Publication: CARACTERIZACIÓN DEL COMPORTAMIENTO DE HORMIGONES REFORZADOS CON FIBRAS SINTÉTICAS FRENTE A CARGAS DE PUNZONAMIENTO
Date
2018
Authors
POO MORALES, FELIPE ALFONSO
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Abstract
Como es bien conocido, la incorporación de fibras en el hormigón mejora considerablemente su respuesta ante el esfuerzo de tracción, aumentando la tenacidad y evitando las fallas frágiles trayendo a su vez un aumento de su vida útil. Por otra parte, el uso de fibras como refuerzo estructural, especialmente en los hormigones proyectados o shotcretes utilizados en el sostenimiento de túneles, ha simplificado faenas que se caracterizan por ser de compleja ejecución. Su adición en hormigones para uso estructural permite reducir el costo al disminuir la armadura de refuerzo y el tiempo al poder aumentar los espacios por el exceso de armadura que hay en algunas estructuras.Estos hormigones deben cumplir ciertas propiedades para ser considerado de uso estructural, como es la resistencia al punzonamiento, cuya falla suele ser de manera abrupta por la falla del refuerzo al corte y que los HRF permitan una falla dúctil detectando fisuras tempranas en los elementos de hormigón. Para controlar las propiedades de los shotcretes reforzado con fibras, normalmente se recurre a la capacidad de absorción de energía, determinada mediante ensayo de paneles cuadrados, los que se muestrean durante el proceso de proyección (según NCh 14488-5)En la actualidad los ensayos de punzonamiento presentan un problema ya que influyen otros factores a la propagación de la falla, como lo es, el efecto de la flexión.En esta memoria se estudia la respuesta de los hormigones reforzado con fibras frente a ensayos de punzonamiento, además, se buscará evidenciar la influencia de la flexión (falla frágil) en los ensayos de punzonamiento, para esto, se fabricarán un total de 45 muestras con tres cuantías de fibras sintéticas Barchip48 (4, 8 y 12 Kg/m3). Las muestras tendrán una base fija de 300x300 [mm] variando su altura (50, 100 y 150 [mm]), obteniendo así 5 muestras para cada dosificación y altura de la muestra.Con los resultados se obtendrán las cargas y deflexiones donde ocurren las fallas por corte y máximos de punzonamiento.También se analizará los diferentes factores que influyen en el ensayo, como los son; altura de la muestra, contenido de fibras, forma del cono de fractura, energía absorbida y resistencia al corte.El fin de la presente memoria es caracterizar el comportamiento de hormigones reforzado con fibras sintéticas frente a cargas de punzonamiento.
As it is well known, the incorporation of fibers in the concrete considerably improves its response to tensile stress, increasing tenacity and avoiding fragile failures, in turn increasing its useful life. On the other hand, the use of fibers as structural reinforcement, especially in the projected concretes or shotcretes used in the maintenance of tunnels, has simplified tasks that are characterized as being of complex execution. Its addition in concrete for structural use allows reducing the cost by decreasing the reinforcement and the time to be able to increase the spaces due to the excess of reinforcement that exists in some structures.These concretes must comply with certain properties to be considered for their structural use, such as punching resistance, whose failure is usually abrupt due to failure of the reinforcement to the cut and HRF allow a ductile failure detecting early cracks in the concrete elements. To control the properties of fiber-reinforced shotcretes, the energy absorption capacity is usually used, determined by testing square panels, which are sampled during the projection process (according to NCh 14488-5).Currently, punching tests have a problem because other factors influence the propagation of the failure, such as the effect of bending.In this report we study the response of reinforced concretes with fibers against the punching shear test, in addition, we will seek to demonstrate the influence of bending (fragile failure) in the punching shear tests, for this, a total of 45 specimen with three quantities of Barchip48 synthetic fibers (4, 8 and 12 Kg / m3). The specimen will have a fixed base of 300x300 [mm] varying their height (50, 100 and 150 [mm]), obtaining 5 specimens for each dosage and height of the specimen.With the results will be obtained the loads and deflections where the failures by cutting and punching shear occur.It will also analyze the different factors that influence the trial, as they are; specimen height, fiber content, fracture cone shape, absorbed energy and cut resistance.The purpose of the present report is to characterize the behavior of concretes reinforced with synthetic fibers against punching shear loads.
As it is well known, the incorporation of fibers in the concrete considerably improves its response to tensile stress, increasing tenacity and avoiding fragile failures, in turn increasing its useful life. On the other hand, the use of fibers as structural reinforcement, especially in the projected concretes or shotcretes used in the maintenance of tunnels, has simplified tasks that are characterized as being of complex execution. Its addition in concrete for structural use allows reducing the cost by decreasing the reinforcement and the time to be able to increase the spaces due to the excess of reinforcement that exists in some structures.These concretes must comply with certain properties to be considered for their structural use, such as punching resistance, whose failure is usually abrupt due to failure of the reinforcement to the cut and HRF allow a ductile failure detecting early cracks in the concrete elements. To control the properties of fiber-reinforced shotcretes, the energy absorption capacity is usually used, determined by testing square panels, which are sampled during the projection process (according to NCh 14488-5).Currently, punching tests have a problem because other factors influence the propagation of the failure, such as the effect of bending.In this report we study the response of reinforced concretes with fibers against the punching shear test, in addition, we will seek to demonstrate the influence of bending (fragile failure) in the punching shear tests, for this, a total of 45 specimen with three quantities of Barchip48 synthetic fibers (4, 8 and 12 Kg / m3). The specimen will have a fixed base of 300x300 [mm] varying their height (50, 100 and 150 [mm]), obtaining 5 specimens for each dosage and height of the specimen.With the results will be obtained the loads and deflections where the failures by cutting and punching shear occur.It will also analyze the different factors that influence the trial, as they are; specimen height, fiber content, fracture cone shape, absorbed energy and cut resistance.The purpose of the present report is to characterize the behavior of concretes reinforced with synthetic fibers against punching shear loads.
Description
Catalogado desde la version PDF de la tesis.
Keywords
FIBRAS SINTETICAS , HORMIGONES REFORZADOS , HRF , PUNZONAMIENTO