The objective of the research programme has been to investigate the behaviour of masonry arch vault collapse mechanisms in the context of the problems besetting the national bridge stock. The programme has primarily involved masonry constitutive theoretical studies, supported by laboratory experimentation, which have led to the formulation of novel masonry hinge modelling. The modelling has been developed for practical application in a four hinge masonry vault mechanism analysis and subjected to testing. The technique has been applied in the field supported by a novel application of information technology (IT) image processing, reflecting the growing importance of IT within the construction industry. All theoretical studies have been mounted as micro-computer software with graphics. The accent is upon engineering requirements in practice. Chapter One reviews the context and history of the masonry vault structural form, whose presence has long been commonplace in the United Kingdom, especially on the nation's road network. It is noted that elderly arched road bridges are under continual pressure to carry ever greater loads yet their strength is uncertain. Historically, structural analysts have attempted to resolve the arch's behaviour but present methods are still inexact. Chapter Two describes how, traditionally, masonry has been assumed to possess either a linear stress-strain property or infinite stiffness and strength. An alternative, novel equation for modelling masonry stress-strain laws is presented which may be configured to mimic the behaviour of real materials as well as that of the infinite strength and linear laws it replaces. A numerical analytical procedure has been developed to 'solve' rectangular masonry sections under combined bending and thrust thereby rendering the earlier approximations unnecessary. Chapter Three develops the theme further leading to the numerical determination of limit state hinge characteristics which furnish a static limit state axial thrust/bending moment interaction diagram and a corresponding serviceability limit state, prevention of cracking interaction diagram. Differentiation is thus made possible between hitherto identically-treated though varying natural materials and comparisons made. It is further postulated that any point on a static limit state interaction diagram locus represents a masonry hinge and an extensive series of laboratory model hinge tests is undertaken to demonstrate the point by testing the foregoing theoretical studies. Chapter Four describes the incorporation of the hinge theory into a mechanism-type computer analytical tool. Crucially, the analysis is different from other mechanism analyses by virtue of the hinge modelling, enabling the effects of material properties on arch behaviour to be studied. The software is tested in Chapter Five against prototype data for laboratory model and full size masonry bridges. Chapter Six introduces computer vision, an IT technique that is relatively novel to the structures field. It is adapted to monitor the above laboratory model arch tests and then extended to the monitoring of a multi-span arch bridge test in the field. Computer vision permits the formulation of a hypothesis regarding the unusual mode of failure that occurred and this is supported by a generalisation of the mechanism hinge theory, thereby demonstrating the merits of both techniques. Finally, Chapter Seven draws conclusions on the foregoing and makes suggestions for further work. Supporting documentation is given in the Appendices.

Orientador: Jefferson Sidney Camacho / Banca: Marcio Antonio Ramalho / Banca: José Antonio Matthiesen / Resumo: O presente trabalho teve como objetivo principal o estudo e o desenvolvimento das técnicas de produção de blocos de concreto para alvenaria estrutural na escala reduzida de (1:4). Os blocos em escala reduzida foram produzidos para apresentarem o mesmo comportamento em termos de resistência à compressão e deformabilidade que os seus pares em escala real. Para as duas escalas em estudo, (1:1) e (1:4), foram produzidos blocos com quatro traços diferentes entre si. Além dos blocos, também foram construídos e ensaiados à compressão prismas de três fiadas, nas duas escalas, de modo a determinar as correlações entre as resistências e deformações nas duas escalas. Para a consecução do objetivo acima, foram desenvolvidos ensaios de compressão axial em unidades e prismas de três blocos, nas escalas (1:1) e (1:4). Os parâmetros observados, medidos e comparados foram as resistências à compressão, os módulos de deformação, as curvas tensão-deformação e as formas de ruptura apresentadas pelos corpos-de-prova. Como resultado final, chegou-se a uma série de procedimentos que, quando observados, permitem a reprodução de blocos de concreto para alvenaria estrutural na escala (1:4), mantendo praticamente as mesmas características de resistência à compressão e deformabilidade, tanto para as unidades quanto para os prismas estudados. / Abstract: The present work had as main objective to study and the development of production techniques of the small-scale concrete blocks for structural masonry in the (1:4) reduced scale. The blocks in the small-scale were produced to present the same behavior in terms of compression strength and deformability as their equivalents in the full scale. For both studied scales, (1:1) and (1:4), blocks were produced in four different mixtures. Additionally to the blocks, it was built and tested three courses prisms, in both scales, in the way to establish the correlations between the compression strength and the deformations. To match the above objective, axial compression tests were developed in units and prisms, on the scales (1:1) and (1:4). The observed, measured and compared parameters were the compression strength, the strains, the stress-strain curves and the rupture forms presented by the specimens. As a final result, it was established a series of procedures that, when observed, allows the reproduction of the concrete blocks for structural masonry in the scale (1:4), keeping practically the same characteristics of compression strength and deformability, either for the units or for the prisms. / Mestre

Orientador: Maria Cecilia Amorim Teixeira da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-08T23:53:42Z (GMT). No. of bitstreams: 1 MarquesNeto_JoseFlorianodeAzevedo_M.pdf: 4190415 bytes, checksum: 0b77d013726f618a364d58b7b7493add (MD5) Previous issue date: 2004 / Resumo: O agronegócio café representa atualmente no mundo a segunda maior commodity e observa-se uma tendência cada vez maior em se trabalhar com esse produto a granel, em grandes volumes. Diversos fatores justificam essa tendência: transporte mais barato e mais seguro em caminhão do tipo container; custo mais barato do container para embarcar nos navios para exportação; diminuição significativa da mão ¿ de ¿ obra de manuseio; maior segurança contra incêndio; maior rapidez na carga e descarga; e eliminação de gastos com valores não agregados ao produto. Visando uma concepção construtiva racional e econômica, o presente trabalho propõe um sistema de armazenagem para café a granel, na forma alternativa aos sistemas tradicionais, quer seja de armazenagem do café em sacos de 60kg, ou mesmo em sacos tipo big-bags, com capacidade individual de 900kg a 1200kg. No projeto proposto, o silo é composto de células em alvenaria estrutural, geminadas duas a duas na largura e com um número variável de células no comprimento, em função do volume desejado de armazenagem. Esse sistema simétrico favorece a racionalidade operacional, garantindo a continuidade entre os fluxos de recebimento e de expedição. O fundo da célula é em forma de tremonha dupla tronco-piramidal, com saída central. Essa alternativa permite a redução da altura da tremonha para uma mesma célula, e conseqüentemente uma redução na altura total do silo, facilitando a concepção estrutural e minimizando o custo da obra. As tremonhas são construídas em painéis treliçados pré-moldados com capeamento de concreto. A sustentação das células e das tremonhas é feita através de vigas e pilares de concreto armado. O isolamento térmico necessário para que a qualidade do café armazenado seja garantida é estabelecido pela utilização de telhas trapezoidais de aço galvanizado, tanto na cobertura como nos fechamentos laterais. A parte superior das células do silo recebe uma laje que tem como função estrutural o travamento da estrutura. Tendo em vista situações de silos multicelulares, as várias situações de carregamento, resultantes das combinações de células cheias e vazias, são analisadas. As especificações e as peculiaridades relativas ao produto armazenado são apresentadas e consideradas na definição do sistema proposto. Para um exemplo de silo adotado, são calculados todos os esforços provenientes das ações que agem nas paredes e nas tremonhas, e também seu dimensionamento, concluindo-se pela viabilidade da concepção construtiva estudada / Abstract: Nowadays, coffee agribusiness represents the second largest commodity in the world. Storing coffee beans in silos, instead of in bags or big-bags, has been an increase tendency. Several factors justify that tendency: cheaper and safer transport by container trucks, lower cost of containers for export shipment, less labor in handling, greater safety against fire, faster filling and discharge, and elimination of extra expenses due to values not aggregated to the product. Aiming at an economic and rational solution for storing coffee beans this paper presents an alternative design: a multi-cell silo group composed of reinforced masonry rectangular cells coupled two by two in width, and a variable number of cells in length according to the volume of desired storage. Such symmetrical system benefits the loading and the unloading operations, and guarantees the continuity between the receipt flow and the shipment flow. The silo bottom is designed as a double pyramidal central opening hopper. That shape reduces the height of the hopper in the cell, and consequently reduces the total height of the silo lowering the cost of the building. The hoppers are built in precast-concrete trussed panels. Cells and hoppers are supported on concrete beams and columns. The thermal insulation needed to preserve the quality of the stored coffee beans is obtained by using galvanized steel trapezoid tiles for the roof as well as for the lateral closure. The roof structure consists of a precast-concrete slab that restrains the silo structure. Several combinations of loaded and unloaded cells are analyzed in the multi-cell silo group to compute the worst combinations of loading. An example is presented and the feasibility of the alternative design is discussed. / Mestrado / Edificações / Mestre em Engenharia Civil

The study presented aims to provide the most viable seismic retrofit solution for rural masonry. Muzffarabad is one such region where excess of unreinforced masonry structures claimed thousands of lives during 2005 earthquake. Field study was conducted in the region to familiarize with the dynamics of local construction industry before suggesting a suitable retrofit solution. Polypropylene (PP-) band retrofit has been selected as the most viable solution for retrofitting existing masonry structures in terms of cost, material availability and ease of application. To prove the efficiency of PP-band retrofit, numerical simulations and laboratory tests were conducted to assess the seismic efficiency of PP-band retrofit. Material tests were conducted in accordance with BS-EN to familiarize with the mechanical properties of locally available materials in Kashmir region and to provide material data for numerical analysis. Tests revealed lower strength and elasticity for bricks in comparison to materials found in developed countries, due to the unregulated and non-standardized manufacturing of masonry units and high water content in mortars. Shake table tests were conducted to test the effectiveness of PP-band retrofit masonry under dynamic vibrations. Results show that PP-band retrofit can enhance the post peak performance by at least 7 times in comparison to non-retrofit specimen. Real-scale structure retrofit with PP-band survived accelerations of up to 2g without any life-threatening damage, thus, proving to be an economic and efficient strengthening solution for rural communities. Following the shortcomings observed in Room-1, connection detail for PP-bands in Room-2 was revised to achieve a 100% performance enhancement. Numerical models were developed to predict cracks in masonry and analyse diagonal compression test models, in accordance with ASTM standards. The results showed 30% higher residual strength after cracking for PP- band retrofit masonry and the wall integrity was maintained for higher deformations.

京都大学 / 0048 / 新制・論文博士 / 博士(地球環境学) / 乙第12836号 / 論地環博第9号 / 新制||地環||25(附属図書館) / 31374 / (主査)教授 ショウ ラジブ, 教授 岡﨑 健二, 准教授 古川 愛子 / 学位規則第4条第2項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

Accelerated dry-stack masonry construction is seen all over the world in the last two decades. Intense investigation on structural behaviour of dry-stack masonry is also seen worldwide. This research work, presents an investigation of the structural behaviour of Hydraform drystack masonry developed in South Africa. Unit compressive strength, masonry wall compressive strength and flexural resistance of dry-stack masonry/reinforced concrete beams were investigated. Due to the interlocking mechanism nature of Hydraform dry-stack blocks, three different unit compressive testing methods were investigated. The methods are described as: - Shoulder test; - Centre test; - Cube test. Tests were carried out under different humidity conditions: - Dry; - Wet; - Normal. Influence of different cement contents within the block units and moisture contents were investigated. The study made proposal of Hydraform block unit grads to be used for design. Compressive strength of dry-stack masonry walls was experimentally investigated. Dry-stack masonry wall specimens made by different block grades were subjected to in-plane vertical uniformly distributed load. Test results were used to establish dry-stack masonry characteristic compressive strength for several block grades. Flexural strength of dry-stack masonry/reinforced concrete composite beams was investigated. Series of beams were tested for flexural resistance. Applicability of conventional reinforced masonry flexural analysis philosophy was established.

<p>Better understanding of the structural behaviour of concrete and masonry structures is facilitated through experimental testing. Although some experimental testing of reinforced masonry (RM) rectangular walls is reported in literature, little experimental data is available on RM walls with flanges or with boundary element. Unlike those pertaining to rectangular walls, seismic design provisions of flanged and end-confined masonry walls are not available in North American masonry design codes.</p> <p>In the current study, the response of seven half scale fully grouted RM shear walls, all with the same length but different end configurations and aspect ratios is investigated. The goal of the study was to evaluate and document the enhanced ductile behaviour of rectangular RM shear walls when flanges and boundary elements are structurally connected at the wall ends. Another goal was to extract specific seismic performance parameters of reinforced concrete-block rectangular, flanged and end-confined shear walls based on quasi-static experimental results. Finally, nonlinear dynamic analysis was conducted on the test walls to quantify seismic force modification factors used in seismic design.</p> <p>High levels of ductility accompanied by relatively small strength degradation were observed in all walls in general with a significant increase in ductility and displacement capabilities for the flanged and end-confined walls compared to the rectangular ones. The drift levels attained at 20% strength degradation by the rectangular, the flanged, and the end-confined walls were 1.0%, 1.5%, and 2.2%, respectively. The ductility values of the flanged and end-confined walls were, respectively, 1.5 and 2.0 times that of their rectangular wall counterparts. In addition to the enhanced ductility, a saving of more than 40% in the amount of vertical reinforcement was achieved using the proposed alternative strategies while maintain the lateral resistance. The relationship between the energy dissipation and the ratio of the post-yield to the yield displacement was found to be almost linear for the test walls. Wall stiffnesses degraded rapidly to about 60% of their gross stiffness at very low drift levels (0.1 % drift). Measured compressive strain at the wall toes were almost double those specified in both North American codes. Extent of plasticity over the wall height was about 75% of the wall length. Equivalent plastic hinge lengths, needed in wall displacement predictions, using theoretical curvatures and experimental displacement ductilities varied between 17% and 40% of the wall length at ultimate load for all the tested walls. The test results indicated that higher seismic force modification factors should be assigned to the flanged and endconfined RM shear walls compared to values currently assigned to rectangular walls.</p> <p>The data presented in this study is expected to facilitate better understanding of RM wall behaviour under in-plane load to researchers, practicing engineers, and code developers. This study aimed at presenting the flanged and end-confined categories as cost-effective alternatives to enhance the seismic performance of midrise RM construction in North America.</p> / Thesis / Doctor of Philosophy (PhD)

Two stack loss efficiency measurement methods, the Total Combustible Carbon (TCC) and Combustibles Meter (CM) methods, have been modified for use on masonry heaters. The applicability of the two methods has been verified with 6 tests on two masonry heaters. Each test starts with a cold heater and requires five firings to achieve two different burn rates. The efficiencies calculated for each firing are weighted according to burn rate following EPA Method 28 for wood heaters. The TCC Method uses carbon balances to calculate the chemical energy loss and the dry stack gas mass for calculation of sensible energy loss. The sensible loss that occurs during the off-period, when combustion of wood has stopped, is measured directly by injecting carbon dioxide in the stack and using it as a tracer gas to measure stack flow rate. In both methods the latent energy loss is calculated from wood moisture content and hydrogen content. The CM Method measures losses more directly and is considered the reference method in this work. The chemical energy loss is measured using a flame combustibles meter. The stack flow rate, which is used for the calculation of sensible loss, is measured directly using carbon dioxide tracer gas during both the on and off periods of the appliance. The overall average efficiencies measured by the two methods, in 5 tests on two different appliances, differed by a maximum of 1.7 percentage points of the fuel energy input. On the average they differed by about 1 percentage point. The results of a one-dimensional finite-difference model of the heat exchanger of one of the tested masonry heaters is compared against thermocouple-measured temperatures. For the 3 tests performed the model predicts the measured temperatures to within 12% during the first half of a firing cycle when the burn rate is high, and to within 5% during the second half of the cycle when the burn rate is low. / Master of Science

Reinforced concrete (RC) shear wall buildings constitute a significant portion of the building inventory in many earthquake-prone regions. A similar type of structural system is fully-grouted reinforced masonry (RM) shear wall structures. The accurate determination of the nonlinear response of reinforced concrete and reinforced masonry (RC/RM) walls subjected to lateral loading is of uttermost importance for ensuring the safety of the built environment. Analytical models provide a cost efficient and comprehensive tool to study the nonlinear response of RC/RM structures, as compared to experimental tests. Predictive models should capture nonlinear material behavior as well as the geometrically nonlinear response of RC/RM shear wall structures during major seismic events. This thesis outlines the formulation and validation of a nonlinear shell element for the simulation of RC/RM structures. The proposed shell element enhances an existing formulation of a four-node Discrete Kirchhoff shell element through the inclusion of a corotational approach to account for geometric nonlinearities and of nonlinear material models to capture the effect of cracking and crushing in concrete or masonry and the nonlinear hysteretic behavior of reinforcing steel. The analytical results obtained from multiple linear and nonlinear analyses are compared against theoretical solutions and experimental test data. These comparative validation studies show the enhanced shell element can satisfactorily capture the salient features of the response of nonlinear reinforced concrete/masonry shear wall structures including axial-shear-flexure interaction, damage patterns, and in-plane and out-of-plane loading. / Master of Science

This is an architectural thesis on weaving. The city is a massive textile, a patchwork of buildings, infrastructure and people. We alter the urban environment within the confines established by lot lines, streets and zoning similar to the weft on a loom, conforming to the rules of the warp. The proposed design aims to incorporate the demands of a globalized world while retaining the identity and scale of the traditional Washington building type - the rowhouse. The architectural project, located near Fourteenth and U Streets, Northwest, in Washington, DC is a hybrid of programs - a textile school, a gallery and bar for the Textile Museum, artist studios, a restaurant, leaseable space for offices and residences as well as a public garden. This complex design reflects the evolving nature of cities and a building's ability to adapt to new demands and technology; similar to the ancient art of weaving's ability to transcend centuries of evolution while retaining its inherent qualities. / Master of Architecture