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An integral equation for damage identification of Euler-Bernulli beams under static loads
No full textOn the definition of seismic vulnerability maps in cross-border Mediterranean areas
Get PDFThe chance to locate and quantify the major risks associated to natural catastrophic events on a territory allows to plan adequate strategies and interventions by civil protection bodies involved in local and international emergencies. The seismic risk depends most of all by the vulnerability of buildings belonging to the urban areas. For this reason the definition, by a deep analysis of the territory, of instruments identifying and locating vulnerability, largely favours the activities of institutions appointed to safeguard the safety of citizens. Seismic and hydro-geological risks constitute the major component of the activities involving assistance actions carried out by civil protection bodies because of their repetitiveness and the amount of human resources needed to face the emergencies. The possible coordinate action and cooperation between different countries is fundamental importance, especially if the procedures are based on standardized rules and civil protection plans are characterized by consciousness of the territory and the associated risks. The promptness of the response is basic for the success of the operations. This feature is however not only achievable by practice exercises aimed to implement a responsiveness system to emergencies, but also through a deep understanding of the existing risks and the major exposure recognized for the urbanized contexts. The challenge for the assessment of seismic vulnerability of buildings is not easy because it involves a large amount on constructions to investigate in a reasonable time. Several researchers, based on the post processing of data coming from the observation of damaged buildings, proposed simplified relationship linking a vulnerability index with the intensity of a seismic event (Benedettini and Petrini (1984), Braga et al. (1984), Angeletti et al. (1988), Casolo et al. (1993). In other studies the interest has been addressed to the definition of fast assessment methods for the vulnerability index and the relative large scale application (Martinelli et al. (1999), Dolce et al. (2004), Dolce and Moroni (2005), Dolce and Martinelli (2005). In this summary the outputs of the activity carried out within the research project "SIMITDevelopment of an integrated cross-border Italian-Maltese civil protection network" are presented with specific reference to the assessment of the seismic vulnerability of buildings and definition of vulnerability maps in terms of vulnerability index and peak ground acceleration limit values. In agreement with the scope of the paper, the criteria adopted for the assessment of vulnerability and definition of the vulnerability maps were calibrated to provide reliable predictions for typically small urban contexts, which are largely widespread in Mediterranean area. The representative test site selected for the activities was the city centre of the island of Lampedusa. The choice was particularly suitable for the prefixed purposes because of the opportunity to operate on a large quantity of buildings concentrated in a small area with and characterized by a repetitiveness of the constructive typology. The final gaol was to develop a standard procedure for the assessment of seismic vulnerability of small urban contexts widespread in the Mediterranean. The specific research activity carried out on the island has been divided in 4 phases, characterized by a progressive level of depth of the analysis, listed below: • Historical, critical, and typological analysis of the urban centre and typical buildings; • Simplified assessment of seismic vulnerability of buildings by standard vulnerability forms; • Choice and validation of a vulnerability model; Definition of fragility functions and vulnerability maps. The historical-critical study was aimed at the recognition of the urban evolution of the city centre of Lampedusa over the time and of the regulations succeeded which have changed the constructive and typological framework of buildings. The subsequent typological analysis of the buildings, performed through several surveys, made it possible to categorize the recurring structural types within the city centre of the island and their similarities and differences in relation to periods of construction. Such preliminary activities permitted to collect fundamental information, necessary for a fast and effective assessment of the buildings vulnerability, carried out by the use of evaluation forms already known in the literature and commonly used in Italy (GNDT (1994)) for the fast assessment of the vulnerability single buildings and building aggregates. The major output coming from the use of such kinds of vulnerability evaluation forms is constituted by possibility to determine a numerical vulnerability index, suitable to be adopted for the definition of the vulnerability maps. The definition of the fragility curves, which provide a relationship between the intensity of the seismic event (synthetically represented by the Peak Ground Acceleration) and the structural damage, passes through a preliminary calibration, necessary to adapt the vulnerability model (index of vulnerability vs. PGA) to the characteristic building context. In the current study, the calibration operations were performed by an experimental dynamic monitoring campaign on two prototype buildings, followed by the realization of the numerical structural models consistent with the experimental results. The seismic assessment of the prototype buildings by static pushover analysis made it possible the determination of the critical PGA values to be linked with indexes of vulnerability previously evaluated, in order to adapt the vulnerability model to the urban context of the island of Lampedusa. The final outputs are the fragility curves and the associated vulnerability maps for the urban area of Lampedusa, presented in terms of index of vulnerability and critical peak ground accelerations
A correction method for the analysis of continuous linear one-dimensional systems under moving loads
No full textA new correction procedure for dynamic analysis of linear, proportionally damped, continuous systems under traveling concentrated loads is proposed; both cases of non-parametric (moving forces) and parametric (moving mass) loads are considered. Improvement in the evaluation of the dynamic response is obtained by separating the contribution of the low-frequency (LF) modes from that of the high-frequency (HF) modes. The former is calculated, as usual, by classical modal analysis, while the latter is taken into account using a new series expansion of the corresponding particular solution. The advantage of the suggested method is immediately shown in the calculation of the stress distribution since it is able to capture the stress discontinuities due to the nature of the applied loads themselves. Numerical results are presented to discuss the convergence of the proposed series and to show the accuracy of the calculated response compared to the classical series expansion solutio
A correction method for dynamic analysis of linear continuous systems
No full textA method to improve the dynamic response analysis of continuous classically damped linear system is proposed. As in fact usually, following a classical approach, a reduced number of eigenfunctions are accounted for and the response is evaluated by integrating the uncoupled differential equations of motion in modal space, neglecting the contribution of high frequency modes (truncation procedure). Here, starting from the given system, it is proposed to set up two differential equations governing the motion of two new continuous systems: the first one contains only the first m non-zero eigenvalues of the given system and the second one contains the remainder non-zero infinity - m eigenvalues. By summing up the response of the two aforementioned systems it is proven that the global response is recovered. Then, the response of the first system is evaluated by classical dynamic methods (Duhamell integral or step-by-step integration procedures), while the particular solution of the second one is obtained in series form that is shown to converge quickly
Compressive strength of solid clay brickwork: calibration of experimental tests
No full textThe assessment procedures for masonry structures require some mechanical parameter to be defined for masonry, at least the compressive strength. Several theoretical approaches, based on the characteristics of the constituents, i.e. bricks and mortar, have been developed but their application to existing masonry turns out to be rather difficult. Therefore, experimental approaches give a fundamental contribution to the identification of the mechanical parameters provided that proper calibration allows a reliable estimation of the experimental error. In this paper, the calibration of compressive tests on large diameter cylinders, drilled from brickwork and loaded on the lateral surfaces, is discussed on the bases of both experimental and theoretical issues. This technique is shown to reproduce the brickwork collapse mechanism, giving reliable estimates of the masonry compressive strengt
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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