RT info:eu-repo/semantics/doctoralThesis
T1 Flexural fatigue of high-strength plain and fiber-reinforced concrete: influence of mesostructure and study of size effect
A1 Mena Alonso, Álvaro
A2 Universidad de Burgos. Departamento de Ingeniería Civil
K1 Fiber-reinforced concrete
K1 Flexural fatigue
K1 Micro-computed tomography
K1 Mesostructure
K1 Size effect
K1 Hormigón reforzado con fibras
K1 Fatiga por flexión
K1 Micro-tomografía computarizada
K1 Mesoestructura
K1 Efecto tamaño
K1 Materiales de construcción
K1 Building materials
K1 Resistencia de materiales
K1 Strength of materials
K1 Ingeniería civil
K1 Civil engineering
K1 3312.09 Resistencia de Materiales
K1 3313.04 Material de Construcción
K1 3305.05 Tecnología del Hormigón
K1 3305.33 Resistencia de Estructuras
AB Equal fatigue tests in concrete, meaning those performed on exactly equal orhomothetic specimens subjected to the same stress levels, present two problems yet to besolved. On the one hand, the high dispersion of the results, which causes the fatigue lifein two apparently identical elements to vary by up to two or more orders of magnitude.On the other hand, the size effect, whereby fatigue strength decreases with increasingelement size.The aim of this research work is to study these two issues in depth. Regarding the firstone, the influence of the dispersion of concrete mesostructure on the dispersion of fatigueresults will be studied; in particular, it will be evaluated whether the stochasticarrangement of fibers (in fiber concrete) or pores (in plain concrete) explains thevariability of fatigue life. As for the size effect, fatigue tests will be performed ongeometrically similar specimens subjected to the same equivalent stress levels.Macroscopic damage indicators, such as crack opening, will be used to determine themagnitude of the size effect and its variation according to the type of concrete (plainconcrete and fiber-reinforced with different fiber contents).The results reveal that the arrangement of fibers and pores varies significantly inapparently identical specimens, and that this partly explains the dispersion of fatigueresults. However, the estimation of the fatigue response of concrete from itsmesostructure requires complex models, comprising several geometrical parameters ofvarious components. In this work, a methodological approach to the problem is made,proposing mesostructure parameters that are reasonably predictive. With respect to thesize effect, it is observed that the presence of fibers reduces the size effect on fatigue life,almost nullifying it. Furthermore, it is concluded that the secondary crack opening rate(dCMOD/dn) is an adequate parameter to explain the fatigue life in general, and the sizeeffect in particular.
YR 2023
FD 2023
LK http://hdl.handle.net/10259/7855
UL http://hdl.handle.net/10259/7855
LA eng
DS Repositorio Institucional de la Universidad de Burgos
RD 09-may-2024