The overall objective of this thesis is to develop a methodology which can be used to investigate the in-service performance of reinforced concrete members subject to shear loading, in order to update assessments of the shear capacity (and therefore the remaining life) of reinforced concrete bridges. To achieve this end tests have been carried out on two types of reinforced concrete members under different types of loading, with the principal response measured being the relative displacement of the top and bottom faces of the member, which has been referred to throughout as the “through-depth displacement”. The first member tested was a two-span continuous beam containing some web reinforcement in its central shear spans. This was loaded in a series of cycles to progressively increasing peak loads, with a few cycles to lower peak loads being carried out after the application of the higher peak loads.

Load transfer analysis deals with an important function of engineering structure, which is the ability of structure in transferring imposed loads to the supporting points. Although stress value has proved to be an efficient index for performing the failure analysis, the necessity of defining an index for evaluation of structure stiffness has led to the introduction of the U* index theory. The U* index characterizes the internal stiffness distributions, as an indicator of the load transfer in the structure. Although U* index theory have been proven to be useful in design, it is missing necessary steps toward becoming a mature theory for structural analysis. Firstly, the U* index theory needed to be examined and validated by experimental testing. Therefore, an experimental setup was proposed and tested, and U* index theory was validated through comparison of results. Secondly, a systematic comparison between the conventional stresses analysis and the U* index analysis was lacking. Such comparison was made for structural analyses of a vehicle component. The results, also compared to observations of experimental testing showed that in some cases, application of conventional stress analysis might be limited or less precise. Thirdly, design modification capability is a significant feature of the U* index theory, and it was necessary to demonstrate that real life problems can benefit from this potential. In this study, sample structures representing the components of multiple passengers carrying vehicles were selected and analyzed by U* index theory and design modifications were proposed and implemented on the structure. Lastly, the U* index theory should be applicable to different types of problems, including nonlinear domain. Hence, to remove the limitations of linear analysis that is a part of the original theory, an extension of U* index theory to the nonlinear domain was proposed and tested. In summary, U* index theory provides an understandable explanation of load transfer in the structure and provides a general awareness regarding structural performance. He presented work showed that the existing methods of structural analysis have limitations in certain aspects that can be overcome by combining the perspective of U* index analysis to the existing structural analysis paradigm. / February 2017

The structural analysis serves as a bridge to link the structure of materials to their properties. Revealing the structure details allows a better understanding on the growth mechanisms and properties of materials, and a further designed synthesis of functional materials. The widely used methods based on X-ray diffraction have certain limitations for the structural analysis when crystals are small, poorly crystallized or contain many defects. As electrons interact strongly with matter and can be focused by electromagnetic lenses to form an image, electron crystallography (EC) approaches become prime candidates for the structural analysis of a wide range of materials that cannot be done using X-rays, particularly nanomaterials with poor crystallinity. Three-dimensional electron diffraction tomography (3D EDT) is a recently developed method to automatically collect 3D electron diffraction data. By combining mechanical specimen tilt and electronic e-beam tilt, a large volume of reciprocal space can be swept at a fine step size to ensure the completeness and accuracy of the diffraction data with respect to both position and intensity. Effects of the dynamical scattering are enormously reduced as most of the patterns are collected at conditions off the zone axes. In this thesis, 3D EDT has been used for unit cell determination (COF-505), phase identifications and structure solutions (ZnO, Ba-Ta3N5, Zn-Sc, and V4O9), and the study of layer stacking faults (ETS-10 and SAPO-34 nanosheets). High-resolution transmission electron microscope (HRTEM) imaging shows its particular advantages over diffraction by allowing observations of crystal structure projections and the 3D potential map reconstruction. HRTEM imaging has been used to visualize fine structures of different materials (hierarchical zeolites, ETS-10, and SAPO-34). Reconstructed 3D potential maps have been used to locate the positions of metal ions in a woven framework (COF-505) and elucidate the pore shape and connectivity in a silica mesoporous crystal. The last part of this thesis explores the combination with X-ray crystallography to obtain more structure details.

A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg , 2018 / The Discrete Element Method (DEM) models and simulates the flow of gran ular material through confining geometry. The method has the potential to significantly reduce the costs associated with the design and operation of bulk materials handling equipment. The challenge, however, is the difficulty of determining the required input parameters. Previous calibration approaches involved direct measurements and random parameter search. The aim of this research was to develop a sequential DEM calibration framework, identify ap propriate calibration experiments and validate the framework on real flows in a laboratory-scale silo and chute. A systematic and sequential DEM calibration framework was developed. The framework consists of categorising the DEM input parameters into three cat egories of determining the directly measured input parameters, obtaining the literature acquired input parameters, and linking physical experiments with DEM simulations to obtain the calibrated parameter values. The direct mea surement parameters comprised the coefficients of restitution and the particle to wall surface coefficient of rolling friction. Literature obtained parameters were the Young’s Modulus and Poisson’s ratio. The calibrated parameters comprised the particle to wall surface coefficient of sliding friction calibrated from the wall fiction angle, the particle to particle friction coefficients (sliding and rolling) calibrated from two independent angles of repose, particle den sity calibrated from bulk density, and adhesion and cohesion energy densities. The framework was then tested using iron ore with a particle size distribution between +2mm and - 4.75 mm in LIGGGHTS DEM software. i Validation of the obtained input parameter values in the silo and chute showed very good qualitative comparisons between the measured and simulated flows. Quantitative predictions of flow rate were found to be particularly sensitive to variations in the particle to particle coefficient of sliding friction. It was concluded that due to their inherent limitations, angle of repose tests were not totally reliable to calibrate the particle to particle coefficient of sliding friction. Sensitivity tests conducted showed that in the quasi-static flow regime, only the frictional parameters were dominant, while both the frictional and colli sional parameters were dominant in the dynamic flow regime. These results are expected to lay a solid foundation for further research in systematic DEM cali bration and greatly increase the effectiveness of DEM models in bulk materials handling applications. / XL2019

Inibidores tipo Kunitz são proteínas de aproximadamente 20 kDa, que geralmente possuem de dois a quatro resíduos de cisteína, formando uma ou duas pontes dissulfeto, sendo responsáveis por inibir uma ou diversas serina proteinases com grande especificidade. Eles são importantes tanto por atuarem em situações de defesa na planta como por estarem envolvidos na inibição de diversas proteinases, como aquelas presentes na cascata de coagulação sanguínea, no processo inflamatório ou e até mesmo atuarem na supressão de tumores. Este trabalho teve como alvo o estudo de um inibidor tipo Kunitz encontrado em sementes de Bauhinia bauhinioides (Martius) Macbr., denominado BbKI (Bauhinia bauhinioides Kallikrein Inhibitor). Um fragmento gênico codificando a seqüência primária madura de BbKI foi amplificado por RT-PCR e clonado no vetor pGEM-T. Através da técnica de RACE (3 e 5) foi possível constatar que a proteína é sintetizada inicialmente como um prepropeptídeo com a seguinte estrutura: peptídeo sinal (19 resíduos de aminoácidos), proteína madura (164 resíduos), e peptídeo C-terminal (10 resíduos). A presença do peptídeo sinal demonstra que a proteína segue uma rota de síntese via retículo endoplasmático e sugere que este inibidor possa seguir para outro compartimento celular, sinalizado pelo peptídeo C-terminal. Para avaliar se este peptídeo não seria um mero inibidor da atividade biológica, foram feitas duas subclonagens em vetores do sistema pET: uma com o fragmento gênico codificador para BbKI madura, e outra adicionando a seqüência codificante para a porção C-terminal na proteína madura. As proteínas recombinantes foram expressas em células de E. coli BL21(DE3), as quais foram purificadas através de cromatografia de afinidade (Ni-NTA) e filtração em gel, apresentando a massa molecular esperada de 20 kDa. Testes de atividade com tripsina mostraram que ambas as proteínas são biologicamente ativas, embora com diferentes constantes de inibição. Estudos de Dicroísmo Circular revelaram estruturas secundárias similares para ambas as proteínas. Quando analisado por espectroscopia de fluorescência, o inibidor maduro mostrou-se estável numa ampla faixa de pH. A proteína madura recombinante foi ainda cristalizada e o cristal foi difratado por raios X até a resolução máxima de 1,9 A, permitindo a resolução e o refinamento de sua estrutura. A análise da estrutura revelou que o inibidor apresenta um enovelamento -trefoil que é típico nos inibidores tipo Kunitz previamente estudados. Sua estrutura terciária mostrou que no centro ativo o loop inibitório está exposto ao solvente e que os únicos W e C ficam escondidos no interior da proteína, rodeados por resíduos hidrofóbicos / Kunitz-type inhibitors are proteins of about 20 kDa that usually contain from 2 to 4 cystein residues used to form one or two dissulfide bridges. They are responsible for inhibiting one or severa1 serine proteinases with large specificity. Kunitz inhibitors are important both for playing defense roles in plants and also for being involved in the inhibition of many proteinases, like those present in the blood coagulation cascade, in inflammatory processes, or even for suppressing tumors. The aim of this work was to study a Kunitz-type inhibitor from Bauhinia bauhinioides (Martius) Macbr. seeds, denominated BbKI (Bauhinia buhinioides Kallikrein Inhibitor). A gene fragment codifying the mature primary sequence of BbKI was amplified by RT-PCR and was cloned in the pGEM-T vector. Using the RACE (3 and 5) technique we could verify that this protein is synthesized as a prepropeptide with the following structure: signal peptide (19 amino acid residues), mature protein (164 residues) and C-terminal peptide (10 residues). The presence of the peptide signal shows this protein follows a synthesis pathway via endoplasmatic reticulum and suggests the inhibitor can move to another cell compartment guided by the C-terminal peptide. To evaluate if this peptide was just an inhibitor of the biological activity, we performed two subclonings in the system pET vectors: one using the gene fragment codifying to mature BbKI, and another adding the codifying sequence for the C-terminal peptide to the mature protein. The recombinant proteins were expressed in E. coli BL21(DE3) cells which were purified by affinity chromatography (Ni-NTA) and gel filtration thus presenting the expected molecular mass of 20kDa. Activity assays with trypsin showed that both of proteins are biologically active, although they presented different inhibition constants. Circular Dichroism studies revealed that both proteins have similar secondary structures. When analyzed by fluorescence spectroscopy the mature inhibitor was stable in a wide pH range. The mature recombinant protein was latter crystallized and the crystal was diffracted by X-ray at 1.9A resolution, allowing the resolution and refinement of its structure. The analysis of this structure revealed the inhibitor presents a -trefoil fold, which is typical in the Kunitz-type inhibitors previously studied. Its tertiary structure showed that in the active site the inhibitory loop is exposed to solvent, and that the W and the C are buried into the protein surrounded by hydrophobic residues.

Este trabalho apresenta a implementação computacional do elemento finito de cabo deslizando sem atrito, em ambiente MATLAB®, com a finalidade de modelar os cabos de borda não-aderentes das estruturas de membrana. Este novo elemento foi incluído no programa de análise de estruturas retesadas SATS, já previamente desenvolvido. Esta ferramenta é capaz de gerar resultados em deslocamentos, tensões e deformações em estruturas retesadas. São apresentadas as formulações utilizadas para a análise de estruturas de membrana, como a formulação do Método de Newton-Raphson para a resolução de equações não-lineares, as formulações do Elemento Finito de Treliça e do Elemento Finito de Cabo Ideal. É proposta, neste trabalho, a generalização da formulação do elemento de cabo de três nós para o super-elemento de cabo ideal de n nós. São desenvolvidas verificações da eficiência dos elementos finitos de cabo, por meio de exemplos simples de aplicação, nos quais são comparados os resultados obtidos com soluções analíticas. Por fim, é estudado o desempenho dos elementos de cabo, associados a elementos de membrana, por meio da análise da estrutura de cobertura do Memorial dos Povos de Belém do Pará. São comparados os resultados obtidos a partir da implementação das duas formulações apresentadas para os cabos, avaliando a influência da discretização e as diferenças em relação aos resultados obtidos em análises tradicionais usando elementos de treliça. Demonstra-se que a consideração do escorregamento nos cabos de borda é importante para a correta representação das tensões e deslocamentos em estruturas retesadas. / This work presents the implementation of a cable finite element, developed in MATLAB® environment, with the aim of modeling the cables at the boundary of membrane structures. It was added to a software named SATS (System for the Analysis of Taut Structures), which is able to give accurate results on displacements, stress and strains. This work also presents formulations used for the analysis of membrane structures, such as, the Newton-Raphson Method for solving non-linear equations, the Truss Finite Element and the Cable Finite Element. A generalization of the formulation from the three node cable element to an n-node cable super-element is proposed. The efficiency of the cable finite element has been verified by applying simple examples, comparing numerical results to analytical solutions. Finally, it has been studied the performance of these cable elements, along with the membrane finite elements, through the analysis of the membrane roof of the amphitheater of the Memorial dos Povos de Belém do Pará. The results from the implementation of both cable formulations and the traditional analysis using truss elements were compared. It has been shown that the consideration of the cable sliding is important for the accurate stress and displacements analysis.

Urban areas contain significant amounts of asphalt pavement. When exposed to the sun, asphalt pavement absorbs solar radiation and stores it as thermal energy raising its temperature. According to the urban heat island effect (UHIE), the pavement releases the thermal energy back to the surrounding air resulting in a rise in local air temperature. A pipe network containing a passing fluid installed in the pavement can reduce the UHIE. The fluid captures the thermal energy stored in the pavement, reducing air and pavement temperatures as well as providing heated water for other applications. The heat transfer/harvesting system can be optimized to produce the desired cooling of the pavements. This research addresses the economic feasibility of a pipe network by design as well as structural performance through computer modeling. To design the pipe network and predict its economic feasibility an Excel spreadsheet was programmed. It requires local air temperature data to determine the yearly temperature profile within the pavement and to calculate the amount of thermal energy that could be extracted. By varying design parameters such as fluid flow rate, it produces a matrix of payback periods. Structural conditions were considered for the installation of the proposed system. To simultaneously evaluate the thermal and structural performance of the pipe network installation, a finite element model was created using COMSOL Multiphysics©. A typical value of solar radiation and a standard truck tire wheel load were applied to the model to simulate the intended application of the pipe network. The result of this thesis is a method and a tool to design and analyze with respect to economic and structural performance a pipe network used to extract the thermal energy stored in asphalt pavements and reduce the UHIE.

A multiscale approach, coined as the High Order Computational Continua (HC2), has been developed for efficient and accurate analysis and design of reinforced concrete structures. Unlike existing homogenization-like methods, the proposed multiscale approach is capable of handling large representative volume elements (RVE), i.e., the classical assumption of infinitesimally is no longer required, while possessing accuracy of direct numerical simulation (DNS) and the computational efficiency of classical homogenization methods. The multiscale beam and plate elements formulated using the proposed HC2 methodology can be easily incorporated into the existing reinforced concrete design practices. The salient features of the proposed formulation are: (i) the ability to consider large representative volume elements (RVE) characteristic to nonsolid beams,waffle and hollowcore slabs, (ii) versatility stemming from the ease of handling damage, prestressing, creep and shrinkage, and (iii) computational efficiency resulting from model reduction, combined with the damage law rescaling methods that yield simulation results nearly mesh-size independent. The multiscale formulation has been validated against experimental data for rectangular beams, I beams, pretensioned beams, continuous posttension beams, solid slabs, prestressed hollowcore slabs and waffle slabs.

In this research, the degradation of carbon fiber/vinylester composites in marine environments was experimentally investigated. Additionally, two types of carbon fiber surface treatments, namely Polyhedral Oligomeric Silsesquioxane (POSS) and the industrial surface treatment F0E, were evaluated to determine their effectiveness in creating a fiber/matrix (F/M) interface for use in the marine environment. Electrochemical Impedance Spectroscopy (EIS) was explored as a new application of an existing technique for use in measuring the amount of water at the F/M interface in carbon fiber/vinylester composites. EIS spectra were used to determine equivalent electric circuit models that allow for the prediction of water at the interface. The location of water within the composite was determined through Positron Annihilation Lifetime Spectroscopy (PALS). Interlaminar shear strength and transverse tensile tests were carried out for dry conditions and after hygrothermal exposure of the composites to study the influence of the integrity of the F/M interface on the macroscopic response of the composite. / by Chris J. Vinci. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Engineers have utilized CAE technique as an analysis tool to refine the engineering design over decades. However, CAE alone is not the key to open the door for the final goal. In order to achieve the practical solution to the real-time engineering problem, we need to integrate CAD, CAE and optimization techniques into a single framework. / In the optimization algorithm part, apart from the general parametric steepest descent (ST) algorithm, we also study the least square (LSQ) based optimization algorithm. As a result, we can solve the problem arisen from the variant dimensional sizes of the different design variables by using the weighted sensitivity information. / In the problem of the structural optimizations, three categories of the approaches can be identified: size, shape and topology optimizations. For size optimization, explicit dimensions are usually chosen as the design variables, for example, the thickness of a beam or the diameter of a cylinder. For shape optimization, the shape related parameters of the geometrical boundary are always considered to be the design variables, like the positions of the control points for a Bezier curve. However, these two methods are lack of the capability to handle the topological changes of the geometry. On the contrary, topology optimization is the generalization of size and shape optimizations, which offers a more flexible and powerful tool to determine the best layout of the materials and the topology to the design problem, and it is becoming increasingly important in the conceptual design phase. In other words, topology optimization gives one the inspiration for the locations where we put holes to reach the best design. / In this thesis, we put forward the algebraic level set (ALS) model with the consideration of the constructive solid geometry (CSG) model so that it is consistent with half-space primitive concept in CSG. Based on general shape derivative, we propose the general shape design sensitivity analysis (SDSA) formulations for general geometric primitives that are represented implicitly, such as line and circle primitives in two-dimensional space and plane primitive in three-dimensional space. We then extend the relevant formulations into corresponding parametrically represented primitives as they are widely used in today's mainstream CAD systems. / The material density method and the boundary-variation method are the popular methods adopted in both academia and industrial community. Even though the former method is dominant in industry, the latter method is more preferable these years owing to its boundary description nature. Undoubtedly, the level set based method is the most promising technique of the boundary-variation type. Scientists successfully developed the optimization algorithms based on the level set method (LSM) in the past few years. With the implicit representation of the LSM, topological changes of the design can be handled easily and the geometrical complexity is then reserved. / The numerical examples for the design optimization problem are successfully implemented with both the implicit geometric representation (2D cases) and the parametric geometric representation (3D cases), which proves the feasibility of the proposed framework. The results show that both shape and topology optimizations of a design could be accomplished in a natural way. / The optimal result given by conventional topology optimization usually involves tedious post-processing to form CAD geometry. Using our parameterizations with basic primitives and the proposed optimization algorithms, we can deliver comparatively complicated shapes with rich topological information. Therefore, the detail design could be conducted directly later. / Zhang, Jiwei. / "December 2010." / Adviser: Yu Michael Wang. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 119-129). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.