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Optimum design for sustainable 'green' overlays : controlling flexural failureLin, Y. January 2014 (has links)
The target of the ‘Green Overlays’ research was a cost effective, minimal disruption, sustainable and environmentally friendly alternative to the wholesale demolition, removal and complete reconstruction of the existing structural concrete pavement. The important problem of flexural resistance for strengthening concrete pavements with structural overlays has been scrutinised. A new mix design method for steel fibre reinforced, roller compacted, polymer modified, bonded concrete overlay has been proposed. The mixes developed were characterized of high flexural strength and high bond strength with the old concrete substrate. ‘Placeability’ and ‘compactability’ of the mix were two dominant issues during laboratory investigation. An innovative approach for establishing the relationship between Stress and Crack Face Opening Displacement for steel fibre reinforced concrete beams under flexure was developed. In addition, a new and simple method for calculating the interfacial Strain Energy Release Rate of both, a two-dimensional specimen and a three-dimensional model of the overlay pavement system were developed. This method can be readily and easily used by practicing engineers. Finally, a new test specimen and its loading configuration for measuring interfacial fracture toughness for concrete overlay pavements were established. The interfacial fracture toughness of a composite concrete beam, consisted of steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete and undergoing flexure, was assessed. In summary, this thesis presents four key findings: A new mix design method for steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete. A new method for establishing the fibre bridging law by an inverse analysis approach. A new, simplified method for calculating strain energy release rate at the interface of a composite beam. A new, innovative technique for calculating strain energy release rate at the interface of an overlaid pavement. The thesis contains a plethora of graphs, data-tables, examples and formulae, suitable for future researchers.
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Monitoramento de uma estrutura de contenção em estacas espaçadas considerando perfil de sucção / Monitoring of sheet pile wall considering a suction profileGomes, Adriana Cristina 14 August 2015 (has links)
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Previous issue date: 2015-08-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study presents the results of an extensive field monitoring program in which the lateral
displacements of a nail reinforced sheet pile wall in Goiânia, Brazil were measured during the
excavation process. The instrumentation methods adopted were multiple point borehole
extensometers (MPBX) and optical surveying. The MPBX showed good results that could be
appropriately interpreted as the excavation progressed. However, the measurements of optical
surveying were not reliable due the low precision of total station and for being highly affected
by user’s errors. In order to determine the geotechnical profile, laboratory test were
undertaken to obtain strength and deformation parameters for unsaturated and saturated soil
conditions. The large variability of the soil, observed in terms of void ratio, presented an
important obstacle, making the determination of representative shear strength parameters a
challenge. As a way to bridge the analysis of field monitoring results, soil properties and the
numerical back analyses of the retaining walls, the water content profile and the soil-water
characteristic curve were measured. Such data was used to obtain the suction profile and
evaluated its influence in the monitored field data. Finally, the numerical code Sheeting
Check (Geo5), which uses the beam on elastic foundation method, was employed to obtain
the soil subgrade reaction modulus (ks) and determine the retaining wall deformation profile
and earth pressures in saturated and unsaturated soil condition. The maximum lateral
displacements values found in the numerical back analyses were compatible with the
monitoring results. Besides, the influence of unsaturated soil conditions and soil suction in the
reduction of the retaining wall deformations and the active earth pressures were observed. / Este estudo apresenta resultados de um extenso monitoramento de deslocamentos horizontais
de uma estrutura de contenção em estacas espaçadas com tirantes passivos na cidade de
Goiânia, Brasil que foram medidas durante o processo de escavação. Os métodos de
instrumentação adotados foram de extensômetros de hastes horizontais múltiplas (EHHM) e
medições topográficas. O EHHM apresentou bons resultados que permitiu interpretar
corretamente o progresso da escavação. Todavia, as medições topográficas não foram
confiáveis devido à baixa precisão da Estação Total e sendo bastante afetados por erros do
usuário. Para determinar o perfil geotécnico do solo, ensaios em laboratório foram realizados
para obter parâmetros de resistência e deformabilidade para o solo na condição natural e
saturada. A grande variabilidade do solo, observada em termos de índice de vazios, se
apresenta como importante obstáculo, tornando a determinação representativa dos parâmetros
de resistência ao cisalhamento um desafio. Buscando acoplar as análises dos resultados de
monitoramento em campo, propriedades do solo e retro análises da estrutura de contenção, o
perfil de umidade e a curva característica solo-água foram medidos. Esses dados foram
utilizados para obter o perfil de sucção do solo e avaliar sua influência nos dados monitorados
em campo. Por fim, a ferramenta numérica Shetting Check (Geo5), que aplica o método de
viga apoiada sobre base elástica, foi utilizada para obter o módulo de reação do solo (ks) e
avaliar o comportamento do perfil de deformação da parede de contenção e do empuxo de
terra para o solo na condição saturada e não saturado. Os valores de deslocamentos
horizontais máximos obtidos a partir da retro análise apresentam-se compatíveis com valores
da literatura. Além disso, a influência da sucção na redução da deformação da parede de
contenção e dos empuxos ativos foi observada.
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Topologická optimalizace závěsu na poddajném podkladu / Topology Optimization of the Hinge on Elastic FoundationBeruashvili, Vasili January 2020 (has links)
Tato diplomová práce se zabývá modifikací původního tvaru součásti za účelem co nejlepšího splnění provozních podmínek daného zatížení a omezujících podmínek v programech M.S.C. NASTRAN, M.S.C. PATRAN a FUSION 360. Součást je připevněna na ortotropní desce (sendvičovém panelu). Cílem této práce je zjištění efektu elastického podkladu na výsledky optimalizace. Součást bude optimalizována za použití různých cílových funkcí a omezení. Elastický podklad změní tuhost, což může změnit napěťový stav součásti. Únosnost původního a modifikovaného tvaru bude srovnána pomocí programu M.S.C NASTRAN/PATRAN. Po tvarové optimalizaci má být 3D model připravený pro výrobní proces, který bude cenově nejefektivnější.
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