1,927 research outputs found
La fatica di strutture in calcestruzzo e muratura valutata con la tecnica delle emissioni acustiche
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Influence of Envelope Design on Energy Performance of a Low-Rise Residential Building in Temperate Climate: Theoretical Analysis and Application to a Case Study Building
No full textDamage analysis of RC beams strengthened with CFRP sheets by acoustic emission technique
No full textShear behaviour of reinforced masonry: efficacy of FRP versus traditional technique
No full textThe aim of this experimental work is to analyse and compare the shear resistance decay after long-term and environmental actions on brickworks structures reinforced by innova-tive (FRP) and traditional technique (strengthening mortar). Laboratory tests were carried out at the Non-Destructive Testing Laboratory of the Politecnico of Turin: ad hoc brickwork speci-mens were manufactured and reinforced by FRP and strengthening mortar (for jacketing walls). Test pieces were subjected both to static and to cyclic loading tests and to freezing-thawing thermo-hygrometric tests, in order to study durability and efficacy of strengthening techniques, and express a judgement on their long term compatibility with historical masonry, thereby avoiding the errors associated with materials that are not mechanically compatible
Analisi dell'evoluzione del danneggiamento nelle murature mediante stima delle velocità del segnale di emissione acustica
No full textImproving comfort and energy efficiency in a nursery school design process
No full textA new nursery school in Milan was designed in the framework of a national research about low-energy buildings in temperate climates. The design of the case study started from a bioclimatic-approach, considering relationship between building envelope and sun path. In particular, orientation and morphology of the school are optimized (i.e. the building shapes improve solar control; classrooms and offices face South, services face North), the envelope is thermally efficient in both its opaque and transparent parts and overhangs are dimensioned to ensure solar gain in winter and to avoid direct solar radiation during summer season. A set of solutions for optimizing both energy efficiency and comfort conditions has been assessed. A floor radiant system, fed by a groundwater heat pump, has been foreseen and combined with a primary air ventilation system, equipped with heat recovery and managed by CO2 sensors. The school will be also equipped with opening window detectors and presence detectors, coupled by daylighting sensors, for controlling both illumination and thermal energy supply (hot water circulation in the radiant floor pipes and primary air cycle). Further, RE has been integrated in the design for hot water production by evacuated solar collectors placed on the roof of the higher block. As a result, a dynamic simulation made by VisualDOE software assessed 20 kWh/m2 of energy heating demand: this value is below national standards foreseen from 2009, referring to the recent Italian implementation of the Energy Performance Building Directive (EPBD)
AE Damage Assessment in the Bell Tower of the Turin Cathedral
No full textHistorical churches, masonry towers and bell towers are structures subjected to high risk, due to their age, elevation and low base area on height ratio. In this work, an innovative monitoring technique for structural integrity assessment of historical buildings is reported. At the same time, the emblematic case study of the Turin Cathedral Bell tower is presented. The damage evolution in the tall masonry structure is described by the evaluation of the cumulative number of AE and by different parameters able to predict the time dependence of damage. In particular, since environmental disturbances have been minimized, and instrumental noises have been filtered out. The b-value analysis shows a downward trend to values compatible with the growth of localized macro-cracks at the base of the tower. These results seem to be in good agreement with the numerical analysis. Extension to longer monitoring periods and, later, investigation of different segments are strongly recommended to assess the stability of the monument
Acoustic Emission Monitoring of the Turin Cathedral Bell Tower: Foreshock and Aftershock Discrimination
No full textHistorical churches, tall ancient masonry buildings, and bell towers are structures subjected
to high risks due to their age, elevation, and small base-area-to-height ratio. In this paper, the results
of an innovative monitoring technique for structural integrity assessment applied to a historical
bell tower are reported. The emblematic case study of the monitoring of the Turin Cathedral bell
tower (northwest Italy) is herein presented. First of all, the damage evolution in a portion of the
structure localized in the lower levels of the tall masonry building is described by the evaluation of
the cumulative number of acoustic emissions (AEs) and by different parameters able to predict the
time dependence of the damage development, in addition to the 3D localization of the AE sources.
The b-value analysis shows a decreasing trend down to values compatible with the growth of localized
micro and macro-cracks in the portion of the structure close to the base of the tower. These results
seem to be in good agreement with the static and dynamic analysis performed numerically by an
accurate FEM (finite element model). Similar results were also obtained during the application of
the AE monitoring to the wooden frame sustaining the bells in the tower cell. Finally, a statistical
analysis based on the average values of the b-value are carried out at the scale of the monument and
at the seismic regional scale. In particular, according to recent studies, a comparison between the
b-value obtained by AE signal analysis and the regional activity is proposed in order to correlate the
AE detected on the structure to the seismic activity, discriminating foreshock, and aftershock intervals
in the analyzed time series
Fatigue behaviour analysis for the durability prequalification of strengthening mortars
No full textAn innovative laboratory procedure used as a preliminary design stage for the pre-qualification of strengthening mortars applied to historical masonry buildings is described. In the analysis of the behaviour of masonry structures and their constituent materials, increasing importance has been assumed by the study of the long-term evolution of deformation and mechanical characteristics, which may be affected by both loading and environmental conditions. Through static and fatigue tests on mixed specimens historical brick-reinforced mortar it has been possible to investigate the durability of strengthening materials, in order to select, from a range of alternatives, the most suitable for the historical masonry. Cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of the historical brick-strengthening mortar system under static long-time loading. This methodology has proved useful in avoiding the errors associated with materials that are not mechanically compatible and guarantees the durability of strengthening work. The experimental procedure has been used effectively in the biggest restoration building site in Europe, the Royal Palace of Venaria, and it is in progress of carrying out at the Special Natural Reserve of the Sacro Monte di Varallo, in Piedmont (Italy)
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