Dissertations / Theses on the topic 'Structural sealant'

Thesis (M.A.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Photochemical tissue bonding (PTB) is an emerging technique used to create an immediate water-tight seal between membranes. While its properties of collagen cross-linking activated under visible light, have yet to be completely understood, much can be described about its applications for repair and structural reinforcement. PTB sealing was tested in conjunction with standard suture repair and treatment with the growth factor leukemia inhibitory factor (LIF) to show that PTB sealing of the sutured wound alone was sufficient to significantly improve functional recovery in rats after peripheral nerve transection. The addition of LIF to potentially improve proximal nerve regeneration did not have a significant effect on functional recovery. Histological findings in all three groups were similar. PTB was also used to reinforce structurally weak membranes, such as the rat spinal cord, imparting the ability to hold sutures and be deftly manipulated. These and other data show that PTB is a powerful tool for cellular, specifically nerve, recovery and regeneration, as well as a useful architectural reinforcer.

This thesis details the work carried out under two research projects at the University of Surrey. The first project titled The Design of Structural Adhesive Joints', was of three years duration from September 1985 to August 1988 and was sponsored by the Science and Engineering Research Council. The second project, sponsored by Ford UK Ltd, and tided 'A General Joint Analysis Facility extended certain aspects of the analysis work initiated In the first period of research. The objective of the work was to address the problem of integrating structural adhesives Into the design process and to provide procedures that would facilitate this integration in a quantitative, rather than the more usual qualitative way. To be effective, such an approach needed to consider not only a means of analyzing a proposed joint but also a way of predicting the actual failure of that joint. An extensive literature survey of analyses available to the design engineer has been completed. The analyses investigated were found to be lacking in several critical respects, and as part of this research, methods of analysis overcoming some of these limitations have been developed. The analyses produced are based on earlier approaches but extended and modified as appropriate. The work on all the analyses produced has been carried out by considering a simple adherend-adhesive sandwich configuration. Five different analyses, considering the sandwich to be modelled with differing degrees of complexity, have been produced. In all of the analyses the adherends are assumed to behave as cylindrically bent plates capable of sustaining both tensile and shear forces and bending moments, with the adhesive transmitting both tensile and/or shear loads. Initially an elastic solution was obtained, adopting a relatively simple approach. This enabled the subsequent enhancement of including non-linear material behaviour to utilize the same governing equations, thus maintaining consistentcy. The General Elastic Analysis (GEA) has been extensively simplified to produce a number of two parameter design formulae suitable for use by an engineer at an early stage in the design process. The two analyses produced by this simplification are called the Simplified Peel Analysis (SPA) and the Simplified Shear Analysis (SSA), so called because they consider the named component of stress in the adhesive layer only. The GEA was then extended to include non-linear material properties in the adhesive layer, and an analysis called the Non-linear Adhesive Analysis (NLAA) was produced. A programme of validation using the NLAA and a non-linear finite element analysis of similar joint configurations was carried out. Additional comparisons with existing analyses have also been undertaken where possible. The NLAA has been shown to produce extremely accurate results for the stresses in the adhesive layer when compared with the component stresses predicted by the finite element method (FEM). The NLAA has been used successfully to determine the spread of yield in a single-lap joint, giving dose agreement with results from analysis using the FEM, but with much reduced computer and operator time. The final stage of the work was concerned with the Inclusion of non-linear adherend material properties, and an analysis called the Full Non-linear Analysis (FNLA) has been produced which Incorporates this refinement to the general model. Again the finite element method has been used to assess the accuracy of this new analysis, and the results from this work are presented here. Derivations of both forms of the elastic analysis and of the non-linear and full non-linear analyses are reported in Chapters 4 and 5 and the software appropriate to each Is described fully. The Initial survey of available literature has shown that there Is considerable lack of knowledge about possible causes of joint failure. Specifically, It Is noted that a criterion by which joint failure can be measured has not been uniquely defined. In an attempt to provide a criterion or criteria to enable the prediction of joint failure a 'Failure Criteria' test and analysis programme has been completed. Joint configurations were manufactured using a range of adhesives with different levels of ductility, and adherends of different stiffnesses. Batches of these test coupons were tested to failure under both predominantly mode I and mode 11ty pes of loading. Both FEM and FNLA analyses of each test configuration have been carried out, and the stress and strain distributions at the levels of failure load were established for each batch and studied to establish any correlation between various proposed failure criteria. Close agreement between certain factors and the equivalent bulk material properties was noted for test batches. The applicability of various failure criteria for both the mode I and mode II test configurations and possible general criteria are discussed. The failure of the mode I test configurations has been shown to be governed by the local level of maximum principal stress at the end of the overlap. The mode II test configurations also show dose agreement in terms of the maximum principal stress, but agreement with bulk data Is poor. Therefore, a further failure criterion is proposed for the mode II joints in terms of the 'global yielding' of the adhesive layer. The bulk property testing of the adherend and adhesive materials to establish their physical properties for use in the finite element analysis of the test programme Is also fully documented.

A physically based model describing the mechanism of surface sealing of soil was evaluated in the context of aggregate stability. The intent of the model study was to better understand the effect of mixing fine-textured mineral subsoil with organic surface soil on structural stability and surface seal formation. The mixing results from tillage and harvesting operations, and management practices such as levelling. The index derived from the model showed that sealing of the shallow organic soil increased with an increase of mineral matter content. The mathematical formulation of the model was based on the principle of conservation of mass and Darcy's law for flow of water through a layered soil column. Assuming convective flow, it was shown theoretically that the rate of surface seal formation is proportional to the flux density of the filtrate, as assumed by Scheidegger (1974). In the model it was further assumed that the pore necks at the soil surface clog first before the seal develops. The assumption that convective flow alone was responsible for the movement of the suspension is likely incorrect for suspensions derived from medium or coarse textured soils, since sedimentation does influence the movement of larger particles. However, introducing a constant sedimentation parameter into the convective flow model did not improve the model. Therefore, it is likely a non-constant sedimentation parameter could improve the model considerably. The model showed that for sufficiently large times the flux density of a filtrate flowing through a soil column at a constant hydraulic head is proportional to inverse square root of time. Testing the model experimentally showed a good agreement between theory and experiment. A highly significant correlation between the soil stability factor derived from the model and aggregate stability suggests that the index is a soil structural attribute. The soil stability factor was exponentially related with aggregate stability and mineral matter content. However, whereas the relationship between the soil stability factor and aggregate stability gave a positive exponent, a negative exponent was obtained with mineral matter content. Further studies showed that structural stability and saturated hydraulic conductivity of the aggregate beds were positively and significantly correlated exponentially. However, saturated hydraulic conductivity and mineral matter content were negatively and significantly correlated exponentially. Collateral to the results of the model, the strong negative correlation between wet-sieved aggregate stability and mineral matter content confirmed the deleterious effect of mixing fine-textured mineral soil on the structure of the shallow organic soil. It was theorized that aggregates stabilized through clay-organic complexing are likely to be much stronger than aggregates stabilized through other mechanisms. This implies that whenever the mineral matter content is much higher than the organic matter content, the surplus mineral matter that does not interact with organic matter will be most dispersible. The high silt content of the mineral matter fraction is likely to be an important factor contributing to the decrease in structural stability with increasing mineral matter content. Once the clay and the organic colloids have interacted, the silt that remains is not capable of forming stable aggregates without colloids (Baver et al. 1972). From measurements of the air to water permeability ratio, the decrease in saturated hydraulic conductivity of the aggregate beds with increasing mineral matter content was attributed to slaking of the mineral matter fraction. However, it is possible for the soil with high mineral matter content to be stable if the mineral matter is allowed to be in contact with the organic matter for a long period of time.
Land and Food Systems, Faculty of
Graduate

Open-cell porous metals and alloys, based on polymer foam replication techniques, have been performing significantly well and, in many cases, replacing traditional porous metals, including metal foams, in various applications because of their unique properties and structural features including high porosity, semi-uniform structure, light weight and high surface to volume ratio. In applications requiring flow of fluids (gas, liquid or both) through open-cell porous structures, for instance in multi-stage filters, heat exchangers, water purification and the storage and transfer of liquid, pressure-drop and flow characteristics of the fluid are essential parameters in application design and performance. Despite the fact that pressure-drop is often sought to be minimised, high pressure-drop is sometimes required such as when used as abradable seals in jet engines. In this work, the structure of Inconel 625, open-cell porous metals (with nominal cell sizes 450, 580, 800 and 1200 pm) were studied in detail using a series of imaging and morphological techniques. The effect of airflow velocity, in the range of 0-70 m s'1, on the pressure-drop characteristics for bulk and structurally tailored, diffusion bonded, multi­layered, open-cell porous structures, as a function of thickness (affected by sectioning), density (affected by compression) and structural alterations (affected by multi-pore sized insets, porous metal stacking and air gaps), were thoroughly investigated. As the air flow velocity increases, fluid properties tend to change and drag force increases in comparison with the viscous effect causing the pressure drop data to deviate from the non­linear, quadratic Forchheimer model into a cubic equation at a velocity value higher than 20 m s'1. The need for accurate pinpointing of the different regimes (Darcy, Forchheimer and Turbulent), which enables precise determination of the permeability (K) and form drag coefficient (C), was highlighted. Understanding the pressure-drop behaviour for multi­layered, open cell porous structures will offer the possibility for combining layers with different porosities and pore sizes giving the ability to tailor the structure to achieve bespoke flow conditions for demanding applications. For example, the use of a 9 mm thick porous structure in three different configurations (bulk, stacked and gapped) causes the pressure-drop to change drastically, while having the same weight (3.38g), thus, the potential for mass-efficient porous structures is readily achievable.

The objective of this study was to increase the bond strength at the surface interface of a thin stainless-steel panel for structural bonding on a helicopter. To achieve this objective, six activation methods for applying the coating to the panel in the surface preparation process are presented and explored. Adhesion and roughness tests were conducted to determine which method consistently initiates the etch and improves the bond at the surface. Based on the test results, three methods proved to be effective in initiating the etch. Of the three effective methods, only one method exhibited significantly improved bond strength at the surface interface as well as consistently initiated the etch in solution. The applicability of this method is discussed, and recommendations are presented for further study.

In this dissertation, four test approaches were developed to characterize the adhesion performance and durability of adhesive bonds for specific applications in areas spanning from structural adhesive joints to popular confectionaries such as chewing gum. In the first chapter, a double cantilever beam (DCB) specimen geometry is proposed for combinatorial fracture studies of structural adhesive bonds. This specimen geometry enabled the characterization of fracture energy vs. bondline thickness trends through fewer tests than those required during a conventional "one at a time" characterization approach, potentially offering a significant reduction in characterization times. The second chapter investigates the adhesive fracture resistance and crack path selection in adhesive joints containing patterns of discreet localized weak interfaces created using physical vapor deposition of copper. In a DCB specimen tested under mode-I conditions, fracture energy within the patterned regions scaled according to a simple rule of mixture, while reverse R-curve and R-curve type trends were observed in the regions surrounding weak interface patterns. Under mixed mode conditions such that bonding surface with patterns is subjected to axial tension, fracture energy did not show R-curve type trends while it was observed that a crack could be made to avoid exceptionally weak interfaces when loaded such that bonding surface with defects is subjected to axial compression. In the third chapter, an adaptation of the probe tack test is proposed to characterize the adhesion behavior of gum cuds. This test method allowed the introduction of substrates with well-defined surface energies and topologies to study their effects on gum cud adhesion. This approach and reported insights could potentially be useful in developing chewing gum formulations that facilitate easy removal of improperly discarded gum cuds from adhering surfaces. In the fourth chapter we highlight a procedure to obtain insights into the long-term performance of silicone sealants designed for load-bearing applications such as solar panel support sealants. Using small strain constitutive tests and time-temperature-superposition principle, thermal shift factors were obtained and successfully used to characterize the creep rupture master curves for specific joint configurations, leading to insights into delayed failures corresponding to three years through experiments carried out in one month.
Ph. D.

Orientador: Jefferson Sidney Camacho
Banca: Rogério de Oliveira Rodrigues
Banca: Ronaldo Bastos Duarte
Resumo: As estruturas de concreto armado vêm se tornando cada vez mais esbeltas, aliadas ao menor tempo de execução das edificações e aos menores prazos de execução da fixação da alvenaria na estrutura, cada vez com mais freqüência observa-se a formação dos estados patológicos nas alvenarias. As estruturas de concreto armado apresentam progressivamente deformações mais acentuadas, fazendo com que as paredes de vedação trabalhem, oferecendo resistência a esses deslocamentos surgindo assim patologias que se apresentam na forma de fissuras na interface pilar/alvenaria. Desse modo, surge a necessidade de estudos das ligações empregadas na interface pilar/alvenaria, que têm por objetivo "solidarizar" estrutura e alvenaria, distribuindo as deformações excessivas da estrutura que se traduzem na forma de fissuras e com isso diminuir a ocorrência de patologias nas alvenarias de vedação. Para tal, foram desenvolvidos ensaios de diferentes formas de ligação da interface pilar/alvenaria de modo a avaliar a eficiência dos dispositivos empregados no mercado da construção de edifícios de São Paulo atualmente, como a tela metálica eletrosoldada. Numa primeira etapa foram realizados ensaios de arrancamento direto à tração, de modo a se estudar o comportamento do dispositivo quando submetido ao esforço de tração. Foram ensaiados também prismas de alvenaria, com diferentes dispositivos de ligação inseridos de modo a se avaliar as resistências à tração das ancoragens inseridas na junta de argamassa, e numa terceira etapa, foram realizados ensaios em pequenas paredes, para se determinar o desempenho das ancoragens na ligação de paredes e pilares de concreto armado, na situação real.
Abstract: Structures of reinforced concrete are becoming more slender, associated to the short time of building construction and with the lesser periods of masonry fixation in the structure, each time with more frequency can be observed the formation of pathological state in masonry. The structures of reinforced concrete progressively presents more accentuated deformation, making masonry to work, offering strength to these displacements, creating pathology that appears like cracks in the interface of column/masonry. Thus, it is necessary to study the bonds used in the interface column/masonry, wich has as objective "join" the structure and the masonry, spreading the excessive deformations of the structure that comes up as cracks, and diminishing the occurrence of damages in the forbid masonry. In order to do this, different tests in the interface column/masonry were developed in order to evaluate the efficiency of device used in the civil construction in São Paulo, as tela metálica eletrosoldada. In the first step, pull-out tests were done to sutdy the behavior of the device when submitted to a tensile strength. Prisms were also tested, with different kinds of bond gadgets inserted in order to evaluate the resistance in a traction of devices in the anchorages inserted in the grouts, and in a third step, small walls were tested to analyze the behavior of anchorages in the bond of wall and column, in the real situation.
Mestre

Bestärkt durch das gesellschaftliche und wirtschaftliche Interesse an nachhaltigen und ressourcenschonenden Formen des Bauens gewinnen Holzkonstruktionen wieder unverkennbar an Bedeutung. Mit dieser Entwicklung bilden sich neue Konstruktionsprinzipien und Materialkombinationen im Bauwesen heraus, zu deren ingenieurtechnischer Beurteilung zum Teil keine ausreichenden Erkenntnisse vorliegen. Verbundkonstruktionen aus Holz und Glas sind eine innovative Bauweise, die zu einer höheren Materialeffizienz in Fassaden beiträgt, deren Wirkungsweise aber noch nicht ausreichend hinterfragt wurde. Werden Holz und Glas durch eine tragende Klebung verbunden, lässt sich das vielfach ungenutzte Tragpotenzial ausschöpfen, das eine in Scheibenebene belastete Verglasung aufweist. Die Qualität der Klebung entscheidet dabei über die Eigenschaften und das Leistungsvermögen des Bauteils. Die üblicherweise an dieser Schnittstelle eingesetzten Silikonklebstoffe weisen eine hohe Nachgiebigkeit und eine vergleichsweise geringe Festigkeit auf. Wenn die Verbundelemente als Aussteifung mitwirken sollen, bleibt ihr Einsatz deswegen auf Gebäude mit höchstens zwei Geschossen limitiert. Die vorliegende Arbeit trägt entscheidend zur Erweiterung der baulichen Möglichkeiten bei, indem sie der Anwendbarkeit von hochfesten Klebstoffen, die für den Einsatz im Bauwesen nur wenig erforscht sind, auf vielschichtige Weise nachgeht. Im Fokus stehen aussteifende Holz-Glas-Verbundelemente für die Fassade. Weder die Bauart noch das Bauprodukt Klebstoff sind derzeit in Deutschland in einer Norm erfasst. Das Klären der baurechtlichen Rahmenbedingungen ist daher unerlässlich und erfolgt mit engem Bezug zum konstruktiven Glasbau. Zusätzlich zur wissenschaftlichen Interpretation wird dadurch eine praxisnahe Bewertung der Versuchsergebnisse möglich, was ein Alleinstellungsmerkmal dieser Arbeit darstellt. Das Verformungsvermögen des Klebstoffs spielt eine zentrale Rolle bei der Materialauswahl und Gestaltung der Holz-Glas-Verbundelemente. Der Einfluss der Klebstoffsteifigkeit auf das Tragverhalten eines Einzelelements und auf dessen Interaktion mit den anderen Bestandteilen des Tragwerks wird an einem Modellgebäude untersucht. Auf Basis dieser Parameterstudie lassen sich drei Steifigkeitsbereiche definieren, auf die sich die Klebstoffauswahl für die weiteren Untersuchungen stützt. Der experimentelle Teil der Arbeit beginnt mit der ausführlichen Charakterisierung von sieben Klebstoffen. Davon werden zwei höherfeste Klebstoffe als geeignet identifiziert. Ein Silikonklebstoff wird als Referenzmaterial zur aktuellen Anwendungspraxis festgelegt. Das Hauptaugenmerk der folgenden Experimente richtet sich auf Aspekte der Alterungsbeständigkeit und des zeitabhängigen Materialverhaltens unter langandauernder mechanischer Beanspruchung. In labormaßstäblichen Alterungsprüfungen werden die Klebstoffproben unterschiedlichen Schadeinwirkungen ausgesetzt, die im Glas- und Fassadenbau relevant sind. Darüber hinaus erfolgen Kriechversuche an kleinen und großen Scherprüfkörpern. Letztere stellen einen besonderen Mehrwert dar, da sie eine realistische Klebfugengeometrie aufweisen und die Ergebnisse dadurch dem tatsächlichen Bauteilverhalten nahekommen. Für diese Zeitstandversuche wurde eine bislang einzigartige Versuchsanlage aus sechs Prüfrahmen mit Gasdruckfederbelastung entwickelt. Im Ergebnis zeigt sich, dass mit den gewählten höherfesten Klebstoffen die Festigkeit der nicht gealterten Klebschichten erwartungsgemäß gesteigert werden kann. Der Bruch des Fügepartners Holz wird zum maßgebenden Versagenskriterium. Die Verformungen des Verbundelements reduzieren sich gegenüber einer Silikonklebung deutlich. Allerdings offenbaren sich in einzelnen Alterungsszenarien und unter langandauernder Belastung auch Schwachstellen dieser Klebstoffe. Ihre Verwendung kann daher nur mit konstruktiven Kompensationsmaßnahmen oder durch Abschirmen der kritischen Einwirkungsgrößen empfohlen werden. Entsprechende Vorschläge werden bei der abschließenden Bewertung der Ergebnisse unterbreitet. Verfahren und Beurteilungsmethoden, die in dieser Arbeit angewendet und entwickelt werden, erleichtern die zukünftige Bewertung weiterer aussichtsreicher Klebstoffe für den Holz-Glas-Verbund
Wooden constructions are on the rise again – encouraged by a strong public and economic trend towards sustainable and resource efficient buildings. Spurred by this growing interest novel design principles and material assemblies in architecture and the building industry evolve. These developments require further research due to the absence of evaluation tools and insufficient knowledge about their design. Load-bearing timber-glass composite elements could contribute to a more efficient use of materials in façade constructions. In this case a linear adhesive bond connects the glass pane to the timber substructure. This enables an in-plane loading of the glass whose capacity is not used to its full potential in conventional façades as it is solely applied as an infill panel. The quality of the adhesive bond defines the characteristics and the performance of the whole structural component. Structural sealants such as silicones, which are typically used for the joint, provide a high flexibility and only a low load-bearing capacity. Considering such elements being part of a bracing system, the mentioned characteristics limit the application range to buildings with not more than two stories. This thesis widens the scope with an in-depth examination of high-modulus adhesives, which have not yet been evaluated for their use in building constructions. Timber-glass composite elements used as a bracing component in façades are the focus of this work. Neither the full structural component nor the adhesive have yet been included into German building standards. Hence it is essential to assess the general requirements of their application. The relevant aspects are clarified in the context of glass constructions. In addition to the scientific discussion of the results, this approach facilitates also a practical evaluation of the findings, which is a unique feature of this work. The deformability of the adhesive becomes a crucial criterion when selecting the individual materials and designing the timber-glass composite elements. A case study assesses the influence of the adhesive stiffness on the behavior of a single element and its interaction with other members of the structural system. Based on the results, three different stiffness classes are introduced to support the selection process of the adhesives to be examined in further investigations. The experimental part of this work is initiated by a comprehensive characterization of seven shortlisted adhesives. The results enable a further differentiation of suitable materials. Two adhesives qualified as suitable for the main experiments. A silicone adhesive complements the test series to serve as a reference material to the current practice. In the next phase attention is drawn to the ageing stability and on the time-dependent material behavior of the adhesives under long-term loading. Small-scale specimens made from adhesively joint timber and glass pieces are exposed to different ageing scenarios which relate to the impacts typically encountered in façades. Beyond that, creep tests are carried out on small and large shear specimen. The latter provide extra benefit as they comprise long linear adhesive joints resembling virtually the situation in a real-size element. A specific long-term test rig was developed for this purpose comprising a loading unit with gas pressurized springs. Based on the results it can be concluded that joints with adhesives of high and intermediate stiffness enable an increase of characteristic failure loads and a significant reduction of deformation. With the stiffer joint near-surface rupture of timber fibers becomes the prevailing failure mechanism. The timber strength limits further loading of the adhesive joint. However, ageing and creep testing reveal also shortcomings of the adhesives. Their application can only be recommended if redundant compensation measures are taken or the joint is protected against critical environmental impacts. Appropriate solutions are proposed with the final recommendations of this work. Methods and assessment tools that have been developed and tested for this work offer the possibility of a more straight-forward evaluation of further promising adhesives and their use in load-bearing timber-glass composites

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Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA)
As estruturas de concreto armado vêm se tornando cada vez mais esbeltas, aliadas ao menor tempo de execução das edificações e aos menores prazos de execução da fixação da alvenaria na estrutura, cada vez com mais freqüência observa-se a formação dos estados patológicos nas alvenarias. As estruturas de concreto armado apresentam progressivamente deformações mais acentuadas, fazendo com que as paredes de vedação trabalhem, oferecendo resistência a esses deslocamentos surgindo assim patologias que se apresentam na forma de fissuras na interface pilar/alvenaria. Desse modo, surge a necessidade de estudos das ligações empregadas na interface pilar/alvenaria, que têm por objetivo “solidarizar” estrutura e alvenaria, distribuindo as deformações excessivas da estrutura que se traduzem na forma de fissuras e com isso diminuir a ocorrência de patologias nas alvenarias de vedação. Para tal, foram desenvolvidos ensaios de diferentes formas de ligação da interface pilar/alvenaria de modo a avaliar a eficiência dos dispositivos empregados no mercado da construção de edifícios de São Paulo atualmente, como a tela metálica eletrosoldada. Numa primeira etapa foram realizados ensaios de arrancamento direto à tração, de modo a se estudar o comportamento do dispositivo quando submetido ao esforço de tração. Foram ensaiados também prismas de alvenaria, com diferentes dispositivos de ligação inseridos de modo a se avaliar as resistências à tração das ancoragens inseridas na junta de argamassa, e numa terceira etapa, foram realizados ensaios em pequenas paredes, para se determinar o desempenho das ancoragens na ligação de paredes e pilares de concreto armado, na situação real.
Structures of reinforced concrete are becoming more slender, associated to the short time of building construction and with the lesser periods of masonry fixation in the structure, each time with more frequency can be observed the formation of pathological state in masonry. The structures of reinforced concrete progressively presents more accentuated deformation, making masonry to work, offering strength to these displacements, creating pathology that appears like cracks in the interface of column/masonry. Thus, it is necessary to study the bonds used in the interface column/masonry, wich has as objective “join” the structure and the masonry, spreading the excessive deformations of the structure that comes up as cracks, and diminishing the occurrence of damages in the forbid masonry. In order to do this, different tests in the interface column/masonry were developed in order to evaluate the efficiency of device used in the civil construction in São Paulo, as tela metálica eletrosoldada. In the first step, pull-out tests were done to sutdy the behavior of the device when submitted to a tensile strength. Prisms were also tested, with different kinds of bond gadgets inserted in order to evaluate the resistance in a traction of devices in the anchorages inserted in the grouts, and in a third step, small walls were tested to analyze the behavior of anchorages in the bond of wall and column, in the real situation.

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Made available in DSpace on 2017-10-16T13:23:47Z (GMT). No. of bitstreams: 1 Andréia Grasiela Führ_.pdf: 1188946 bytes, checksum: 1e639f31e0753bea5b50ab2319cc96a4 (MD5) Previous issue date: 2017-07-19
Nenhuma
É crescente a preocupação com o desempenho das edificações concomitantemente com os danos causados ao meio ambiente durante a execução de uma obra. No âmbito do conceito do tripé da sustentabilidade é de extrema importância analisar os materiais que compõem uma edificação, pois estes influenciam os fatores que podem reduzir custos, melhorar o desempenho da edificação e minimizar os impactos ambientais. Com o intuito de melhorar o desempenho térmico, reduzir o peso próprio e reduzir custos com a estrutura, podem ser utilizados painéis monolíticos com núcleo de poliestireno expandido (EPS) como vedações verticais. Os painéis monolíticos são compostos por um núcleo de EPS, envolto por malha metálica e camadas interna e externa de revestimento argamassado, composto por fibras de polipropileno. Foi analisada a influência no dimensionamento da estrutura e nos custos da obra com painéis monolíticos em EPS e paredes convencionais de alvenaria de blocos cerâmicos. Esta análise foi realizada a fim de verificar a redução do volume de concreto, do peso de aço e no custo total da obra, ao utilizar este sistema. Para tal finalidade, foi utilizado um projeto de uma edificação multiresidencial de 4 pavimentos com área total de 1432,00m² e outro projeto de um condomínio horizontal com área total de 600,43m², avaliando duas tipologias. A partir destes projetos foi dimensionada cada edificação com as vedações verticais em blocos cerâmicos e painéis monolíticos em EPS. Os modelos de cálculo foram analisados, para quantificar o total de concreto e aço em cada opção. Através da análise do quantitativo de concreto observou-se uma redução de 10,69% na edificação de 4 pavimentos e 7,23% no condomínio horizontal com os painéis monolíticos de EPS. Já no quantitativo de aço, a diferença foi um pouco menor, de 6,02% na edificação de 4 pavimentos e 1,69% no condomínio horizontal. Os painéis monolíticos em EPS também apresentaram vantagens em relação ao orçamento total da estrutura e vedações e em relação ao tempo de execução da obra. O orçamento da edificação de 4 pavimentos com vedações verticais em EPS ficou 4,92% mais barata, o que representa uma economia de R$ 30.698,08. E o tempo de execução foi reduzido em 19 dias, adotando este sistema. Já no orçamento do condomínio horizontal, a diferença foi semelhante, de 4,90%, o que representa uma economia de R$ 12.227,74. E o tempo de execução desta edificação seria reduzido em 18 dias.
There is growing the concern about the performance of buildings concorcomitantly with the damage caused to the environment during the execution of a work. Under the concept of the triple bottom line, it is extremely important to analyse the materials that make up a building, as they influence the factors that can reduce costs, improve performance of the building and minimize environmental impacts. In order to improve thermal performance, reduce your weight and reduce costs with the structure can be used monolithic panels in EPS and vertical seals. Monolithic EPS panels comprise a core of expanded polystyrene (EPS), surrounded by metal mesh and a coating layer. It will be consideration to influence of the structure and cost of the work is the masonry walls were replaced by monolithic panels in EPS. For this purpose, it will be used a design of a building of 4 floors with área of 1342,00 m² and another project of a horizontal condominium with a total area of 600,43m², evaluating two typologies. From this projects was dimensioned the structure with walls in ceramic blocks and monolithic panels in EPS. The calculation models were analyzed to quantify the total concrete and steel in each option. The concrete quantitative analysis showed a reduction of 10,69% in the building of 4 floors ans 7,23% in the condominium with the monolithic panels of EPS. In the quantity of steel, the difference was slightly lower, of 6,02% in the building of 4 floors and 1,69% in the horizontal condominium. EPS monolithic panels also had advantages over the total budget of the structure and fences and in relation to the execution time of the work. The budget os the building with 4 floors was 4,92% cheaper, wich represents a saving of R$ 30.698,08. And the execution time was reduced by 19 days, adopting this system. In the horizontal condominium budget, the difference was similar, of 4,90%, wich represents a saving of R$ 12.227,74. And the execution time of this building would be reduced in 18 days.

The diploma thesis describes design and assessment of foundation of tall building. Existing reinforced concrete slab-pile foundation structure was assessed as unsatisfactory at the ultimate limit state. Design of two new options was processed: slab-pile foundation with adjusted slab thickness and slab foundation without piles. Both options were assessed at the ultimate limit state and the serviceability limit state. Foundation options were designed as water-impermeable structure of white tank and meet requirements for this type of structures.

碩士
國立聯合大學
材料科學工程學系碩士班
104
The glasses are widely used in sealing applications, such as electronic components, solid oxide fuel cells, and other glass hermetic thin-film devices. The organic films provide self-illumination for OLEDs. However, the quality and intensity of displayed image organic film degrade when exposed to oxygen and moisture, which leads to the premature failure of the device. Therefore, the device must be hermetically sealed. In this study, the glass paste is a mixture of the glass frit with organic solvents and binders. The glass paste was screen-printed on the glass substrates. The optimum sealing temperatures is 10oC above the softening temperature. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) were employed to study the performancet with glass paste. The good adhesion can be observed at the interfaces. Bismuth borate glasses have the unique structure and some exceptional physical and chemical properties such as low glass softening point and excellent chemical resistance. These properties lead to strong competitive advantages and potential for use as a sealing material.

碩士
輔仁大學
物理學系
88
In the present study, an effort is made to understand how the structure and elastic (or mechanical) properties change with the composition of either alkaline-earth oxides or transition-metal oxides added into a 56P2O5-10B2O3-4Al2O3-15Li2O-15Na2O glass by infrared reflectivity, Raman scattering and ultrasonic pulse-echo measurement. When a modifier cation was incorporated into chain-like phosphate glasses, it will shorten the chain by disrupting the P-O-P bond and form ionic cross-bonding between the broken chains. These glasses exhibit higher values for Young’s modulus and bulk modulus than the pure P2O5 glass. The strengthening of the glass resulting in increased elastic modulus values is proposed to occur through chain entanglement mechanisms.

碩士
國立臺北科技大學
化學工程與生物科技系化學工程碩士班
106
In this study, we focus on the investigation and development of UV-curable moisture/water resistant Adhesives. Three series of ladder-structured polysilsesquioxanes resins (LPSQs) which composed of acrylate-based siloxane and alcohol-based acrylate monomers, were prepared by sol-gel process. Then a miniscule amount of end-terminated silanol groups on LPSQs reacting with five different acid chlorides to produce an ester was used as oligomer. Finally with the incorporation of diluent, nano-filler and photo-initiator to form UV-curable organic / inorganic hybrid nanocomposite. It successfully cured and adhered to PET film by using ultraviolet light . We also compare graphene oxide, silane-functionalized graphene oxide and SiO2 nanoparticle) via solvent blending dispersion methods. The water vapor transmission rate (WVTR) was measured by Mocon. The WVTR of the best sealant in the initial period (when the beginning of the package) and a later period (when ambient storage after 20 days) was lower than 0.01 (g/cm2·day) and 0.6 (g/cm2·day), respectively. On 50µm coating layer films, pencil hardness was 9H, cross-cut adhesion test were 5B, optical transmittance were 87% to 89%.The sealants showed 5% and 10% weight loss temperatures under nitrogen at 340~378(℃) and 380~414(℃)respectively, and water absorption were 2.59 to 4.38(w.t%). The results show that the UV-curable organic-inorganic hybrid nanocomposite adhered to PET film has excellent moisture barrier property, high adhesion, high hardness, good optical property, rapid curing and so on. In the future, we look forward to applying it in edge packaging of flexible optoelectronic components, which can protect internal components, extend life and stability.

碩士
國立臺灣科技大學
機械工程系
94
The interfacial characteristic of the 7056 glass-to-Kovar sealing and wetting behavior of glass to Kovar were studied. The effect of oxide layer of Kovar on the glass-to-Kovar sealing was also investigated. With another treatment of oxidization as reoxidization, the interfacial structures between glass and Kovar are changed. The shear stress test was carried out to evaluate the influence of sealing experimental parameters on the shear stress strength of glass-to-Kovar sealing. The optical microscope (OM) was used for observation of interfacial characteristic. The scanning electronic microscope (SEM) was employed for investigating the composition distribution across the interface. Experimental results showed that the rough interface with by #600 abrasive paper had the fine and narrow dendritic structures, but the fine interface with reoxidization by #1500 had the loose and wide ones. Comparing the shear stress strength, the preoxidized Kovar-to-glass had better strength than the non-preoxidized sample such as the rough interface (#600) with the fine and narrow dendrtic structures, and the worse sealing strength was the fine interface (#1500) with loose and wide dendrtic structures. It proved the dendrtic structures were bad factors in the glass-to-metal sealing.

碩士
國立臺灣藝術大學
視覺傳達設計學系碩士班
101
Recently, Universal Design is a trend of international designs and blooms in various design fields. The situation points out that the whole world shows the high concern about human so the human-centered concepts of design are brought up. In Taiwan, Universal Design research has got abundant harvests in industrial design and space design fields for several years. However, when other design fields are compared with industrial and space design, they just reveal their curtains. Therefore, in order to broaden the horizon, this project focuses on the relationship between packaging structure design and Universal Design. We are eager to provide some useful consequence for packaging design. This research applied KJ method to select 10 symbolic samples as follow: cigarette packaging, sleeve packaging, sealing with glue packaging, inserting packaging, tearing packaging, zipper packaging, lift-open and tearing packaging, lift-open with tray packaging, seal-up with house-shaped packaging, and buckling packaging. And then we separated the survey candidates into two parts: 160 normal candidates and 8 design-background experts. The normal candidates would be divided into four layers by ages: under 14, between 15 and 44, between 45 and 64, and above 65. Additionally, we individually applied Questionnaire Survey and Structured Indirect Interview Method to these symbolic samples for evaluation. In order to conclude the initial direction of design criteria, we referred to the Universal Design Principles, ISO Guide 71, and other related principles. Afterward, we modified the design criteria with back-testing experiment and gradually derived the final design criteria of sealing packaging structures consisting with Universal Design Principles.According to our research, the high-evaluated symbolic samples are lift-open with tray packaging, sleeve packaging, life-open and tearing packaging, buckling packaging. Universally speaking, the four samples have some characteristics in common: easy open, easy to take out from inside, low-strength for use. However, they still have some defects to modify including “open ways tend to singularize”, “open guides are unclear”, and “limit for open directions”. As to its used situation, we could depict the conclusion in three ways as follow: self-structure, in-use period, and after-use period. On the perspective of self-structure, the criteria as follow: guidance, simplicity and intuitive use, multiple open ways, and flexible structure. On the perspective of in-use period, the criteria as follow: unlimited ways for opening, tolerance for errors, and low physical manipulation. On the perspective of after-use period, the criteria as follow: amble spaces or size for taking out, expected space for use, buckle repeatedly for use.With applying the design criteria to the packaging structure, we could provide a referable model for investigation and abroaden packaging design field.

The Little Grand Wash normal fault near Green River, eastern Utah, hosts a series of naturally occurring CO₂ seeps in the form of active and extinct CO₂-charged springs distributed along the fault zone. I have studied the association of fault structure with CO₂-related alteration as an analogue for the long-term (1,000- to 10,000-year) effects of leakage through faults in CO₂ sequestration reservoirs. Structure and alteration in a portion of the Little Grand Wash fault zone were mapped at a 1:700 scale in order to determine the association of faulting with CO₂-related diagenesis. I combined structural and diagenetic mapping were combined with laboratory analyses of mineralogical, isotopic and textural changes in order to assess controls on the migration of CO₂ traveling up the fault and its effects on the fault itself. The fault zone is 200 m wide at its widest and contains 4-5 major subparallel fault segments that form multiple soft- and hard-linked relay ramps. The area includes a travertine deposit and related sandstone alteration: outcrop-visible coloration, porosity-occluding calcite cement and veins occasionally so abundant that they obliterate the rock fabric. Structural mapping shows that the travertine is located at an intersection of major fault segments constituting the hard link of a 450-meter-long relay ramp. Sandstone alteration is confirmed to be related to the CO₂ seep by mapping its distribution, which shows a decrease in concentration away from the travertine, and by the unique isotopic signature of calcite cement near the travertine. At distances greater than 25 m from the travertine intense alteration disappears, though scattered fault-subparallel veins and patchy, burial-related calcite cement remain. Intense alteration is limited to major fault overlaps and does not permeate the fault zone along its entire length, nor does it extend outside the zone. This indicates that rising CO₂-laden fluids do not flow uniformly through the entire fault zone, but that vertical flow is channeled at fault intersections. In thin section, porosity near the travertine has been extensively or completely occluded by calcite cement. Permeability in some conduit samples is less than 1 mD, three or four orders of magnitude lower than sandstone away from the travertine. In active CO₂ conduits, such reduction in porosity and permeability would occlude the preferred flow conduit and ultimately restrict upward flow of CO₂-charged water. X-ray diffraction detects small amounts of goethite and hematite and a decrease in chlorite-smectite in altered conduit sandstones. Calcite is abundant, but many authigenic minerals predicted by geochemical models of CO₂ influx into sandstone reservoirs are not observed, including kaolinite, aragonite, dolomite, siderite, ankerite or dawsonite. This difference between observed and predicted mineral occurrence likely results from differences in mineral kinetics between natural and laboratory systems. Prediction of leakage risk based on fault geometry improves the ability to assess the suitability of potential carbon sequestration reservoirs, many of which will be faulted. The point seep nature of leakage through a fault zone limits the amount of CO₂ that can escape over time and also enables targeted surface monitoring for CO₂ escape into the atmosphere--both critical for ensuring the effectiveness of injection projects and earning the trust necessary for carbon sequestration to gain public acceptance. The point seep nature of leakage also accelerates the rate at which conduits may seal through mineralization, since precipitation from a large volume of fluid is focused in a narrow conduit. The presence of multiple fossil and active seep locations along the Little Grand Wash fault, active at different times in the geologic past, indicates that cementation may be effective in sealing single conduits but that fault systems with complex geometry such as Little Grand Wash may continue to leak for a long period of time.
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Bestärkt durch das gesellschaftliche und wirtschaftliche Interesse an nachhaltigen und ressourcenschonenden Formen des Bauens gewinnen Holzkonstruktionen wieder unverkennbar an Bedeutung. Mit dieser Entwicklung bilden sich neue Konstruktionsprinzipien und Materialkombinationen im Bauwesen heraus, zu deren ingenieurtechnischer Beurteilung zum Teil keine ausreichenden Erkenntnisse vorliegen. Verbundkonstruktionen aus Holz und Glas sind eine innovative Bauweise, die zu einer höheren Materialeffizienz in Fassaden beiträgt, deren Wirkungsweise aber noch nicht ausreichend hinterfragt wurde. Werden Holz und Glas durch eine tragende Klebung verbunden, lässt sich das vielfach ungenutzte Tragpotenzial ausschöpfen, das eine in Scheibenebene belastete Verglasung aufweist. Die Qualität der Klebung entscheidet dabei über die Eigenschaften und das Leistungsvermögen des Bauteils. Die üblicherweise an dieser Schnittstelle eingesetzten Silikonklebstoffe weisen eine hohe Nachgiebigkeit und eine vergleichsweise geringe Festigkeit auf. Wenn die Verbundelemente als Aussteifung mitwirken sollen, bleibt ihr Einsatz deswegen auf Gebäude mit höchstens zwei Geschossen limitiert. Die vorliegende Arbeit trägt entscheidend zur Erweiterung der baulichen Möglichkeiten bei, indem sie der Anwendbarkeit von hochfesten Klebstoffen, die für den Einsatz im Bauwesen nur wenig erforscht sind, auf vielschichtige Weise nachgeht. Im Fokus stehen aussteifende Holz-Glas-Verbundelemente für die Fassade. Weder die Bauart noch das Bauprodukt Klebstoff sind derzeit in Deutschland in einer Norm erfasst. Das Klären der baurechtlichen Rahmenbedingungen ist daher unerlässlich und erfolgt mit engem Bezug zum konstruktiven Glasbau. Zusätzlich zur wissenschaftlichen Interpretation wird dadurch eine praxisnahe Bewertung der Versuchsergebnisse möglich, was ein Alleinstellungsmerkmal dieser Arbeit darstellt. Das Verformungsvermögen des Klebstoffs spielt eine zentrale Rolle bei der Materialauswahl und Gestaltung der Holz-Glas-Verbundelemente. Der Einfluss der Klebstoffsteifigkeit auf das Tragverhalten eines Einzelelements und auf dessen Interaktion mit den anderen Bestandteilen des Tragwerks wird an einem Modellgebäude untersucht. Auf Basis dieser Parameterstudie lassen sich drei Steifigkeitsbereiche definieren, auf die sich die Klebstoffauswahl für die weiteren Untersuchungen stützt. Der experimentelle Teil der Arbeit beginnt mit der ausführlichen Charakterisierung von sieben Klebstoffen. Davon werden zwei höherfeste Klebstoffe als geeignet identifiziert. Ein Silikonklebstoff wird als Referenzmaterial zur aktuellen Anwendungspraxis festgelegt. Das Hauptaugenmerk der folgenden Experimente richtet sich auf Aspekte der Alterungsbeständigkeit und des zeitabhängigen Materialverhaltens unter langandauernder mechanischer Beanspruchung. In labormaßstäblichen Alterungsprüfungen werden die Klebstoffproben unterschiedlichen Schadeinwirkungen ausgesetzt, die im Glas- und Fassadenbau relevant sind. Darüber hinaus erfolgen Kriechversuche an kleinen und großen Scherprüfkörpern. Letztere stellen einen besonderen Mehrwert dar, da sie eine realistische Klebfugengeometrie aufweisen und die Ergebnisse dadurch dem tatsächlichen Bauteilverhalten nahekommen. Für diese Zeitstandversuche wurde eine bislang einzigartige Versuchsanlage aus sechs Prüfrahmen mit Gasdruckfederbelastung entwickelt. Im Ergebnis zeigt sich, dass mit den gewählten höherfesten Klebstoffen die Festigkeit der nicht gealterten Klebschichten erwartungsgemäß gesteigert werden kann. Der Bruch des Fügepartners Holz wird zum maßgebenden Versagenskriterium. Die Verformungen des Verbundelements reduzieren sich gegenüber einer Silikonklebung deutlich. Allerdings offenbaren sich in einzelnen Alterungsszenarien und unter langandauernder Belastung auch Schwachstellen dieser Klebstoffe. Ihre Verwendung kann daher nur mit konstruktiven Kompensationsmaßnahmen oder durch Abschirmen der kritischen Einwirkungsgrößen empfohlen werden. Entsprechende Vorschläge werden bei der abschließenden Bewertung der Ergebnisse unterbreitet. Verfahren und Beurteilungsmethoden, die in dieser Arbeit angewendet und entwickelt werden, erleichtern die zukünftige Bewertung weiterer aussichtsreicher Klebstoffe für den Holz-Glas-Verbund.:1 Einleitung 13 1.1 Motivation 13 1.2 Zielsetzung 18 1.3 Abgrenzung 20 1.4 Vorgehensweise 21 2 Die Holz-Glas-Verbundbauweise 25 2.1 Tragprinzip und Wirkungsweise 25 2.2 Forschungsschwerpunkte und Anwendungen 27 2.2.1 Geklebte Verglasungssysteme für Fenster 27 2.2.2 Träger 28 2.2.3 Wandscheiben und Schubfelder 32 2.2.4 Verbundplatten 36 2.3 Tragendes Glas im Verbund 37 2.3.1 Relevanz für Holz-Glas-Verbundlösungen 37 2.3.2 Historische Vorbilder 37 2.3.3 Verbundglas und Verbund-Sicherheitsglas 38 2.3.4 Verbundträger 40 2.3.5 Wandscheiben aus Glas 43 2.4 Konstruktionsprinzipien von tragenden Wand und Fassadenelementen aus Holz und Glas 46 2.4.1 Aufbau 46 2.4.2 Verglasung 46 2.4.3 Ausbildung der Klebfuge 48 2.4.4 Marktreife Systeme mit Koppelleiste 49 2.4.5 Identifizieren geeigneter Tragsysteme 52 2.4.6 Skelett-, Tafel- und Massivholzbauweise 53 2.5 Zusammenfassung wesentlicher Erkenntnisse 55 3 Klebverbindungen im Glasbau 57 3.1 Fügen von Glas 57 3.1.1 Besondere Merkmale des Fügewerkstoffs 57 3.1.2 Wirkprinzip und Fügeverfahren 60 3.1.3 Vor- und Nachteile von Klebverbindungen 61 3.1.4 Glasoberfläche 65 3.2 Typische Anwendungsbeispiele im Glasbau 67 3.2.1 Klassifizierung 67 3.2.2 Einordung der Holz-Glas-Verbundbauweise 69 3.2.3 Structural Sealant Glazing 71 3.2.4 Ganzglaskonstruktionen 74 3.3 Planungsstrategien 76 3.3.1 Sicheres Bauteilversagen 76 3.3.2 Redundanz und Versagensszenarien 78 3.3.3 Besonderheiten bei geklebten Verglasungen 80 3.4 Baurechtliche Rahmenbedingungen 82 3.4.1 Normung und Verfahrensweise in Deutschland 82 3.4.2 Harmonisierung auf europäischer Ebene 84 3.4.3 ETAG 002 – Leitlinie für Structural Glazing 86 3.4.4 Der Weg zur geklebten Glaskonstruktion 88 4 Einfluss der Klebstoffsteifigkeit auf aussteifende Holz-Glas-Verbundtragwerke 91 4.1 Aussteifung von Holzbauten 91 4.2 Berechnungsverfahren 92 4.2.1 Begründung der Auswahl der Verfahren 92 4.2.2 Verteilung von Horizontallasten auf die Wandscheiben eines Aussteifungssystems 93 4.2.3 Wandscheibe als Schubfeld 95 4.2.4 Federmodelle 97 4.3 Randbedingungen für die Analyse 101 4.3.1 Modellgebäude 101 4.3.2 Konstruktive Gestaltung 103 4.3.3 Lastannahmen 104 4.4 Parameterstudie 107 4.4.1 Nachgiebigkeit der Kernwände 107 4.4.2 Nachgiebigkeit eines Verbundelements 108 4.4.3 Auswirkung der Elementanordnung 112 4.4.4 Lastumlagerung bei Ausfall von Elementen 114 4.4.5 Horizontallastanteil auf Fassade und Kern 116 4.5 Rückschlüsse auf die Tragsystemgestaltung und die Klebstoffauswahl 120 5 Materialauswahl und -charakterisierung 123 5.1 Untersuchungsprogramm 123 5.2 Materialeigenschaften der Fügeteile 124 5.2.1 Glas 124 5.2.2 Holz und Holzwerkstoffe 126 5.3 Klebstoffe 128 5.3.1 Auswahlkriterien für Holz-Glas-Klebungen 128 5.3.2 Vorauswahl der Klebstoffsysteme 130 5.4 Experimentelle Methoden zur Charakterisierung der Klebstoffe 134 5.4.1 Dynamisch-mechanische Analyse 134 5.4.2 Einaxialer Zugversuch 135 5.4.3 Scherversuch 138 5.5 Versuchsergebnisse 141 5.5.1 Glasübergangstemperatur 141 5.5.2 Spannungs-Dehnungs-Beziehung 145 5.5.3 Einpunktkennwerte 150 5.5.4 Scherfestigkeit und Bruchbildanalyse 151 5.6 Klebstoffauswahl für die Hauptuntersuchungen 155 6 Experimentelle Untersuchungen an Klebverbindungen im Labormaßstab 157 6.1 Methodik 157 6.1.1 Untersuchungsgegenstand 157 6.1.2 Beurteilungsgrundlagen 158 6.1.3 Untersuchungsprogramm 159 6.1.4 Auswertungsmethoden 162 6.2 Geometrie und Herstellung der Prüfkörper 164 6.2.1 Prüfkörper zum Bestimmen der Haftfestigkeit vor und nach künstlicher Alterung 164 6.2.2 Scherprüfkörper für Kriechversuche 165 6.2.3 Vorbereiten und Konditionieren der Proben 166 6.3 Verfahren zur mechanischen Prüfung und zur künstlichen Alterung 168 6.3.1 Zug- und Scherversuche 168 6.3.2 Lagerung unter UV-Bestrahlung 170 6.3.3 Lagerung in Reinigungsmittellösung 171 6.3.4 Holzfeuchtewechsel bei +20 °C 172 6.3.5 Lagerung in schwefeldioxidhaltiger Atmosphäre 173 6.3.6 Kriechversuche 174 6.4 Auswertung der Versuchsergebnisse 176 6.4.1 Anfangsfestigkeit im Scherversuch 176 6.4.2 Anfangsfestigkeit im Zugversuch 181 6.4.3 Sichtbare Veränderungen der Klebschicht 183 6.4.4 Restfestigkeit nach Alterung 185 6.4.5 Analyse der Versagensmuster 189 6.4.6 Kriechverhalten 192 6.4.7 Restfestigkeit nach Vorbelastung 198 7 Experimentelle Untersuchungen an bauteilähnlichen Prüfkörpern 201 7.1 Untersuchungsprogramm und Methodik 201 7.1.1 Ziel der Untersuchungen 201 7.1.2 Materialien 202 7.1.3 Großer Scherprüfkörper 203 7.1.4 Herstellung der Prüfkörper 205 7.1.5 Versuchsprogramm – Bauteilversuche 207 7.2 Entwicklung eines Kriechprüfstands 210 7.2.1 Prüfrahmen 210 7.2.2 Lasteinleitung 211 7.2.3 Belastungsvorgang 212 7.2.4 Messtechnik und Monitoring 213 7.2.5 Modifikation für Kurzzeitversuche 214 7.3 Große Scherversuche unter Kurz- und Langzeiteinwirkung 215 7.3.1 Tragfähigkeit bei kurzzeitiger Lasteinwirkung 215 7.3.2 Spannungsverteilung im Glas 219 7.3.3 Kriechversuche mit 1000 Stunden Laufzeit 221 7.3.4 Verlängerte Kriechversuche am Klebstoff mit mittlerer Steifigkeit 226 7.3.5 Tragfähigkeit nach Vorbelastung 230 8 Bewertung und Handlungsempfehlung 231 8.1 Alterungsverhalten 231 8.2 Korrelation der Ergebnisse aus Fügeteil- und 233 Bauteilversuchen 8.2.1 Versuche bei kurzzeitiger Lasteinwirkung 233 8.2.2 Versuche bei langandauernder Lasteinwirkung 235 8.3 Der Vorzugsklebstoff und seine Einsatzgrenzen 238 8.4 Konstruktion 241 9 Zusammenfassung und Ausblick 243 9.1 Zusammenfassung 243 9.2 Ausblick 249 10 Literatur 253 11 Abbildungsverzeichnis 263 12 Tabellenverzeichnis 267 13 Bezeichnungen 268 Anhang A Materialkennwerte zur Klebstoffauswahl 271 B Klebverbindungen im Labormaßstab 287 C Bauteilähnliche Prüfkörper 373
Wooden constructions are on the rise again – encouraged by a strong public and economic trend towards sustainable and resource efficient buildings. Spurred by this growing interest novel design principles and material assemblies in architecture and the building industry evolve. These developments require further research due to the absence of evaluation tools and insufficient knowledge about their design. Load-bearing timber-glass composite elements could contribute to a more efficient use of materials in façade constructions. In this case a linear adhesive bond connects the glass pane to the timber substructure. This enables an in-plane loading of the glass whose capacity is not used to its full potential in conventional façades as it is solely applied as an infill panel. The quality of the adhesive bond defines the characteristics and the performance of the whole structural component. Structural sealants such as silicones, which are typically used for the joint, provide a high flexibility and only a low load-bearing capacity. Considering such elements being part of a bracing system, the mentioned characteristics limit the application range to buildings with not more than two stories. This thesis widens the scope with an in-depth examination of high-modulus adhesives, which have not yet been evaluated for their use in building constructions. Timber-glass composite elements used as a bracing component in façades are the focus of this work. Neither the full structural component nor the adhesive have yet been included into German building standards. Hence it is essential to assess the general requirements of their application. The relevant aspects are clarified in the context of glass constructions. In addition to the scientific discussion of the results, this approach facilitates also a practical evaluation of the findings, which is a unique feature of this work. The deformability of the adhesive becomes a crucial criterion when selecting the individual materials and designing the timber-glass composite elements. A case study assesses the influence of the adhesive stiffness on the behavior of a single element and its interaction with other members of the structural system. Based on the results, three different stiffness classes are introduced to support the selection process of the adhesives to be examined in further investigations. The experimental part of this work is initiated by a comprehensive characterization of seven shortlisted adhesives. The results enable a further differentiation of suitable materials. Two adhesives qualified as suitable for the main experiments. A silicone adhesive complements the test series to serve as a reference material to the current practice. In the next phase attention is drawn to the ageing stability and on the time-dependent material behavior of the adhesives under long-term loading. Small-scale specimens made from adhesively joint timber and glass pieces are exposed to different ageing scenarios which relate to the impacts typically encountered in façades. Beyond that, creep tests are carried out on small and large shear specimen. The latter provide extra benefit as they comprise long linear adhesive joints resembling virtually the situation in a real-size element. A specific long-term test rig was developed for this purpose comprising a loading unit with gas pressurized springs. Based on the results it can be concluded that joints with adhesives of high and intermediate stiffness enable an increase of characteristic failure loads and a significant reduction of deformation. With the stiffer joint near-surface rupture of timber fibers becomes the prevailing failure mechanism. The timber strength limits further loading of the adhesive joint. However, ageing and creep testing reveal also shortcomings of the adhesives. Their application can only be recommended if redundant compensation measures are taken or the joint is protected against critical environmental impacts. Appropriate solutions are proposed with the final recommendations of this work. Methods and assessment tools that have been developed and tested for this work offer the possibility of a more straight-forward evaluation of further promising adhesives and their use in load-bearing timber-glass composites.:1 Einleitung 13 1.1 Motivation 13 1.2 Zielsetzung 18 1.3 Abgrenzung 20 1.4 Vorgehensweise 21 2 Die Holz-Glas-Verbundbauweise 25 2.1 Tragprinzip und Wirkungsweise 25 2.2 Forschungsschwerpunkte und Anwendungen 27 2.2.1 Geklebte Verglasungssysteme für Fenster 27 2.2.2 Träger 28 2.2.3 Wandscheiben und Schubfelder 32 2.2.4 Verbundplatten 36 2.3 Tragendes Glas im Verbund 37 2.3.1 Relevanz für Holz-Glas-Verbundlösungen 37 2.3.2 Historische Vorbilder 37 2.3.3 Verbundglas und Verbund-Sicherheitsglas 38 2.3.4 Verbundträger 40 2.3.5 Wandscheiben aus Glas 43 2.4 Konstruktionsprinzipien von tragenden Wand und Fassadenelementen aus Holz und Glas 46 2.4.1 Aufbau 46 2.4.2 Verglasung 46 2.4.3 Ausbildung der Klebfuge 48 2.4.4 Marktreife Systeme mit Koppelleiste 49 2.4.5 Identifizieren geeigneter Tragsysteme 52 2.4.6 Skelett-, Tafel- und Massivholzbauweise 53 2.5 Zusammenfassung wesentlicher Erkenntnisse 55 3 Klebverbindungen im Glasbau 57 3.1 Fügen von Glas 57 3.1.1 Besondere Merkmale des Fügewerkstoffs 57 3.1.2 Wirkprinzip und Fügeverfahren 60 3.1.3 Vor- und Nachteile von Klebverbindungen 61 3.1.4 Glasoberfläche 65 3.2 Typische Anwendungsbeispiele im Glasbau 67 3.2.1 Klassifizierung 67 3.2.2 Einordung der Holz-Glas-Verbundbauweise 69 3.2.3 Structural Sealant Glazing 71 3.2.4 Ganzglaskonstruktionen 74 3.3 Planungsstrategien 76 3.3.1 Sicheres Bauteilversagen 76 3.3.2 Redundanz und Versagensszenarien 78 3.3.3 Besonderheiten bei geklebten Verglasungen 80 3.4 Baurechtliche Rahmenbedingungen 82 3.4.1 Normung und Verfahrensweise in Deutschland 82 3.4.2 Harmonisierung auf europäischer Ebene 84 3.4.3 ETAG 002 – Leitlinie für Structural Glazing 86 3.4.4 Der Weg zur geklebten Glaskonstruktion 88 4 Einfluss der Klebstoffsteifigkeit auf aussteifende Holz-Glas-Verbundtragwerke 91 4.1 Aussteifung von Holzbauten 91 4.2 Berechnungsverfahren 92 4.2.1 Begründung der Auswahl der Verfahren 92 4.2.2 Verteilung von Horizontallasten auf die Wandscheiben eines Aussteifungssystems 93 4.2.3 Wandscheibe als Schubfeld 95 4.2.4 Federmodelle 97 4.3 Randbedingungen für die Analyse 101 4.3.1 Modellgebäude 101 4.3.2 Konstruktive Gestaltung 103 4.3.3 Lastannahmen 104 4.4 Parameterstudie 107 4.4.1 Nachgiebigkeit der Kernwände 107 4.4.2 Nachgiebigkeit eines Verbundelements 108 4.4.3 Auswirkung der Elementanordnung 112 4.4.4 Lastumlagerung bei Ausfall von Elementen 114 4.4.5 Horizontallastanteil auf Fassade und Kern 116 4.5 Rückschlüsse auf die Tragsystemgestaltung und die Klebstoffauswahl 120 5 Materialauswahl und -charakterisierung 123 5.1 Untersuchungsprogramm 123 5.2 Materialeigenschaften der Fügeteile 124 5.2.1 Glas 124 5.2.2 Holz und Holzwerkstoffe 126 5.3 Klebstoffe 128 5.3.1 Auswahlkriterien für Holz-Glas-Klebungen 128 5.3.2 Vorauswahl der Klebstoffsysteme 130 5.4 Experimentelle Methoden zur Charakterisierung der Klebstoffe 134 5.4.1 Dynamisch-mechanische Analyse 134 5.4.2 Einaxialer Zugversuch 135 5.4.3 Scherversuch 138 5.5 Versuchsergebnisse 141 5.5.1 Glasübergangstemperatur 141 5.5.2 Spannungs-Dehnungs-Beziehung 145 5.5.3 Einpunktkennwerte 150 5.5.4 Scherfestigkeit und Bruchbildanalyse 151 5.6 Klebstoffauswahl für die Hauptuntersuchungen 155 6 Experimentelle Untersuchungen an Klebverbindungen im Labormaßstab 157 6.1 Methodik 157 6.1.1 Untersuchungsgegenstand 157 6.1.2 Beurteilungsgrundlagen 158 6.1.3 Untersuchungsprogramm 159 6.1.4 Auswertungsmethoden 162 6.2 Geometrie und Herstellung der Prüfkörper 164 6.2.1 Prüfkörper zum Bestimmen der Haftfestigkeit vor und nach künstlicher Alterung 164 6.2.2 Scherprüfkörper für Kriechversuche 165 6.2.3 Vorbereiten und Konditionieren der Proben 166 6.3 Verfahren zur mechanischen Prüfung und zur künstlichen Alterung 168 6.3.1 Zug- und Scherversuche 168 6.3.2 Lagerung unter UV-Bestrahlung 170 6.3.3 Lagerung in Reinigungsmittellösung 171 6.3.4 Holzfeuchtewechsel bei +20 °C 172 6.3.5 Lagerung in schwefeldioxidhaltiger Atmosphäre 173 6.3.6 Kriechversuche 174 6.4 Auswertung der Versuchsergebnisse 176 6.4.1 Anfangsfestigkeit im Scherversuch 176 6.4.2 Anfangsfestigkeit im Zugversuch 181 6.4.3 Sichtbare Veränderungen der Klebschicht 183 6.4.4 Restfestigkeit nach Alterung 185 6.4.5 Analyse der Versagensmuster 189 6.4.6 Kriechverhalten 192 6.4.7 Restfestigkeit nach Vorbelastung 198 7 Experimentelle Untersuchungen an bauteilähnlichen Prüfkörpern 201 7.1 Untersuchungsprogramm und Methodik 201 7.1.1 Ziel der Untersuchungen 201 7.1.2 Materialien 202 7.1.3 Großer Scherprüfkörper 203 7.1.4 Herstellung der Prüfkörper 205 7.1.5 Versuchsprogramm – Bauteilversuche 207 7.2 Entwicklung eines Kriechprüfstands 210 7.2.1 Prüfrahmen 210 7.2.2 Lasteinleitung 211 7.2.3 Belastungsvorgang 212 7.2.4 Messtechnik und Monitoring 213 7.2.5 Modifikation für Kurzzeitversuche 214 7.3 Große Scherversuche unter Kurz- und Langzeiteinwirkung 215 7.3.1 Tragfähigkeit bei kurzzeitiger Lasteinwirkung 215 7.3.2 Spannungsverteilung im Glas 219 7.3.3 Kriechversuche mit 1000 Stunden Laufzeit 221 7.3.4 Verlängerte Kriechversuche am Klebstoff mit mittlerer Steifigkeit 226 7.3.5 Tragfähigkeit nach Vorbelastung 230 8 Bewertung und Handlungsempfehlung 231 8.1 Alterungsverhalten 231 8.2 Korrelation der Ergebnisse aus Fügeteil- und 233 Bauteilversuchen 8.2.1 Versuche bei kurzzeitiger Lasteinwirkung 233 8.2.2 Versuche bei langandauernder Lasteinwirkung 235 8.3 Der Vorzugsklebstoff und seine Einsatzgrenzen 238 8.4 Konstruktion 241 9 Zusammenfassung und Ausblick 243 9.1 Zusammenfassung 243 9.2 Ausblick 249 10 Literatur 253 11 Abbildungsverzeichnis 263 12 Tabellenverzeichnis 267 13 Bezeichnungen 268 Anhang A Materialkennwerte zur Klebstoffauswahl 271 B Klebverbindungen im Labormaßstab 287 C Bauteilähnliche Prüfkörper 373

Soil is an irreplaceable natural resource, a fundamental component of the environment and a source of livelihood. At present, however, urban sprawl is excessive and land cover is detrimental to the agricultural system; these are the leading contributors to soil damage and the loss of its function. The most serious type of soil degradation is "land grabbing". Such land grabbing may be considered one of the major environmental problems of the Czech Republic. Development in greenfield sites has significant environmental impacts, such as the loss of good agricultural or forest land. Unlike tools to protect forests, tools to protect agricultural land resources (ALR) appear to be ineffective. The objective of the present thesis is to explain how such tools are applied in practice, and to analyze the tools and to answer the crucial question: How do tools to protect agricultural land resources work in practice and for what reasons do tools to protect ALR appear to be ineffective? The theoretical section of the thesis provides the legislative and theoretical background. This section is primarily based on Act No. 334/1992 Sb. on the protection of agricultural land resources and Act No. 289/1995 Sb. on forests. An analysis is made and the defined issues are assessed in practice. I used qualitative research,...