124,887 research outputs found
Structural design criteria for safety by monitoring of the architectural heritage damage: state of the art reviews
No full textThe events that mainly undermine structural safety are both earthquakes, ground subsidence, natural
disasters (landslides, floods, hurricanes), both degradation, neglect and lack of maintenance, or even
improper maintenance.
So, earthquakes aren't the only responsible for buildings collapsing: some structural failures, occurred
in the city of Naples, are connected to the characteristics of its subsoil permeated by underground
cavities that can turn into huge ‘holes’ swallowing the foundations of buildings. In 2015, in the centre of
Naples, a historic building used as the Faculty of Veterinary Medicine of the Federico II University
collapsed. Few premonitory signs (creaks during the night) preceded the disaster. Same fate for an
important building, located on the Riviera di Chiaia, where it was said that the causes were to be found
in the excavations of the adjacent underground.
At the light of most recent events too, as the collapse of part of a church façade in piazza Cavour
(Naples, 20 January 2021), which seems to be attributable to the floor of an adjacent palace in Vico ai
Miracoli, the work aims to explore the most suitable approach possibilities particularly refers to masonry
structures classifiable as ancient buildings.
For many years now, the design has been adapting to earthquake criteria, but it has not yet adapted to
‘other’ events such as bursting a pipe or a terrorist attack or even a progressive simple leaching of the
foundation soil.
So, it is important to initiate a discussion on issues about the correct approach to safe structural design
for the historical heritage, respect to events of a different kind other than dynamic actions
Seismic assessment and rehabilitation of a historical theatre based on a macro-element strategy
No full textThe structural and seismic assessment of the 19th-century Petruzzelli theater in Bari (Italy) is presented. The macro-elements strategy was adopted to dismantle the whole structure in parts. The steel dome was verified through dynamic multi-modal analysis based on finite element model. Each masonry macro-element was firstly verified through a kinematic analysis aiming at excluding local collapse mechanisms. Afterwards, a nonlinear static analysis was carried out in order to evaluate its overall seismic capacity. The effectiveness of linear or nonlinear analyses and of the macro-element strategy compared with other modeling techniques is also discussed. After highlighting the structural deficiencies of the theater, upgrading solutions are proposed with consideration of the safety needs and the architectural preservation requirements based on the historical importance of the buildin
Linee guida per la valutazione e la mitigazione del rischio valanghe di neve sulle infrastrutture e costruzioni
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Fractals, renormalization group theory and scaling laws for strength and toughness of disordered materials
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A Monte Carlo Sampling Strategy for the Automated Operational Modal Analysis of Road Bridges
No full textAutomated Operational Modal Analysis (AOMA) is a highly convenient technique
to identify the modal properties of a target system, based only on its measured output and
without human supervision. In particular, AOMA is very useful for permanent and continuous
bridge monitoring, as it would otherwise be impractical to perform input-output dynamic
testing on such large and complex structures or to manually process the acquisitions on a
daily basis.
Nevertheless, its implementation requires a fairly articulated algorithm, made up of several
steps. Some of them have been well-optimised throughout the years thanks to contributions by
many researchers. Other aspects, however, are still open to improvements.
Specifically, the standard AOMA procedure operates on the so-called stabilisation diagram,
i.e. a complete set of identified dynamic properties for different model orders. Traditionally,
the model order n is increased from an initial (and arbitrary) minimum, nmin, up to a
similarly arbitrary maximum nmax, with a constant step and no omissions.
However, feeding the AOMA algorithm with all the models included in the [nmin,nmax]
range is here proved to not be the most efficient course of action. Instead, a Monte Carlo
Sampling strategy is proposed, randomly picking a set of models with order n ∈
[nmin, nmax]. This is verified on an experimental dataset, the Z24 bridge, to provide
comparable results in terms of accuracy and at a lower computational cos
Strain localization in a continuum as an instability event
No full textThe paper presents a novel physical model, based on perturbation theory, to describe localization pattern formation in a solid material as a result of system instabilities. Such kind of approach has been inspired by the theory of population dynamics. In particular, the sinergetic phenomenon of strain localization into a stressed continuum, and its subsequent evolution to cohesive cracking, is obtained through the competition of an external source of energy (e.g., strain energy) and of the internal behavior of the material. The hypothesis of mobile energy entities within material bulk is put forward. These entities, which under low strain conditions are evenly distributed throughout the body, can be considered as strain quanta. The quantization of mechanical quantities is not new in continuum and fracture mechanics, [see, e.g., Novozhilov (1969, Prik Mat Mek 33:212-222)]. With increasing strain, a certain critical point is reached when the homogeneous situation becomes unstable and the strain quanta begin to aggregate into bands, leading to periodic strain localization patterns. The model, which is only theoretical at this stage, can be applied to the particular case of dry snow avalanches. In these cases, snow avalanche triggering is due toinstability (onset of sliding onto a weak plane) and is controlled by external loading (e.g., weight of the slope, load by skiers) and by internal factors (e.g., temperature changes, snow phase transformations etc.). © Springer Science+Business Media B.V. 2006
Multifractal scaling law: an extensive application to nominal strength size effect of concrete structures
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