Estudio del comportamiento de los coeficientes β en vigas de gran peralto mediante el Método de Bielas y Tirantes (STM)
Fecha
2017-07
Autores
Rodríguez Herrera, Maylenis
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Editor
Universidad Central “Marta Abreu” de Las Villas. Facultad de Construcciones. Departamento de Ingeniería Civil.
Resumen
En la presente investigación se realiza un estudio del comportamiento de vigas de gran peralto de hormigón armado bajo cargas estáticas con predominio de esfuerzos de cortante. El método empleado para el desarrollo de este trabajo es la simulación numérica a partir del Método de Bielas y Tirantes (STM o Strut and Tie Method por sus siglas en inglés) en combinación con la experimentación existente a nivel internacional como vía de calibración y validación, propiciando una mejor comprensión del comportamiento de los elementos y brindando la posibilidad de desarrollar un estudio profundo de los fenómenos que ocurren en el interior de las estructuras, ofreciendo al ingeniero una alternativa económica en comparación con la realización de ensayos reales. Además se confecciona el procedimiento de trabajo a seguir para la simulación virtual de las probetas con el software de propósitos generales CAST , desarrollando los cálculos y la metodología para el diseño estructural haciendo énfasis en aspectos como la modelación de la geometría, condiciones de contorno y propiedades de los elementos STM.
Cabe destacar que se observa una adecuada correspondencia entre la respuesta numérica de la probeta virtual y la respuesta físico-mecánica del ensayo experimental de referencia, resultados que vinculan precisión, fiabilidad y economía en la predicción de la capacidad resistente última de las vigas pared en términos de carga de rotura, modo de fallo, deformación y propagación de grietas, lo que nos permite concluir que el empleo del STM es válido y acertado en el pronóstico del comportamiento de estas vigas. Es importante decir que la modelación numérica nos permite presenciar fenómenos que ocurren a nivel micro estructural y que no pueden ser observados ni cuantificados con detalle en ensayos reales puesto que estudios de esta magnitud implicarían una complejidad técnica y material para nuestro país.
También se realiza una revisión profunda de diferentes códigos existentes a nivel mundial para la estimación de la capacidad resistente en este tipo de estructuras como por ejemplo el ACI 318-2002, el Eurocode (ENV-2001) y la Canadian Standard (CSA-1994) así como del criterio expuesto por diversos autores: Nielsen (1978), MacGregor (1986,1988 y1997), Schlaich (1987 y 1991) y Marti (1985).
Posteriormente se lleva a cabo un estudio paramétrico para evaluar la influencia de factores físico-mecánicos y del refuerzo en el comportamiento estructural de este tipo de vigas ( específicamente en el comportamiento de los coeficientes β involucrados en la resistencia de diseño empleando el Método de Bielas y Tirantes) mediante una propuesta de formulación empírica que ratifica que los
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enfoques empíricos constituyen procedimientos menos laboriosos, más precisos y menos generales que los analíticos (ya que no son aplicables a cualquier tipo de estructuras y a todo tipo de condicionantes), pero a su vez permiten al proyectista una valoración sencilla de la influencia de los principales elementos resistentes de la viga pared.
In the present investigation is carried out a study of the behavior of beams wall of armed concrete under static loads with prevalence of efforts of sharp. The method used for the development of this work is the numeric simulation starting from the Strut and Tie Method (STM or Strut and Tie Method for their initials in English) in combination with the existent experimentation at international level as calibration road and validation, propitiating a better understanding of the behavior of the elements and offering the possibility to develop a deep study of the phenomena that happen inside the structures, that which offers the engineer an economic alternative in comparison with the realization of real tests. The work procedure is also made to continue for the virtual simulation of the test tubes with the software of general purposes CAST, developing the calculations and the methodology for the structural design making emphasis in aspects like the modulation of geometry, contour conditions and properties of the elements STM. It is necessary to highlight that one observes an appropriate correspondence between the numeric answer of the virtual test tube and the physical-mechanical answer of the experimental test of reference, results that they link precision, reliability and economy in the prediction of the resistant last capacity of the beams wall in terms of break load, failure way, deformation and propagation of cracks, what allows us to conclude that the employment of STM is valid and guessed right in the presage of the behavior of these beams. It is important to say that the numeric modulation allows us to witness phenomena that happen at level structural micro and that they cannot be observed neither quantified with detail in real tests since studies of this magnitude would imply a technical complexity and material for our country. Is also carried out a deep revision of existent different codes at world level for the estimate of the resistant capacity in this type of structures as for example ACI-1999, ACI 318-2002, Eurocode (ENV-2001) and Standard (CSA-1994) Canadian as well as of the approach exposed by diverse authors: Nielsen (1978), MacGregor (1986,1988 y1997), Schlaich (1987 and 1991) and Marti (1985). Later on it is carried out a parametric study to evaluate the influence of factors physical-mechanics and of the reinforcement in the structural behavior of this type of beams (specifically in the behavior of the coefficients β involved in the design resistance using the Strut and Tie Method) by means of a proposal of empiric formulation that ratifies that the empiric focuses constitute less laborious, more precise and less more general procedures that the analytic (since they are not applicable to any type of structures and all type of conditions) ones, but in turn they allow the planner a simple valuation of the influence of the resistant main elements of the beam wall.
In the present investigation is carried out a study of the behavior of beams wall of armed concrete under static loads with prevalence of efforts of sharp. The method used for the development of this work is the numeric simulation starting from the Strut and Tie Method (STM or Strut and Tie Method for their initials in English) in combination with the existent experimentation at international level as calibration road and validation, propitiating a better understanding of the behavior of the elements and offering the possibility to develop a deep study of the phenomena that happen inside the structures, that which offers the engineer an economic alternative in comparison with the realization of real tests. The work procedure is also made to continue for the virtual simulation of the test tubes with the software of general purposes CAST, developing the calculations and the methodology for the structural design making emphasis in aspects like the modulation of geometry, contour conditions and properties of the elements STM. It is necessary to highlight that one observes an appropriate correspondence between the numeric answer of the virtual test tube and the physical-mechanical answer of the experimental test of reference, results that they link precision, reliability and economy in the prediction of the resistant last capacity of the beams wall in terms of break load, failure way, deformation and propagation of cracks, what allows us to conclude that the employment of STM is valid and guessed right in the presage of the behavior of these beams. It is important to say that the numeric modulation allows us to witness phenomena that happen at level structural micro and that they cannot be observed neither quantified with detail in real tests since studies of this magnitude would imply a technical complexity and material for our country. Is also carried out a deep revision of existent different codes at world level for the estimate of the resistant capacity in this type of structures as for example ACI-1999, ACI 318-2002, Eurocode (ENV-2001) and Standard (CSA-1994) Canadian as well as of the approach exposed by diverse authors: Nielsen (1978), MacGregor (1986,1988 y1997), Schlaich (1987 and 1991) and Marti (1985). Later on it is carried out a parametric study to evaluate the influence of factors physical-mechanics and of the reinforcement in the structural behavior of this type of beams (specifically in the behavior of the coefficients β involved in the design resistance using the Strut and Tie Method) by means of a proposal of empiric formulation that ratifies that the empiric focuses constitute less laborious, more precise and less more general procedures that the analytic (since they are not applicable to any type of structures and all type of conditions) ones, but in turn they allow the planner a simple valuation of the influence of the resistant main elements of the beam wall.
Descripción
Palabras clave
Coeficientes β, Métodos de Vielas y Tirantes, Vigas, Estudio