Stress Wave Scattering in Concrete: An Investigation Through Simple Finite Element Models
Fancher, Nanette Bagwell
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https://hdl.handle.net/2142/72204
Description
Title
Stress Wave Scattering in Concrete: An Investigation Through Simple Finite Element Models
Author(s)
Fancher, Nanette Bagwell
Issue Date
1993
Doctoral Committee Chair(s)
Murtha, J.P.,
Department of Study
Civil Engineering
Discipline
Civil Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Civil
Abstract
This study presents a method to estimate the scattering component of stress wave attenuation in concrete and concretelike materials through the use of simple finite element models in two dimensions. The method employs a correction to account for losses due to normal radiation pattern effects and test setup geometry. Among the test samples for which results appear are models of various thicknesses and models with differing inclusion parameters such as spatial distribution, concentration, size, and shape; the tests employ a range of input frequencies. Tested spatial distributions include both periodic and aperiodic arrangements of inclusions.
The procedure for estimating the scattering due to aggregate inclusions is a version of the substitution method of measuring attenuation in physical experiments. The substitute material in this case is homogeneous concrete with an elastic modulus based on an effective modulus expression. Normal displacement amplitude at surface locations is the physical quantity forming the basis for scattering calculations for both through-transmission mode and pulse-echo mode tests.
In contrast to physical experiment measurements of losses in concrete, the numerical model approach in this research circumvents typical sources of error such as transducer coupling medium and spurious reflections that corrupt desired response data. The method developed and the results from this study contribute to understanding stress wave scattering in concrete and can help to improve physical experiment measures of attenuation in concrete.
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