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La fatica di strutture in calcestruzzo e muratura valutata con la tecnica delle emissioni acustiche
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Damage 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
Get PDFThe 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 textCaratterizzazione Sperimentale del Danneggiamento nei Materiali Granulari mediante Analisi Spettrale di Segnali Ultrasonici
No full textSignal-Based Dynamic Identification of Composite Steel–Concrete Bridges Using Short-Duration Records
Get PDFtructural Health Monitoring (SHM) of existing bridges increasingly relies on dynamic measurements to assess structural performance and detect potential damage. However, the practical implementation of long-term vibration-based monitoring is still constrained by the volume of data required and the complexity of continuous acquisition systems. In the context of ensuring the safety and performance of existing bridge infrastructure, vibration-based monitoring offers a powerful tool for detecting changes in structural behavior. This study presents an extended investigation of dynamic monitoring applied to composite steel–concrete viaducts, focusing particularly on the signal-analysis framework and methodological enhancements. Short-duration accelerometric records are processed through an automated signal-selection pipeline and advanced modal-parameter extraction algorithms to yield identification of modal features. Emphasis is placed on the statistical evaluation of modal-parameter stability, effects of operational and environmental variability, and the potential for long-term trend detection. The results highlight the limits of short-length recordings when OMA techniques are applied. Nevertheless, appropriate signal processing and data handling can provide acceptable insights into the dynamic characteristics of large bridge systems. The methodological findings provide a foundation for improved monitoring workflows, showing the amount of information that can be retrieved using a cost-effective hardware deployment and supporting further development toward structural digital twins
Fatigue behaviour analysis for the durability prequalification of strengthening mortars
Get PDFAn 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)
Frequency Analysis of Acoustic Emission Signal to Monitor Damage Evolution in Masonry Structures
No full textAbstract. A crucial aspect in damage evaluation of masonry structures is the analysis of longterm
behaviour and for this reason fatigue analysis has a great influence on safety assessment
of this structures.
Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro
and macro-defects and their temporal evolution in several materials. This technique permits to
estimate the velocity of ultrasound waves propagation and the amount of energy released
during fracture propagation to obtain information on the criticality of the ongoing process.
By means of AE monitoring, an experimental analysis on a set of reinforced and unreinforced
masonry walls under variable amplitude and static loading has been carried out. During these
tests, the AE signals were recorded. The AE signals were analysed using Fast Fourier
Transform (FFT) to examine the frequency distribution of the micro and macro cracking. It
possible to evaluate the evolution of the wavelength of the AE signal through the two
characteristic peak in the AE spectrum signals and the wave speed of the P or S waves. This
wavelength evolution can be represent the microcrak and macrocrack evolution in masonry
walls. This procedure permits to estimate the fracture dimension characteristic in several
loading condition and for several masonry reinforced condition
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