1,720,972 research outputs found
UN PRIMO INVENTARIO DEI DANNI IN EDIFICI PREFABBRICATI A SEGUITO DEL SISMA DELL’EMILIA DEL 2012
No full textThe 2012 Emilia (Italy) earthquakes hit a
highly industrialized area including several
thousands of precast RC buildings. Due to the
lack of specific design and detailing for
earthquake resistance, these buildings suffered
from severe damages and even partial or total
collapses in many cases. The present study
reports a preliminary data inventory of damages
from field surveys concerning 1133 prefabricated
industrial buildings. The damage distributions
were related first with the epicentral distance.
Then, making use of available shakemaps of the
mainshocks, empirical vulnerability curves of
buildings with different damage grades were
developed. It was found that about 90% of
severely damaged to collapsed buildings are
located at epicentral distances smaller than 14 km
and experienced a Pseudo-Spectral Acceleration
for a period of 1 second (PSA at 1 s) larger than
0.13g. For 90% of the buildings with slight to
moderate damages, the minimum epicentral
distance is smaller than 23 km and the maximum
PSA at 1 s did not exceed 0.07g. Finally, it has
been underlined that 10% of the undamaged
buildings are located within 9 km from the closest
epicentre and suffered from a maximum PSA at 1
s greater than 0.21g
Stima di curve di fragilità sismica per strutture prefabbricate in c.a. sulla base di dati osservazionali sul danneggiamento prodotto dal terremoto dell’Emilia
No full textLa memoria presenta modelli parametrici di fragilità sismica per strutture prefabbricate in calcestruzzo armato,
calibrati sulla base di dati osservazionali sul danneggiamento prodotto dal terremoto dell’Emilia del 2012. In
particolare è stato classificato il danneggiamento di 1890 edifici utilizzando una scala a sei livelli derivata dalla Scala
Macrosismica Europea. La completezza della base dati sul danneggiamento è stata valutata attraverso confronti con
dati catastali. La misura di intensità dello scuotimento sismico utilizzate per la definizione dei modelli di fragilità è
la accelerazione di picco al suolo (PGA), che è stata stimata a partire dalle shakemap pubblicate dall’Istituto Italiano
di Geofisica e Vulcanologia (INGV). I parametri dei modelli di fragilità sono stati calibrati utilizzando tecniche di
regressione Bayesiana. Un confronto tra le curve di fragilità qui presentate ed i modelli di letteratura validi per le
strutture a telaio in c.a. gettate in opera evidenzia la grande fragilità dei prefabbricati
A FE-BIE coupled method for the static analysis of beams on 3D half-space
No full textThis contribution presents a simple and effective numerical model for performing static analyses of beams in frictionless and bilateral contact with a three-dimensional (3D) elastic and isotropic half-space. Such a problem can suitably represent the behaviour of strip footings and shallow foundations in building structures.
A coupled finite element-boundary integral equation (FE-BIE) method, already introduced for beams on half-plane [1], is here extended to the case of beams on 3D half-space, by adopting a mixed variational formulation which assumes as independent fields both beam displacements, rotations and contact surface tractions. Mixed formulation includes the Green function of the 3D half-space [2]. The resulting numerical model makes use of locking-free “modified” Hermitian shape functions [3] for the beam and piecewise constant function for the substrate tractions. For this purpose, only the contact surface underneath the foundation needs to be discretized with rectangular elements; furthermore, traction distribution in beam transverse direction is considered with an adequate mesh refinement of contact surface in both plane directions.
Numerical tests of both Euler-Bernoulli and Timoshenko beams subject to several load conditions are dealt with. Results in terms of displacements, contact tractions and bending moment are obtained, showing the effectiveness of the model and its convergence to existing analytical and numerical solutions [4].
References
[1] Tullini, N., Tralli, A., “Static analysis of Timoshenko beam resting on elastic half-plane based on the coupling of locking-free finite elements and boundary integral”, Computational Mechanics, 45(2–3) pp. 211–225 (2010).
[2] Johnson, K.L., Contact mechanics, Cambridge University Press, Cambridge (1985).
[3] Reddy, J.N., “On locking-free shear deformable beam finite elements”, Computer Methods in Applied Mechanics and Engineering, 149(1-4), pp. 113–132 (1997).
[4] Biot, M.A., “Bending of an infinite beam on an elastic foundation”, Journal of Applied Mechanics, 4, pp. A1–A7 (1937)
Logarithmic stress singularities at clamped-free corners of a cantilever orthotropic beam under flexure
No full text
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
- …
