In order to predict the strength of shear wall with cold-formed steel framing members, analytical models were reviewed. Multiple analytical models were studied, as well as twenty-one connection tests were performed. The connection tests consist of 50-ksi cold-formed steel framing track, different fastening configurations, and different sheathing thicknesses (1/8" and 1/2"). No.12 screw resulted in the highest peak load of all fastening configurations, while the rivet connection had the lowest peak load. In addition, failure modes were observed after conducting the connection tests including shear in fastening, screw pullout, and bearing in the sheathing. However, only the rivet and No.10 screw fastening configurations were used in the prediction analysis of the shear wall by the elastic model. Six shear wall tests were conducted on both panels (1/2"and 1/8" thickness). After doing the comparison between the experimental and the elastic model, the percentage difference for the 1/8" and the 1/2" polymer composite panels (3''along the edge and 6''along the chord stud), was very small. It was 6.2% for the 1/8" and 2.96% for the 1/2" panels. This means the analytical model can predict the shear wall peak load. However, the percentage difference was slightly higher being 7.4% for the 1/2" polymer composite panels with 6" along the perimeter with the 12" at the chord stud. After comparing the experimental values to the predicted value of shear walls, it was concluded that this model is the most appropriate analytical method for predicting the shear wall capacity framed with cold-formed steel sheathed with polymer composite panels. Many of these configurations were used in a prototype shelter that was constructed and built at the structural testing laboratory at the University of North Texas.

Orientador: Katia Lucchesi Cavalca Dedini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-09T21:40:12Z (GMT). No. of bitstreams: 1 Ramalho_DeniseAlves_M.pdf: 10823264 bytes, checksum: 8b25eba0e7c26b9c543a70020d208299 (MD5) Previous issue date: 2006 / Resumo: O objetivo deste trabalho é estender e melhorar a análise dinâmica de um sistema rotorfundação-solo através da inclusão de modelos distintos de perfis de solo. Obtém-se a resposta desbalanceada de um rotor Laval (Jeffcott) simples bidimensional com mancais rígidos. O rotor é colocado sobre uma fundação de bloco rígido. Os perfis de solo incluem o modelo clássico de semi-espaço e o modelo de solo sobre base rígida. Em particular, uma camada sobre base rígida com diferentes valores de profundidade será considerada. A resposta dinâmica do solo é obtida no domínio da freqüência. O mecanismo de amortecimento interno do solo é considerado. Vários estudos paramétricos são realizados para avaliar o papel da espessura da camada do solo, do coeficiente de amortecimento do solo, da inércia da fundação e da altura dos mancais na resposta ao desbalancemento do rotor. Acredita-se que a análise deste modelo simples de rotor-fundação-solo ajudará a esclarecer o papel dos parâmetros mencionados na resposta dinâmica do rotor / Abstract: The aim of the present work is to extend and improve the dynamic analysis of a rotorfoundation-soil system by including the modelling of distinct soil profiles. The unbalance response of a simple two-dimensional Laval (Jeffcott) rotor with rigid bearings is performed. The rotor is attached to a rigid strip foundation (block foundation). The soil profiles, on the other hand, include the classical half-space but also stratified soils. In particular, a layer with various depths over a bedrock will be considered. The soil¿s dynamic response is furnished in terms of frequency dependent complex impedances. The soil internal damping mechanism is also addressed by making the soil a viscoelastic continuum. A series of parametric studies are perfomed to assess the role of soil layer thickness, soil internal damping coefficient, foundation inertia and bearing height on the rotor unbalance response. It is believed that the analysis of this simple otor-foundation-soil model will help to clarify the role of the mentioned parameters on the rotor dynamic response / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

It is widely known that Central Corneal Thickness (CCT) and Radius of Curvature (RoC) in uence the estimated IntraOcular Pressure (IOP) obtained from Goldmann Applanation Tonometry (GAT). However, not much is known about the in uence of corneal material properties, especially in a clinical setting. Several numerical studies have been conducted in an attempt to quantify the in uence of corneal material properties on the IOP. These studies agree that corneal material properties do in uence the estimated IOP, which contradict the initial premise on which GAT was designed, namely that material properties do not in uence the obtained GAT readings. Also, there is no consensus among these studies with respect to corneal material properties, thus a wide range of proposed properties exist. A possible explanation for this range of available corneal properties is the numerical modi elling assumptions used, which seem to be quite different. Different sets of experimental in ation test data were used to calibrate the constitutive models and different limbal boundary conditions were applied to simulate the experimental setup as well as in vivo conditions during GAT simulations. Therefore the purpose of this study is to determine whether these modelling assumptions in uence the obtained IOP and ultimately the overall conclusions. A Finite Element (FE) model of the human cornea is developed, implementing a constitutive model to represent the complex corneal structure and two limbal boundary conditions. This model is then calibrated using two different sets of experimental in ation test data. During calibration of the fibre reinforced elastic constitutive model it is found that independent of the assumptions made regarding the material coe cients, that the numerical in ation data compare well with the experimental data for all cases. Using this model a GAT simulation is conducted to estimate the IOP and the in uence of the modelling assumptions, cornea geometry and material properties are then investigated. The results indicate that the modelling assumptions, cornea geometry and material properties do infuence the estimated IOP. However, when assuming the cornea ground substance stiffness to be constant, it is found that the in uence on IOP due to material properties is not as significant. A correction equation is also proposed to account for the corneal geometric properties by calibrating the numerical model for a numerically normal cornea. This is done by utilising the various data sets which are obtained during the calibration of the constitutive model with the experimental inflation test data. It is concluded that using only inflation data to calibrate the constitutive model is not sufficient to uniquely describe the corneal material. This is evident as different material data sets are obtained, even though the experimental inflation data is matched well for a variety of considered cases. Each of these material data sets, in conjunction with geometric properties, yield different estimates for IOP during GAT simulations. This study therefore recommends the use of additional experimental data, such as strip extensometry, along with inflation test data to adequately calibrate a numerical model. It should also be noted that when modelling GAT care should be taken when considering the choice of limbal boundary condition, experimental data for calibration and assumptions made with regards to material coe cients, as these choices could potentially influence the outcomes and conclusions of a study. / Dissertation (MEng)--University of Pretoria, 2014. / gm2014 / Mechanical and Aeronautical Engineering / unrestricted

Asphalt mix design includes the determination of a gradation, asphalt content, other volumetric properties, the evaluation of mechanical properties and moisture damage potentials. In this study, a computational method is developed to aid mix design. Discrete element method (DEM) was used to simulate the formation of skeleton and voids structures of asphalt concrete of different gradations of aggregates. The optimum gradation could be determined by manipulating the particle locations and orientations and placing smaller particles in the voids among larger particles. This method aims at an optimum gradation, which has been achieved through experimental methods. However, this method takes the mechanical properties or performance of the mixture into consideration, such as inter-aggregate contacts and local stability. A simple visco-elastic model was applied to model the contacts between asphalt binder and aggregates. The surface texture of an aggregate particle can be taken into consideration in the inter-particle contact model. The void content before compactions was used to judge the relative merits of a gradation. Once a gradation is selected, the Voids in Mineral Aggregate (VMA) can be determined. For a certain air void content, the mastics volume or the binder volume or the asphalt content can be determined via a digital compression test. The surface area of all the aggregates and the film thickness can be then calculated. The asphalt content can also be determined using an alternative approach that is based on modeling the inter-particle contact with an asphalt binder layer. In this study, considering the necessity of preservation of the compaction temperature, the effect of various temperatures on Hot Mix Asphalt (HMA) samples properties has been evaluated. As well, to evaluate the effect of this parameter on different grading, two different grading have been used and samples were compacted at various temperatures. Air voids also influence pore water pressure and shrinkage of asphalt binder and mixture significantly. The shrinkage is measured on a digital model that represents beams in a steel mold and is defined as the linear autogenous deformation at horizontal direction. / Ph. D.

The subject of the thesis is the investigation of asymptotic properties of solutions of the Cauchy problem for structurally damped sigma-evolution operators with time dependent, monotonous, dissipation term. An appropriate energy for solutions of the sigma-evolution equations is defined and some estimates for energies of higher order are proved. In the scale invariant case the optimality of these estimates is shown. Further, the influence of properties of the time dependent dissipation on L^p-L^q estimates for the energy with p and q bigger or equal to 2 and from the conjugate line is clarified. Also smoothing properties of the operators under consideration are investigated. The connection between the regularity of the data and the regularity of the solution in terms of L^2 based Gevrey spaces is considered. Finally, L^1-L^1-estimates in the special case delta = sigma/2 and decreasing dissipative coefficient. / Thema der vorliegenden Dissertation ist die Untersuchung asymptotischer Eigenschaften von Lösungen des Cauchy Problems für strukturell gedämpfte sigma-Evolutions-Operatoren mit zeitabhängigem, monotonen Dissipationskoeffizienten. Es wird eine geeignete Energie definiert und für diese Abschätzungen, auf für entsprechende Energien höherer Ordnung gezeigt. Darüber hinaus wird der Einfluss des Dissipationskoeffizienten auf L^p-L^q Abschätzungen auf und entfernt von der konjugierten Linie untersucht. Im skaleninvarianten Fall wird die Schärfe der Abschätzungen bewiesen. Weiterhin wird der Zusammenhang zwischen der Regularität der Daten und der der Lösung in Termen von L^2-basierten Gevrey-Räumen untersucht. Schließlich werden L^1-L^1-Abschätzungen für den Spezialfall delta = sigma/2 und monoton fallenden Dissipationskoeffizienten gezeigt.

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La presente investigación tiene como objetivo principal evaluar la influencia del CBR en el terreno de fundación vial limo arcilloso para determinar espesores de mejoramiento mediante modelos elásticos y la metodología AASHTO 1993. Se evaluaron 21 sectores críticos en la zona de estudio mediante ocho criterios geotécnicos. Se determinó que los materiales evaluados son inadecuados, por lo tanto, no son aptos para asegurar la estabilidad de la estructura del pavimento. Para estabilizar el terreno de fundación se eligió la técnica de reemplazo de material con un CBR de 20%. Se determinaron los espesores razonables de mejoramiento utilizando un enfoque de diseño empírico-mecanicista. Para ello, se utilizó los modelos matemáticos de la teoría elástica propuesto por Boussinesq, Burmister y Odemark para determinar las respuestas mecánicas de la estructura. Estos se han limitado mediante parámetros admisibles para evitar el fallo de la estructura durante el periodo de diseño. Se ha realizado un análisis comparativo entre los espesores de mejoramiento obtenidos según los modelos elásticos y la metodología AASHTO 1993. Se encontró que los espesores de mejoramiento determinados con el modelo de Odemark y la metodología AASHTO son similares para un CBR de 1.9% a 2.2%. Sin embargo, entre la metodología AASHTO con los modelos de Burmister y Boussinesq hay una diferencia que oscila hasta en un 25%. Así mismo, a partir de un CBR>3.5%, los espesores de mejoramiento se van equiparando, evidenciándose una similitud entre las metodologías aplicadas. Los resultados mostraron que el incremento del CBR tiene una influencia significativa en la profundidad de mejoramiento. / The main objective of this research is to assess the influence of CBR in the silty-clayey road foundation ground to determine the improvement depth of subgrade soil using elastic models and AASHTO 1993 methodology. Twenty-one critical sectors in the study area were evaluated using eight geotechnical criteria. It was determined that the materials evaluated are inadequate, therefore, they are not suitable to ensure the stability of the pavement structure. To stabilize the foundation ground, the material replacement technique with a CBR of 20% was chosen. Reasonable improvement depth of subgrade soil were determined using an empirical-mechanistic design approach. For this purpose, the mathematical models of the elastic theory proposed by Boussinesq, Burmister and Odemark were used to determine the mechanical responses of the structure. These have been limited by admissible parameters to avoid failure of the structure during the design period. A comparative analysis has been made between the improvement depth of subgrade soil obtained according to the elastic models and the AASHTO 1993 methodology. It was found that the improvement depth of subgrade soil determined with the Odemark model and the AASHTO methodology are similar for a CBR of 1.9% to 2.2%. However, between the AASHTO methodology and the Burmister and Boussinesq models there is a difference of up to 25%. Also, from a CBR>3.5%, Improvement depth of subgrade soil become equal, showing a similarity between the applied methodologies. The results showed that the increase in CBR has a significant influence on the improvement depth of subgrade soil. / Tesis

The subject of the thesis is the investigation of asymptotic properties of solutions of the Cauchy problem for structurally damped sigma-evolution operators with time dependent, monotonous, dissipation term. An appropriate energy for solutions of the sigma-evolution equations is defined and some estimates for energies of higher order are proved. In the scale invariant case the optimality of these estimates is shown. Further, the influence of properties of the time dependent dissipation on L^p-L^q estimates for the energy with p and q bigger or equal to 2 and from the conjugate line is clarified. Also smoothing properties of the operators under consideration are investigated. The connection between the regularity of the data and the regularity of the solution in terms of L^2 based Gevrey spaces is considered. Finally, L^1-L^1-estimates in the special case delta = sigma/2 and decreasing dissipative coefficient. / Thema der vorliegenden Dissertation ist die Untersuchung asymptotischer Eigenschaften von Lösungen des Cauchy Problems für strukturell gedämpfte sigma-Evolutions-Operatoren mit zeitabhängigem, monotonen Dissipationskoeffizienten. Es wird eine geeignete Energie definiert und für diese Abschätzungen, auf für entsprechende Energien höherer Ordnung gezeigt. Darüber hinaus wird der Einfluss des Dissipationskoeffizienten auf L^p-L^q Abschätzungen auf und entfernt von der konjugierten Linie untersucht. Im skaleninvarianten Fall wird die Schärfe der Abschätzungen bewiesen. Weiterhin wird der Zusammenhang zwischen der Regularität der Daten und der der Lösung in Termen von L^2-basierten Gevrey-Räumen untersucht. Schließlich werden L^1-L^1-Abschätzungen für den Spezialfall delta = sigma/2 und monoton fallenden Dissipationskoeffizienten gezeigt.