Wood construction platforms are a common method for inexpensive, temporary soil stabilization under heavy machinery; however, platforms are not typically thought of as an engineered product. Review of literature has shown that only one design method is currently available and is specific to one type of platform configuration. The purpose of this thesis is to develop a design method that is simple, versatile and accurate. The proposed design method was intentionally developed so that the designer would have input in multiple areas of the design. Instrumentation allowed for increased insight into the mechanical behavior of the platforms. The objective of this research is to use measured strain, load, and deflection in conjunction with fundamental engineering mechanics principles to predict a single platform’s mechanical behavior on the ground. Results from this method compare favorably with the only other design guide available and improves the knowledge base by developing design guidance for any type of wood construction platform.

Despite the crucial role they play in transferring loads from the superstructure to the foundation, steel column-to-footing connections have received little attention in research. Though shallow embedded connections are typically characterized as pinned, studies have shown that they exhibit significant rotational stiffness. The objective of this thesis is to quantify the rotational stiffness of such connections. A method named the continuum model is developed by which the rotational stiffness of embedded connections may be calculated. Outputs from this model are compared with experimental data on steel connections embedded in concrete. The continuum model is shown to be capable of reasonably predicting the rotational stiffness of such connections. Results from the model were consistent with those of previous experimental studies that showed that embedment lengths greater than twice the column depth fail to significantly increase stiffness. Plots of rotational stiffness vs. embedment length developed from the continuum model are provided such that rotational stiffness may be calculated for any wide flange shape at any embedment length. Simplified equations provide a simpler way for engineers to estimate the same information.

Obtaining the modal parameters of a deflected and rolling tire represents a challenge due to the complex vibration characteristics that cause the tire's symmetry distortion and the natural frequencies' bifurcation phenomena. The modal parameters are usually extracted using a detailed finite element model. The main issue with full modal models (FEA, for example) is the inability to integrate the tire modal model with the vehicle models to tune the suspension system for optimal ride comfort. An in-plane rigid–elastic-coupled tire model was used to examine the 200 DOF finite difference method (FDM) modal analysis accuracy under non-ground contact and non-rotating conditions. The discrete in-plane rigid–elastic-coupled tire model was modified to include the contact patch restriction, centrifugal force, Doppler, and Coriolis effects, covering a range of 0-300 Hz. As a result, the influence of the contact patch and the rotating tire conditions on the natural frequencies and modes were obtained through modal analysis. The in-plane rigid–elastic-coupled modal model with varying conditions was created that connects any two DOFs around the tire's tread or sidewall as inputs or outputs. The vertical movement of the wheel was incorporated into the in-plane rigid–elastic-coupled tire modal model to extract the transfer function (TF) that connects road irregularities as an input to the wheel's vertical movement as an output. The TF was utilized in a quasi-static manner to obtain the tire's enveloping characteristics rolling over short wavelength obstacles as a direct function of vertical wheel displacement under varying contact patch length constraints. The tire modal model was implemented with the quarter car model to obtain the vehicle response rolling over short wavelength obstacles. Finally, a sensitivity analysis was performed to examine the influence of tire parameters and pretension forces on natural frequencies. / Doctor of Philosophy / The goal of vehicle manufacturers is to predict the vehicle's behavior under various driving conditions using mathematical models and simulation. Automotive companies rely heavily on computational simulation tools instead of real-time tests to shorten the product development cycle and reduce costs. However, the interaction between the tire and the road is one of the most critical aspects to consider when evaluating automobile stability and performance. The tires are responsible for generating the forces and moments that drive and maneuver the vehicle. Tires are complex products due to their intricate design, and their characteristics are affected by many factors such as vertical load, inflation pressure, speed, and a road with an uneven surface profile. Consequently, this project aims to describe the influence of various driving circumstances and load conditions on tire properties, as well as to develop a model that can represent the vertical tire and vehicle behavior while traveling over a cleat under different vehicle loads.

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.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2016-03-31T20:10:43Z No. of bitstreams: 2 Dissertação - Adriana Cristina Gomes - 2015.pdf: 14045273 bytes, checksum: 9bf9ee1429dd1afc11c6d19ff58a65c7 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-04T11:48:47Z (GMT) No. of bitstreams: 2 Dissertação - Adriana Cristina Gomes - 2015.pdf: 14045273 bytes, checksum: 9bf9ee1429dd1afc11c6d19ff58a65c7 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-04-04T11:48:47Z (GMT). No. of bitstreams: 2 Dissertação - Adriana Cristina Gomes - 2015.pdf: 14045273 bytes, checksum: 9bf9ee1429dd1afc11c6d19ff58a65c7 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) 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.