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Paola Salvatori (a cura di), Il fascismo e la storia
No full textRecensione a Paola Salvatori (a cura di), Il fascismo e la stori
Seismically isolated building response under far fault 2016 earthquake in central Italy
No full textAfter L’Aquila 2009 earthquake (Central Italy), many new and retrofitted buildings with base isolation have been realized in the area. Collapsed buildings, or heavily damaged buildings, were demolished and reconstructed with base isolation. The isolation systems were generally composed by both rubber high damping isolators, and plane friction isolators (sliding), and, in some buildings, by single and double pendulum sliding devices. Some buildings, with minor structural damage were retrofitted also with isolation systems, both with rubber high damping isolators, and plane friction isolators, and also by double pendulum sliding isolators. All these isolated buildings were interested by the strong seismic events in Central Italy. The seismic sequence during years 2016 and 2017 involved a great area In Central Italy, interesting four regions and more than 100.000 buildings. Several main shock events occurred, namely Amatrice earthquake (Mw 6.0 on August 24th, 2016), Valnerina earthquakes (Mw 5.9 and 5.4 on October 26th,2016), Norcia earthquake (Mw 6.5 on October 30th, 2016), and Montereale – Capitignano earthquakes (Mw5.0, 5.5 on January 18th, 2017). The seismically isolated buildings in L'Aquila area were involved by the seismic sequence. Several different dynamic and seismic behaviour were observed in those buildings, depending upon isolation system (noticeable differences have been observed between curved sliding isolators and rubber high damping isolators) and upon soil – structure interaction. Significant displacement has been observed caused by soft soil, and inverse velocity seismic soil profile. In the work several buildings are examined, analysing the seismic behaviour both in the 2009 earthquake (without seismic isolation) and during 2016 – 2017 seismic events (retrofitted by seismic isolation). Differences in the seismic behaviour do not depend by the isolation system
Computational characterization of attractor-basin bifurcation structure in nonlinear structural dynamics
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Basin bifurcation and chaotic attractor in an elastic oscillator with quadratic and cubic nonlinearities
No full textAn oscillator with quadratic and cubic nonlinearities representative of the finite forced dynamics of a structural system with initial curvature is considered. Numerical techniques are used to calculate the fixed points of the response, to identify chaotic attractors, to obtain basins of attraction of coexisting solutions. Geometrical analysis of the invariant manifolds of unstable periodic motions in control-phase portraits is performed to understand the global attractor structure and the attractor and basin bifurcations
Seismic monitoring of buildings with base isolation
No full textThe seismic monitoring of buildings is important for two fundamental reasons: - evaluate the possible dynamic behavior of these structures during earthquakes; - gain experience on the general seismic behavior of the structures so that the experience and the database can be used in the future for design and analysis. The results of previous efforts in seismic monitoring of the structures have facilitated the development of a database, which in turn was used in the creation of new formulas and reference values for the estimation of the fundamental periods of the structures and the percentage of critical damping from use during dynamic analyzes. The database is very well supplied with data on traditional buildings, but there is still not enough data for buildings isolated at the base. Some different structures with seismic base isolation have been monitored during recent strong earthquakes in Italy, namely Amatrice earthquake (2016/08/24, Mw=6.0) and Norcia earthquake (2016/10/30, Mw=6.5). For the structure under examination, amplification phenomena have been noticed, up to about twice the accelerations on the superstructure, for very low energy value inputs. In these cases, however, it is noted that the amplified accelerations are extremely small, and very far from being able to damage the structure. Records from the ENEA permanent accelerometric network, installed on the structure under examination, and the tests carried out on the same isolators used for the qualification tests of the devices mounted below the analyzed structure, permit to describe the behavior of the isolators in terms of force and displacement defining two non-linear laws, derived from experimental data
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
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