M.Tech. (Department of Civil Engineering, Faculty of Engineering and Technology), Vaal University of Technology / This research investigated the structural bond strength of GFRP rebars in concrete beams under dynamic loading with the aim to characterize the structural bond behaviour and evaluate the limitations of the GFRP rebars under dynamic loading. The dynamic loading in this study was set at 500 repeating cycles to simulate a more realistic dynamic loading scenario such as earthquake since most dynamic loading studies are carried under ten repeating cycles. The experimental work was divided into 2 main tests which were firstly, the tensile tests of the GFRP rebars in order to evaluate the tensile strength of the rebars and characterize their properties. Secondly, the flexural tests of GFRP and steel reinforced concrete beams in order to evaluate the bond strength of GFRP and steel rebars, to characterize the average bond strength of GFRP and steel reinforced concrete beams under dynamic loading and finally to compare the average bond strength of GFRP rebars to Steel rebars in both dynamic and static loadings. The tensile tests were carried out using a Universal Testing Machine (UTM) and the results of the tensile tests of the GFRP rebars showed that the average experimental tensile strength of GFRP rebars was only 56.65% of the nominal tensile strength provided on the supplier data sheet. As for flexural tests, they were carried out through a four-point bending test using a UTM in conjunction with a universal dynamic shaker to create the dynamic loading set up. Steel reinforced concrete beams were used as control beams during the tests and factors such as the tensile strength of the GFRP rebars, the slip of the rebars, the load-deflection relationship and the stress-strain relationship were investigated. The results of the tests showed that the tensile strength of the GFRP rebar is strongly proportional to the maximum beam load bearing capacity and the maximum stresses of GFRP reinforced concrete beams. The results also showed that the average bond strength of GFRP rebars in static loading (8.44 MPa) was only 80% of the average bond strength in dynamic loading (10.95 MPa). Moreover, the experimental work showed that the failure of GFRP reinforced concrete beams depicted large deflections (19 mm) and slips (5 mm to 12.5 mm) when compared to steel reinforced concrete beams (for which the maximum deflection was 9.66 mm at failure and slippage values of 2 mm to 10 mm). Based on that it could be stipulated that the tensile strength of GFRP rebars is one determinant factor to the bond strength behaviour of GFRP rebars in concrete. Hence, the structural bond behaviour of GFRP rebars could be well-defined if more studies were done on the bond behaviour of GFRP rebars in concrete beams under dynamic loading using another type of GFRP rebars that would consist of a relatively high tensile strength as compared to the ones used in this study and different surface texture.

Active Structural Acoustic Control (ASAC) is a subcategory of the more widely known field of Active Noise control (ANC). ASAC is different from traditional ANC methods because it seeks to attenuate noise by altering the noise producing structure instead of altering the acoustic waves traveling through the air. The greatest challenge currently facing ASAC researchers is that a suitable parameter has not yet been discovered which can be easily implemented as the minimization quantity in the control algorithms. Many parameters have been tried but none effectively attenuate the sound radiation in a way that can be easily implemented. A new parameter was recently developed which showed great potential for use as a minimization quantity. This parameter has been termed the "weighted sum of spatial gradients" (WSSG) and was shown by previous researchers to significantly reduce noise emissions from a vibrating simply supported plate in computer simulations. The computer simulations indicate that WSSG-based control provides as good or better control than volume velocity and does so with a single point measurement which is relatively insensitive to placement location. This thesis presents the experimental validation of the WSSG computer simulations. This validation consists of four major components. First, additional research was needed in to extend the use of WSSG from computer simulations to experimental setups. Second, the WSSG-based control method was performed on simply supported plates to validate the computer simulations. Third, the WSSG-based control method on was used on clamped plates to validate the computer simulations, and fourth, the WSSG-based control method was validated on plates with ribs. The important results are discussed and conclusions summarized for each of these sections. Recommendations are made for future work on the WSSG parameter.

The demand for more power and performance from electronic equipment has constantly been growing resulting in an increased amount of heat dissipation from these devices. Thermal management of high-density power control units for hybrid electric vehicles is one such application. Over the last few years, the performance of this power control unit has been improved and size has been reduced to attain higher efficiency and performance causing the heat dissipation as well as heat density to increase significantly. However, the overall cooling system has remained unchanged and only the heat exchanger corresponding to the power control unit (PCU) has been improved. This has allowed the manufacturing costs to go down. Efforts are constantly being made to reduce the PCU size even further and also to reduce manufacturing costs. As a consequence, heat density will go up (~ 200 – 250 W/cm2) and thus, a better high performance cooler/heat exchanger is required that can operate under the existing cooling system design and at the same time, maintain active devices temperature within optimum range (<120 – 125 °C) for higher reliability. The aim of this dissertation was to study the various cooling options based on jet impingement, mini-channel, ribbed mini-channel, phase change material and double sided cooling configurations for application in hybrid electric vehicle and other similar consumer products and perform parametric and optimization study on selected designs. Detailed experimental and computational analysis was performed on different cooling designs to evaluate overall performance. Severe constraints such as choice of coolant, coolant flow-rate, pressure drop, minimum geometrical size and operating temperature were required for the overall design. High performance jet impingement based cooler design with incorporated fin-like structures induced swirl and provided enhanced local heat transfer compared to traditional cooling designs. However, the cooling scheme could manage only 97.4% of the target effectiveness. Tapered/nozzle-shaped jets based designs showed promising results (~40% reduction in overall pressure drop) but were not sufficient to meet the overall operating temperature requirement. Various schemes of mini-channel arrangement, which were based on utilizing conduction and convection heat transfer in a conjugate mode, demonstrated improved performance over that of impingement cooling schemes. Impingement and mini-channel based designs were combined to show high heat transfer rates but at the expense of higher pressure drops (~5 times). As an alternate, mini-channel based coolers with ~1.5 mm size channels having trip strips or ribs were studied to accommodate the design constraints and to enhance local as well as overall heat transfer rates and achieve the target operating temperature. A step by step approach to the development of the heat exchanger is provided with an emphasis on system level design. The computational based optimization methodology is confirmed by a fabricated test bed to evaluate overall performance and compare the predicted results with actual performance. Additionally, one of the impingement based configuration (Swirl-Impingement-Fin) developed during the course of this work was applied to the internal cooling of a turbine blade trailing edge and was shown to enhance the thermal performance by at least a factor of 2 in comparison to the existing pin-fin technology for the conditions studied in this work. / Ph. D.

Pour améliorer l'efficacité des procédés thermiques de craquages et réduire les phénomènes de cokage liés à la température de paroi trop élevée, l'utilisation de tubes nervurés est une technique potentiellement car elle permet d'améliorer le mélange et d'augmenter les transferts de chaleur. Cependant, la perte de charge est significativement augmentée. En raison de la complexité de l'écoulement turbulent, du système chimique et du couplage turbulencechimie, il est difficile d'estimer a priori la perte réelle en termes de sélectivité des tubes nervurés. Les expériences représentatives de laboratoire combinant turbulence, transferts de chaleur et chimie sont très rares et trop coûteuses à l'échelle industrielle. Dans ce travail, l'approche simulation aux grandes échelles résolue à la paroi (WRLES) est utilisée pour étudier écoulement non-réactif puis réactif dans des tubes à la fois lisses et nervurés, pour quantifier leur impact sur la turbulence et sur la chimie. Le code AVBP, qui résout les équations de Navier-Stokes compressibles pour les écoulements turbulents, est utilisé avec des schémas chimique réduites du craquage de l'éthane puis du butane. L'écoulement à la paroi est analysé en détail et comparé pour les deux géométries, fournissant des informations utiles pour le développement ultérieur de modèles de parois pour ce type de rugosité. L'impact de la résolution du maillage et du schéma numérique est également discuté, pour trouver le meilleur compromis entre coût et précision de calcul pour une application industrielle. L'impact des structures d'écoulement turbulent ainsi que leurs effets sur le transfert thermique et le mélange sur les réactions chimique sont étudiés à la fois pour les tubes lisses et les tubes nervurés. Perte de pression, transfert de chaleur et conversion chimique sont finalement comparés. / To improve the efficiency of thermal-cracking processes, and to reduce the coking phenomena due to high wall temperature, the use of ribbed tubes is an interesting technique as it allows better mixing and heat transfer. However it also induces significant increase in pressure loss. The complexity of the turbulent flow, the chemical system, and the chemistry-turbulence interaction makes it difficult to estimate a priori the real loss of ribbed tubes in terms of selectivity. Experiments combining turbulence, heat transfer and chemistry are very rare in laboratories and too costly at the industrial scale. In this work, Wall-Resolved Large Eddy Simulation (WRLES) is used to study non-reacting and reacting flows in both smooth and ribbed tubes, to show the impact of the ribs on turbulence and chemistry. Simulations were performed with the code AVBP, which solves the compressible Navier-Stokes equations for turbulent flows, using reduced chemistry scheme of ethane and butane cracking for reacting cases. Special effort was devoted to the wall flow, which is analyzed in detail and compared for both geometries, providing useful information for further development of roughness-type wall models. The impact of grid resolution and numerical scheme is also discussed, to find the best trade-off between computational cost and accuracy for industrial application. Results investigate and analyze the turbulent flow structures, as well as the effect of heat transfer efficiency and mixing on the chemical process in both smooth and ribbed tubes. Pressure loss, heat transfer and chemical conversion are finally compared.

This thesis solves the construction of a pension that is situated on the street Vídeňská in Mikulov. It is 3-storey building and it is based on strip foundations. The roofing of the pension is solved with hipped mansard roof. The building plot is on the mildly sloping terrain, situated towards the south. Technical design solves the object, which is suitable for short accommodation in form of the pension with full board. The purpose of the use of the building is providing accommodation and restaurant services.

The diploma thesis is focused on the design of a new steel structure of a single-track railway bridge with bottom bridge deck. The solved bridge construction is located on line No. 123 between Nemšová and Trenčianska Teplá at the point, where the line crosses over the river Váh. The existing bridge on the line has a span of 50 + 50 + 50 + 50 m. The assignment was processed in five variants of a steel bridge structure with a bottom orthotropic deck. Each variant has a different static system, a different number of fields and a different type of superstructure. The comparison of variants was performed using multicriterial evaluation based on selected criteria. The most suitable variant was elaborated in more detail. The calculations were performed according to valid ČSN EN standards.

A control metric, the weighted sum of spatial gradients (WSSG), has been developed for use in active structural acoustic control (ASAC). Previous development of WSSG [1] showed that it was an effective control metric on simply supported plates, while being simpler to measure than other control metrics, such as volume velocity. The purpose of the current work is to demonstrate that the previous research can be generalized to plates with a wider variety of boundary conditions and on less ideal plates. Two classes of plates have been considered: clamped flat plates, and ribbed plates. On clamped flat plates an analytical model has been developed for use in WSSG that assumes the mode shapes are the product of clamped-clamped beam mode shapes. The boundary condition specific weights for use in WSSG have been derived from this formulation and provide a relatively uniform measurement field, as in the case of the simply supported plate. Using this control metric, control of radiated sound power has been simulated. The results show that WSSG provides comparable control to volume velocity on the clamped plate. Results also show, through random placement of the sensors on the plate, that similar control can be achieved regardless of sensor location. This demonstrates that WSSG is an effective control metric on a variety of boundary conditions. Ribbed plates were considered because of their wide use in aircraft and ships. In this case, a finite-element model of the plate has been used to obtain the displacement field on the plate under a variety of boundary conditions. Due to the discretized model involved, a numerical, as opposed to analytical, formulation for WSSG has been developed. Simulations using this model show that ASAC can be performed effectively on ribbed plates. In particular WSSG was found to perform comparable to or better than volume velocity on all boundary conditions examined. The sensor insensitivity property was found to hold within each section (divided by the ribs) of the plate, a slightly modified form of the flat plate insensitivity property where the plates have been shown to be relatively insensitive to sensor location over the entire surface of the plate. Improved control at natural frequencies can be achieved by applying a second control force. This confirms that ASAC is a viable option for the control of radiated sound power on non-ideal physical systems similar to ribbed plates.

Examensarbetets syfte är att finna en beräkningsgång för ribbdäcksbjälklag så att en spännviddstabell kan skapas. Ett ribbdäcksbjälklag består av stående limträbalkar med en liggande KL-träskiva ovan som fungerar som golv. I detta examenarbete är KL-träskivan 2,4 meter bred och vilar på två limträbalkar. Full samverkan mellan de olika materialen råder. Idag finns det några aktörer på marknaden som levererar liknande typer av bjälklag men det finns ingen beräkningsgång preciserad i Eurokod. Förstudien till examensarbetet har visat på att tillvägagångssättet för att lösa den mest problematiska beräkningen har varit densamma för de företagen vi har kollat på. Svårigheten är att beräkna den effektiva bredden för tvärsnittet. Det finns även olika standarder som gäller för hur stor nedböjningen får vara för ett bjälklag. I examensarbetet utförs beräkningar för att uppfylla de krav som gäller i Sverige samt de krav som gäller i Österrike. Detta görs för att dalamissivträ misstänker att kraven på de österrikiska bjälklagen är högre ställda med avseende på svikt, de vill kunna erbjuda ett styvare bjälklag. I tabellen ska dimensioner anges för att respektive krav ska uppfyllas. De österrikiska kraven har visat sig vara hårdare ställda jämfört med de svenska och kommer därför att kräva en balk av större dimension i de lägre lastfallen. I fallen med större laster kommer balkdimensionerna mellan de olika lastfallen inte att skilja sig. Där har det visast sig att branddimensioneringen varit helt dimensionerande. Tabellen ska vara ett hjälpmedel för företaget Dala massivträ att lättare nå ut till beställare. Beräkningsgången har gjorts i Mathcad, där okända parametrar har lösts ut och beräknats fram. Vissa parametrar har varit fasta utifrån Dala massivträs önskemål, så som KL-träskivans tjocklek och ingående komponenters materialegenskaper. När beräkningarna har gjorts har de kontrollerats så att momentkapacitet och tvärkraftskapacitet är tillräcklig i respektive last fall och spännvidd. Nedböjningen har kontrollerats liksom branddimensioneringen. Har bjälklaget inte uppfyllt hållfastighetsdimensionering eller kraven för svenskstandard alternativt österrikiskstandard har en högre dimension valts på limträbalken. Limträbalk har valts utifrån Setra trävarors standardsortiment. Resultatet av beräkningarna har förts in i en spännviddstabell som byggts upp för att enkelt kunna välja balk utifrån tänkt last fall. Beräknings exempel finns redovisat i en bilaga där ett lastfall och en spännvidd redovisas. Resultatet leder till att varje spännvidd och lastfall får två dimensioner, en för att klara svensk standard och en för att klara österrikiskstandard. I diskussionen diskuteras eventuella felkällor, effekten av tätare placering med limträbalkar och orsaken till en differens i jämförelsen mellan Mathcad och Calculatis. Även resultatet i spännviddstabellen diskuteras. / The purpose of the degree project is to find a calculation path for ribbed deck joists so that a span width table can be created. A ribbed deck joists consists of standing glulam beams with a lying cross laminated timber slab above which functions as a floor. In this thesis, the cross laminated timber board is 2.4 meters wide and rests on two glulam beams. Full cooperation between the different materials prevails. Today, there are some players in the market that deliver these types of floor but there is no calculation rate specified in Eurocode. The preliminary study for the degree project has shown that the approach to solving the most problematic calculation has been the same for the companies we have looked at. The difficulty is to calculate the effective width of the cross section. There are also different standards that apply to how large the deflection may be for a beam. In the thesis work, calculations are performed to meet the requirements that apply in Sweden and the requirements that apply in Austria. Dimensions must be specified in the table for fulfilling the respective requirements. The Austrian requirements have proved to be harder compared to the Swedish ones and will therefore require a beam of greater dimension in the lower load cases. In case with the larger loads, the beam dimensions between the different loads will not differ because it has been shown that the fire has been dimensional. The table should be a tool for the company Dala massivträ to reach the customer more easily. The calculation path has been made in Mathcad, where unknown parameters has been solved and calculated. Some parameters have been fixed based on Dala massivträ´s wishes, such as the thickness of the cross laminated timber board and the material properties of the component parts. Once the calculations have been made, they have been checked so that torque capacity and transverse power capacity are sufficient in the respective load cases and span. The deflection has been checked as well as the fire dimensioning. The flooring has not fulfilled the dimensioning or the requirements for Swedish standard alt. Austrian standard has a higher dimension selected on the glulam beam. Glulam beam has been selected based on Setra's wood products standard range. The result of the calculations has been entered into a span table which has been built up in order to be able to easily select the beam from outside the intended load case. The calculation example is presented in an annex where a load case and a span are reported. The result is that each span and load fall get two dimensions, one to meet the Swedish standard and one to cope with the Austrian standard. In the discussion, is discussed possible sources of error, the effect of denser placement with glulam beams and the cause of a difference in the comparison between Mathcad and Calculatis. The result in the span table is also discussed.

Made available in DSpace on 2016-06-02T20:09:13Z (GMT). No. of bitstreams: 1 3338.pdf: 4319897 bytes, checksum: 32b80c93c455c298962c6b33fd51002a (MD5) Previous issue date: 2010-02-18 / The big surge in use of systems for flat slabs gave up the search for freedom in the definition and organization of architectural interior spaces in buildings. The design and construction of buildings on flat slabs, which allow great mobility in defining the internal space of the building and reducing its height. The slabs with prefabricated trussed beams using forms lost in blocks of expanded polystyrene (EPS) or removable forms, brought new perspectives to the design of flat slabs, allowing greater spans with low deadweight. The precast elements are lightweight, easy handling, transport and assembly, and require the use of molds and special equipment and requires little bracing. Computer programs have emerged in recent years provide more refined calculations that predict the behavior of the structure in service with greater precision. This way the designers have increased security in systems design less common as flat slabs ribbed, without internal beams, capitals and even edge beams. In Brazil the predominant culture in the design and implementation of flat slabs is given by the system option molded on site. The objectives of this study are: to seek answers to the prevailing cultural behavior, and to compare their advantages and disadvantages when compared with cast on site, presenting the normative regulations and simplified calculation method according to ABNT NBR 6118:2003, provide subsidies for the project and implementation of flat slabs with ribbed prefabricated trussed beams, provide a calculation method for the infinitely rigid diaphragm; present a real case study as a comparison of costs. / O grande impulso na utilização dos sistemas de lajes lisas deu-se pela busca de liberdade na definição e organização arquitetônica de espaços internos em edifícios. O projeto e execução de edificações em lajes lisas, permitem grande mobilidade na definição do espaço interno do edifício e na redução da sua altura final. As lajes pré-fabricadas com vigotas treliçadas que utilizam fôrmas perdidas em blocos de Poliestireno Expandido (EPS) ou fôrmas removíveis trouxeram novas perspectivas ao projeto de lajes lisas, permitindo vãos maiores com baixo peso próprio. Os elementos pré-moldados são leves, de fácil manuseio, transporte e montagem, dispensam o uso de fôrmas e equipamentos especiais e requerem pouco escoramento. Programas computacionais surgidos nos últimos anos propiciam cálculos mais refinados que permitem prever o comportamento em serviço da estrutura com maior precisão. Dessa maneira, os projetistas têm maior segurança no projeto de sistemas menos usuais, como lajes lisas nervuradas, sem vigas internas, capitéis e até mesmo vigas de borda. No Brasil, a cultura predominante no projeto e execução de lajes lisas se dá pela opção do sistema moldado no local. Nestes termos, os objetivos do presente trabalho são: buscar respostas para o comportamento cultural predominante; comparar suas vantagens e desvantagens em relação aos sistemas moldados no local; apresentar as regulamentações normativas e o método de cálculo simplificado segundo a ABNT NBR 6118:2003; fornecer subsídios para o projeto e execução das lajes lisas nervuradas pré-fabricadas com vigotas treliçadas; apresentar um método de cálculo para o diafragma infinitamente rígido e apresentar um estudo de caso real como comparativo de custos.

This Master's thesis "Multi-function building" deals with a project of new multi-function building. It is in a stage of project documentation. An object is design as a detached house. The house is slab-on-ground with four stories. In the object are designed 8 flats with 7 garages. In the first story is situated a wellness centre and an office. The roof is flat, projected as single-skin. A carrier system is made from sacrificial formwork system. A construction of a ceiling is projected as ribbed floor. Windows and entering doors are plastic, interior doors are wooden. A part of work is a specialization from a branch concrete structures.