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 confiabilidade / Structural 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

(EN) Thesis deals with an approximation of static moduli in wells from dynamic moduli determined by acoustic well logging using T-matrix model. Proposed approach makes possible to determine moduli values, which are close to values of static moduli, which would be determined by loading tests. This approach is based on an idea, that an intact rock with sufficiently high compressional strength sc and sufficiently high value of static Young's modulus Es, manifests more or less linear elastic behaviour. In such case, the values of static and dynamic moduli are identical. This fact has been experimentally verified for rocks with values of sc and Es in order of higher tens of MPa and GPa respectively. In case of a rock damage presence in such rock, it's behaviour becomes nonlinearly elastic. The amount of nonlinearity is proportional to increasing amount of rock damage. This results in the difference between values of static and dynamic moduli. T-matrix model is used to quantify this difference. This model is based on an anisotropic rock matrix with ellipsoidal inclusions. These inclusions can affect each other. The result of this model calculation is a group of values of elastic constants, which we call effective moduli. These effective moduli include the effect of porosity in the rock as well and they...

The importance of aggregate structure and air voids distribution for asphalt mixture rutting and cracking performance has been well established on the basis of experience and is well documented in the literature. Past and current investigations are limited to assessment of performance based on macroscopic behavior due to the difficulty associated with the quantitative measurement and analysis of the internal structure of asphalt mixtures. Lately, technical advances in X-ray Computed Tomography (CT) and image processing and analysis has made possible to bring the attention also to the internal structure of asphalt mixtures. SPT results from asphalt field cores, including dynamic modulus (before and after loading) and microstrain accumulation (flow number), exhibited significant variability; most likely, induced by irregularities in the core shape. The analysis of aggregate structure and air voids distribution performed trough X-ray CT, clearly identified segregation in the asphalt mixture as a key factor that induced variability in SPT results. / QC 20120320

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-08-16T13:06:28Z No. of bitstreams: 1 Fernando Henrique Fernandes Sousa_.pdf: 2658604 bytes, checksum: e7b64f91760b00255d2c12f5440cf17d (MD5) / Made available in DSpace on 2018-08-16T13:06:28Z (GMT). No. of bitstreams: 1 Fernando Henrique Fernandes Sousa_.pdf: 2658604 bytes, checksum: e7b64f91760b00255d2c12f5440cf17d (MD5) Previous issue date: 2018-05-28 / Nenhuma / 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.

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.

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.

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.

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.

This master’s thesis deals with the determination of dynamic modulus of elasticity non-destructive methods of brick body. The test samples were laboratory-made from two types of brick earth and further were used cotouts from the full brick types clinker. For measuring were used ultrasonic impulse and resonant-impact method.

This diploma thesis is focused on methodology for sorting of solid fired bricks for reconstruction of historical buildings. The theorethical part of this thesis includes description of production technology of solid fired bricks and diagnostic methods. In practical part there are these methods aplied on the solid fired bricks, which are intended for reconstruction of the bridge in Sedlec. There are monitored changes in structure of solid fired bricks caused by repeated freezing and defrosting. This changes are monitored by resonant frequency method and ultasonic pulse method.