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Bhattacharjee, Chandan. "Bayesian prediction of modulus of elasticity of self consolidated concrete." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2467.
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Schoppe, Brett Michael. "SHRINKAGE & MODULUS OF ELASTICITY IN CONCRETE WITH RECYCLED AGGREGATES." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/500.
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This paper presents results on experimental research for concrete produced using recycled coarse aggregates (RCA). Five types of coarse aggregates were used in this study, four of which were RCA. The main purpose of this research was to examine how different types and properties of coarse aggregate affected compressive strength, modulus of elasticity, and shrinkage in concrete when natural coarse aggregates were replaced with RCA. Concrete batches were made with water-cement (w/c) ratios of 0.30, 0.45, and 0.60, and substitution percentages ranged from 0% to 100% of natural aggregate with RCA. Test results clearly show that compressive strength, modulus of elasticity, and shrinkage greatly depend on the quality and type of coarse aggregate used. In addition to testing of hardened concrete, predictive models for elasticity and ultimate shrinkage were developed to formulate and reinforce proposed conclusions about the properties and performance for the different RCA.
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Axson, Daniel Peter. "Ultimate Bearing Strength of Post-tensioned Local Anchorage Zones in Lightweight Concrete." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33711.
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Currently, NCHRP Report 356 has published an equation to estimate the ultimate strength of the
local zone in normal weight concrete. The local zone is the area of concrete directly ahead of the
bearing plate. The equation can be broken into two distinct parts: unconfined bearing strength of
concrete enhanced by the A/Ab ratio and the enhancement of strength due to the presence of
confining. Research has shown that the strength enhancement of the A/Ab ratio and confining
reinforcing is less in lightweight concrete than in normal weight concrete.
To determine the strength of the local zone in lightweight concrete 30 reinforced prisms, 2
unreinforced prisms, and concrete cylinders were tested. The dimensions of the prisms were 8
in. x 8 in. x 16 in. and the cylinders were 4 in. x 8 in. cylinders. The simulated reinforcing in the
prisms extended only through the top 8 in. of the prism and consisted of either ties or spirals with
different spacing or pitch, respectively. To determine the effect of the A/Ab ratio for each
spacing or pitch arrangement of the reinforcing, one of two different size bearing plates were
used.
From the testing performed in this research and other research, it is apparent that the NCHRP
equation is unconservative when estimating the ultimate strength of the local zone in lightweight
concrete. By modifying both parts of the NCHRP equation it is possible to conservatively
predict the ultimate strength of the local zone in lightweight concrete.
Also investigated in this thesis are equations to predict the splitting cylinder strength and
modulus of elasticity of lightweight concrete. For a sand-lightweight concrete, as defined by
ACI 318-05 Building code and Commentary, the splitting tensile strength can be accurately
predicted by multiplying the square root of the compressive strength by 5.7.Master of Science
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Potočková, Michaela. "Vliv vícenásobného cyklického zatěžování na hodnotu statického modulu pružnosti betonu v tlaku v konstrukcích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240134.
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This thesis deals with the dependence of static modulus of elasticity of concrete in compression on number of load cycles. The deformation of test specimens during multiple cyclic loading was measured with resistive strain gages. Up to 1600 load cycles was conducted. Static modulus of elasticity in compression was determined from measured deformations. The aim of this thesis is assessment changes in the values of static modulus of elasticity depending on the number of load cycles.
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Gujel, Daniele Artini. "Avaliação do comportamento elástico de concretos produzidos com substituição parcial dos agregados graúdos naturais por reciclados de concreto a partir de ensaios Estático e Dinâmico." Universidade do Vale do Rio dos Sinos, 2014. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4352.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
FINEP - Financiadora de Estudos e Projetos
A construção civil é um setor que causa elevado impacto ambiental devido à geração de resíduos e ao elevado consumo de matérias-primas. Demandas cada vez maiores por áreas a serem destinadas a aterros, aliadas à escassez de recursos naturais, favorecem a utilização de resíduos de construção e demolição como fonte para agregados. Neste contexto, muitos estudos estão sendo feitos a respeito de concretos produzidos com resíduos de construção e demolição, focados principalmente nas propriedades mecânicas de resistência à tração e à compressão. Para aplicação como material estrutural, entretanto, a relação tensão x deformação e, particularmente, o Módulo de Elasticidade são importantes parâmetros a serem analisados, pois são diretamente relacionados com o projeto de estruturas. Frente ao exposto, o presente trabalho utilizou agregado graúdo reciclado de concreto (ARC) na confecção de novos concretos e teve como objetivo analisar o comportamento elástico dos mesmos. Para tanto, foram confeccionados concretos com 0% e 50% de substituição de agregados graúdos naturais (AGN) por ARC. O comportamento elástico foi determinado através de um método destrutivo (Estático) e através de um método não destrutivo (Dinâmico) nas idades de 7, 28 e 63 dias para os níveis de carregamento de 0 (somente Dinâmico), 20, 30, 40, 50, 60, 70 e 80% da resistência do concreto. Os resultados encontrados para o Módulo de Elasticidade foram comparados com estimativas a partir de métodos empíricos previstos nas normas CEB-FIP Model Code 1990, ACI 318 (2011) e NBR 6118 (ABNT, 2007 e 2014). Com isso, visou-se observar a influência do ARC nas propriedades elásticas do concreto, comparar o comportamento elástico dos concretos de referência aos resultados dos concretos com ARC, estudar a correlação entre os dois métodos experimentais (Dinâmico e Estático) e verificar a correspondência entre os resultados experimentais obtidos com os normativos. Como principais conclusões, pôde-se verificar que os concretos com ARC apresentam limite elástico similar aos concretos que utilizam somente AGN (este limite situa-se entre 40 e 50% da ƒc); não foi possível identificar uma relação única entre os valores de módulo obtidos pelo Método Dinâmico e pelo Método Estático para ambos os concretos; não é possível afirmar que concretos de resistências similares, mas idades diferentes apresentaram módulos diferentes; os concretos com e sem ARC estudados apresentaram valores de Módulo de Elasticidade obtidos pelo método Estático bastante inferiores aos previstos pelas normas estudadas; os valores de Módulo de Elasticidade obtidos pelo método Dinâmico, para concretos com e sem ARC, estão contidos na faixa entre a norma mais conservadora e a menos conservadora e as curvas obtidas mostram que os concretos com ARC têm comportamento similar aos concretos sem ARC, mas são menos rígidos (maiores deformações para as mesmas tensões).
The construction industry causes a great environmental impact due to the generation of waste and the high consumption of raw material. Increasing demands for areas to become landfills, as well as shortages of natural resources, have favored the use of construction and demolition waste as a source of aggregate. In this context, many studies have been made regarding concretes produced with the use of demolition and construction waste; mainly focused on the mechanical properties of tensile and compressive strength. However, in order to use concretes produced with waste as a structural material, the stress-strain behavior and, particularly, the elastic modulus are important parameters to be analyzed, once they are directly related to structural design. Based on that, the objective of this project is to analyze the elastic behavior of concretes using coarse natural aggregates (NA) and 50% of substitution of these aggregate by coarse recycled concrete aggregates (RCA). The elastic behavior was determined by both a destructive method (static) and a nondestructive one (dynamic) on the ages of 7, 28 and 63 days for the loading levels of 0 (only dynamic), 20, 30, 40, 50, 60, 70 and 80% of respective concrete strength. The found results for the Modulus of Elasticity have been compared to estimates based on the empirical recommendations by CEB-FIP Model Code 1990, ACI 318 (2011) and NBR 6118 (ABNT, 2007 and 2014) standards. The objectives of this work were to observe the influence of the RCA on the elastic properties of concrete; to compare the elastic behavior between concretes with and without RCA, to study the correlation of both experimental methods (dynamic and static) and finally to check the relation between measured and calculated values of modulus of elasticity. The conclusions indicate that concretes with and without RCA have similar elastic limits (between 40% and 50% of the concrete strength); it is not possible to identify a unique relationship between the values obtained by dynamic and static methods for both concretes; it is not possible to assert that concretes with similar strength, but different ages, have different modulus; the values of modulus of elasticity obtained by the static method for both concretes are significantly below that indicated by the considered standards; the values of modulus of elasticity obtained by the dynamic method for concrete with and without RCA are contained in the range between the more and less conservative standards and concretes with RCA have a similar behavior than concretes without RCA, but are less rigid (larger strain for the same stress).
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Marchi, Renata D\'Agostino De. "Estudo sobre a variabilidade do módulo de deformação do concreto associada a fatores intrínsecos à produção do material." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-23032012-102942/.
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Em função da especificação do módulo de elasticidade ou módulo de deformação do concreto ser cada vez mais frequente, se faz necessário o conhecimento da variabilidade desta propriedade, relacionada ao processo de produção, de modo a tornar mais confiável sua avaliação e que possibilite melhores condições no controle de produção para o atendimento aos requisitos associados a esta propriedade. Várias pesquisas têm comprovado que a variabilidade das propriedades mecânicas dos materiais de construção obedece a processos aleatórios. Portanto, os métodos de segurança no projeto estrutural devem estar fundamentados no conceito da teoria das probabilidades e não em métodos deterministas. Isso já acontece para a determinação da resistência à compressão, conforme estabelecido pela ABNT NBR 12655 (2006). A presente dissertação tem como objetivo principal estudar o controle experimental do módulo estático de deformação do concreto, mostrando a influência da variação dos materiais constituintes do concreto, dentro da realidade de uma Central de Concreto. Também objetiva apresentar uma discussão da aplicabilidade do conceito semiprobabilístico das normas nacionais de projeto, dosagem e controle tecnológico à propriedade módulo de deformação do concreto. A metodologia da pesquisa envolveu a escolha de uma central dosadora de concreto localizada na cidade de São Paulo, com a avaliação em dois concretos de resistências características (f ck ) de 25 e 30 MPa, que são comumente solicitados no mercado em que se insere. Para cada f ck foram realizados ensaios para determinação do módulo de deformação secante, E cs, três vezes por semana por um período de nove meses. Em função da precisão observada em pesquisa recente, foi utilizada a instrumentação clip gage para avaliação da propriedade módulo de deformação. Foram realizados ensaios sob o plano de carregamento secante, previsto na ABNT NBR 8522 (2008). Concluiu-se que, pelo fato do módulo de deformação do concreto ser influenciado pela resistência à compressão, que obedece a uma distribuição probabilística, não se pode atribuir à propriedade uma característica determinística, incorrendo no risco de não atendimento da propriedade. Recomendou-se o estabelecimento de tolerâncias para a especificação do módulo de deformação, uma vez que é uma variável com distribuição de probabilidade de rejeição. Sugeriu-se a discussão de mudança de enfoque no controle do módulo de deformação do concreto, com o controle por valor característico, tal qual ocorre para a resistência à compressão, atribuindo-se um estimador que atribua valores inferiores ao módulo de deformação, considerando-se uma rejeição aceitável. Também pode-se atribuir uma faixa de variação aceitável do valor em torno da média, uma vez que a responsabilidade estrutural do parâmetro módulo de deformação é menor do que o da resistência à compressão.The modulus of elasticity requirements for concrete structures is becoming even more frequent. So, the knowledge of the variables involved in the experimental results became more important in order to make more reliable its assessment and enabling better conditions for specifications requirements attendance in relation to this property. Several studies have shown that the variability of mechanical properties of construction materials is subjected to random processes. Therefore, the security methods in the structural design must be based in the probability theory concept rather than deterministic methods. The randomness of the, compressive strength of concrete is already take in account in the quality control process according to the Brazilian Standard ABNT NBR 12655 (2006). The present work aims to study the experimental control of static modulus of elasticity of concrete, showing the influence of the constituent materials used in a Concrete Ready Mix Plant. It also intends to present a discussion on the applicability of the semi-probabilistic concept of national design standards in the mix design and production control of concrete in order to attend the elastic modulus requirements. The research methodology had two main steps: the first one, developed at a Concrete Ready Mix Plant located in São Paulo City, was based on the assessment of two characteristic compressive strength (f ck ) of 25 MPa and 30 MPa, which are commonly demanded in this market. For each strength class, tests were done to evaluate the variability of static modulus of elasticity of concrete, E cs, three times per week, during a period of nine months. On the second step, an analysis of elastic modules of concretes provided at six different sites, where the characteristic strength was 30 MPa, which was made using the same materials used in the first step. It has been used the clip gage instrumentation for measuring deformation to the assessment of static modulus of elasticity of concrete. It was used due to the precision that has been observed in recent research. The evaluation has been done according to the Brazilian Standard ABNT NBR 8522 (2008). It was possible to conclude that the modulus of elasticity of concrete is influenced by the compressive strength, so it follows a probabilistic distribution and cannot be associated to a deterministic model of quality control, due to the risk of non-compliance of the requirement. It was recommended the establishment of tolerances for the measured modulus of elasticity results, taking in account its random characteristic. The possibility of changing the focus on modulus of elasticity quality control was proposed, turning the deterministic criterion as occurs for the compressive strength, giving an estimator that assigns lower values to the modulus of elasticity, considering an acceptable rejection. It can be also based in a method that allows the acceptance of a concrete that lies within a predetermined tolerance around the average value, because the structural responsibility of modulus of elasticity is lower than the compressive strength.
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Kocuba, Robert. "Diagnostika a hodnocení prefabrikované železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372269.
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This thesis deals with inspection and constructionally technical research of reinforced concrete prefabricated construction from the second half of 20th century. In theoretical part, the research of literature, documents and valid standards is performed, with a focus on production and construction of prefabricated elements and also on the metodology of research. In practical part, the detection of reinforcement of individual elements of the construction and concrete properties is performed. The result of this work is the assessment of the state of the construction, static calculation of the ceiling panel and idea proposal for eventual reconstruction.
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Kocáb, Dalibor. "Experimentální stanovení faktorů ovlivňujících statický modul pružnosti betonu s využitím nedestruktivních zkušebních metod." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-355639.
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The Ph.D. thesis deals with one of the most important characteristics of hardened concrete; i.e. the modulus of elasticity. The thesis aims to describe and evaluate the important factors that affect the final value of concrete modulus of elasticity, especially those that can be influenced during construction. Another aim is to find ways to determine the static modulus of elasticity of concrete by non-destructive means (primarily ultrasonic pulse method, resonance method and use of electronic rebound hammers), thus to determine the possibility of creating calibration curve for NDT determination of the modulus of elasticity.
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Sousa, Fernando Henrique Fernandes. "Avaliação da relação entre os módulos de elasticidade estático e dinâmico de concretos produzidos com agregados graúdos reciclados em substituição aos agregados graúdos naturais." Universidade do Vale do Rio dos Sinos, 2018. http://www.repositorio.jesuita.org.br/handle/UNISINOS/7170.
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O módulo de elasticidade é um parâmetro que mensura a rigidez do concreto, sendo uma das propriedades que é levada em consideração na verificação da segurança estrutural, pois expressa as condições dos estados limites último e de serviço. Quando é avaliada - a influência da substituição de agregados graúdos naturais por agregados graúdos reciclados - o comportamento elástico do concreto torna-se imprescindível, uma vez que não é similar ao comportamento de resistência à compressão, que por sua vez pode alcançar resistências superiores ao concreto produzido inteiramente com agregados graúdos naturais. Nesse sentido, o uso da resistência à compressão como parâmetro único, para se estimar o módulo de elasticidade do concreto produzido com agregados graúdos reciclados, tem sido cada vez mais questionável. Tratando-se da influência do uso de agregado graúdo reciclado no módulo de elasticidade do concreto, poucos são os estudos que apresentam os valores de módulo de elasticidade estático e módulo de elasticidade dinâmico. Diante disso, o objetivo desta pesquisa é avaliar a relação entre o módulo de elasticidade estático e o módulo de elasticidade dinâmico de concretos produzidos com agregados graúdos reciclados em substituição aos agregados graúdos naturais, com o intuito de relacionar o tipo de agregado graúdo ao módulo de elasticidade. Para tal, foram utilizados agregados graúdos reciclados de concreto e agregados graúdos reciclados de cerâmica vermelha em taxa de substituição de 30% em relação ao agregado graúdo natural. Os concretos foram produzidos em três traços experimentais, sendo eles: traço pobre (maior relação a/c), traço intermediário e traço rico (menor relação a/c). As propriedades dos concretos foram avaliadas aos 28 dias, sendo elas: massa específica do concreto no estado fresco e endurecido; porosidade; resistência à compressão; módulos de elasticidade estático e dinâmico. Como principais resultados, verificou-se que o tipo de agregado graúdo reciclado de modo geral influenciou negativamente o módulo de elasticidade, sendo essa influência mais pronunciada no módulo de elasticidade dinâmico; não foi possível obter uma relação entre o módulo de elasticidade estático e dinâmico dos concretos produzidos com agregados graúdos reciclados; o módulo de elasticidade estático dos concretos produzidos com agregados graúdos reciclados é mais fortemente relacionado à resistência e à compressão; o módulo de elasticidade dinâmico possui maior relação com a porosidade dos concretos produzidos com agregados graúdos reciclados; os módulos de elasticidade estimados por equações algébricas apresentam elevada variabilidade.
Modulus of elasticity is a parameter that measures the stiffness of the concrete, being one of the properties taken into account in the structural safety check, since it expresses the conditions of the ultimate and service boundary state. When the influence of the replacement of natural aggregates by recycled aggregates is evaluated, the elastic behavior of the concrete becomes essential, since it cannot be compared to the behavior of compressive strength, usually lower than the concrete produced with natural aggregates. The use of compressive strength as a single parameter to estimate the modulus of elasticity of concrete produced with recycled aggregates has been increasingly questionated. Considering the influence of the use of recycled aggregate on the modulus of elasticity of concrete, only a few studies have compared the values of static elastic modulus and dynamic modulus. This research aims to evaluate the relationship between the static elastic modulus and the dynamic elastic modulus of concrete produced with recycled aggregates in replacement of natural aggregates, in order to correlate the type of aggregate to the modulus of elasticity, verifying the relationship between the two procedure of determination of elasticity modulus. Aggregates made of recycled concrete and of ceramic bricks were used in a replacement rate of 30% to the natural aggregate. The concretes were produced in three experimental proportions (lower w/c ratio, intermediate w/c ratio and higher w/c ratio). The properties evaluated at 28 days are: bulk concrete mass; porosity; compressive strength; static and dynamic modulus of elasticity. The main conclusions are: the recycled aggregate decrease the modulus of elasticity, mainly the dynamic modulus; there are no relationship between the static and dynamic modulus of elasticity of concrete produced with recycled aggregates; the static modulus of concrete produced with recycled aggregates has a higher relationship to the compressive strength; the dynamic modulus of elasticity is higher related to the porosity of concrete produced with recycled aggregates; the moduli of elasticity estimated by algebraic equations present high variability.
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Montija, Fernando Celotto. "Aspectos da variabilidade experimental do ensaio de módulo de deformação do concreto." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-01042009-135948/.
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Esta dissertação insere-se nas áreas de qualidade laboratorial e de ensaios de controle de concreto, especificamente quanto à propriedade módulo estático de deformação ou módulo de Young. A motivação do trabalho é a elevada variabilidade de resultados experimentais observada pelo meio técnico nacional em ensaios interlaboratoriais, cujos resultados indicam desvios-padrão totais da ordem de 3,5 GPa, valor significativo para o controle tecnológico de obras de construção civil. Os objetivos buscados foram a identificação das parcelas da variabilidade oriundas da produção e do ensaio, com especial atenção àquela originada na instrumentação para medida das deformações durante o ensaio, e a discussão da aplicabilidade do conceito semiprobabilístico normativo à propriedade módulo de deformação do concreto. Além disso, a própria discussão da aplicabilidade da sistemática de pesquisa e análise sobre este tipo de ensaio e de material constou como um objetivo do trabalho. Para tal, desenvolveu-se um programa experimental em duas etapas: a primeira foi destinada às avaliações de acurácia (precisão e exatidão) do método de ensaio. As avaliações se deram segundo roteiros da área metrológica para validação de métodos e sistemas de medida. De quatro instrumentações para medida das deformações testadas, uma se mostrou mais precisa (identificada como clip gages) e outra se mostrou a mais suscetível a erros sistemáticos e aleatórios entre as testadas (identificada como compressômetro com dois relógios comparadores). Recomendou-se a ampliação do programa experimental para o âmbito interlaboratorial, pois, a rigor, o método de ensaio vigente não poderia ser considerado validado em termos de acurácia baseando-se unicamente nos resultados deste programa experimental. Porém, concluiu-se pela possibilidade de aceitação prática do método independentemente da utilização de três de um total de quatro tipos de instrumentação para medida das deformações testados em ensaio, sem que houvesse prejuízo para a produção ou o controle tecnológico usual desta propriedade. Na segunda etapa, obteve-se um Diagrama de Dosagem e estudou-se um cenário de fornecimento de concreto sob critérios estatísticos diferentes de atendimento à especificação de módulo de deformação: utilização do valor característico e do valor médio, com diferença de 4 GPa entre eles. Estimou-se um aumento da ordem de 9% no deslocamento vertical de uma viga simples bi-apoiada quando executada com o concreto de menor módulo em relação à execução com o de maior módulo. Por sua vez, o concreto de maior módulo exigiria um aumento no consumo de cimento da ordem de até 200 kg/m3, se conservados todos os insumos materiais e os demais parâmetros tecnológicos contidos nos traços. Concluiu-se pela aplicabilidade do uso da sistemática empregada na avaliação da acurácia do método de ensaio e do uso do conceito semiprobabilístico para esta propriedade.This work is developed into the areas of laboratorial quality and concrete control tests, specifically focusing on the static modulus of elasticity or Young´s modulus. The motivation of this work is the high variability of experimental results observed by national technicians in interlaboratorial tests. These results show total standard deviations of around 3.5 GPa, a significant value for the technological control for civil construction. The main objectives are the identification of the variability fragments derived from the production and test, specially the ones related to the instrumentation for measuring deformations during the test, and the discussion of the semi-probabilistic concept applicability on the concrete Young´s modulus control. Moreover, the discussion of the applicability of the procedure used in this work and its analysis are also objective pursued here. The experimental program was developed in two steps: the first step covered the accuracy assessments (precision and exactness) of test method. The assessments were carried out according to instructions from Metrology concepts for the validation of the methods and the measure systems. One out of four instrumentations for measuring the tested deformations proved to be more precise (identified as clip gages) and another one proved to be more susceptible to systematic and random errors (identified as a compressometer with two dial indicators). The extension of the experimental program to an interlaboratorial scope is recommended because the current test method could not be considered valid based only on the results of this experimental program. However, it was shown that the practical acceptance of the test method for three among the four kinds of instrumentations analyzed, without damaging the production or the usual technological control of this property, is possible. On the second step, a mix design diagram was obtained and a case of supply of concrete under different statistical criteria (fulfillment the modulus of elasticity specification): the use of the characteristic value and the average value, with difference of 4 GPa between them. An increase of 9% on the vertical transference of a simple dual supported beam was observed when using a lower modulus concrete, when compared to another one with a higher modulus. On the other hand, the modulus increase would require an increment in the cement consumption up to 200 kg per cubic meter, if all the material inputs and further technological parameters is maintained. The final conclusion was that the procedure used on the assessment of the test method accuracy and the semi-probabilistic concept on this material property is applicable.
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Persson, Anna, and Martin Strand. "Stabilisering av betongstommar : Beräkning av en ekvivalent beräkningsmodul med hänsyn till samverkande kort- och långtidslast." Thesis, KTH, Byggteknik och design, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125745.
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Vid stabilisering av betongstommar är det komplicerat att välja en korrekt elasticitetsmodul. Detta då stommens laster verkar under både kort och lång tid. I detta examensarbete utförs en noggrann kryptalsberäkning för varje plans vertikala element, där hänsyn tas till den varierande byggtiden. Utifrån det analyseras kort- och långtidslaster med respektive elasticitetsmodul för att erhålla en ekvivalent elasticitetsmodul som tar hänsyn till de olika belastningstiderna. Denna elasticitetsmodul bestäms efter förhållandet mellan stommens knäcksäkerhet, snedställning och den vindlast som verkar på byggnaden. Den ekvivalenta elasticitetsmodulen ligger till grund för mer noggrann indata än tidigare vid stabilitetsberäkningar och redovisas i diagram som sedan kan användas i det praktiska ingenjörsarbetet. Där inget annat anges utförs beräkningar enligt Eurokod 2.Där inget annat anges är figurerna ritade av författarna.When considering stabilization of concrete structures it is difficult to assign a correct modulus of elasticity to the structure. This is due to the presence of both short- and long-term loads. In this thesis a detailed calculation of each vertical elements creep coefficient is performed, which takes into account the varying construction time. Furthermore short and long term loads with respective modulus of elasticity are analyzed to obtain an equivalent modulus of elasticity corresponding to the two previously mentioned. The equivalent modulus of elasticity is determined by the relationship between the buckling resistance of the structure, initial imperfections and the wind load acting on the building. The equivalent modulus of elasticity is the basis for a more accurate input for stability calculations and is presented in graphs that can be used in the practice of engineering. Unless otherwise stated, calculations are performed according to Eurocode 2.Unless otherwise stated, the figures are drawn by the authors.
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Halamová, Romana. "Problematika zjišťování statického modulu pružnosti betonu v konstrukcích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265362.
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The thesis deals with the measurement of the elastic modulus of concrete in existing structures and possibilities of applicability of equations for the calculation of characteristic values of concrete compressive strength on the modulus of elasticity. The modulus of elasticity is determined by dynamic and static methods on specimens taken from the concrete blocks, whose composition varies by a water cement ratio and varying amounts of admixtures. In conclusion, the results of the measurements are compared and the characteristic values of the modulus of elasticity is determined.
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Jirásková, Iveta. "Analýza rizik navrhování staveb s ohledem na vybrané materiálové charakteristiky." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-233174.
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This thesis focuses on the verification of physical and mechanical characteristics of hardened concrete, especially concrete compressive strength, static and dynamic modulus of elasticity. The job description is to perform a series of laboratory analyzes for structural concrete and evaluate the test results meet requirements that are specified in the European standards for designing buildings. The work also includes selected techniques for risk assessment (FMEA, Pareto diagram, Ishikawa diagram) and their application to selected process. Part of the work is also a static comparison of measured characteristics and consideration of the risks associated with variations in the monitored quantities.
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Benetti, Joana Kirchner. "Avaliação do módulo de elasticidade dinâmico de concreto produzido com agregado graúdo reciclado de concreto." Universidade do Vale do Rio dos Sinos, 2012. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4523.
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O setor da construção civil apresenta um grande potencial de geração de resíduos sólidos, caracterizando-se como um dos maiores geradores deste material no mundo. Por este motivo, é importante adotar um novo modelo de desenvolvimento, que busque, gradativamente, a não geração e a minimização de resíduo, assim como alternativas para o reaproveitamento destes resíduos na própria construção civil, e, assim, atingir um desenvolvimento mais sustentável. Neste contexto, muitos estudos sobre o concreto confeccionado com agregados reciclados de concreto vêm sendo desenvolvidos, tanto em nível nacional como internacional. Entretanto, é possível perceber que a maior parte das pesquisas tem seu foco voltado para a resistência à compressão e à tração, sendo mais escassos aqueles que dão ênfase para o comportamento elástico destes concretos. Frente ao exposto, o presente trabalho tem como objetivo analisar o módulo de elasticidade dinâmico de concretos produzidos com a utilização de agregado reciclado de concreto. Para tanto, confeccionou-se concretos que foram divididos em dois grupos. Um dos grupos empregou agregados reciclados de duas resistências (18 e 50 MPa), que foram inseridos em um novo concreto de 32 MPa, nos teores de substituição de 25%, 50%, 75% e 100%. O outro grupo empregou dois tipos de resíduos, gerados em maior quantidade por uma indústria de pré-fabricados de concreto. Um deles é o resíduo de concreto plástico, com cura convencional ao ar, e o outro é o resíduo de concreto seco, com cura térmica à vapor de água, sendo que substituiu-se 50% em volume do agregado graúdo natural pelo reciclado, em três novos concretos de distintas resistências. O módulo de elasticidade dinâmico foi calculado conforme especificado na C597 (ASTM, 2009), sendo analisada a influência da umidade do concreto no momento do ensaio, do tipo de resíduo e do teor de substituição de agregado natural pelo reciclado no módulo de elasticidade dinâmico. O tipo de agregado reciclado de concreto influenciou o módulo de elasticidade dinâmico, assim como os diferentes teores de substituição e a umidade do concreto no momento do ensaio. Para os materiais avaliados, o módulo de elasticidade não variou em função da resistência à compressão do concreto que gerou o agregado reciclado de concreto, e verificou-se correlação positiva entre o módulo de elasticidade e a resistência à compressão do concreto.
The construction industry is one of the largest solid waste generator. For this reason, it is important to adopt a new model aiming for thereuse of construction waste and thereby achieve a more sustainable development. In this context, studies on concrete made with recycledaggregate concrete have been developed, focused to determine compressive strength and tensile strength, with little emphasis on the elastic behavior of concrete. This work aims to analyze the dynamic modulus of elasticity of concrete produced with waste concrete as aggregate. To this end, it was made two groups of concrete using two types of waste generated in larger quantities by an industry of prefabricated concrete. The first group was made with a residue of plastic concrete, air-cured, and concrete made with of heat curing. The concrete aggregates were used to replace 50% by volume of natural coarse aggregate. In the second group recycled aggregates was produced in two strengths (18 and 50 MPa), being used to produce a new concrete of 32 MPa. The levels of substitution were 25%, 50%, 75% and 100%. The dynamic modulus of elasticity was calculated as specified in C597 (ASTM, 2009). It was analyzed the influence of moisture content and the type of waste recycled aggregate replacement in the natural dynamic modulus of elasticity. The type of recycled aggregate influenced the dynamic modulus of elasticity, as well as different levels of moisture and replacement of concrete at the time of trial. For the materials tested, the modulus of elasticity did not vary as a function of the compressive strength of recycled aggregate concrete, bu there was a positive correlation between the modulus of elasticity and compressive strength of concrete.
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Tichý, Aleš. "Vliv velikosti a tvaru zkušebního tělesa na modul pružnosti lehkých betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391974.
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The diploma thesis deals with the determination of the influence of size, shape and type of test specimen on values of modulus of elasticity of light-weight concrete. A lot of different specimens were prepared from two concrete’s mixtures for the experiment. Tests for measurement of static modulus of elasticity and dynamic modulus of elasticity by ultrasonic impulse velocity method were made. The results were assessed and summarized in tabular and graphical form.
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Gajdoš, Jan. "Samozhutnitelné betony SCC pro monolitické konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227748.
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This thesis contains two parts: theoretical and experimental. In the theoretical part are described materials for production SCC and their effect on the properties of fresh and hardened concrete. Practical part is divided into two experiments. First experiment deals with the design, production and properties of hardened SCC strength classes C16/20, C20/25 and C25/30 with high volume fly ash and inert admixtures. The main endpoints were long-term compressive strength and modulus of elasticity. Second experiment of practical part deals with designs SCC with modulus of elasticity more than 40 kN/mm2.
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Láníková, Lucie. "Vliv druhu a dávky rozptýlené výztuže na vybrané vlastnosti betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225736.
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The Master’s thesis is focused on the research influence the dose and type of scattered reinforcement in a reference concrete on physical and mechanical properties of the resulting composite. The investigated properties of composite belongs compressive strength, tensile strength in the flexural and tensile strength in the transverse, static modulus of elasticity in compressive strength, dynamic modulus of elasticity determined using NDT tests. The reference concrete mixture is certified as structural concrete of the class, which is commonly used on construction sites.
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Hanuš, Petr. "Experimentální ověření vlivu typu vláken na chování vláknobetonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392039.
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This diploma thesis deals with the comparison of different properties of fibre-reinforced concrete according to the type of fibres. The main monitored property is flexural strength, tested on prisms with a cross section of 150x150 mm and a length of 600 mm. Four concretes of natural aggregate and four concrete of lightweight aggregate were prepared for the experiment. There were 2 reference concrete and 6 fibre-reinforced concrete. Three types of fibres were used: steel, polypropylene and glass. More than 2500 kg of concrete was produced. The aim of the thesis is to assess the influence of fibres on the flexural strength and other characteristics of fibre-reinforced concrete.
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Ivan, Lukić. "Komparativna analiza osnovnih svojstava konstrukcijskih betona spravljenih sa različitim vrstama lakih agregata." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2015. http://www.cris.uns.ac.rs/record.jsf?recordId=93149&source=NDLTD&language=en.
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U disertaciji su prikazani rezultati sopstvenog eksperimentalnog istraživanja na osnovu kojih je izvršena komparativna analiza uticaja različitih vrsta lakih agregata i vrste i količine cementa na osnovna fizičko-mehanička svojstva lakoagregatnih betona. Takođe, analizirana je i mogućnost zamene dela cementa mineralnim dodacima u cilju smanjenja negativnih uticaja proizvodnje betona na životnu sredinu. Rezultati su pokazali da je primenom svih analiziranih vrsta agregata moguće dobiti konstrukcijski lakoagregatni beton, čak i sa manjim količinama cementa, odnosno sa zamenom dela cementa mineralnim dodacima, kao i da je moguće uspostaviti pouzdane korelacione veze između pojedinih svojstava betona i primenjenih komponentnih materijala.In dissertation are presented results of own experimental research of acomparative analysis of the impact of different types of lightweightaggregates and the type and quantity of cement on basic physical andmechanical properties of structural lightweight concrete. Also, the possibilityof replacing part of cement with mineral admixtures is analyzed in order toreduce the negative impact of concrete production on the environment. Theresults showed that it is possible to obtain structural lightweight aggregateconcrete with all types of lightweight aggregates and even with lowerquantities of cement or with a replacement of part of a cement with mineraladmixtures. Also, it is possible to establish a reliable correlation betweencertain properties of concrete and used component materials.
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Almeida, Sandra Freire de. "Análise dinâmica experimental da rigidez de elementos de concreto submetidos à danificação progressiva até a ruptura." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-20092005-183049/.
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Uma das aplicações da análise modal experimental é a avaliação da integridade estrutural. O ensaio dinâmico fornece os valores de freqüência natural, cujas variações podem ser utilizadas para identificar a presença e a magnitude do dano e determinar a rigidez equivalente de peças já fissuradas. Atualmente, as pesquisas sobre o efeito dinâmico nas estruturas civis estão se tornando mais freqüentes. Dentre os vários aspectos de interesse relacionados ao comportamento dinâmico das estruturas de concreto armado, cita-se como relevante a questão da danificação progressiva de seus elementos. Com a evolução da fissuração, existe uma diminuição da freqüência natural e um aumento do amortecimento. Essa variação dos parâmetros permite obter os valores de rigidez equivalente para os diversos estágios de fissuração da peça, o que pode indicar a proximidade da ruptura. Neste trabalho foi avaliada a integridade de elementos estruturais de concreto, discutindo os resultados da análise modal experimental em função do nível de danificação. Foram realizados ensaios em elementos de concreto simples para avaliação do módulo de elasticidade, tanto pelo método estático como pelo método dinâmico, observando a sua variação em função da microfissuração, resistência à compressão e idade do concreto. Os ensaios experimentais foram realizados em corpos-de-prova cilíndricos e prismáticos, sendo os resultados dos ensaios de vibração livre comparados aos resultados obtidos com os ensaios estáticos usuais. Também foram realizados ensaios estáticos e dinâmicos em vigas de concreto armado, de tamanho reduzido, para análise do comportamento de parâmetros dinâmicos ao longo de um processo de danificação. Demonstra-se a viabilidade dos ensaios não-destrutivos dinâmicos para a determinação das propriedades do material e dos elementos de concreto armado, além das vantagens econômicas, facilidade de execução e confiabilidadeStructural integrity assessment may be performed by experimental modal analysis. The dynamic tests provide natural frequencies values whose changes may be used to identify existent damage and to estimate the equivalent stiffness of cracked elements. Nowadays more researches about dynamic effects on civil structures are becoming available. Among all aspects related to the dynamic behaviour of reinforced concrete structures, the progressive damage of their elements is one of great relevance. According to the damage progress, the natural frequencies decrease and the damping factors increase. These dynamic characteristics changes allow getting the equivalent stiffness values for the various degrees of cracking, even indicating the closeness to failure. The objective of this research is to assess the concrete elements integrity and to discuss the results from experimental modal analysis due to different damage levels. There were carried through dynamic and static experiments to evaluate the modulus of elasticity of concrete. It was observed its changes related to concrete micro-cracking, compression strength and age. The experimental testings had been carried through in cylindrical and prismatic specimens. The results obtained from free vibration tests were compared with the ones obtained from the usual static tests. Reinforced concrete beams were also subjected to static and dynamic testings to assess the behavior of the dynamic parameters throughout a damage process. The dynamic non-destructive tests can be used to find out concrete and reinforced beam properties, beyond its economic advantages, easiness to do and trustworthiness
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Renzová, Martina. "Prodloužení životnosti cementobetonových krytů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226449.
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The aim of the theoretical part of this Master´s thesis is to make a research of possible ways in repairing PCC pavements without anchoring transverse joints. The pratical part is focused on the design of PCC pavements segmentations in experimental sections and evaluation measurement by testing muted impact.
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Myšičková, Lucie. "Vývoj a zkoušení vysokohodnotných betonů pro subtilní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226971.
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Thesis describes properties of HPC compared to concretes of normal and high strength. It further describes the input materials and the procedure for designing the composition of the mixture. It gives examples of already completed structures made of HPC. The experimental part describes the optimization of concrete mix and production of specimens. In the end results of testing the properties of the developed mixes from tests of dynamic and static modulus of elasticity, compressive strength and tensile strength by bending are described.
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Bartulíková, Radka. "Vliv provzdušnění a ošetřování na vývoj modulu pružnosti betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225737.
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Master's thesis deals with influence of various factors on the concrete compressive strength and modulus of elasticity. This work concentrates mainly on the influence of early curing and air entrainment of concrete. One part of this work is the evaluation of laboratory measurement, which was carried out on cubes of standard and norm prisms. The development of elastic moduli was monitored in time to 730 days of age with respect to air entrainment and curing conditions. The second part of the experiment deals with a comparison of theoretical creep curves depending on the value of the modulus of elasticity based on different standards. Again, the air entrainment effect and influence of initial conditions are reflected.
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Křížová, Klára. "Studium závislostí složení betonů na hodnoty modulů pružnosti." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-233789.
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The modulus of elasticity is one of the basic characteristics of concrete defining elastic deformation of concrete and it plays a significant role in the static design of structures. Due to current trends in concrete technology, offering a wide variability in the proposals of the composition of concrete, there are changes not only in strength characteristics but also in the modulus of elasticity of concrete. The aim of this doctoral thesis is to study the dependence of different compositions on modulus of elasticity of concrete. Design of concrete composition is prepared with respect to the use of different types of cement, mineral admixtures, types and fractions of aggregates. The work is mainly focused on the determination of static modulus of elasticity in compression with the addition of dynamic modules. In the first phase determined modulus of elasticity are compared with tabulated values according to Eurocode 2, which are derived for the specific strength class of concrete. Part of this work is the compilation of the main technological aspects of concrete which can favorably affect the modulus of elasticity.
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ARAÚJO, Suélio da Silva. "Influência do tipo de medição na determinação do módulo estático de elasticidade do concreto." Universidade Federal de Goiás, 2011. http://repositorio.bc.ufg.br/tede/handle/tde/658.
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Previous issue date: 2011-08-15The knowledge of the compressive strength and static modulus of elasticity is fundamental to the study of deformations of concrete, since deformations can cause cracks that compromise both the structural behavior of the element and serve as an entry to deleterious agents. For purposes of correlating values of compressive strength and static modulus of elasticity of concrete, cylinders were cast with different strengths, different types of strain measurements were taken, different specimen sizes and the loading speed of the testing machine. The specimens were tested at the age of 28 days to determine the compressive strength and static module of elasticity according to ABNT NBR 8522:2008, using different types of strain measurement devices: two mechanical dial indicators, surface bonded strain gages, clip gauges and LVDT (Linear Variable Differential Transducer). Two hundred and fifty eight specimens were cast with dimensions 150 mm x 300 mm and 100 mm x 200 mm using conventional normal strength concrete (NC - Class C30) and high strength concrete (HSC - Class C60). The experimental program was divided into two stages. First the static modulus of elasticity of concrete was measured to evaluate the accuracy of the method using different measuring devices and the accuracy of the method to a loading speed of 0.6 MPa/s. Then, the modulus of elasticity using different deformation measuring devices at a loading speed of 0.3 MPa/s and 0.6 MPa/s was measured. As for concrete NC and HSC, it was found that the specimens 100 mm x 200 mm obtained higher dispersion in relation to 150 mm x 300 mm specimens. In the first stage of the research, 100 mm x 200 mm specimens showed a higher dispersion when using mechanical dial gages and LVDT. The 150 mm x 300 mm NC class C30 specimens showed greater dispersion when using in mechanical dial gages and external strain gages. However, the HSC showed higher dispersion when mechanical dial gages and LVDT were used. In both concretes tested, the mechanical dial gages showed greater dispersion. In the second stage of the research, 150 mm x 300 mm specimens tested at the loading speed of 0.3 MPa/s showed greater dispersion when electrical strain gages and clip gauges were used. The 150 mm x 300 mm specimens tested at loading speed of 0.6 MPa/s showed greater dispersion when electrical strain gages and mechanical dial gages were used.
O conhecimento da resistência à compressão e do módulo estático de elasticidade é fundamental para o estudo das deformações do concreto, uma vez que as deformações podem gerar fissuras capazes de comprometer tanto o comportamento estrutural do elemento de concreto, como servir de caminho de entrada aos agentes deletérios. Não só fissuras, mas também deformações excessivas. Para fins de correlação de valores de resistência à compressão e módulo estático de elasticidade do concreto, foram moldados corpos-de-prova variando-se a classe do concreto, o tipo de medidores de deformação, a dimensão do corpo-de-prova e a velocidade de carregamento da máquina de ensaio. Os corpos-de-prova foram ensaiados na idade de 28 dias para determinação da resistência à compressão e do módulo estático de elasticidade, normalizado pela ABNT NBR 8522:2008, utilizando-se diferentes tipos de medidores de deformação, a saber: compressômetro mecânico com dois relógios comparadores acoplados, extensômetro elétrico resistivo de colagem superficial ( strain gage ), extensômetro elétrico resistivo de fixação externa ( clip gage ) e LVDT (Transdutor Diferencial de Variação Linear). Foram moldados 258 corpos-de-prova com dimensões 150 mm x 300 mm e 100 mm x 200 mm utilizando concreto convencional de resistência normal (CC Classe C30) e concreto de alta resistência (CAR Classe C60). O programa experimental foi dividido em duas etapas: a primeira contemplou o estudo do módulo estático de elasticidade do concreto para avaliação da precisão do método utilizando diferentes medidores de deformação e da acurácia do método com velocidade de carregamento e descarregamento da máquina de ensaio em um nível: 0,6 MPa/s. A segunda etapa contemplou o estudo de determinação do módulo estático de elasticidade utilizando diferentes medidores de deformação com velocidade de carregamento e descarregamento da máquina de ensaio em dois níveis: 0,3 MPa/s e 0,6 MPa/s. Quanto ao concreto Classe C30 e CAR, verificou-se que os corpos-de-prova de dimensão 100 mm x 200 mm apresentaram maior dispersão em relação aos corpos-de-prova de dimensão 150 mm x 300 mm. Na primeira etapa da pesquisa, quanto à dimensão 100 mm x 200 mm, verificou-se que o concreto Classe C30 e o concreto de alta resistência (CAR) apresentou maior dispersão nos medidores de deformação compressômetro mecânico e LVDT. Quanto à dimensão 150 mm x 300 mm, verificou-se que o concreto Classe C30 apresentou maior dispersão nos medidores de deformação compressômetro mecânico e extensômetro elétrico de fixação externa. Já no concreto de alta resistência (CAR) apresentou maior dispersão nos medidores de deformação compressômetro mecânico e LVDT. Em ambas as classes de concreto ensaiadas, o medidor de deformação compressômetro mecânico apresentou maior dispersão. Na segunda etapa da pesquisa, quanto à dimensão 150 mm x 300 mm ensaiada com velocidade de carregamento e descarregamento da máquina de ensaio de 0,3 MPa/s, verificou-se que apresentou maior dispersão nos medidores de deformação extensômetro elétrico de colagem superficial e extensômetro elétrico de fixação externa. Quanto à dimensão 150 mm x 300 mm ensaiada com velocidade de carregamento e descarregamento da máquina de ensaio de 0,6 MPa/s, verificou-se que apresentou maior dispersão nos medidores de deformação extensômetro elétrico de colagem superficial e compressômetro mecânico.
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Beck, Sílvio Maurício. "EFEITOS NAS PROPRIEDADES MECÂNICAS, ELÁSTICAS E DE DEFORMAÇÃO EM CONCRETOS COM ALTOS TEORES DE ESCÓRIA E CINZA VOLANTE." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/7721.
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The use of byproducts and industrial waste as pozzolanic, is an alternative to achieve the sustainability, economy and durability in concrete structures. This survey has as its purpose to analyze the effect on mechanical, elastic and deformation properties on concrete with a high level of granulated slag from blast furnace and fly ash in place of Portland bulk cement. The use of high levels of mineral additions has the purpose of increasing the durability and
reducing the consumption of cement, the use of hydrated lime aims to activating these adittions, restore part of the calcium hydroxide consumed by the pozzolanic reactions, increasing the initial and final strength to the mixtures. This way, three mixtures of concrete have been studied: one of them without mineral additions, only using Portland cement (CP V-ARI), taken as a control, with relations a/c 0.40, 0.60 and 0.83, and two mixtures with mineral additions in place of cement in equal mass, with 70% of slag and 20% of fly ash, being one of them with addition of 20% of hydrated lime on the mass of binders in addition to the cement, both to the relations a/mc 0.30/0.33, 0.40 and 0.49, which have been renamed as R, EV and EVC. Tests were held to resistance to axial compression in bodies of evidence (10x20cm) the ages of 07 28, 91 and 300 days, whose results range from 18.2 MPa and 81 MPa, tests of resistance to traction by diametral compression and module of elasticity at 28, 91 and 300
days, as well as tests of total shrinkage on prismatic bodies of evidence (10x10x30 cm) at 28, 91, 180 and 300 days. The results of mechanical, elastic and strain resistance have been also correlated with some intervening and independent variables, as well as some existing
regulatory requirements. The results have been analyzed to each trace individually, in relation to the control traces, in relation to the evolution of the resistance, effectiveness of the use of the hydrated lime and in equal relationship a/mc 0.4. In the analysis of the equal relationship a/mc 0.400, in the case of reference concrete, in the initial age, the resistance to the
axial compression of the concrete EV was, in media, 72% of the one presented by it, being the resistance to the EVC 55%, and in the final age, 65% and 50% respectively. In the case of the traction by diametral compression, to 28 days the concrete EV presented 76% of the resistance of the reference, and the concrete EVC 58%. This relation to 300 days was 80% and 61% respectively. To the elasticity module, to 28 days, the concrete EV presented 82%
and the EVC 70% of the result obtained by the reference mixture, maintaining this proportion until the final age (300 days). In the analysis of the total retraction, the concrete EV presented an inferior retraction 10% inferior to the reference trace, while the concrete EVC to
300 days presents a good retraction 16% superior to it. The observation through the conjuncture of the results found shows a satisfactory relation among the different traces studied, making feasible the use of high levels of mineral additions in substitution to the large portion
of cement in bulk.A utilização de subprodutos e resíduos industriais como pozolanas, é uma alternativa para atingir a sustentabilidade, economia e durabilidade em estruturas de concreto. Esta pesquisa possui o objetivo de analisar os efeitos nas propriedades mecânicas, elásticas e de deformação em concretos com elevados teores de escória granulada de alto-forno e cinza volante em substituição ao cimento Portland em massa. O uso de altos teores de adições minerais tem por fim o aumento da durabilidade e redução do consumo de cimento, tendo o uso de cal hidratada a finalidade de ativar estas adições, repor parte do hidróxido de cálcio consumido pelas reações pozolânicas, aumentando as resistências iniciais e finais das misturas. Desta forma, estudaram-se três misturas de concreto: uma sem adições minerais, somente com cimento Portland (CP V-ARI), tomada como referência, com relações a/c 0.40, 0.60 e 0.83, e duas misturas com adições minerais em substituição ao cimento em igual massa, com 70% de escória e 20% de cinza volante, sendo uma delas com adição de 20% de cal hidratada em relação á massa de aglomerantes em adição ao cimento, ambas para relações a/mc 0.30/0.33, 0.40 e 0.49, as quais foram renomeadas como R, EV e EVC. Foram realizados ensaios de resistência a compressão axial em corpos de prova (10x20 cm) nas idades de 07, 28, 91 e 300 dias, cujos resultados variaram entre 18.2 MPa e 81 MPa, ensaios de resistência a tração por compressão diametral e módulo de elasticidade aos 28, 91 e 300 dias, assim como ensaios de retração total em corpos de prova prismáticos (10x10x30 cm) aos 28, 91, 180 e 300 dias. Também se correlacionou os resultados das resistências mecânicas, elásticas e de deformação com algumas variáveis intervenientes e independentes apresentadas, assim como com algumas prescrições normativas existentes. Os resultados foram analisados para cada traço individualmente, em relação aos traços referências, em relação à evolução da resistência, eficiência do uso da cal hidratada e em igualdade de relação a/mc 0.4. Na análise de igualdade de relação a/mc 0.400, em relação ao concreto referência, na idade inicial, a resistência a compressão axial do concreto EV foi, em média, 72% da apresentada por este, sendo a resistência do EVC 55%, e na idade final, 65% e 50%, respectivamente. Em relação à resistência a tração por compressão diametral, aos 28 dias o concreto EV apresentava 76% da resistência do referência, e o concreto EVC 58%. Esta relação, aos 300 dias foi de 80% e 61% respectivamente. Para o módulo de elasticidade, aos 28 dias, o concreto EV apresentou 82% e o EVC 70% do resultado obtido pela mistura referência, mantendo-se esta proporção até a idade final (300 dias). Na análise da retração total, o concreto EV apresentou uma retração 10% inferior ao traço referência, enquanto o concreto EVC aos 300 dias apresentou uma retração 16% superior ao mesmo. A observação através da conjuntura dos resultados obtidos demonstra uma satisfatória relação entre os diferentes traços estudados, viabilizando o uso de elevados teores de adições minerais em substituição a grande parcela de cimento em massa.
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Juste, Andrea Elizabeth. "Estudo da resistência e da deformabilidade da alvenaria de blocos de concreto submetida a esforços de compressão." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-26052006-151504/.
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O estudo da resistência à compressão e da deformabilidade de paredes de alvenaria de blocos de concreto é de fundamental importância para a caracterização desse material e o desenvolvimento de análises de estruturas compostas por esse tipo de painel. Este trabalho trata desse tema, objetivando prever com maior acuidade os principais parâmetros de deformação e de resistência de paredes de alvenaria de blocos de concreto, a saber: resistência à compressão e módulo de elasticidade longitudinal nas direções paralela e perpendicular à junta de assentamento. Foi desenvolvido um trabalho experimental para estimar a influência da resistência dos blocos, da resistência da argamassa e da direção de aplicação de forças no comportamento mecânico da alvenaria de blocos de concreto não-grauteada, quando submetida a esforços de compressão. Para tanto, realizaram-se ensaios de laboratório em blocos, argamassas, prismas de três blocos e paredinhas com dimensões de 80 cm x 80 cm. Por inferência estatística não foram obtidas correlações aceitáveis entre as variáveis estudadas. Porém, obtiveram-se tendências de comportamento dos corpos de prova estudados, confirmando a influência das características da argamassa e do bloco no comportamento estrutural da alvenaria quando submetida a esforços de compressãoThe study of strength and the curved stress/strain relationship of blockwork masonry walls is basic for the material characterization and the development of structural analysis of blockwork walls. This work deals with that subject, aiming at the evaluation of the main elastic parameters and the strength of concrete blockwork walls: the compressive strength and modulus of elasticity for masonry in two orthogonal directions, parallel and perpendicular to bed joints. An experimental program was developed to evaluate the influence of the strength of blocks and mortar, and the load application direction on the mechanical behavior of ungrouted concrete block masonry under compression. A series of laboratory tests was carried out with blocks, mortar, prisms of three blocks and wallets (80 cm x 80 cm). It was impossible to obtain acceptable correlations of the defined variables, using statistical inference. However, tendencies of the specimens behavior were obtained, confirming the influence of mortar and block properties on the structural behavior of concrete blockwork walls under compression
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Procházka, David. "Vytvoření předpokladů pro hodnocení vlastností vysokopevnostních betonů s využitím nedestruktivních metod zkoušení." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-233795.
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High-strength concrete (HSC) belongs in the recent years to frequently used types of concrete. It allows realization of static challenging structures and also shows due to its dense structure greater durability especially against aggressive media. Currently HSC construction realization abroad is not exceptional. It’s using in the Czech Republic is still limited. When realized, then in a small scale in civil engineering works. The realization of high-strength concrete structures is closely related with the concrete construction quality verification. Good efficiency of the quality control methods can provide non-destructive testing methods (NDT), especially when investigating strength of concrete built in structure. A lack on relevant data for non-destructive testing of HSC in technical and normative rules is to be considered as a significant deficiency. Evident for HSC generally is the lack in literature on deeper analysis of the factors affecting their non-destructive testing, as well a meaningful methodology or practically usable calibration relationships. HSC differs from ordinary concrete not only by used components, but also by more compact structure with different strength – elastic characteristics. Considering these differences, HSC strength prediction can not be performed by using calibration relationships developed for ordinary concrete. Moreover, the question is to what extent the current knowledge of the NDT results influencing factors can be considered as valid. The paper presents findings on the effects of the key factors affecting the measurement results of Schmidt hardness method and ultrasonic pulse method, including recommendations for the practical application of these methods. The problematic of static vs. dynamic modulus of elasticity was also solved. Calibration equations for predicting the compressive strength of HSC from the non-destructive testing parameter were elaborated, showing high cohesion among variables and practically usability.
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Kallel, Hatem. "Influence de la température et de l'hygrométrie sur le comportement instantané du béton." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3013/document.
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Les enceintes de confinement sont sollicitées lors d'un accident grave par la modification thermodynamique du milieu interne qui génère une pression pouvant monter jusqu'à 5 bars, une température évaluée au maximum à 180 °C et une humidité relative pouvant aller jusqu'à la saturation. Au-delà de calculs réglementaires, la complexité de la sollicitation nécessite une bonne connaissance du comportement mécanique et thermique des matériaux et en particulier du béton dans la gamme de température et d'hygrométrie imposée afin d’être capable de mener les simulations numériques les plus réalistes possibles.Notre étude présente les évolutions des caractéristiques mécaniques et thermiques essentielles pour les simulations numériques d'un béton dans la plage de pression, température et humidité imposées lors d'un accident grave. Les essais mécanique et thermique sont réalisés sous chargement thermo-hydrique contrôlées. La température (T) est fixée à cinq valeurs cibles : 30, 90, 110, 140 et 160 °C. Les cinq degrés de saturation en eau liquide du béton (Sw) varient entre 36 % et 100 %. Les différents degrés de saturation en eau liquide des éprouvettes sont obtenus par le contrôle de l’humidité relative de l’ambiance entourant l’éprouvette pendant leur cure. L’essai DCT (Disk-shape Compact Tension) a été choisi pour déterminer l’évolution de l’énergie de fissuration, du module d'élasticité et de la résistance en traction en fonction de la température et de Sw, en raison de son caractère très compact favorable pour la mise en oeuvre des essais sous pression (essai au-delà de 100 °C). Les propriétés thermiques sont évaluées par la méthode de la Source Plane Transitoire (TPS). C’est une technique permettant de déterminer la conductivité thermique, la diffusivité thermique et d'en déduire la chaleur spécifique. L’évolution de la perméabilité relative à l’azote du béton en fonction de la température jusqu'à 90 °C et du degré de saturation en eau du béton a été évaluée également. Après avoir déterminé les propriétés thermiques et mécaniques du béton, une modélisation numérique a été réalisée afin de passer de l’échelle de laboratoire à l’échelle de la structure. Un couplage entre un modèle hydrique et un modèle d’endommagement a été réaliséIn case of severe accident, confinement chambers are submitted to thermodynamic variations of their internal environment. Pressures can increase up to 5 bars, temperature reaches 140 °C and relative humidity attains saturation. Beyond regulatory calculations, the complexity of the solicitation needs a good knowledge of the thermo-mechanical behaviour of concrete under the imposed conditions of temperature and relative humidity. This, in turns allows to develop numerical simulations as realistic as possible. The present study investigates the evolution of the mechanical and thermal characteristics of concrete. These properties are essential to develop numerical computations under the levels of pressure, temperature and relative humidity imposed during a severe accident. Mechanical and thermal tests are carried out under controlled hydro-thermal conditions. Temperature (T) is fixed at five target values: 30, 90, 110, 140 and 160 °C. Five levels of degree of saturation (Sw) range from 36 % to 100 %. The different target values of degree of saturation are attained by controlling relative humidity in the surrounding environment of the specimens during curing. DCT (Disk-shape Compact tension) tests was chosen to determine the dependence of the fracture energy, elastic modulus and traction resistance on temperature and degree of saturation of concrete because of its compact shape that is more suitable for testing under pressure (temperature above 100°C). Thermal properties are determined by means of the Transient Plane Source (TPS) method. This technique allows to determine thermal conductivity, thermal diffusivity and hence to deduct specific heat. The dependence of the permeability to liquid nitrogen on temperature up to 90 °C and on the degree of saturation was also analysed. After determining thermal and mechanical properties of concrete, numerical simulations have been developed in order to pass from laboratory scale to the structure scale. A coupled hydro-mechanical model and a damage model are proposed
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MARTINS, Danilo Gomes. "INFLUÊNCIA DO TAMANHO DO CORPO DE PROVA NOS RESULTADOS DE ENSAIOS DE MÓDULO DE DEFORMAÇÃO E RESISTÊNCIA À COMPRESSÃO E SUAS CORRELAÇÕES PARA CONCRETOS PRODUZIDOS EM GOIÂNIA - GO." Universidade Federal de Goiás, 2008. http://repositorio.bc.ufg.br/tede/handle/tde/653.
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Previous issue date: 2008-10-03Even though the different sizes of cylindrical specimens for tests in concrete are standardized to get the simple compressive strength and the modulus of elasticity, this factor is not usually studied in most researches. So, the goal of this thesis was to evaluate the influence of the size of the specimens in the initial tangent modulus of elasticity (Eci) and in the compressive strength (fc), correlate the values of fc and Eci, and compare the values of modulus of elasticity that were estimated by the equations proposed by the Brazilian code (NBR 6118/2003) and by the American norm (ACI 318/2002). Concretes with three levels of strength were used after 28 days: 25MPa, 30MPa and 40MPa. They were all proportionally mixed with materials of the region and supplied by only one concrete batching plant of Goiânia GO. The tests of compressive strength and initial tangent modulus of elasticity were done in cylindrical specimens of 100 x 200 mm and 150 x 300 mm after 28 days. The samples were collected during the delivery of the concrete in the construction sites. For each truck, ten specimens were molded, five of 100 x 200 mm and five of 150 x 300 mm. Of the 600 specimens that were molded, 240 tests of compressive strength and 360 tests of modulus of elasticity were done. The cure was in a tank with water saturated with limestone. After the tests were done, the statistical analysis of the results was done. The variance analysis (ANOVA) indicated that the size of the specimen exerts influence only on the results of the initial tangent modulus of elasticity (Eci). There is a tendency for the specimens of 100 x 200 mm to show greater results for the modulus of elasticity of the concrete than the specimens of 150 x 300 mm. In the compressive strength, only the level of strength significantly exerted influence on the results. It was also observed that the NBR 6118/2003 overestimates the values of modulus of elasticity of the researched concretes and the results are better adequate to the model proposed by the ACI 318/02.
Apesar dos parâmetros de ensaios, como o tamanho do corpo de prova, influenciarem nos resultados do módulo de deformação e da resistência a compressão, normalmente esse fator não é estudado na maioria das pesquisas. Assim, esta dissertação objetivou avaliar a influência do tamanho dos corpos de prova no módulo de deformação tangente inicial (Eci), e na resistência a compressão (fc), correlacionar os valores de fc e Eci e comparar os valores de módulo de deformação alcançados com os valores estimados pelas equações propostas pela norma brasileira (NBR 6118/2003) e pelo amaericana (ACI 318/2002). Utilizaram-se concretos com três níveis de resistência aos 28 dias: 25MPa, 30MPa e 40Mpa, todos dosados com materiais da região e fornecidos por uma mesma central de concreto de Goiânia - GO. Os ensaios de resistência à compressão e de módulo de deformação tangente inicial foram realizados em corpos de prova cilíndricos de 100 x 200 mm e 150 x 300 mm aos 28 dias. As amostras foram coletadas durante a entrega do concreto nas obras. A cada caminhão, eram moldados dez corpos de prova, cinco de 100 x 200 mm e cinco de 150 x 300 mm. Foram moldados 600 corpos de prova, onde realizaram-se 240 ensaios de resistência à compressão e 360 de módulo de deformação. A cura foi em tanque com água saturada com cal. Após a realização dos ensaios, fez-se a análise estatística dos resultados obtidos. A análise de variância (ANOVA) indicou que o tamanho do corpo de prova exerce influência apenas nos resultados do módulo de deformação tangente inicial (Eci). Houve uma tendência dos corpos de prova de 100 x 200 mm apresentarem maiores resultados para o módulo de deformação do concreto que os corpos de prova 150 x 300 mm. Na resistência à compressão, como já era esperado, apenas a classe de resistência influenciou significativamente nos resultados. Observou-se também que a NBR-6118/2003 superestima os valores de módulo de deformação dos concretos estudados e que os resultados obtidos se adequam melhor ao modelo proposto pelo ACI318/02.
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Alexa, Martin. "Vliv mnohonásobného zatěžování na vybrané parametry lehkého betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371809.
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The diploma thesis deals with the observation of the values of selected parameters (especially the static modulus of elasticity) of light-weight concrete in compression before and after multiple cyclic loading. The deformation of test specimens during multiple cyclic loading were measured with resistive strain gauges. Test specimens (cylinders with a diameter of 150 mm and height of a 300 mm) were cyclically loaded and up to 4 500 loading cycles were performed. The aim of this thesis is assessment changes in the values of static modulus of elasticity depending on the number of loading cycles.
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Izquierdo, Indara Soto. "Uso de fibra natural de sisal em blocos de concreto para alvenaria estrutural." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-05042011-164738/.
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A utilização de fibras vegetais como reforço constitui um grande interesse na obtenção de novos materiais para a construção civil produto de seu baixo custo, alta disponibilidade e reduzido consumo de energia para sua produção. Este trabalho avalia a incorporação de fibras de sisal, de comprimento 20 e 40 mm, e fração volumétrica de 0,5 e 1%, em concretos para a alvenaria de blocos estruturais e determina o uso destas unidades na execução de prismas e mini-paredes. Foram realizados os testes de caracterização da fibra, blocos e argamassa de assentamento e os ensaios de resistência à compressão axial das unidades, prismas e mini-paredes. O sisal apresentou baixa massa específica aparente e elevada absorção de água, constituindo uma característica comum desse tipo de material pela grande incidência de poros permeáveis. As propriedades físicas dos blocos com e sem adição cumpriram com os requisitos das normas estabelecidas validando sua utilização. Os resultados do ensaio à compressão mostraram que as mini-paredes reforçadas com fibras obtiveram valores muito próximos ou mesmo superiores aos obtidos para as mini-paredes sem fibras, apresentando melhor desempenho que os blocos e prismas. Todos os elementos com adição mostraram um ganho da capacidade de deformação e ductilidade conferida pelas fibras, observado nas curvas tensão x deformação. O modo de ruptura dos blocos, prismas e mini-paredes de referência foi caracterizado por uma fratura brusca e catastrófica e os reforçados mantiveram suas partes unidas pelas fibras, não perdendo sua continuidade e tornando a ruptura um processo progressivo.The use of natural fibers as reinforcement is a great interest in obtaining new materials for construction, owing of its low cost, high availability and reduced energy consumption for its production. This paper evaluates the incorporation of sisal fibers of 20 mm and 40 mm length and volume fraction of 0.5 and 1%, for concrete for masonry structural blocks, and determines the use of these units in making of prisms and mini-walls. The laboratory tests were carried to characterize physical properties the fiber, blocks and mortar, and besides axial compression tests of the units, prisms, and mini-walls. The sisal had low apparent density and high water absorption, constituting a common feature of such material by the high incidence of permeable pores. The physical properties of the blocks with and without addition complied with the requirements of standards established by validating their use. The axial compression test results showed that mini-walls reinforced with fibers obtained values very close to or even superior to those obtained for the mini-walls without fibers, showing better performance than the blocks and prisms. All elements with the addition had increased the deformation capacity and ductility afforded by the fibers, observed in the curves stress/strain. The rupture mode of blocks, prisms and mini-walls reference was characterized by an abrupt and catastrophic fracture, and elements reinforced maintained their shares together by the fibers, without losing its continuity and becoming a progressive rupture.
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Haloun, Jan. "Stavební průzkum a diagnostika železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409952.
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The first part of this diploma thesis is about late and current methods used in Engineering surveys. The theoretical part is focused on description of individual testing methods and their evaluation based on relevant standarts. Detailed description of diagnostic methods is dependent on methods used in a practical part. The practical part is focused on defining of material characteristics of used materials and way of reinforcing of reinforced concrete elements. Based on those defined pieces of information the static recalculation of girder and pile was made.
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Hoduláková, Michaela. "Experimentální ověření modulu pružnosti v tlaku jemnozrnných kompozitů na bázi silikátových pojiv." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265508.
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Since their inception, building materials are constantly improving. New ways to explore and improve the material's properties are constantly investigated (especially to improve the mechanical and deformation characteristics of the materials). This thesis is focused on identifying and comparing values of the modulus of elasticity of fine-grained composites. These features are compared with respect to water cement ratio, ageing and compressive strength of the investigated materials. Afterwards, the values of the modulus of elasticity are studied in the relation to the tested materials.
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Wünsche, Dominik. "Diagnostika a hodnocení mostní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-433535.
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The diploma thesis deals with the issue of bridge strustures, especially their diagnostics and evaluation. The work consists of two parts, theoretical and practical. The theoretical part deals with the basic description and division of bridge structures, brigde inspections and test methods, especially those that were used in the thesis during bridge inspections. The practical part includes a visual inspection of two bridges, their description, detection of faults and defects and their documentation. In the practical part, the basic maretial characteristics of concrete bridges were determined, the condition of structures was assessed and a proposal for the elimination of failures and defects was developed. In the end, the work deals with the evaluation of both bridges.
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Šnédar, Jaroslav. "Průzkum a hodnocení železobetonové mostní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409961.
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The aim of this thesis is to evaluate the real condition of reinforced concrete beam bridge located in Brno Jundrov. In order to evaluate this condition, there was made the main bridge inspection. Subsequently, a number of diagnostic methods were used, such as hardness tests, concrete stress strenght, ultrasonic pulse method, including their evaluation. In terms of the main inspection, the condition of construction of the bridge was evaluated as V - bad. We found out that the concrete from which the bridge is built of is in very good condition. The problem, however, is the condition of the reinforcement located on the bridge. Based on its condition there must be expected lifespan within the next 5-10 years.
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Ondráček, Michal. "Vývoj vysokopevnostních betonů definovaných vlastností s využitím druhotných surovin." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-233787.
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Civil engineering development is connected with the application of new construction methods and the development of new building materials. Concrete, as one of the basic building materials, is part of this development. A major turning point in the development of concrete and its properties occurred with the use of new, more efficient plasticizing additives. This allowed to produce concrete with lower water cement ratio, while increasing the strength of concrete. Gradually, the compressive strength of concrete boundary has moved by several levels, when there are currently commonly used concrete with strength of about 100 N/mm2 and with the special methods of concrete production strength range from 250 to 300 N/mm2. A negative aspect of the development of (ultra) high-strength concrete is their energy and economic demands. A characteristic feature of high-strength concrete is a high content of cement and very fine admixtures, especially silica fume. One way to improve the economics of these types of concrete is the application of cheaper admixture based on industrial waste. The content of this work is the observation and description of the properties of high-strength concrete and reactive powder concrete, in which the admixtures were based on industrial waste were applied. Part of this work is the comparison of economic parameters for individual types of concrete.
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Balash, Alan. "Stavební průzkum a hodnocení stavu konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392275.
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This diploma thesis is focused on building survey and evaluating of the state of the three-storey industrial hall. The diploma thesis consists of two parts - theoretical and practical. In the theoretical part is described a common procedure for evaluation of the state of existing structures, methods used in diagnostics (selected ones - more detailed), advantages and disadvantages of methods. In the practical part is carried out construction and technical survey of the industrial hall, the concrete strength evaluation and verification of presence and type of reinforcement. At the end of the work - evaluation of objects.
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Jindrová, Barbora. "Možnosti stanovení mrazuvzdornosti betonu v konstrukci." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409955.
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The diploma thesis deals with different methods of determining levels of degradation of concrete due to freezing, also considering the options of freeze thaw resistance determination in structure. At first the properties of concrete and possible mechanisms of concrete degradation are described – mainly the effects of freezing water in the inner structure and of the combination of freezing water and de-icing chemicals on the surface. Principle and properties of air-entrained concrete are also mentioned. An overview of the approaches that current standards use to determine the freeze-thaw resistance of concrete is listed, followed by description of the tests that are used on air-entrained concrete specimens in the main part of the thesis. A portion of the test specimens was made in moulds while the rest was obtained from structure (concrete block). The non-destructive tests used are evaluated in several different ways and their results are compared with the destructive tests. Comparison and evaluation of different approaches used to determine the freeze-thaw resistence of concrete are the main outcome of this thesis.
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Zanella, Andrigo Kemel. "ANÁLISE DAS PROPRIEDADES MECÂNICAS DE CONCRETOS PARA PAVIMENTAÇÃO EMPREGANDO DIFERENTES PROCESSOS DE CURA." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/7861.
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To develop a project sizing concrete pavement is necessary to know the mechanical properties and the different treatment processes of material to be used. This study aimed to analyze the mechanical properties such as flexural strenght, compressive strength, indirect tensile strength and static modulus of concrete paving. The three types of concrete were studied: An actual reference (typically used in paving, one with the addition of polypropylene fibers (common practice for floors), and a high strength concrete used to rapidly release the traffic. Different methods of curing were applied: chemical cure with and without the use of wet burlap bags (widely applied in pavements) and curing in a moist chamber (as recommended by standard). This evaluation of the mechanical properties for the concrete studied in different curing methods applied, showed that the microstructure of concrete is significantly interfering with the results, especially in cured concrete to track conditions (chemical cure without and with the placement of burlap sacks). Where factors such as the absorption and reabsorption of water evaporation to cement hydration, cracking the interface folder / aggregate, ambient conditions related to temperature and humidity, are interfering with the tensile strength in bending, compressive strength, indirect tensile strength and particularly in the static modulus and still, from the results obtained in this study and those reported by other authors who studied a high-strength concrete, it is possible to verify that there are particularities still unknown about the behavior of high strength concrete.Para o desenvolvimento de um projeto de dimensionamento de pavimentos de concreto é necessário conhecer as propriedades mecânicas e os diferentes processos de tratamento do material a ser utilizado. Este trabalho teve por objetivo analisar as propriedades mecânicas, tais como, resistência à tração na flexão, resistência à compressão axial, resistência à tração por compressão diametral e módulo de elasticidade estático em concretos para pavimentação. Foram estudados os três tipos de concretos: um concreto referência, (tipicamente empregado em pavimentação, outro com a adição de fibras de polipropileno (prática comum em pavimentos) e um concreto de alta resistência, utilizado para rápida liberação ao tráfego. Diferentes métodos de cura foram aplicados: cura química com e sem a utilização de sacos de aniagem úmidos (largamente aplicados em pavimentos) e cura em câmara úmida (conforme preconizado por norma). A avalição das propriedades mecânicas para os concretos estudados, nos diferentes métodos de cura aplicados, mostrou que a microestrutura dos concretos, está interferindo de forma significativa nos resultados obtidos, principalmente nos concretos curados para condições de pista (cura química sem e com a colocação de sacos de aniagem), onde fatores como a absorção e reabsorção da água de evaporação para hidratação do cimento, a fissuração da interface pasta/agregado, as condições ambientes relacionadas à temperatura e umidade, estejam interferindo na resistência à tração na flexão, resistência à compressão axial, resistência à tração por compressão diametral e principalmente no módulo de elasticidade estático e ainda, a partir dos resultados obtidos na presente pesquisa e daqueles apresentados por outros autores que estudaram um concreto de alta resistência, é possível verificar que existem particularidades ainda desconhecidas sobre o comportamento do concreto de alta resistência.
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Garcia, Pedro Henrique. "Abordagem inversa para obtenção de propriedades mecânicas de agregados em concretos leves por meio de simulação computacional." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/5385.
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O concreto de agregado leve é conhecido pelo reduzido peso específico e alta capacidade de isolamento térmico e acústico. Um dos grandes desafios relacionados a esse tipo de concreto é a obtenção de algumas propriedades mecânicas dos agregados leves, tais como o módulo de elasticidade e a resistência à compressão, em função de suas dimensões reduzidas, o que gera dificuldades na realização de ensaios experimentais. É possível encontrar trabalhos na literatura que tentam determinar as propriedades mecânicas dos agregados leves por meio de métodos baseados em formulações matemáticas e deduções empíricas. Uma alternativa a tais métodos é o emprego de modelos de simulação e a resolução de um problema inverso para a previsão de tais propriedades. O objetivo do trabalho é a aplicação de um procedimento inverso para obtenção do módulo de elasticidade e da resistência à compressão de agregados leves presentes em concretos via simulação computacional de ensaios de compressão uniaxiais em corpos de prova. O corpo de prova de concreto é representado por um modelo computacional mecânico bidimensional e bifásico, constituído por argamassa e agregados leves de formato circular, e as simulações foram conduzidas no programa Abaqus R. Os resultados encontrados foram satisfatórios em comparação com outros métodos da literatura, chegando a casos com diferenças menores que 2% para um corpo de prova com 15% de agregados. A abordagem proposta emerge como uma possível solução para análises de propriedades mecânicas de agregados leves em concretos com um reduzido tempo e custo, sendo aplicada para diversos tipos de curvas granulométricas, tipos de argamassa e diferentes porcentagens de agregados no corpo de prova. Além da previsão das propriedades mecânicas dos agregados em concretos leves, a abordagem traz um melhor entendimento da relação dos diversos conjuntos de agregados leves com as argamassas.
The lightweight aggregate concrete is known for its low specific weight and high thermal and acoustic insulation capacity. One of the great challenges related to this type of concrete is to get some mechanical properties of lightweight aggregate, such as the modulus of elasticity and the compressive strength, due to its reduced size, which generates difficulties to carry out experimental tests. It is possible to find works in the literature that try to determine the mechanical properties of the lightweight aggregate through methods based on mathematical formulation and empirical deductions. An alternative to such methods is the use of simulation models and the resolution of an inverse problem for the prediction of lightweight aggregate properties. The objective of this study is the application of an inverse procedure to obtain the modulus of elasticity and the compressive strength of lightweight aggregates present in concrete by computational simulation of uniaxial compression tests in specimens. The concrete specimen is represented by a two-dimensional and biphasic mechanical computational model, constituted by mortar and circular lightweight aggregates, and the simulations were conducted in the Abaqus R program. The results were satisfactory compared to other methods in the literature, reaching cases with differences of less than 2 % for a test specimen with 15 % of aggregates. The proposed approach emerges as a possible solution for the analysis of mechanical properties of lightweight aggregates in concrete with reduced cost and time, being applied for several types of grain sizes, mortar types and different percentages of aggregates in the concrete specimen. In addition, the approach brings a better understanding about the connection between lightweight aggregates and mortars.
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Akhi, Taohida Parvin. "Experimental investigation of effective modulus of elasticity and shear modulus of brick masonry wall under lateral load." ISIS Canada Research Network, 2011. http://hdl.handle.net/1993/5304.
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The primary objective of this research program was to investigate the effective modulus of elasticity and shear modulus of brick masonry walls under lateral load, and to to justify using the Jaeger and Mufti method to calculate the effective modulus of elasticity and shear modulus of brick masonry walls. The experimental program involved the testing of three unreinforced brick masonry walls under in-plane and vertical loads. Linear Variable Differential Transducers were used to record the horizontal and vertical displacements of the walls. The experimental results were used to evaluate the modulus of elasticity and the shear modulus of walls under flexure. The experimental results were compared to the finite element analysis results. It was found that the finite element analysis yields similar results to the experimental results. It was also found that the Jaeger and Mufti method to calculate effective modulus of elasticity and shear modulus of brick masonry walls is effective for design purposes.
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Ip, Felix. "Compressive strength and modulus of elasticity of masonry prisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ48451.pdf.
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Ip, Felix (Mong Kau Felix) Carleton University Dissertation Engineering Civil and Environmental. "Compressive strength and modulus of elasticity of masonry prisms." Ottawa, 1999.
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Vukovic, Nikola. "Comparison of laboratory and field modulus of elasticity of rocks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ44047.pdf.
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Busch, Amanda J. "Vacuum-Assisted Wet Shaping of Paper." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10567.
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Premium absorbent paper products (e.g., two-ply towel and tissue) can achieve higher fluid holding capacity per unit dry weight by means of increasing their void volume per unit weight. In turn, high void volume can be attained by increasing the overall thickness of each ply through molding the paper into a three-dimensional ("mini-egg-crate") structure before drying it.
This research investigates the effect of three types of parameters: mold geometrical, operational, and paper parameters. These variables are examined with respect to their effect on the resulting overall thickness. Because the experimental research is fundamental in nature, it employs molding structures of a simplified geometry (produced via rapid prototyping techniques) rather than the geometrically complex molding fabrics used commercially.
A goal of the project is the understanding of the physics of the wet shaping process, in which vacuum is used to deform the wet paper web into the openings in the molding structure. Another goal is identification of limitations or boundaries of the wet shaping
process (e.g., conditions for which "pinholes" occur in the paper). Supporting theoretical analysis of the shaping/molding problem is performed, to provide bases for correlating experimental data and for the optimization of molding geometrical parameters. The result of this study provides quantitative information for some variables that affect the final sheet thickness.
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Nortemann, Markus. "Characterisation of Young's modulus and loss factor of damping materials." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1021036.
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Given the importance of simulation techniques in automotive engineering, there is a lack of implementation regarding these techniques in the acoustics of damping materials for air-borne sound. Biot’s calculations have proven its abilities to simulate the acoustic characteristics of these damping materials. However, the characterisation of essential structural parameters, such as Young’s modulus and loss factor, in order to conduct Biot’s calculations have been inconclusive. Thus, the primary research objective of this study is to propose a new measurement system for the structural Biot parameters. After a comprehensive literature review has been undertaken on damping materials, as well as measurement apparatuses for Young’s modulus and loss factor of damping materials, two causes of measurement errors have been identified. Unknown stresses in measurement apparatuses and inhomogeneous, polytrophic and viscoelastic behaviour of specimens. A new measurement system that does not affect the specimens with unknown stresses and accounts for their complex behaviour required investigation. Non-contact ultrasound had been selected as a solution to determine the aforementioned parameters, since these methods do not necessarily touch or compress the specimen, which led to unknown stresses and neglection of the complex specimen behaviour with the aforementioned techniques. Although ultrasound had been used to determine structural parameters on various types of materials, it has never been used to measure soft porous damping materials. In order to find possible solutions, various sources using ultrasonics to investigate struc- tural parameters had been reviewed. In order to calculate structural parameters, the longitudinal and transversal wave velocity inside the specimen had to be determined. The main findings showed that non-contact ultrasound will be able to evaluate the Young’s modulus, loss factor as well as Poisson’s ratio. Consequently, it was shown that longitudinal velocity measurements could be conducted using well known transmission measurements. However, well known approaches would not be sufficient measuring the transversal wave velocity in soft damping materials. This problem was addressed with a special gas to be used, with lower sound speed velocity in the fluid than in the solid. Moreso, a new method determining the transversal wave velocity had been found, as it would enable the use of an even larger range of damping materials, especially ones with heavy frames and lower porosity. It will use refracted waves inside the specimen and the determination of the convertion position of the transversal to the longitudinal wave at the rear specimen surface. At the end of the study, hardware components were selected and a test rig was constructed, which should be able to prove that a determination of structural Biot parameters with non-contact ultrasound is possible with less errors instead of using mechanical transfer function systems. The development of measurement software as well as the testing of the measurement system and its validation was not under investigation in this dissertation. This study has expanded on the body of literature knowledge regarding non-contact ultrasound. Furthermore, a significant contribution has been made towards a new measurement system measuring Young’s modulus and loss factor which circumvents errors in mechanical transfer function systems. This will contribute to more precise simulations of damping materials and damped enclosures, which may ultimately result in enhanced efficiency of damping materials as well as the acoustic packaging of cars.
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Škapová, Pavla. "Problematika testování stříkaných betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226742.
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The master‘s thesis focuses on testing the shotcrete prepared in laboratory conditions. The main observed properties are compresive strenght of shotcrete and modulus of elasticity. The aim is assessment of methods for measuring those parameters. The calibrating correlations for strenght characteristics of shotcrete are given by obtaining the results of used methods. The shotcrete composition, amount and type of accelerating additive as well as economic aspect of using shotcrete is also assessed.
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Bert, Stephen M. "Using Maturity to Predict Girder Camber." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32852.
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The objective of this research was to determine if differential camber of prestressed concrete girders could be reduced by accurate prediction of initial camber at release of prestress. Maturity at prestress transfer was used to calculate modulus of elasticity for predicting camber at release. The research consists of a literature review of maturity methods, testing of a standard concrete mix to determine strength and modulus functions and measurement of girder camber and maturity.
Both the Nurse-Saul and the Arrhenius maturity models were evaluated. Maturity relationships were developed for concrete mixes containing Type II and Type III cements. A relationship of modulus as a function of maturity was developed. Seven girders were tested. Camber predictions within 0 to ¼ in. of actual camber were obtained using modulus of elasticity calculated from a maturity based function. Comparison was made between maturity based modulus and standard strength based modulus models. Camber predictions based on modulus calculated based on field cured cylinder strengths were within 0 to ½ in.Master of Science
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Momen, Mostafa. "Complex Modulus Determination of Asphalt Concrete Using Indirect Tension Test." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-10252004-040231/.
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MOMEN, MOSTAFA HASSAN. Dynamic Modulus Determination of Asphalt Concrete Mixtures Using Indirect Tension Test. (Under the direction of Dr. Y. Richard Kim). The purpose of this research is to present the results from an analytical/experimental study on the dynamic modulus testing of hot mix asphalt (HMA) using the indirect tension (IDT) mode. The analytical solution for dynamic modulus determination in IDT was developed by Kim (14) using the theory of linear viscoelasticity. To verify the analytical solution, temperature and frequency sweep tests were conducted on 24 asphalt mixtures commonly used in North Carolina, using both axial compression and IDT test methods. In doing so, a modified dynamic modulus test protocol is introduced that reduces the required testing time by using more frequencies and fewer temperatures based on the time-temperature superposition principle. A comparison of results from the axial compression and IDT test methods shows that the dynamic modulus mastercurves and shift factors derived from the two methods are in good agreement. It was also found that Poisson?s ratio is a weak function of the loading frequency; its effect on the phase angle mastercurve is discussed. After verification of the analytical solution, another study was conducted to evaluate the effect of aggregate size on the variability of test results, where the coefficient of variation (CV) was computed for each aggregate size and the results were compared. It was found that mixes with a larger nominal maximum size of aggregate (NMSA) had a greater CV than those with a smaller NMSA. Digital image Correlation was used to further support the findings and reveal physical explanations for the results obtained from this statistical analysis.