foggia, Italy), an appraisal of the effect of strengthening interventions is here discussed. In particular, the seismic analysis by non linear static procedure has been performed both on the reinforced configuration and on the original structure and critically discussed
Analisi sismica non lineare statica e dinamica di torri campanarie:applicazioni e confronti
No full textLa memoria riguarda la valutazione della vulnerabilità sismica dei campanili in muratura in Italia, che viene eseguita confrontando due metodi non lineari di analisi: analisi dinamica al passo e analisi pushover. Viene considerato un caso di studio ideale, al fine di confrontare la risposta strutturale prevista dai due metodi e valutarne le prestazioni. Il problema è semplificato, usando uno schema 2D piano, ed un modello specifico a masse rigide e molle per descrivere la dinamica nel piano. Le leggi costitutive sono state assegnate seguendo un approccio euristico semplificato, in cui sono contemplati i più significativi meccanismi di danno presenti alla meso-scala: i) resistenza a trazione molto bassa; ii) rilevante ortotropia ed effetti di tessitura in fase post-elastica; iii) diverse regole di danneggiamento assiale e a taglio; iv ) diversa resistenza a taglio a seconda della giacitura considerata (verticale o orizzontale); v) dissipazione isteretica dell’energia indotta dai carichi ciclici. Pur utilizzando una mesh abbastanza rada, il modello risulta
abbastanza ed efficiente, ed è in grado di cogliere anche gli effetti dei modi di vibrare superiori con un ragionevole sforzo computazionale. Analisi statiche non lineari sono state eseguite utilizzando il modello RBSM, ottenendo la curva di capacità e la valutazione della domanda sismica. Un confronto tra i due approcci, si propone, al fine di valutare la differenza di risultati (con particolare attenzione agli effetti danno indotto da modi di vibrazione più elevata) e di valutare la qualità e significatività dei risultati in termini di inconvenienti operativi e riduzione dei tempi di calcolo.The paper concerns the seismic vulnerability assessment of masonry bell towers in Italy, by comparing full non-linear dynamic and non-linear static analysis. An idealized case study is considered, in order to assess some basic and common features of the seismic structural response and to appraise the performance of the proposed approaches. The problem is simplified by using a plane 2D scheme. A specific Rigid Body and Spring Model is adopted to describe the in-plane dynamics. Constitutive laws were assigned following a simplified heuristic approach including the main meso–scale damage mechanisms: i) very low tensile strength; ii) significant post-elastic orthotropy plus texture effects; iii) different rules for post-elastic axial and shear damage; iv) different dependence of the shear strength on the vertical and horizontal axial stress component; v) hysteretic energy dissipation due to cyclic loading. Even using a quite coarse mesh, the model is capable to describe the higher vibration modes with a reasonable computational effort and using realistic accelerograms. Non linear static analysis was performed, by using the RBSM model, obtaining the capacity curve and assessing the seismic demand. A comparison between the two approaches is proposed, in order to appraise the difference in the results and to evaluate quality and significance of results in terms of operational drawbacks and reduction of computational times. Particular attention is devoted to the fact that static non-linear analyses tends to neglect the damage effects induced by higher vibration modes, as well as the influence of the shear response on the global damage
Assessment of the reliability of Structural Concretes During Execution Phases
No full textThe quality control of concrete is basically an assessment of compressive strength from which also depends the durability of the material. In the case of important constructions, the control of design prescriptions is not always easy. In addition to the uncertainty factors related to the composition of the material, there are also factors relating to the construction phases. These problems are amplified if the production is on site. These reasons can often suggest to perform, destructive and non-destructive test after the completion of the structure, in order to obtain further information about in-place concrete strength. These investigations, if accompanied by appropriate evaluation procedures, allow to determine the degree of concrete compaction, that if unsatisfactory, makes the material more permeable, less durable and less mechanically efficient. This paper collects the numerical elaboration of resistances measured on cubes made during the concrete placing and on cores extracted after the completion of the structure, for the concrete used in the construction of the "Esaro" Dam facilities (Cosenza, Italy). In addition to the statistical treatment of the sample, aimed to assess the analytical congruence with the homogeneous classes provided in the design, the influence of compaction degree on in place strength value was qualitatively evaluate, with the aid of an analytical methodology
GIS Multisource Data for the Seismic Vulnerability Assessment of Buildings at the Urban Scale
Full text linkThe paper presents a methodology of extraction, integration and elaboration of data from different sources using the geographic information system (GIS), to realize a georeferenced building database (GBD) useful for the seismic vulnerability assessment of existing buildings on a large scale. Three levels of GIS entities have been defined and equipped with the related information: census section (CS), urban block (UB), and individual building (IB), depending on the level of detail of dataset. Additional information about the typological and structural features has been extracted by CARTIS catalogue, to refine the data associated with each building. The data have been validated using detailed information gathered on a proper sample of buildings, which have been filed and analyzed one-by-one. The alphanumeric format of data allows for the automatic implementation of different methods available in the literature, which provide a qualitative seismic vulnerability index at different scales (whole urban district, an urban block, and a single building). Finally, the 3D representation of data and results have been elaborated, providing a tool easily searchable and constantly implementable. An application has been developed for a case study in Puglia, Italy: Bisceglie, for which 3726 IB have been assessed. The work addresses the issue of the lack of information typical of large-scale applications, exploiting all the available data sources to achieve nearly complete knowledge of existing building stock finalized to a rapid but extensive evaluation of the seismic vulnerability on an urban scale with very low computational efforts and the use of limited resources in terms of time and cost
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