9,450 research outputs found
Vertical collapse mechanisms in masonry buildings due to seismic vertical component
No full textThe acceleration histories recorded in the epicentral areas during the last earthquake in Central
Italy (2016-17) show very intense vertical components. During the post-earthquake damage assessment operations
in the epicentral areas, some damage frameworks different from those described in the literature have
been observed, with a macro-element collapse mode attributable to the action of the earthquake vertical component.
The paper presents some of these buildings characterized by the presence of horizontal cracks, by the
displacement of the highest levels, by vertical cracks in the sub-window walls. The masonry walls are undamaged
without the typical shear or flexure failure cracks and the lower levels do not show any damage. The
crack pattern and the associated collapse mechanisms cannot be included within the classic in-plane and outof-
plane mechanisms. A collapse mechanism characterized by the loss of vertical connection of entire structural
bodies is therefore hypothesized. The activation of this type of mechanism would seem to exclude the
formation of the classic collapse mechanisms on which the seismic capacity checks of the masonry structures
provided by the technical codes are based. A simplified linear kinematic analysis able to analyze the described
behavior is proposed and illustratively applied to a case study building. Criteria for the identification and verification
of the proposed mechanisms are described, with the aim to introduce the method in design codes
An energy-based approach for nonlinear static analysis of structures
No full textCurrent codes and guidelines provide different methods to perform nonlinear static
analysis of structures that require some non-intuitive assumptions in their application. In the
present paper an energy-based method for nonlinear static analysis that allows to overcome
these assumptions is proposed. In the method the capacity and the demand are both expressed
in terms of energy. An energy capacity curve is computed considering that at each step the
work of the lateral forces is equal to the structure internal work. The demand is represented in
terms of an energy quantity, defined pseudo-energy, that is computed from both the maximum
response displacement and the maximum response force. Constant ductility pseudo-energy
spectra are introduced as energy demand design spectra, alternative to the input energy
demand spectra. The definition of the performance point does not require iterative procedures
for equating the internal dissipated energy to the demand energy. For the direct evaluation
of the performance point two different operative procedures are proposed. The proposed
method is evaluated comparing the earthquake-induced deformations of single degree-offreedom
systems resulting from the application of the presented nonlinear static analysis
procedures with those obtained from the time-history analysis and from the application of
the EC8 nonlinear static analysis procedure. The method is also applied in the case of a RC
plane frame representing the inner frame of a six story building. The results obtained with
the proposed method are in good agreement with those computed using nonlinear dynamic
analyses, moreover they are characterized by a better accuracy with respect to the results
obtained with the method provided by EC8
L’isolamento sismico come risposta alle aspettative di sicurezza dell’edilizia scolastica: il nuovo Istituto Tecnico G. Lombardo Radice di Bojano
No full textPOR Campania, FSE 2007/2013, Asse IV e V, Reti di Eccellenza tra Università- Centri di Ricerca- Imprese, Tematica 4/subcomparto: Trasporti- Aeronautica- Spazio
No full textLa presente unità di ricerca si propone di sviluppare e applicare metodologie di indagine, numeriche e sperimentali, per l'analisi delle fenomenologie fluidodinamiche presenti nella progettazione e sviluppo di mezzi di trasporto a basso impatto ambientale, nell'ambito di una sicurezza sostenibile
Isolamento sismico a grande scala per la salvaguardia del tessuto urbano nella ricostruzione post-sisma
No full textAfter a seismic event, the observation of the consequences to buildings and infrastructures always highlights
extensive damage situations in old or historical district of the hit towns. Damage depends not only on the local
amplification of the seismic action, but also on the quality of the materials and the construction technique. The
negative consequences of traditional design and construction approaches appeared in all their negative evidence in
all areas of Central Italy affected by recent seismic sequences of medium intensity (M5-M6) in 2016-17. Now the
reconstruction should solve the problem to rebuild with safety but preserving the historical aspect of buildings and
landscape. This paper proposes a particular application of the known technique of seismic isolation for the integral
seismic protection of entire urban quarter or entire small centers characterized by building of different characteristics
also significantly irregular. The adoption of seismic isolation systems at village or quarter scale involves the
construction of large floating slabs, supported by seismic isolators and/or dampers, above which to construct
buildings that can present the aesthetic and constructive characteristics of the collapsed traditional ones. These large
slabs could have the size of entire compartments (hundreds of meters on each side). Solution of ground isolation have
already been implemented in various countries to isolate complex of buildings.
The solution allows a correct interpretation of the objective to rebuild "as it was, there where it was", safeguarding
the landscape, prolonging the lifetime, and saving the expected cost. The paper illustrates a case study related to a quarter of a historic town in central Italy and shows the constructive solutions
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