In this dissertation, a research effort aimed at development and implementation of a direct field test method to evaluate the linear and nonlinear shear modulus of soil is presented. The field method utilizes a surface footing that is dynamically loaded horizontally. The test procedure involves applying static and dynamic loads to the surface footing and measuring the soil response beneath the loaded area using embedded geophones. A wide range in dynamic loads under a constant static load permits measurements of linear and nonlinear shear wave propagation from which shear moduli and associated shearing strains are evaluated. Shear wave velocities in the linear and nonlinear strain ranges are calculated from time delays in waveforms monitored by geophone pairs. Shear moduli are then obtained using the shear wave velocities and the mass density of a soil. Shear strains are determined using particle displacements calculated from particle velocities measured at the geophones by assuming a linear variation between geophone pairs. The field test method was validated by conducting an initial field experiment at sandy site in Austin, Texas. Then, field experiments were performed on cemented alluvium, a complex, hard-to-sample material. Three separate locations at Yucca Mountain, Nevada were tested. The tests successfully measured: (1) the effect of confining pressure on shear and compression moduli in the linear strain range and (2) the effect of strain on shear moduli at various states of stress in the field. The field measurements were first compared with empirical relationships for uncemented gravel. This comparison showed that the alluvium was clearly cemented. The field measurements were then compared to other independent measurements including laboratory resonant column tests and field seismic tests using the spectral-analysis-of-surface-waves method. The results from the field tests were generally in good agreement with the other independent test results, indicating that the proposed method has the ability to directly evaluate complex material like cemented alluvium in the field. / text

No description available.

This study determined whether variation in clone, weed control treatment, or stem dimensions, could have an impact upon outerwood stiffness in 17 year old Pinus radiata stems. An experiment located south west of the Dunsandel township in Canterbury, New Zealand, was used to collect measures of acoustic velocity (windward and downward sides) from each of the 278 trees. Diameter at breast height, tree height, and height to live crown were also recorded for each tree. Findings from this research were compared with previous research carried out when the trees were ages eight and eleven. Assuming a green density of 1,000 kg/m3, Young’s Modulus equation was used to convert acoustic velocity to wood stiffness, or, Modulus of Elasticity (MOE). The effect of wind direction upon mean wood stiffness was not significant (α = 0.05). Consequently, one measure of wood stiffness was calculated per tree. Mean stem slenderness and mean wood stiffness values were calculated by block, weed control treatment, and clone. Weed control treatments had a significant impact upon mean wood stiffness in comparison to the control treatment (0.03 m2 area of weed control). Significant differences did not exist between different levels of weed control, ie., 0.75 m2, 3.14 m2 and 9 m2 chemical spot spray area. Clonal variation and stem slenderness significantly affected mean wood stiffness measures. Stem slenderness appeared to be correlated with clonal variation (interaction between clone and slenderness was not significant), however, according to Dr. Euan Mason, this finding is not corroborated by findings from other research on the wood quality of clones in Canterbury (personal communication, September 16, 2013). An analysis of covariance (ANCOVA) determined that mean height to the live crown was not a significant predictor of wood stiffness. Comparison with earlier research showed no change in the ranking of wood stiffness values by clone or treatment.

This thesis investigates the application of ultra-high modulus carbon fiber reinforced polymer (CFRP) plates to strengthen damaged reinforced concrete beams and slender columns. In the first phase, two different pre-repair loading histories were simulated in seven 3000x300x150 mm reinforced concrete beams, namely cracking within the elastic range, and overloading in the plastic range. After unloading, the beams were repaired with either high- or ultra-high modulus (210 or 400 GPa) CFRP plates, or a hybrid system, and then reloaded to failure. It was shown that the level of pre-existing damage has an insignificant effect on the strengthening effectiveness and the failure mode at ultimate. The 210 and 400 GPa CFRP of reinforcement ratio ρf = 0.17% increased the ultimate strength by up to 29 and 51%, respectively, despite the 40% lower tensile strength of the 400 GPa CFRP, due to the change in failure mode from debonding to rupture. Doubling ρf of the 400 GPa CFRP to 0.34% resulted in a 63% overall gain in flexural strength, only 8% increase in ultimate strength over ρf = 0.17%, due to change in failure mode from rupture to concrete cover delamination. The beam retrofitted by hybrid CFRP showed remarkable pseudo ductility and warning signs before failure. However, a parametric study revealed a critical balance in proportioning the areas of hybrid CFRP to achieve reliable pseudo ductility. In the beam with ρf =0.34%, this was achieved using a maximum of 30% ρf of the 400 GPa CFRP. The second phase of this thesis presents an analytical model developed by modifying the provisions of the ACI 318-08 code and employing the computer software Response 2000, to predict the performance of CFRP strengthened slender reinforced concrete columns. Response 2000 is used to establish the interaction curve while the modified ACI 318-08 code is used to acquire the slender column loading path to failure including the second order effects. The model predicts that the effectiveness of the FRP strengthening system increases as the slenderness ratio and FRP reinforcement ratio increase. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-09-24 12:36:48.352

Master of Science / Department of Architectural Engineering and Construction Sciences / Kimberly Waggle Kramer / Bill Zhang / Cold-formed steel members quickly are becoming a popular material for both commercial and residential construction around the world. Their high strength to weight ratio makes them a viable alternative to timber framing. In most cases cold-formed steel is used as a repetitive member in floor, wall, or roof assemblies. Structural sheathing is used in conjunction with the framing members in order to transfer loads between individual members. This sheathing is connected mechanically to the cold-formed steel through a variety of methods. The most common method uses screws spaced at close intervals, usually between 6 to 12 inches on center. When such assemblies are constructed, load is transferred from the sheathing through the connectors into the cold-formed steel, forming a composite assembly in which load is transferred and shared between two materials, providing a higher strength and stiffness over individual members themselves. The amount of load that can be transferred is dependent on the amount of slip that occurs when the assembly is loaded. This slip value describes the amount of composite action that takes place in the assembly. The amount of slip can be described by a value called the slip modulus. The composite, or effective, bending stiffness can be calculated using the slip modulus. In current design of cold-formed steel composite assemblies this composite action is not being taken into account due to a lack of research and understanding of the composite stiffness present in these assemblies. Taking composite action into account can lead to decreased member sizes or increased spacing of members, thereby economizing design. Furthermore, improved understanding of the effective stiffness can lead to more accurate design for vibrations in floor systems. This thesis tests cold-formed steel plywood composite members in an effort to verify previously established slip modulus values for varying steel thicknesses and establishes new values for varying fastener spacings. The slip modulus values obtained are used to calculate effective bending stiffness values in an effort to prove that composite action should be utilized in design of cold-formed steel composite assemblies.

Master of Science / Civil Engineering / Hani G. Melhem / Bill Zhang / Composite action is the joint behavior of two elements connected or bonded together. It is a phenomenon that is utilized in several applications throughout engineering. Previous studies have shown that cold formed steel (CFS) sheathed with structural wood panels exhibits a degree of partial composite action behavior. However currently in the design process, CFS and wood sheathing systems are considered separately in a non-composite manner due to the absence of sufficient supporting data. These systems can include the floors, roofs, and walls of a building. In order to determine the level of composite action present, the slip modulus is needed. The slip modulus describes the relationship between the shear force and the displacement exhibited by two elements in a composite system. The scope of this research is to determine the influence of fastener spacing on the slip modulus and provide a foundation of information to fully define the composite action between CFS and wood sheathing.

Esta pesquisa apresenta os resultados obtidos em análise laboratorial de misturas asfálticas de módulo elevado para aplicação em camada de base de pavimento. Historicamente, pode-se dizer que este tipo de mistura asfáltica em camadas de base resulta em melhor comportamento mecânico comparado com o de misturas asfálticas usinadas com CAP convencional. As misturas de módulo elevado apresentam vantagens em relação às convencionais com maior resistência à deformação permanente e maior vida de fadiga. Inicialmente, foram realizados ensaios laboratoriais de caracterização dos agregados e de três tipos de ligantes asfálticos: CAP A e CAP B, ambos ligantes duros com penetração entre 10 e 20dmm, e um CAP convencional, CAP 30/45. Foram dosadas três misturas asfálticas, com uma graduação preestabelecida, e com os três ligantes asfálticos estudados, pelos métodos Marshall e SUPERPAVE. Os teores de projeto pelo método Marshall foram de 0,2 a 0,3% superiores ao calculado pelo SUPERPAVE. Verificou-se o atendimento das especificações francesas quanto ao volume de vazios das misturas compactadas com os CAPs A e B pelo compactador giratório francês PCG). Foram determinados os danos por umidade induzida, tendo sido verificado que a mistura com CAP B requer um melhorador de adesividade. Determinaram-se os afundamentos por deformação permanente, as resistências à tração, os módulos de resiliência em dois equipamentos diferentes (MTS e UTM), os módulos dinâmicos, e a vida de fadiga por compressão diametral e por flexão em viga de 4 pontos, das três misturas asfálticas estudadas. As deformações permanentes para as misturas com CAP A e CAP B são menores que o limite máximo estabelecido pelas diretrizes europeias, e inferiores ao valor obtido com o mistura com CAP 30/45. Os módulos de resiliência mostraram rigidez distinta entre as misturas do módulo elevado, sendo que a mistura com CAP B é duas vezes mais rígida que a mistura com CAP A, que por sua vez é similar ao módulo com CAP 30/45. Obtiveram-se resultados similares de módulo de resiliência com equipamentos distintos. Os resultados dos ensaios de módulo dinâmico demonstraram proximidade de comportamento da mistura asfáltica com CAP A com misturas asfálticas com ligantes modificados; o módulo dinâmico da mistura com CAP B é similar àquele com CAP 30/45. Os resultados dos dois ensaios de fadiga empregados neste estudo demonstraram o melhor comportamento de misturas asfálticas compostas por ligantes duros e de módulo elevado, quando comparada com a mistura convencional. Todos os resultados demonstram que há benefícios de misturas de módulo elevado como camada de base em relação às misturas com CAP convencional, e que esta é uma solução com grande potencial para estruturas de pavimento para tráfego pesado. / This study presents the results obtained in laboratory analysis, about high modulus asphalt mixtures for use in base layer of pavement. Historically, it can be said that this type of mixture, when use in base layer, results in better mechanical behavior when compared with conventional asphalts. High modulus mixtures provide better behavior as it related layer`s permanent deformation and a higher fatigue life. Initially, laboratory tests for characterizing aggregates and three types of asphalt binders were carried out: Binder A and Binder B, both hard binders with penetration between 10 and 20dmm, and a conventional binder, namelly 30/45. Three types of asphalt mixtures were designed, with one predefined graduation and with those three asphalt binders, using Marshall and SUPERPAVE methods. Marshall`s binder contents were from 0.2 to 0.3% higher than SUPERPAVE. The compacted asphalt mixtures were in compliance with French specifications in terms of air void content of Binder A and Binder B using the French gyratory compactor (PCG). Moisture-induced damage test was performed and it was verified that Binder B needs an antistrip agent. Rutting, indirect tensile strength, resilient modulus in two different machines (MTS and UTM), dynamic modulus, and fatigue life by diametral compression and four point bending tests, were carried out with the three asphalt mixtures studied. The results of rutting for mixtures with Binders A and B were lower than the maximum limit of European specifications, and lower than the result with Binder 30/45. Resilient modulus showed different stiffness between the high modulus mixtures, where the asphalt mixture with Binder B was twice stiffer than the mixture with Binder A, which in turn is similar to the resilient modulus of the asphalt mixtures with Binder 30/45. Analogous results were observed in different resilient modulus machines. Dynamic modulus results showed similar behavior between the asphalt mixture with Binder A and asphalt mixture with modified binders; dynamic modulus of the asphalt mixture with Binder B was similar to the asphalt mixture with Binder 30/45. Results in the two fatigue tests were better for the asphalt mixtures with hard binders and high modulus in comparison with the conventional asphalt mixture. All the results demonstrate benefits of high modulus mixtures as base layer in pavements in comparison with asphalt mixtures with conventional binders, and the solution has a great potential in pavement structures for heavy traffic.

In this work, we used atomic force spectroscopy to obtain the elastic modulus of melanoma and keratinocytes fixed cells, with the purpose to determine the initial conditions for studies of confluente cultures of these cells in the future. The cell lines used were HaCaT cells and WM1366 melanoma cell, the last one is derived from a radial growth melanoma and both were analyzed, parental WM1366 cells (WM1366 shSCR cells) and galectin-3 silenced WM1366 cells (WM1366 shGal3). Cells were located and images of them were obtained by AFM contact mode under liquid conditions. Single force curves acquired in the central region of cells were used to determine the elastic modulus by the Hertzian contact model for the pyramidal tip, allowing to establish a comparison patter between cancer and normal cells. It was found that the melanoma cell (21.8 ± 0.5 kPa) exhibit smaller elastic modulus than keratinocytes cells (31.9 ± 0.4 kPa). For WM1366 shGal3 was found a elastic modulus of 16.1 ± 0.6 kPa, therefore, we found that for large indentation depth it is possible to distinguish between the same melanoma cell line, which represents general alterations in the organization of the cytoskeleton induced by the presence or absence of the galectin-3 protein. On the other hand, to detect local elastic modulus variations along the cell and to identify subcellular regions characterized by specific stiffness associated with local structures, we took elasticity maps in which a single force curve is acquired in each probe position. In order to interpret these maps, the cell was sliced into several different heights, curves of each height section were analyzed and represented in histograms, adjusted by the binomial distribution function. It was observed that the gradient of elastic modulus in cells from the nuclear region towards the cell periphery is more pronounced in cells devoid of galectin-3 than parental cells. The increased elastic modulus in the pericellular region of cells devoid of galectin-3 suggests that the organization of the extracellular matrix in these areas is different than those observed around HaCaT and shSCR WM1366 cells. / Neste trabalho, utilizamos espectroscopia de força atômica para obtenção do módulo elástico de células fixadas de melanoma e queratinócitos, com o objetivo de determinar as condições iniciais de estudos a serem realizados futuramente de culturas de células confluentes do mesmo tipo. As linhagem celulares utilizadas foram as células HaCaT e as células de melanoma WM1366, sendo a última derivada de um melanoma de crescimento radial sendo analisadas tanto as células parentais (células WM1366 shSCR) e as células WM1366 silenciadas com galectina-3 (WM1366 shGal3). As células foram localizadas e imageadas no modo AFM contato em meio líquido. Curvas de força adquiridas na região central das células foram utilizadas para determinar o módulo elástico, a partir do modelo de contato hertziano por uma ponta piramidal, permitindo estabelecer um padrão para comparação entre células normais e cancerígenas. Verificou-se que a célula de melanoma exibe menor módulo de elasticidade (21.8 ± 0.5 kPa) do que as células de queratinócitos (31.9 ± 0.4 kPa). Para as células WM1366 shGal3 foi encontrado um módulo elástico de 16.1 ± 0.6 kPa. Portanto, verificou-se que, para grandes profundidades de indentação, é possível distinguir entre a mesma linhagem de melanoma, células que apresentam alterações gerais na organização do citoesqueleto induzidas pela presença ou ausência da proteína galectina-3. Por outro lado, para detectar variações locais do módulo elástico ao longo da célula e identificar regiões subcelulares, caracterizadas por rigidez específica associada a estruturas locais, foram obtidos mapas de elasticidade nos quais uma única curva de força é adquirida em cada posição da sonda. Para interpretar estes mapas, a célula foi dividida em regiões de diferentes alturas e curvas de cada seção de altura foram analisadas e representadas em histogramas, ajustadas pela função de distribuição binomial. Observou-se que o gradiente de módulo de elasticidade em células da região nuclear em direção à periferia celular é mais acentuado em células desprovidas de galectina-3 do que em células parentais. O aumento do módulo de elasticidade na região pericelular das células desprovidas de galectina-3 sugere que a organização da matriz extracelular nestas áreas é diferente das observadas em torno das células HaCaT e shSCR WM1366.

No description available.

Low embodied energy, ability to act as a carbon store and ease of recycling gives forest products an important role within a low carbon built environment. Almost 25 % of the coniferous resource within the South West of England is Douglas-fir, a species reputed for producing high quality timber. Despite this, the region is facing challenges in delivering the resources full potential, a contributing factor to which is a loss of knowledge regarding its quality. The aim of the work presented is to gain an improved understanding of the quality of Douglas-fir grown within the region, from the perspective of uses in structural applications, the factors which influence material quality and their interrelationships. Flexural modulus of elasticity, flexural and compressive strength were determined utilising small clear specimens derived from 1.3 and 8 m heights within 27 trees from six sites across the South West. Results showed a rise in the magnitude of properties with increasing cambial age, particularly so at younger ages. Differences in values were also recorded between stem heights and with rate of growth. These were however less than age related variations. Results compared favourably to those reported in other studies conducted on the species. Utilising SilviScan-3, anatomical properties including density, microfibril angle and cellular dimensions were measured. Significant variations were recorded with cambial age, and in some instances sampling height. The influence of growth rate on anatomical properties was small. Through statistical and composite modelling, microfibril angle was found to be strongly associated with changes in modulus of elasticity within juvenile wood. Within mature wood and for strength properties, density was the controlling factor. It was shown that a moderate proportion of variations in mechanical properties can be accounted for utilising visually identifiable wood characteristics. The new understanding that has been gained through this work presents opportunities for improved utilisation, the implementation of effective management practices and the development of more efficient visual grading techniques.