Effects of stress non-uniformity on failure mechanisms of concrete/rocks

Hossein Bineshian

    Research output: ThesisDoctoral Thesis

    402 Downloads (Pure)

    Abstract

    [Truncated abstract] Evaluation of the effect of bending moment on failure mechanisms of concrete and rocks using strain measurement has been conducted in this research.

    Experimental section of this research is devoted to uniaxial compression testing on 60 cylindrical fine grain concrete and aluminium 6061 alloy specimens using ASTM C192/C192 M, ASTM C617, and ASTM C39. We used three types (cases) of loading: Case 1 - spherical upper and lower platens; Case 2 - spherical upper platen and fixed lower platen, and Case 3 - fixed upper and lower platens. Standard deviation for measured strain equals 0.00001 and 0.00002 for Case 1 and 3 respectively.

    The external factors producing the bending moment during uniaxial compression testing are assessed and modelled using ABAQUS 6.10-1 code via implicit dynamic FEA method while energy plots and sensitivity analyses conducted for reaction force and generated mesh confirmed the accuracy of the carried out numerical simulations as 99.84%.

    It is shown that the Case 1 loading is the most reliable as in this condition no external factors from the platens can affect the bending moment in longitudinal axis of the specimens and therefore no eccentric load is affecting the specimens’ failure mechanisms.

    Two methods for strain measurements including DIC technique by IP procedure using VIC-3D and conventional method using polyester foil strain gauges are considered in this research and the results are compared. Consequently different output variables such as longitudinal strain, strain rate, displacement, velocity, principal strain angle, in-plane rotation, and confidence interval for full field of view of the specimens are considered in analyses.

    The calculated relative error for aluminium and concrete specimens using VIC-3D equals 0.42 and 2.38% respectively. Measured strain using VIC-3D is 1.01 and 1.02 times the observed values for aluminium and concrete specimens respectively.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2013

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