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Cette thèse est consacrée à l'étude des vases de cuisson d'époque romaine et byzantine du sud-est de l'Anatolie. Elle est basée principalement sur le matériel trouvé à Zeugma par les équipes archéologiques françaises entre 1996 et 2000. La céramique culinaire de Zeugma appartient à la production appelée brittle ware, largement diffusée en Syrie du Nord. La brittle ware était produite par plusieurs ateliers le long de l'Euphrate et en Syrie occidentale. Le répertoire est composé de formes complémentaires (pots, casseroles, plats), et tourné dans une pâte rouge finement dégraissée. La zone de diffusion de la production a été précisée : entre le 2e et le 7e s, la brittle ware domine complètement le marché de la céramique dans les limites de l'antique province de Syrie, mais uniquement à l'intérieur des terres ; elle est toujours associée à une occupation romaine ou byzantine. / This PhD. thesis is about Roman and Byzantine cooking ware in South-East Anatolia. It is mainly based on the material found in Zeugma by the French archeological teams between 1996 and 2000. Zeugma cooking ware belongs to the production called brittle ware, widely distributed in North Syria. Brittle ware was produced by several workshops located along the Euphrates and in West Syria. The shapes are complementary (pots, casseroles, pans), and made of iron-rich clay. The diffusion of the production zone has been specified : between the 2nd and the 7th century, the brittle ware controlled the market of cooking ceramics completly in the borderline of antic country of Syria. The production is dispersed over several hundred of kilometers, only in inner lands and always associated to a Roman or Byzantine occupation.

The theoretical stress-strain behaviour of individual fibre reinforced cement composites is reviewed. Based on the multiple cracking concept of the existing theory, analytical expressions are developed to describe the tensile stress-strain behaviour of a fibre-cement hybrid composite consisting of three components, i.e. two reinforcing fibres with different moduli, strengths and strains to failure and a common cement binder. The model predicts that the tensile stress-strain curve of the hybrid composites consists of five stages, instead of three stages of the existing models for individual fibre cements, and relates the tensile behaviour of each stage to the component properties of the components and the test system parameters. A description is given of the physical and mechanical properties of four types of reinforcing fibres used in the study. These were fibrillated polypropylene film, alkali-resistant glass, polyvinyl alcohol fibres and carbon fibres. A small number of direct tensile tests on continuous glass, carbon and polyvinyl alcohol were performed. The tensile stress-strain behaviour of four types of fibre-cement hybrid composites was studied with particular emphasis on that of the glass- polypropylene hybrids for which the flexural load-deflection behaviour was also examined. It is shown that the fibre-cement hybrid composites yield superior engineering properties over their parent composites and the improvements are sensitive to volume fractions of each of the two fibres. The measured tensile stress-strain curves of the hybrids were compared with the theoretical predictions and satisfactory agreement in general is obtained. Implications from the present work for the design of fibre-cement hybrid composites are assessed.

The effects of microcracking on the mechanical properties of Salem limestone were investigated in three phases: introduction of quantifiable levels of microcracks by thermal treating, mechanical testing of limestone samples with varying levels of microcracks, and modification of a numerical model to incorporate the measured effects. This work demonstrated that this approach is useful for examination of the effects of microcracking on quasi-brittle materials and can be used to improve the predictive capabilities of material models. Thermal treating was found to consistently induce quantifiable levels of microcracks in Salem limestone. Sonic wave velocities indicated that the induced microstructural changes were a function of the maximum temperature. The wave velocities showed little variability demonstrating the effectiveness of the approach for inducing consistent levels of microcracking. X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis confirmed that no composition changes occurred for the temperature range of interest. Computed tomography scanning, scanning electron microscopy, and optical microscopy (OM) were used to observe microstructural changes caused by the heat treatments. OM analysis was the primary method used in the microcrack characterization and yielding qualitative and quantitative data. OM images showed an increase in grain boundary and intragranular cracking with increasing maximum heat treatment temperatures. Stereological evaluation provided microcrack data indicating that microcrack density increased as function of the maximum heat treatment temperatures. Mechanical testing was performed to characterize the mechanical response of the intact and damaged limestone. Quasi-static tests included uniaxial compression, triaxial compression, hydrostatic compression, and uniaxial strain / constant volume tests. Microcracking did not affect the limestone’s strength at pressures greater than 10 MPa. Dynamic tests were performed using a modified split Hopkinson pressure bar. Microcracking did not have an effect on the dynamic strength of the limestone. The results of the mechanical tests were used to modify the HJC model. Modifications were made to account for shear modulus degradation and failure surface changes. The original and modified HJC models were used in a numerical analysis of the mechanical tests performed in this work. The modified HJC provided better results for damaged material when compared with the quasi-static and dynamic experiments.

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Submitted by Marcele Costal de Castro (costalcastro@gmail.com) on 2017-09-06T13:30:34Z No. of bitstreams: 0 / Made available in DSpace on 2017-09-06T13:30:34Z (GMT). No. of bitstreams: 0 Previous issue date: 1984-05 / This work is concerned with the application of the finite element method to the study of creep brittle rupture of structural components. In the formulation material behavior is described by an elastocreep model in which the total strain rates are assumed to be the sum of elastic and creep components. The elastic strain rates are given by Hooke’s law while the creep strain rates and the damage rates are espressed by the multiaxial form of the Kachanov-Rabotnov equations proposed by Leckie and Hayhurst. The incremental equations of motion are derived from the principle of virtual work using an updated Lagrangian formulation which accounts for geometric effects due to large displacements, large rotations and deformation dependent loadings. The finite element incremental equations are developed according to a displacement-based formulation. Isoparametric elements with quadratic shape functions are employed for the domain discretization and simple numerical procedures are developed to deal with the presence of partially and/or fully ruptured elements in the mesh. For integration of the creep strain rate equations a family of implicit time marching schemes is developed which can be regarded as Runge-Kutta methods of second order. The integration of the coupled damage rate equations is performed using a first order predictor-corrector scheme with automatic time step length control. For material nonlinear problems only, a substructuring technique is employed in conjunction with the time integration algorithms. Selected numerical applications are presented and discussed in detail. Comparison with alternative numerical, analytical and/or experimental results is made whenever possible.