Development of a methodology for evaluating the structural integrity of reinforced concrete elements and other building materials (Doctoral thesis)

Μπαλάσκας, Ιωάννης

Concrete structures are the basis of contemporary technical civilization. They support transportation, storage of goods and shelter humans in large numbers. Despite their endurance, they have ceased to be considered as maintenance-free. They are subject to long- term loading due to own weight, dynamic loading scenarios including earthquakes, as well as environmental degradation. Concrete structures need to undergo inspection and evaluation of their health condition while proper maintenance actions should be proposed. In order to prolong their useful life span, a robust monitoring methodology should be applied. The first and basic information is extracted from visual inspection. However, this concerns only the surface distress indications. Defects may start to grow from the interior and therefore, an assessment based solely on visual observation would not be complete. Among monitoring methodologies that assess the full volume of the structure, acoustic emission (AE) has started to be applied in a wide basis. AE is a passive n on de s t ru c t iv e e v a lu a t io n (NDE) technique that offers specific advantages like real time monitoring of defects propagation, which enables to characterize the critical moments of the structure in relation to the applied operational load. The objective of this thesis is the development and application of a novel methodology with NDE techniques, especially acoustic emission (AE) and ultrasonic (Ultrasound Pulse Velocity UPV), for the evaluation and monitoring of induced damage in the elements of the structure. The prediction of the remaining life of a structure can be assisted by the characterization of the current cracking mode. Usually, tensile phenomena precede shear fracture. Due to the different movement of the crack sides according to the dominant mode, the emitted elastic energy possesses waveforms with different characteristics. These are captured by acoustic emission sensors and analyzed for their frequency content and waveform parameters. Therefore, identification of the mode of fracture in building materials using elastic wave methods has been achieved. Finally, an innovative methodology for damage investigation cement-based structural elemens, using elastic wave approaches has been developed.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών
Subject classification: Building materials
Keywords: Building materials
Appears in Collections:Διδακτορικές Διατριβές

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