Os objetivos deste trabalho foram: 1) avaliar o efeito do envelhecimento por ciclagem mecânica (1 milhão de ciclos a uma freqüência de 2 Hz) sobre a resistência à flexão biaxial de três materiais cerâmicos utilizados para a construção infra-estruturas de próteses parciais fixas: a) uma zircônia tetragonal policristalina estabilizada por ítria (Y-TZP); b) uma alumina policristalina (AL) e c) um compósito de alumina e zircônia infiltrado por vidro (ICZ) e 2) determinar a influência da tensão gerada durante a ciclagem sobre a degradação da resistência das cerâmicas estudadas, já que para cada material a ciclagem foi realizada com dois níveis diferentes de tensão. Material e método: Espécimes em forma de disco (12 mm x 2 mm e 12 mm x 1 mm) foram confeccionados conforme as recomendações dos fabricantes. A resistência à flexão desses materiais foi determinada por meio do ensaio de flexão biaxial. Para o grupo controle de todos os materiais estudados (espécimes de 1 mm de espessura), foi realizada estatística de Weibull para determinação da resistência característica (0) e módulo de Weibull (m). Após o envelhecimento por ciclagem mecânica, realizado para todos os materiais nas duas espessuras, os espécimes foram fraturados e os valores obtidos foram comparados com seus respectivos grupos controle. Resultados: O valor de m foi estatisticamente semelhante para todos os materiais, o ICZ (12,2) apresentou o maior valor comparado ao do Y-TZP (9,0) e do AL (8,4). Os valores de resistência característica, 0, apresentaram diferenças significantes para todos os materiais, 828 MPa para a Y-TZP, 405,8 MPa para a AL e 328 MPa para o ICZ. Não houve diferenças estatisticamente significantes entre as resistências medidas para os grupos controle e ciclado para nenhum dos materiais nas duas espessuras avaliadas. Conclusão: O envelhecimento por ciclagem mecânica não causou alterações significativas nos valores de resistência à flexão de nenhuma das cerâmicas testadas. O aumento no nível de tensão aplicada na ciclagem mecânica não gerou um aumento na degradação da resistência dos materiais estudados. / The objectives of this study were: 1) To evaluate the effect of aging by mechanical cycling (1 million cycles at a frequency of 2 Hz) on the biaxial flexural strength of three dental ceramics used as framework materials for fixed partial dentures (FPDs): a) yttria partially stabilized zirconia tetragonal polycrystals (Y-TZP), b) alumina polycrystals (AL) and c) alumina-based zirconia-reinforced glass infiltrated ceramic (ICZ) and 2) determine the influence of stress level generated during mechanical cycling on the flexural strength degradation of the studied ceramics. Materials and Methods: Disc-shaped specimens (12 mm x 2 mm and 12 mm x 1 mm) were prepared according to manufacturer\'s recommendations. The flexural strength of these materials was determined by biaxial flexure test for the control group of all materials. The Weibull statistics was performed to determine the characteristic strength (0) and Weibull modulus (m). After mechanical aging, the specimens were fractured and the values obtained were compared with their respective control groups. Results: No statistically significant differences were founded between the strength obtained for the control and cycled groups for any of the materials in the two thicknesses tested. The m value was similar for all materials, ICZ (12.2) which showed the highest value, followed by the Y-TZP (9) and AL (8.4). The values for characteristic strength (0) showed significant differences for all materials, 828 MPa for Y-TZP, 405.8 MPa for AL and 328 MPa for ICZ. Conclusion: Aging by mechanical cycling did not cause significant changes in the values of flexural strength for all the ceramics tested. The increase in the stress level during cyclic loading did not cause an increase in the strength degradation of the materials studied.

Student Number : 0100677A - PhD thesis - School of Civil and Environmental Engineering - Faculty of Engineering and the Built Environment / This thesis presents the findings on empirical study of dry-stack masonry. Dry-stack masonry refers to a method of building masonry walls, where most of the masonry units are laid without mortar in the joints. Of late (since mid eighties) in modern construction, dry-stacking or mortarless technology is increasingly becoming popular because of its advantages. The construction industry is acknowledging the need to accelerate the masonry construction process, as the traditional method is labour intensive and hence slower due to the presence of a large number of mortar joints. Early attempts were made to increase the size of masonry units (block instead of brick), thereby reducing the number of mortar joints, wherein the use of bedding mortar imposed constraints on the number of courses to be constructed in a day. Elimination of bedding mortar accelerates construction; thereby reducing cost, variation due to workmanship and generally small pool of skilled labour is required in dry stacking. Dry-stack masonry is a relatively new technology not yet regulated in the code of practice and therefore very limited information on the structural behaviour of the masonry is available. This project is based on the investigation of the HYDRAFORM dry-stack system, which utilises compressed soil-cement interlocking, blocks. The system is now widely used in Africa, Asia and South America. The main objective of the project was to establish through physical testing the capacity of the system to resist lateral load (e.g. wind load), vertical load and dynamic load such as earthquake loading. In the first phase of the project investigations were conducted under static loading where series of full-scale wall panels were constructed in the laboratory and tested under lateral loading, and others were tested under vertical loading to establish the mode of failure and load capacity of the system. Series of control tests were also conducted by testing series of wallettes to establish failure mechanism of the units and to establish the flexural strength of the system. Finally the test results were used for modelling, where load prediction models for the system under vertical loading and under lateral loading were developed. The theoretical load prediction models were tested against the test results and show good agreement. After the load capacity was established the next step in the study was to further improve the system for increased capacity particularly under dynamic loading. The normal Hydraform system was modified by introducing a conduit, which allows introduction of reinforcements. Series of dry-stack seismic systems were constructed and initially tested under static lateral loading to establish the lateral load capacity. The second Phase of the project was to investigate the structural behaviour and performance of the Hydraform system under seismic loading. A shaking table of 20 tonnes payload, (4m x 4m) in plan was designed and fabricated. A full-scale plain dry-stack masonry house was constructed on the shaking table and subjected to seismic base motions. The shaking table test was performed using sine wave signals excitations starting from low to very severe intensity. A conventional masonry test structure of similar parameters was also constructed on the table and tested in a similar manner for comparison. The tests were conducted using a frequency range of 1Hz to 12Hz and the specimens were monitored for peak accelerations and displacements. For both specimens the initial base motion was 0.05g. The study established the mode of failure of the system; the structural weak points of unreinforced dry-stack masonry, the general structural response of the system under seismic condition and the failure load. The plain dry-stack masonry failed at 0.3g and the conventional masonry failed at 0.6g. Finally recommendations for further strengthening of system to improve its lateral capacity were proposed.

O objetivo do presente estudo foi de avaliar a influência de soluções de resina com diferentes proporções de monômeros e diferentes concentrações em massa de nanofibras nas propriedades flexurais de compósitos resinosos experimentais reforçados com nanofibras de poliacrilonitrila (PAN). Materiais e métodos: Nanofibras de PAN foram produzidas pelo processo de eletrofiação e caraterizadas por teste de tração e microscopia eletrônica de varredura (MEV). Os compósitos experimentais foram produzidos pela infiltração das mantas de nanofibras com diferentes misturas de BisGMA-TEGDMA (BisGMA/TEGDMA: proporções em % massa de 30/70, 50/50, e 70/30). Foram incorporadas diferentes concentrações em massa de nanofibras (de 0% a 8%). Espécimes em forma de barra foram seccionados a partir de blocos do compósito experimental e armazenados em água na temperatura de 37oC por 24h anteriormente à realização dos testes de flexão de três pontos. Foram avaliados a resistência flexural (RF), o módulo flexural (MF) e o trabalho de fratura (TF). Resultados: Os testes de tração das nanofibras de PAN demonstraram um comportamento anisotrópico das mantas de nanofibras. As propriedades mecânicas exibiram maiores valores na direção perpendicular ao eixo de rotação do coletor metálico utilizado na produção das fibras por eletrofiação. Maiores proporções de BisGMA nas misturas de resina resultaram em maiores valores de RF e MF, o que não ocorreu para os valores de TF. A adição de diferentes concentrações de nanofibras não afetou as propriedades de RF e MF em comparação com o grupo controle (resina pura) (p>0.05). No entanto, a adição das nanofibras promoveu um aumento significante do TF, principalmente para as misturas de resina com maior proporção de TEGDMA (p<0,05). Significância: A inclusão de nanofibras de PAN em resinas de modo a formar compósitos resinosos reforçados por nanofibras não afetou negativamente as propriedades flexurais do material e resultou em um aumento significativo da tenacidade, uma propriedade desejável para um material a ser utilizado para aplicação restauradora. / The present study had the objectives to evaluate the influence of different resin blends concentrations and nanofibers mass ratio on flexural properties of experimental Poliacrylonitrile (PAN) nanofibers reinforced composite. Materials and Methods: Poliacrylonitrile (PAN) nanofibers mats were produced by electrospinning and characterized by tensile testing and scanning electron microscopy (SEM). Experimental resin-fiber composite beams were manufactured by infiltrating PAN nanofiber meshs with varied concentrations of BisGMA-TEGDMA resin blends (BisGMA/TEGDMA: 30/70, 50/50 and 70/30 weight %). The mass ratio of fiber to resin varied from 0% to 8%. Beams were cured and stored in water at 37oC. Flexural strength (FS), flexural modulus (FM) and work of fracture (WF) were evaluated by three-point bending test after 24 hs storage. Results: The tensile properties of the PAN nanofibers indicated an anisotropic behavior being always higher when tested in a direction perpendicular to the rotation of the collector drum. Except for WF, the other flexural properties (FS and FM) were always higher as the ratio of BisGMA to TEGDMA increased in the neat resin beams. The addition of different ratios of PAN fibers did not affect FS and FM of the composite beams as compared to neat resin beams (p>0.05). However, the addition of fibers significantly increased the WF of the composite beams, and this was more evident for the blends with higher TEGDMA ratios (p<0.05). Significance: The inclusion of PAN nanofibers into resin blends did not negatively affect the properties of the composite and resulted in an increase in toughness that is a desirable property for a candidate material for restorative application.

Delaminations in concrete bridge decks result primarily from corrosion of the reinforcing bars (or rebar). This corrosion leads to volumetric expansion of the rebar. When the rebar expands, concrete cracks, and there is a localized separation of the concrete cover from the underlying concrete. Impact-echo testing is an effective technique to map delaminations on concrete bridge decks. However, mapping speed is limited by necessary retrieval of the impactor for traditional tests. To achieve higher scanning speeds, it is advantageous to use both a non-contact measurement (air-coupled impact-echo) and disposable-impactor excitation. Disposable impactors have the potential advantage of achieving greater deck scanning speeds because they do not need to be retrieved, and they can also be used with air-coupled measurement systems. This thesis reports impact excitation of concrete using disposable impactors such as water droplets and ice balls. The impact characteristics of these impactors are compared with those of steel balls and chain links. Comparing the acoustic recordings on intact and delaminated concrete surface shows that water droplets and ice balls are able to excite flexural resonant modes associated with delamination defects. The use of water droplets and ice balls for shallow delamination detection in concrete is thus demonstrated.

Impact strength is one of the most important structural properties for a designer to consider, but is often the most difficult to quantify or measure. A constant concern in the field of composites is the effect of foreign object impact damage because it is often undetectable by visual inspection. An impact can create interlaminar damage that often results in severe reductions in strength and instability of the structure. The main objective of this study is to determine the effectiveness of a damage arrestment device (DAD) on the mechanical behavior of composite sandwiches, following a low-velocity impact. A 7.56-lbf crosshead dropped from a height of 37.5-inches was considered for the low-velocity impact testing. In this study, the experimental and numerical analysis of composite sandwiches were investigated, which included static 4-point bend and vibration testing. Composite sandwiches were constructed utilizing four-plies of Advanced Composites Group LTM45EL/CF1803 bi-directional woven carbon fiber face sheets with a General Plastics Last-A-Foam FR-6710 rigid polyurethane core. Specimens were cured in an autoclave, using the manufacturer’s specified curing cycle. In addition to the experimental and numerical analysis of composite sandwiches, developing and building a data acquisition (DAQ) system for the Dynatup 8250 drop weight impact tester was accomplished. Utilizing National Instruments signal conditioning hardware, in conjunction with LabView and MATLAB, complete testing software was developed and built to provide full data acquisition for an impact test. The testing hardware and software provide complete force vs. time history and crosshead acceleration of the impact event, as well as provide instantaneous impact velocity of the projectile. The testing hardware, software, and procedures were developed and built in the Aerospace Structures/Composites laboratory at Cal Poly for approximately 15% of the cost from the manufacturer. In the first study, static 4-point bend testing was investigated to determine the residual flexural strength of composite sandwich beams following a low-velocity impact. Four different specimen cases were investigated in the 4-point bend test, with and without being impacted: first a control beam with no delamination or DAD, second a control beam with a centrally located 1-inch long initial delamination, third a DAD key beam with two transverse DADs centrally located 1-inch apart, and finally a DAD key beam with a centrally located initial delamination between two transverse DADs. The specimens used followed the ASTM D6272 standard test method. The specimens were 1-inch wide by 11-inch long beams. The experimental results showed that the presence of DAD keys significantly improved both the residual stiffness and ultimate strength of a composite sandwich structure that had been damaged under low-velocity impact loading, even with the presence of an initial face-core delamination. In the second study, vibration testing was investigated as a means to detect a delamination in the structure and the effect of impact damage on the vibrational characteristics, such as damping, on composite sandwich plates. Four different specimen cases were investigated in the vibration test, both with and without being impacted: first a control plate with no delamination or DAD, second three control plates with varying 1-inch initial delamination locations at the 1st, 2nd, and 3rd bending-mode nodes, third a DAD key plate with one DAD running the entire length longitudinally along the center of the plate, and finally three DAD key plates with one DAD running the entire length longitudinally along the center of the plate and varying 1-inch delamination locations at the 1st, 2nd, and 3rd bending mode-nodes. The response accelerometer location was varied at 1-inch increments along the length of the plate. From the experimental results, it was determined that varying the location of the accelerometer had a significant effect on the detection of face-core delamination in a composite sandwich structure. Additionally, it was shown that damping characteristics significantly degraded in control case plates after a low-velocity impact, but they were better retained when a DAD key was added to the structure. Numerical analysis utilizing the finite element method (FEM) was employed to validate experimental testing, as well as provide a means to examine the stress distribution and impact absorption of the structure. The impact event was modeled utilizing the LS-Dyna explicit FE solver, which generated complete force vs. time history of the impact event. Static 4-point bending and vibration analysis were solved utilizing the LS-Dyna implicit solver. Finally a damaged mesh was obtained from the explicit impact solution and subjected to subsequent static 4-point bending and vibration analysis to numerically determine the residual mechanical behavior after impact. All cases showed good agreement between the numerical, analytical, and experimental results.

This thesis investigates the flexural behavior of interlocking compressed earth block (ICEB) shear walls. In-plane cyclic tests were conducted to evaluate the performance of three flexure dominant large scale ICEB specimens: a slim wall with a 2:1 height to width aspect ratio, a flanged wall, and a wall with an opening at the center. Following the experimental investigation, two types of analyses were conducted for calculating the ultimate strength of flexure dominant ICEB walls: a nonlinear static analysis model assuming lumped plasticity and a plastic analysis model. In addition, incremental dynamic analysis was conducted to address the seismic performance of flexure dominant ICEB buildings. Based on the database from the incremental dynamic analysis, the collapse potential of demonstration ICEB buildings were compared for the countries of interest.

Aluminium foam has a range of properties that are desirable in many applications. These properties include good stiffness and strength to weight ratios, impact energy absorption, sound damping, thermal insulation and non combustibility. Many of these characteristics are particularly attractive for core materials within sandwich structures. The combination of aluminium foam cores with thermoplastic composite skins is easily manufactured and has good potential as a multifunctional sandwich structure useful in a range of applications. This thesis has investigated the flexural behaviour of such structures using a combination of experimental and modelling techniques. The development of these structures towards commercial use requires a thorough understanding of the deformation and strain mechanisms of the structure, and this will, in turn, allow predictions of their structural behaviour in a variety of loading conditions. ¶ The experimental research involved the use of an advanced 3D optical measuring technique that produces realtime, full-field strain evolution during loading. This experimental characterisation of strain evolution in this class of sandwich structure under flexural loading is the first of its kind in the world. The experimental work studied the sandwich structure undergoing four-point bend testing. Initial studies compared the behaviour of the aluminium foam structure with a more traditional polymer foam sandwich structure. The aluminium foam structure was found to have equivalent or improved mechanical properties including more ductile deformation and an enhanced energy absorption. An investigation was conducted on the effect of core and skin thickness on the metal structure and a range of flexural behaviours were observed. Analysis of the strain distribution showed a complex development including localised effects from the non-uniform cellular structure of the material. An understanding of the variation with size is important in establishing design methods for utilising these structures. In particular, it is desirable that finite element simulations can be used to predict behaviour of these structures in a diverse range of loading conditions. This aspect was considered in the second half of this study. An existing constitutive model for aluminium foam, developed for use in compression energy absorption studies, was used to investigate finite element simulations of the flexural behaviour of the sandwich structure. The FE model was able to predict the general deformation behaviour of the thinner skinned structures although the magnitude of the load-displacement response was underestimated. It is suggested this may be related to the size effect on the input parameter characterisation. The strain distribution corresponded well with the experimental strain measurements. It was found a simple increase in the material model input parameters was able to more closely match the magnitude of the load-displacement response while maintaining the appropriate strain distribution. The general deformation shape of the model with the thicker skin corresponded reasonably well with the experimental observations. However, further work is necessary on the element failure criterion to capture the shear cracking observed. The strain distributions of the model predicted this failure with high strain concentrations matching those of the experimental contours. The last part of the thesis describes a parametric study on the effect of the foam material model input parameters on the flexural behaviour of the sandwich structure model. An important conclusion of this work is that this material model for aluminium foam can, with some development, be utilized to provide a viable method for simulating aluminium foam composite sandwich structures in flexural loading situations.

Les microtubules sont des composants structuraux de cellules et gouvernent des fonctions cellulaires essentielles telles que les mitoses et le transport des vésicules. Ils sont composés de deux sous-unités non identiques (tubulines α et β), formant un dimère, et sont arrangés de sorte à former une structure tubulaire de 20nm de diamètre. Généralement, ils sont constitués de 13 ou 14 protofilaments arrangés en spirale. Les liaisons longitudinales entre dimères sont plus rigides et fortes que les liaisons latérales. Aussi, les microtubules sont des structures fortement anisotropes. Dans ces travaux de thèse, nous avons pour but de définir l'ensemble des coefficients élastique qui permet de reproduire leur comportement atomistique ainsi que de rendre compte de leur réponse mécanique selon des chemins de chargement variés. En négligeant la discontinuité hélicoïdale souvent observée, un microtubule est représenté par une structure triangulaire de dimères à partir desquels un volume élémentaire représentatif est défini. Un potentiel harmonique est utilisé pour décrire les interactions entre dimères voisins. A partir de l'estimation des constantes élastiques et de l'utilisation de la méthode proposée par Arslan et Boyce (2006) -alors pour analyser le comportement mécanique d'un réseau triangulaire de spectrines composant les membranes des globules rouges-, un modèle continu de comportement mécanique est présenté pour reproduire le comportement des parois des microtubules. Un modèle numérique éléments finis est ensuite créé pour modéliser le comportement d'un microtubule dans sa globalité. Des éléments coques sont utilisés pour reproduire les fines parois des microtubules. Les propriétés du modèle éléments finis sont ajustées à partir des résultats du modèle présenté ainsi qu'aux données expérimentales provenant de la littérature. La rigidité de flexion calculée au cours de simulation des tests de flexion 3 points est en accord avec les valeurs de la littérature. Ces tests révèlent les mécanismes de déformation en fonction de la longueur utile du tube utilisé: Flexion et cisaillement locaux de la paroi gouvernent la déformation pour de "petits" tubes. Pour des longueurs "moyennes" le cisaillement et la flexion du tube prédominent. Enfin, dans le cas de tubes "longs", la déformation est uniquement associée aux effets de flexion. Ces résultats témoignent de l'influence de l'anisotropie du tube sur la réponse observée selon différents mode de sollicitation. Ils permettent également d'expliquer l'évolution de la rigidité de flexion avec la longueur utile du tube, comme reportée dans la littérature. Enfin, des micrographes montrent la propension des extrémités des microtubules à diverger radialement -"à boucler"-. Une telle géométrie est causée par des instabilités propres aux microtubules et implique un état précontraint. Un «modèle d'interactions» est alors proposé de manière à considérer un état précontraint et ainsi reproduire la cinétique des instabilités des microtubules au cours de la polymérisation/dépolymérisation.

Self consolidating concrete (SCC) is widely used in the construction industry. SCC is a high performance concrete with high workability and consistency allowing it to flow under its own weight without vibration and making the construction of heavily congested structural elements and narrow sections easier. Fiber reinforced polymer (FRP) reinforcement, with its excellent mechanical properties and non-corrosive characteristic, is being used as a replacement for conventional steel reinforcement. In spite of the wide spread of SCC applications, bond and flexural behaviour of SCC beams reinforced or prestressed with FRP bars has not been fully studied. Furthermore, the ACI 440.1R-06 equation for determining the development length of FRP bars is based on Glass FRP (GFRP) bars and may not be applicable for Carbon FRP (CFRP) bars. This research program included an experimental and analytical study to investigate the flexural and bond behaviour of SCC beams reinforced with FRP bars and SCC beams prestressed with CFRP bars. In the experimental phase, fifty-six beams were fabricated and tested. Sixteen of these beams were prestressed with CFRP bars and forty beams were reinforced with non-prestressed GFRP or CFRP bars. Four concrete batches were used to fabricate all the specimens. Three mixes were of self consolidating concrete (SCC) and one mix was of normal vibrated concrete (NVC). The test parameters for the non-prestressed beams were the concrete type, bar type and bar diameter, concrete cover thickness and embedment length while the test parameters for the prestressed beams were the concrete type and the prestressing level (30%, 45% and 60%). The transfer length of the prestressed CFRP bars was determined by means of longitudinal concrete strain profile and draw-in methods. All beams were tested in four-point bending to failure. Measurements of load, midspan deflection, bar slip if any at the beam ends, strain in reinforcing FRP bar at various locations, and strain in concrete at the beam midspan were collected during the flexural test. The concrete compressive strength at flexural tests of SCC mix-1, mix-2, and mix-3 were 62.1MPa, 49.6MPa and 70.9MPa, respectively and for the NVC mix was 64.5MPa. The material test results showed that SCC mixes had lower modulus of elasticity mechanical properties than the NVC mix. The modulus of elasticity of the SCC mixes ranged between 65% and 82% of the NVC mix. The modulus of rupture of the SCC mixes was 86% of the NVC mixes. The test results for beams prestressed with CFRP bars revealed that the variation of transfer length of CFRP bars in SCC versus their prestressing level was nonlinear. The average measured transfer lengths of 12.7mm diameter CFRP bars prestressed to 30%, 45% and 60% was found to be 25db, 40db, 54db, respectively. Measured transfer lengths of the 12.7mm diameter CFRP bar prestressed to 30% in SCC met the ACI440.4 prediction. However, as the prestressing level increased, the predicted transfer length became unconservative. At a 60% prestress level, the measured/prediction ratio was 1.25. Beams prestressed with CFRP bars and subjected to flexural testing with shear spans less than the minimum development length had local bar slippage within the transmission zone. Beams that experienced local bond slip, their stiffness was significantly decreased. A modification to the existing model used to calculate the transfer and development lengths of CFRP bars in NVC beams was proposed to account for the SCC. The test results for beams reinforced with FRP bars indicated that the average bond strength of CFRP bars in NVC concrete is about 15% higher than that of GFRP bars in NVC. The ACI 440.1R-06 equation overestimated the development length of the CFRP bars by about 40%, while CAN/CSA-S6-06 equation was unconservative by about 50%. A new factor of (1/1.35) was proposed to estimate the development length of the CFRP bars in NVC when the ACI440.1R-06 equation is used. Beams made from SCC showed closer flexural crack spacing than similar beams made from NVC at a similar loading. The deflection of beams made from SCC and reinforced with CFRP bars was found to be slightly larger than those made from NVC. The average bond stresses of GFRP and CFRP bars in SCC were comparable to those in NVC. However, FRP bars embedded in SCC beams had higher bond stresses within the uncracked region of the beams than those embedded in NVC beams. In contrast, FRP bars in SCC had lower bond stresses than FRP bars in NVC within the cracked region. The average bond strength of GFRP in SCC was increased by 15% when the concrete cover thickness increased from 1.0db to 3.0db. Cover thicknesses of 2db and 3db were found to be sufficient to prevent bond splitting failure of GFRP and CFRP bars in SCC, respectively. Bond splitting failure was recorded when the cover thickness dropped to 1.5db for the GRP bars and to 2.0db for the CFRP bars. An insignificant increase in average bond stress was found when the bar diameter decreased from 12.7mm to 6.3mm for the CFRP bars, and a similar increase occurred in GFRP bars when the bar diameter decreased from 15.9mm to 9.5mm. New models to calculate the development length of GFRP and CFRP bars embedded in SCC were proposed based on the experimental results. These models capture the average bond stress profile along the embedment length. A good agreement was found between the proposed model and the experimental results. Analytical modeling of the load-deflection response based on the effective moment of inertia (ISIS Canada M5) was unconservative for SCC beams reinforced with CFRP bars by 25% at ultimate loading. A new model for bond stress versus Ma/Mcr (applied moment to cracking moment) ratio was developed for GFRP and CFRP bars in SCC and for CFRP bars in NVC. These bond stress models were incorporated in a new rigorous model to predict the load-deflection response based on the curvature approach. The FRP bar extension and bond stress models were used to calculate the load-deflection response. With these models 90% of the calculated deflections were found to be within ± 15% of the experimental measured results for SCC beams reinforced with FRP bars. Analytical modeling of the load-deflection for NVC and SCC beams prestressed with CFRP bars are proposed done. The moment resistance was calculated using Sectional Analysis approach. The deflection was calculated using simplified and detailed methods. The simplified method was based on the effective moment of inertia while the detailed method was based on effective moment of inertia and effective centroid. The experimental results correlated well with the detailed method at higher loads range. This study provided an understanding of the mechanism of bond and flexural behaviour of FRP reinforced and prestressed SCC beams. The information presented in this thesis is valuable for designers using FRP bars as flexural reinforcement and also for the development of design guidelines for SCC structures.

This thesis consists of two topics. We proposed a low power half-run RC5 cipher for portable biomedical devices in the first part of this thesis. The second topic is to realize a frequency-shift readout system for FPW-based biosensors. In the first topic, a half-round low-power RC5 encryption structure is proposed. To reduce hardware cost as well as power consumption, the proposed RC5 cipher adopts a resource-sharing approach, where only one adder/subtractor, one bi-directional barrel shifter, and one XOR with 32-bit bus width are used to carry out the entire design. Two data paths are switched through the combination of four multiplexers in the encryption/decryption procedure. For the sake of power reduction, the clock in the key expansion can be turned off when all subkeys are generated. In the second topic, an IgE antigen concentration measurement system using a frequency-shift readout method for a two-port FPW (flexural plate-wave) allergy biosensor is presented. The proposed frequency-shift readout method adopts a peak detecting scheme to detect the resonant frequency. A linear frequency generator, a pair of peak detectors, two registers, and an subtractor are only needed in our system. According to the characteristics of the FPW allergy biosensor, the frequency sweep range is limited in a range of 2 MHz to 4 MHz. The precision of the measured frequency is proved to the 4.2 kHz/mV, which is for better than that of existing designs.