1,721,163 research outputs found
Seismic response and capacity of inelastic acceleration-sensitive nonstructural elements subjected to building floor motions
No full textThe paper investigates the seismic response of nonstructural elements (NEs),
focusing on acceleration-sensitive components housed in buildings, modelled
as inelastic Ibarra–Medina–Krawinkler (SDOF) systems. Incremental dynamic
analysis (IDA) is carried out considering (a) representative suites of building
floor motions (real loading histories recorded within reinforced concrete (RC)
buildings and table testing protocol inputs) and (b) a wide range of NE models
(with elastic frequencies ranging within 1–9 Hz). The Ibarra-Medina-Krawinkler
(IMK) model was implemented in OpenSees, defining the key modeling parameters
according to the formulations provided by Lignos and Krawinkler. Both
IDA curves and component (acceleration) amplification factor (CAF) are characterized,
also considering statistical measures. The seismic capacity of the
investigated NEs is estimated through fragility curves, accounting for five incremental
damage states (DSs). The fragility parameters are correlated with the
frequency of the NE models, and (statistical-based) closed-form capacity criteria
are provided. The study provides a robust technical and scientific methodological
framework for assessing the seismic capacity of NEs that can be modeled
by inelastic SDOF systems. The findings have a potential major impact on
both research and practice, enriching scientific knowledge and providing useful
applicative tools. In particular, quantitative response and capacity measures
are supplied, and the developed capacity criteria can be particularly useful
for expeditious but reliable design and assessment, as well as for comparison
purposes
Sul comportamento sismico di telai piani in c.a. caratterizzati da irregolarità in elevazione
No full textPotenza-Matera, Itali
Validation of numerical models for hospital building contents: rigid blocks and FEM models
No full textThe post-earthquake functionality of hospital buildings is an essential performance objective to achieve in a modern resilient community (Bruneau and Reinhorn, 2007). Such a performance may, however, be impaired due to the damage to non-structural components and building contents. Recent surveys carried out in the aftermath of major world-wide earthquakes (e.g. (Di Sarno et al., 2013, Jacques et al., 2014, Masi et al., 2014, among others) have shown that the overturning of cabinets, containing medical files with patient details, the failure of electronic panels is a typical non-structural component damage recorded after moderate-to-large earthquakes. Hazardous contaminants may also be released when medical cabinets and bookshelves overturn; hence there is a number of dangerous consequences caused by the lack of adequate seismic design. Comprehensive experimental and numerical studies were carried out in the last decade to investigate the seismic performance of a variety of furniture items, medical appliances and service utilities of typical hospital buildings and pharmacies, e.g. (Cosenza et al., 2014, Furukawa et al., 2013, Kuo et al., 2011). Numerical modeling of such components is still a key issue to be addressed.
In this study, simplified finite element models of the tested components have also been implemented in software platforms to adequately simulate the dynamic properties of sample medical components. Different numerical modeling approaches are validated upon the outcomes of a comprehensive experimental campaign on hospital building contents carried out by shake table testing at the University of Naples Federico II, Italy.
Finite element modeling approach is adopted to investigate the dynamic behavior of hospital cabinets in case they do not exhibit any rocking mechanism, i.e. pre-rocking behavior. The validation of a FEM model for the dynamic performance of cabinets is presented. Its ability to reproduce horizontal acceleration in the cabinets is also discussed. The developed numerical model gave a fairly good matching in terms of natural frequencies of the sample components. Nonlinear dynamic analyses are performed on the defined models. Recorded table acceleration are applied at the base of both the cabinets for the three different test groups. It is concluded that the defined model is able to recognize the occurrence of the rocking mechanism in the cabinets.
Medical components, such as the tested cabinets, typically exhibits a rocking behavior as the seismic intensity increases. Thus, the dynamic behavior of rigid blocks is investigated for the post-rocking behavior of cabinets. Tested cabinets are modelled as equivalent rigid blocks and subjected to the experimental base accelerations. The ability to predict the occurrence of both rocking mechanism and overturning is verified. Given the good model fidelity, a preliminary study is performed aimed at the identification of the most efficient seismic intensity measure (IM) for rigid blocks and the influence of the geometric properties of rigid blocks on their dynamic performanc
Seismic response of innovative glass partitions
No full textThe condition of undamaged or lightly damaged internal partitions after seismic events is of utmost importance
for at least three building performance levels: i) life safety, ii) operational and iii) damage. Indeed, victims
may be caused by the weight of falling partitions, the obstruction of the ways out and the dust released by some
(e.g. brick) partitions. Cracks and dislocations of internal partitions, which can be also caused by frequent
earthquakes, may lead to the downtime of the building hosting the partitions; downtime cannot be accepted in
case of strategic buildings and may lead to large losses in case of industrial and commercial buildings. Large
economic losses are also related to the damage itself of the partitions. Consequently, modern seismic codes
pay attention to the protection of these nonstructural elements: i) imposing their seismic qualification; ii)
providing strength verifications, based on accelerations, and displacement verifications, based on story drifts.
Their protection also conditions the structural design: seismic codes link the stiffness of the structure to the
damage of the partitions and the structural strength distribution to the possible irregular distribution of the
partitions.
Contemporaneous architectural choices are leading to a large increase of the use of glass partitions, for both
aesthetic and functional reasons: sound and thermic compartmentations should not be also visual barriers.
Glass partitions are more and more used in offices, belonging also to strategic buildings. On the other hand,
fragility, stiffness and weight of the glass sheets are features increasing the seismic vulnerability of this
partition type. Consequently, the development of glass partitions, remaining operational after strong
earthquakes, is an urgent need, which cannot be reached without a strong cooperation between research and
industry. Indeed, glass partitions are sophisticated industrial products, characterized by a detailed and
expensive manufacture of glass and either steel or aluminum.
The paper shows the development of glass partitions which remain operational after very severe earthquakes,
i.e. under large accelerations and story drifts, as shown by shake table tests. Four types of partitions are
developed, fully glass, glass partition with a glass door, mixed glass and steel and, finally, mixed glass and
wood. It is confirmed that, as already known, simple details may largely increase the seismic performance of
nonstructural element
Innovative hysteretic device for seismic retrofit of single-story RC precast buildings
No full textIn the last decades, many efforts have been made by the scientific community and technicians in order to develop effective and practical retrofit approaches for industrial RC precast buildings. Given the aftermath of recent earthquakes, which identified structural and non-structural dry joints as the highest source of seismic vulnerability, the majority of the retrofit techniques involves interventions at the connections level. The primary function of creating an adequate constraint is nowadays frequently associated to energy dissipation, allowing to both remove the major building weakness and decreasing the seismic demand in terms of elements’ stresses and deformations. In the following, a novel metallic hysteretic device intended for beam-to-column connection retrofit is presented. An existing one-story RC precast building with friction beam-to-column joints is considered as case-study structure; mechanical properties of the device are calibrated, and its effectiveness validated though nonlinear dynamic analyses. The proposed device demonstrates its ability in both restrain the relative displacement between structural elements and dissipate an adequate amount of input energy coming from ground motions, preventing structural damage. A comparison with the same device without hysteretic properties, i.e., a non-dissipative device, is also carried out, highlighting the benefits in using the hysteretic version
Pneumolabyrinth following eustachian tube insufflation
No full textPneumolabyrinth is a condition in which the vestibule and/or cochlea is filled with air1.
Eustachian tube insufflation is a type of treatment for recurrent serous otitis media which is still popular in Europe.
To our knowledge no case of a pneumolabyrinth due to barotrauma provoked by Eustachian tube insufflation has previously been described.
The aim of this paper is to present the case of a female previously operated on for stapedotomy who developed a pneumolabyrinth with sudden profound deafness and vertigo following eustachian
tube insufflation
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