1,720,966 research outputs found
Application of seismic design procedures on three modern URM buildings struck by the 2012 Emilia earthquakes: inconsistencies and improvement proposals in the European codes
No full textThe seismic performance of three modern unreinforced masonry buildings struck by the earthquake sequence of May 2012 in Emilia (Italy) has been investigated, to define the safety margins and possible critical issues in the seismic design according to the European seismic codes. The selected structures have been redesigned, applying linear and static nonlinear analyses, and verified against collapse according to both Eurocodes 6 and 8 and Italian Norms for Constructions. The design has provided inconsistent results, in particular with the application of Eurocodes, where none of the three buildings fulfilled the safety checks even at very low lateral action, although two of these structures did not attain any visible damage after the events of May 2012. The requirements of the Italian seismic code have provided, at least for static nonlinear analyses, results more in line with the actual seismic response of the buildings. The main issues and some proposals for the improvement of the codified procedures for seismic design of unreinforced masonry buildings are finally discussed
A comparative study on a complex URM building: part I—sensitivity of the seismic response to different modelling options in the equivalent frame models
No full textThe paper presents the comparison of the results of nonlinear static analyses carried out using six software packages (SWs) available at professional level and operating in the field of the equivalent frame (EF) approach on a model representative of a complex masonry building. The structure is inspired by the school “P. Capuzi” in Visso (MC, Italy), proposed as one of the benchmark structures in the “URM nonlinear modelling—Benchmark project” funded by the Italian Department of Civil Protection within the context of the ReLUIS projects. The 2-stories building is characterized by an irregular T-shaped plan and load-bearing walls consisting of two-leaf stone masonry with a rather regular bond scheme. The school was severely damaged by the seismic sequence that hit Central Italy in 2016/2017 and essentially exhibited a global in-plane box-type response, with a clear evidence of cracks concentrated in piers and spandrels. The availability of an accurate survey of the crack extension represents a precious and rare reference to firstly address in the paper the rules to be adopted in the EF models for the definition of the structural elements geometry. Then, the comparison of results is made with a twofold aim: firstly, by setting the models adopting shared and consistent modelling assumptions across the SWs; secondly, by investigating the sensitivity of the seismic response to some common epistemic and modelling uncertainties (namely: the adoption of various EF idealization rules for walls, the out-of-plane contribution of piers, the flange effect). In both cases, results are post-processed to define reference values of the achievable dispersion. The comparison is carried out in relation to a wide set of parameters, namely: global parameters (e.g. dynamic properties, pushover curves and equivalent bilinear curves); synthetic parameters of the structural safety (i.e. the maximum acceleration compatible with the ultimate limit state); the damage pattern simulated by SWs
Second-order effects in URM walls subjected to compression and out-of-plane bending: From numerical evaluation to proposal of design procedures
No full textAlthough the load-bearing capacity of masonry walls has been receiving researchers’ attention since the 1950s both analytically and experimentally, in the scientific and technical community there is still heated debate on the actual methodology to adopt for the verification of URM walls subjected to eccentrically loaded walls, considering second-order effects. Moreover, it is still not well recognised that safety checks on structural walls subjected to significant lateral (e.g. seismic) actions require to be verified in terms of lateral flexural capacity and that buckling effects also need to be properly considered in these cases. To date, possible design procedures for evaluating second-order effects in strength verification of walls are based on axial load and moment capacity reduction factors, here respectively called φm and φM. This paper offers a refinement of the numerical calculations of φm and φM, leading to polynomial-type models and analytical formulations that improve accuracy in evaluating both factors. Moreover, it has analytically and numerically been demonstrated that there is a one-to-one correspondence between the two reduction factors φ, since they represent two ways of characterising the same effect. The results on the reduction factors are finally compared with those from past experimental campaigns and from some standards and can serve as reference for codified procedures
Modelling the seismic response of a 2-storey URM benchmark case study: comparison among different equivalent frame models
No full textThe paper presents the comparison of the results of non-linear static analyses performed with different software based on the equivalent frame (EF) modelling approach on a simple two-story unreinforced masonry building with rigid diaphragms. This study is part of a wider research activity carried out in the framework of the Italian Network of Seismic Laboratories (ReLUIS) projects, funded by the Italian Department of Civil Protection. Different configurations have been considered varying the layout of the openings on the bearing walls and the structural details. The EF models have been defined adopting as much as possible common assumptions, in order to reduce the epistemic modelling uncertainties and to facilitate the interpretation of the differences in the results obtained by the software. The comparison involved different aspects: the global scale response, in terms of capacity curves, the predicted damage pattern as well as checks at the local scale, in terms of distribution of the generalized forces. Moreover, in order to assess the reliability of the obtained results, the numerical predictions have been compared to an analytical upper bound reference solution. Finally, the sensitivity of the numerical response to the criterion adopted for the EF idealization of masonry walls has been investigated
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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