Fracture process zone in notched concrete beam under three-point bending by acoustic emission

Ohno, Kentaro; Uji, Kimitaka; Ueno, Atsushi; Ohtsu, Masayasu

doi:10.1016/j.conbuildmat.2014.05.012

Cited by 130 publications

(36 citation statements)

References 10 publications

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“…However, a certain amount of Mode II cracks also appeared due to local mixed mode crack propagations around inhomogeneities. These findings were in agreement with literature studies, e.g., see [36,37]. Direct visual observation (when possible) and identification of the cracking mode by AE wave's RT analysis, as far as not supported by other survey methods such as digital image correlation [38] or X-ray diffraction analysis [39], was important; in fact, this allowed for the characterizing the cracking mode based on information obtained from a small number of sensors.…”

Section: Resultssupporting

confidence: 78%

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

2017

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Abstract:The Acoustic Emission (AE) and Dynamic Identification (DI) techniques were applied simultaneously, in an original way, to examine the stress dependent damage progress in pre-notched concrete beams tested in four-point bending. The damage mechanisms were characterized by analyzing the AE signals registered during the tests, conducted by increasing the specimen's vertical deflection. In particular, the dominant fracture mode was identified, and correlations between dissipated and emitted energies were investigated. Moreover, variations in the natural bending frequencies, produced by the crack advancement under loading, were detected and put in relation with the cumulated AE energy. Two different types of piezoelectric (PZT) sensors, operating in well distinct frequency ranges, were used to measure AE and modal signals. This study may be of interest with an outlook on possible correlations between a multi-parameter structural monitoring and the solution of inverse problems by numerical models.

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Section: Resultssupporting

confidence: 78%

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

2017

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“…It was called the fracture process zone (FPZ). The study of FPZ is vital to improve the fracture resistance of its member as well as crack propagation [2].…”

Section: Introductionmentioning

confidence: 99%

Fracture mechanic modeling of fiber reinforced polymer shear-strengthened reinforced concrete beam

Shahbazpanahi

Ali

Kamgar

et al. 2015

Composites Part B: Engineering

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a b s t r a c tA numerical method is developed to model shear-strengthening of reinforced concrete beam by using fiber reinforced polymer (FRP) composites. Tensile crack is simulated by a non-linear spring element with softening behavior ahead of the crack tip to model the cohesive zone in concrete. A truss element is used, parallel to the spring element, to simulate the energy dissipation rate by the FRP. The strain energy release rate is calculated directly by using a virtual crack closure technique. It is observed that the length of the fracture process zone (FPZ) increases with the application of FRP shear-strengthening. The present model shows that the main diagonal crack is formed at the support in the control beam while it appears through the shear span in the shear-strengthened beam. Another important observation is that the load capacity increases with the number of CFRP sheets in the shear span.

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“…La técnica de la Emisión Acústica (AE, Acoustic Emission) ha sido utilizada para monitorear en tiempo real ensayos mecánicos de especímenes de hormigón debido a su gran sensibilidad para detectar la evolución del daño desde su comienzo [15][16][17][18]. La AE es un fenómeno físico que ocurre dentro de los materiales cuando son solicitados.…”

Section: Introductionunclassified

Monitoreo mediante Emisión Acústica de vigas de hormigón de alta resistencia con y sin fibras expuesto a alta temperatura

et al. 2018

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RESUMENLa adición de fibras a la matriz cementicia, dando lugar a los hormigones reforzados con fibras, tiene por objeto mejorar la baja ductilidad que se observa en la respuesta mecánica del hormigón frente a distintos tipos de solicitación, particularmente bajo esfuerzos de tracción directa. En este trabajo, se estudia el proceso de fisuración y degradación mecánica de elementos de hormigón utilizando la técnica de emisión acústica, con el objetivo de analizar la incidencia de la acción de altas temperaturas sobre el comportamiento de falla de vigas de hormigón de alta resistencia con y sin fibras. Se presentan resultados de un plan experimental que incluye distintos ensayos mecánicos sobre especímenes de hormigón con y sin adición de una combinación híbrida de fibras de acero y de polipropileno. La incorporación de las fibras de polipropileno tiene por objeto mejorar el comportamiento del hormigón frente a temperaturas elevadas. Se analiza la evolución de las emisiones acústicas registradas durante los ensayos de flexión y su relación con la respuesta mecánica. Se observa que frente a la exposición a una temperatura de 600°C, las propiedades del hormigón reforzado con fibras fueron relativamente menos afectadas que las del hormigón sin fibras, conservando cierta capacidad de absorber energía en el pos-pico. Asimismo, se confirma que la técnica de monitoreo utilizada tiene una correlación directa con el proceso de degradación del hormigón.Palabras clave: Hormigón de alta resistencia, Hormigón reforzado con fibras, Emisión Acústica, Alta temperatura, Ensayo de flexión de tres puntos. ABSTRACTThe addition of fibers to the cementitious matrix, giving rise to fiber-reinforced concrete, aims to improve the low ductility observed in concrete mechanical response under different load scenarios, particularly under direct tension. In this work, cracking and mechanical degradation processes of concrete elements using acoustic emission technique are examined, with the objective of analyzing the incidence of high temperatures on the failure behavior of high-strength concrete beams with and without fibers. Results of an experimental campaign including different mechanical tests on concrete specimens with and without the addition of a hybrid combination of steel and polypropylene fibers are presented. The incorporation of polypropylene fibers is intended to improve the behavior of concrete against elevated temperatures. The evolution of acoustic emission measurements during bending tests and its relation with the mechanical response is analyzed. It is observed that after being exposed to a temperature of 600°C, properties of fiber reinforced concrete were relatively less affected than those of plain concrete, retaining some capacity to absorb energy in the post-peak regime. It is also confirmed that the monitoring technique used, has a direct correlation with the degradation process of concrete.

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Fracture process zone in notched concrete beam under three-point bending by acoustic emission

Cited by 130 publications

References 10 publications

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

Acoustic Emission and Modal Frequency Variation in Concrete Specimens under Four-Point Bending

Fracture mechanic modeling of fiber reinforced polymer shear-strengthened reinforced concrete beam

Monitoreo mediante Emisión Acústica de vigas de hormigón de alta resistencia con y sin fibras expuesto a alta temperatura

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