Mesoscale modelling of concrete specimens under high-speed impact loads

Yifei Hao

    Research output: ThesisDoctoral Thesis

    364 Downloads (Pure)

    Abstract

    [Truncated abstract] It is widely accepted that the uniaxial compressive and tensile strengths of concrete and concrete-like material increase with strain rate. These strength increments are usually modelled by a Dynamic Increase Factor (DIF) at given strain rates in the analysis and design of concrete structures to dynamic loads. Many empirical relations of concrete material strength DIF have been obtained primarily based on laboratory impact tests and proposed for use in the design and analysis. However, it is commonly agreed that a few parameters associated with stress wave propagation will affect the DIF values from impact tests, including the lateral and axial inertia confinement, end friction confinement and stress wave propagation effect. Many different measures have been proposed to eliminate or limit the influences of these effects in dynamic tests of material properties. Unfortunately, owing to the nature of dynamic loadings, especially those with high loading rates, it is very unlikely to neither completely eliminate these influences in physical testing nor quantify these influences from the laboratory testing data. Moreover, most of these empirical relations were obtained from testing data of concrete-like materials, i.e. the testing specimens were made of mortar matrix only without coarse aggregates owing to constraints in preparing the concrete specimens for high-speed impact tests. Because concrete is a composite material with mortar matrix, interfacial transition zone (ITZ) and aggregates, and these components have different material properties, using specimens made of mortar material alone in tests may not give accurate concrete dynamic material properties. In addition, aggregates in concrete mix are usually made of rocks and the DIF of rock materials obtained in impact tests is also affected by the factors such as lateral inertia confinement and end friction confinement.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2012

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