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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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Brunetti, Carlotta. "Frequency-dependent response of snow in uniaxial compression and comparison with numerical simulation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7820/.
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La determinazione del modulo di Young è fondamentale nello studio della propagazione di fratture prima del rilascio di una valanga e per lo sviluppo di affidabili modelli di stabilità della neve. Il confronto tra simulazioni numeriche del modulo di Young e i valori sperimentali mostra che questi ultimi sono tre ordini di grandezza inferiori a quelli simulati (Reuter et al. 2013). Lo scopo di questo lavoro è stimare il modulo di elasticità studiando la dipendenza dalla frequenza della risposta di diversi tipi di neve a bassa densità, 140-280 kg m-3. Ciò è stato fatto applicando una compressione dinamica uniassiale a -15°C nel range 1-250 Hz utilizzando il Young's modulus device (YMD), prototipo di cycling loading device progettato all'Istituto per lo studio della neve e delle valanghe (SLF). Una risposta viscoelastica della neve è stata identificata a tutte le frequenze considerate, la teoria della viscoelasticità è stata applicata assumendo valida l'ipotesi di risposta lineare della neve. Il valore dello storage modulus, E', a 100 Hz è stato identificato come ragionevolmente rappresentativo del modulo di Young di ciascun campione neve. Il comportamento viscoso è stato valutato considerando la loss tangent e la viscosità ricavata dai modelli di Voigt e Maxwell. Il passaggio da un comportamento più viscoso ad uno più elastico è stato trovato a 40 Hz (~1.1•10-2 s-1). Il maggior contributo alla dissipazione è nel range 1-10 Hz. Infine, le simulazioni numeriche del modulo di Young sono state ottenute nello stesso modo di Reuter et al.. La differenza tra le simulazioni ed i valori sperimentali di E' sono, al massimo, di un fattore 5; invece, in Reuter et al., era di 3 ordini di grandezza. Pertanto, i nostri valori sperimentali e numerici corrispondono meglio, indicando che il metodo qui utilizzato ha portato ad un miglioramento significativo.
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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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Amin, Diyar. "Triaxial testing of lime/cement stabilized clay : A comparison with unconfined compression tests." Thesis, KTH, Jord- och bergmekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160626.
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Detta examensarbete presenterar resultat från en laboratoriestudie på en lera från Enköping stabiliserad med kalk och cement. I laboratoriet har isotropiskt konsoliderade odränerade aktiva triaxialförsök utförts på provkroppar och jämförts med enaxliga tryckförsök som utförts på provkroppar från samma inblandningstillfälle. De två metoderna har visat sig ge likvärdiga värden på utvärderad odränerad skjuvhållfasthet. Elasticitetsmodulen har däremot visat sig vara mycket högre för triaxialförsöken än enaxliga tryckförsök. För triaxialförsöken har förhållandet mellan sekantmodulen och den odränerade skjuvhållfastheten legat mellan 112-333. För de enaxliga tryckförsöken ligger förhållandet mellan sekantmodulen och den odränerade skjuvhållfastheten inom intervallet 44-146. Inget mönster har dock kunnat urskiljas då förhållandet mellan de två olika försöken har varierat mellan 1,0-3,5. Ett lägre och högre back pressure användes under triaxialförsöken. Till skillnad från tidigare studier har dock båda dessa back pressures vattenmättat provkroppen. Resultaten visar på att back pressure inte påverkar testresultaten, förutsatt att provet blivit fullt vattenmättat. Utöver denna jämförelse har ytterligare passiva triaxialförsök utförts. De passiva triaxialförsöken har utförts som isotropiskt konsoliderade odränerade försök.. Däremot har två olika metoder använts under skjuvningsfasen. I första typen av försök har den axiella spänningen minskats medan den radiella spänningen har hållits konstant. I den andra typen av försök har i stället den radiella spänningen ökats samtidigt som den axiella spänningen har hållits konstant. Skjuvhållfastheter har jämförts med resultat från kalkpelarsondering i fält och visar på att skjuvhållfastheten genomgående varit högre i fält än i laboratoriet. Dessutom har skjuvhållfastheter och elasticitetsmoduler testats efter olika lagringstider genom enaxliga tryckförsök.This master thesis presents results from a laboratory study on a clay from Enköping which was stabilized with lime and clay. Isotropic consolidated undrained compressive tests were performed on samples and compared to unconfined compressive testing. The two methods have shown no difference in the evaluation of undrained shear strength. However the modulus of elasticity was shown to be much higher for the triaxial tests. For the unconfined compressive tests the relation between the undrained shear strength and secant modulus was within the range of 44-146. The equivalent for the triaxial tests was in the interval of 112-333. However no pattern was extinguishable between the two tests as this relation has varied between 1,0 to 3,5. A lower and higher back pressure was used during the triaxial testing. However, both back pressures have succeeded in saturating the sample. Results show that the back pressure has little effect on the results, as long as the sample has been fully saturated. In addition to this extension tests were performed on samples as well. The tests performed were isotropic consolidated undrained. However two different shearing methods were used. The first test was strain rate dependant while the second test was stress rate dependant. In the first test the vertical stress decreased while the radial stresses were kept constant, while in the other test the radial stresses increased while the vertical stress were kept constant. The undrained shear strength was compared to lime/cement column penetration tests in field. Results showed that tests in field show a much higher undrained shear strength than laboratory testing.
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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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Granju, Jean-Louis. "Modelisation des pates de ciment durcies : caracterisation de l'etat d'hydratation, lois d'evolution de la resistance en compression et du module de deformation longitudinale." Toulouse 3, 1987. http://www.theses.fr/1987TOU30060.
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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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Ranawaka, Thanuja. "Distortional buckling behaviour of cold-formed steel compression members at elevated temperatures." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16417/.
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In recent times, light gauge cold-formed steel sections have been used extensively in residential, industrial and commercial buildings as primary load bearing structural components. This is because cold-formed steel sections have a very high strength to weight ratio compared with thicker hot-rolled steel sections, and their manufacturing process is simple and cost-effective. However, these members are susceptible to various buckling modes including local and distortional buckling and their ultimate strength behaviour is governed by these buckling modes. Fire safety design of building structures has received greater attention in recent times due to continuing loss of properties and lives during fires. Hence, there is a need to fully evaluate the performance of light gauge cold-formed steel structures under fire conditions. Past fire research has focused heavily on heavier, hot-rolled steel members. The buckling behaviour of light gauge cold-formed steel members under fire conditions is not well understood. The buckling effects associated with thin steels are significant and have to be taken into account in fire safety design. Therefore, a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the distortional buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research program more than 115 tensile coupon tests of light gauge cold-formed steels including two steel grades and five thicknesses were conducted at elevated temperatures. Accurate mechanical properties including the yield strength, elasticity modulus and stress-strain curves were all determined at elevated temperatures since the deterioration of the mechanical properties is one of the major parameters in the structural design under fire conditions. An appropriate stress-strain model was also developed by considering the inelastic characteristics. The results obtained from the tensile coupon tests were then used to predict the ultimate strength of cold-formed steel compression members. In the second phase of this research more than 170 laboratory experiments were undertaken to investigate the distortional buckling behaviour of light gauge coldformed steel compression members at ambient and elevated temperatures. Two types of cross sections were selected with various thicknesses (nominal thicknesses are 0.6, 0.8, and 0.95 mm) and both low and high strength steels (G250 and G550 steels with minimum yield strengths of 250 and 550 MPa). The experiments were conducted at six different temperatures in the range of 20 to 800°C. A finite element model of the tested compression members was then developed and validated with the help of experimental results. The degradation of mechanical properties with increasing temperatures was included in finite element analyses. An extensive series of parametric analyses was undertaken using the validated finite element model to investigate the effect of all the influential parameters such as section geometry, steel thickness and grade, mechanical properties and temperature. The resulting large data base of ultimate loads of compression members subject to distortional buckling was then used to review the adequacy of the current design rules at ambient temperature. The current design rules were reasonably accurate in general, but in order to improve the accuracy further, this research has developed new design equations to determine the ultimate loads of compression members at ambient temperature. The developed equation was then simply modified by including the relevant mechanical properties at elevated temperatures. It was found that this simple modification based on reduced mechanical properties gave reasonable results, but not at higher temperatures. Therefore, they were further modified to obtain a more accurate design equation at elevated temperatures. The accuracy of new design rules was then verified by comparing their predictions with the results obtained from the parametric study. This thesis presents a description of the experimental and numerical studies undertaken in this research and the results including comparison with simply modified current design rules. It describes the laboratory experiments at ambient and elevated temperatures. It also describes the finite element models of cold-formed steel compression members developed in this research that included the appropriate mechanical properties, initial geometric imperfections and residual stresses. Finally, it presents the details of the new design equations proposed for the light gauge coldformed steel compression members subjected to distortional buckling effects at elevated temperatures.
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Jeffries, Thomas Mason. "Relationships of growth rate and mechanical properties in sweetgum, Liquidambar styraciflua." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31225.
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Sweetgum, Liquidambar styraciflua, is a diffuse-porous hardwood occurring in the southeastern United States. In this observational study, trees from two plantations of sweetgum were evaluated for mechanical properties. The two plantations were similar in age, soil type, competition control, and water availability, but differed in nutrient availability, growing season, and growth rate. Three trees representing different crown classes were removed from both plantations. Each tree was sampled for compression strength parallel to grain along the height of the merchantable stem. Oven-dry specific gravity was then calculated for each sample. The results indicate that young sweetgum trees grow weaker wood than mature trees. It was observed that dominant trees were stronger and denser than other trees. Denser wood was formed in the plantation with the shortest growing season and smallest growth rate. Three of six trees showed significant correlations of strength and stiffness with height in the tree.Master of Science
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Heva, Yasintha Bandula. "Behaviour and design of cold-formed steel compression members at elevated termperatures." Queensland University of Technology, 2009. http://eprints.qut.edu.au/29310/.
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Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements and non-load bearing structural elements (partitions) due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. Cold-formed steel members are often made from thin steel sheets and hence they are more susceptible to various buckling modes. Generally short columns are susceptible to local or distortional buckling while long columns to flexural or flexural-torsional buckling. Fire safety design of building structures is an essential requirement as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge cold-formed steel structures under fire conditions. The buckling behaviour of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research, a detailed review was undertaken on the mechanical properties of light gauge cold-formed steels at elevated temperatures and the most reliable predictive models for mechanical properties and stress-strain models based on detailed experimental investigations were identified. Their accuracy was verified experimentally by carrying out a series of tensile coupon tests at ambient and elevated temperatures. As the second phase of this research, local buckling behaviour was investigated based on the experimental and numerical investigations at ambient and elevated temperatures. First a series of 91 local buckling tests was carried out at ambient and elevated temperatures on lipped and unlipped channels made of G250-0.95, G550-0.95, G250-1.95 and G450-1.90 cold-formed steels. Suitable finite element models were then developed to simulate the experimental conditions. These models were converted to ideal finite element models to undertake detailed parametric study. Finally all the ultimate load capacity results for local buckling were compared with the available design methods based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Part 1.2 and the direct strength method (DSM), and suitable recommendations were made for the fire design of cold-formed steel compression members subject to local buckling. As the third phase of this research, flexural-torsional buckling behaviour was investigated experimentally and numerically. Two series of 39 flexural-torsional buckling tests were undertaken at ambient and elevated temperatures. The first series consisted 2800 mm long columns of G550-0.95, G250-1.95 and G450-1.90 cold-formed steel lipped channel columns while the second series contained 1800 mm long lipped channel columns of the same steel thickness and strength grades. All the experimental tests were simulated using a suitable finite element model, and the same model was used in a detailed parametric study following validation. Based on the comparison of results from the experimental and parametric studies with the available design methods, suitable design recommendations were made. This thesis presents a detailed description of the experimental and numerical studies undertaken on the mechanical properties and the local and flexural-torsional bucking behaviour of cold-formed steel compression member at ambient and elevated temperatures. It also describes the currently available ambient temperature design methods and their accuracy when used for fire design with appropriately reduced mechanical properties at elevated temperatures. Available fire design methods are also included and their accuracy in predicting the ultimate load capacity at elevated temperatures was investigated. This research has shown that the current ambient temperature design methods are capable of predicting the local and flexural-torsional buckling capacities of cold-formed steel compression members at elevated temperatures with the use of reduced mechanical properties. However, the elevated temperature design method in Eurocode 3 Part 1.2 is overly conservative and hence unsuitable, particularly in the case of flexural-torsional buckling at elevated temperatures.
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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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Yoo, Jiyoun. "Modeling Compressive Stress Distributions at the Interface between a Pallet Deck and Distribution Packaging." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/39939.
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Three components, a pallet, packaging, and material handling equipment, of the unit load portion of the supply chain are physically and mechanically interacting during product storage and shipping. Understanding the interactions between two primary components, a pallet and packaging, in a unit load is a key step towards supply chain cost reduction and workplace safety improvement. Designing a unit load without considering physical and mechanical interactions, between those two components, can result in human injury or death caused from a unsafe workplace environment and increased supply chain operating costs, due to product damage, high packaging cost, disposal expense, and waste of natural resources.
This research is directed towards developing predictive models of the compressive stress distributions using the principle of the beam on an elastic foundation and experimentally quantifying the compressive stress distributions. The overall objective of this study is to develop a model that predicts compressive stress distributions at the interface between a pallet deck and packaging as a function of: pallet deck stiffness, packaging stiffness, and pallet joint fixity. The developed models were validated by comparison to the results of physical testing of the unit load section. Design variables required for modeling included Modulus of Elasticity (MOE) of pallet deckboards, Rotation Modulus (RM) for nailed joints, and packaging stiffness.
Predictive models of the compressive stress distributions were non-uniformly distributed across the interface between pallet deckboards and packaging. Maximum compressive stresses were observed at the deckboard ends over stringer segments. All predictive compressive stress
distributions were influenced by pallet deck stiffness, packaging stiffness, and joint fixity. The less the joint fixity the greater the pallet deck deflection. The stiffer deckboards are more sensitive to joint fixity. For predictive compressive stress distribution models, the measure of the stress concentrations was the Compressive Stress Intensity Factor (SIF), which was the ratio of the estimated maximum compressive stress to the applied stress. Less stiff pallets and stiffer packaging resulted in greater SIF for all end condition models. SIF was reduced by stiffer joint, stiffer pallet deck and more flexible packaging. The stiffer the pallet deck and pallet joint the greater the effective bearing area. The lower stiffness packaging resulted in the greater effective bearing area with all three packages. The predicted effective bearing area was more influenced by pallet deck stiffness than the packaging stiffness.
The developed prediction models were validated by comparison to experimental results. All prediction models fell within 95% confidence bounds except the 3/8-inch deck with free ends and 3/4-inch deck with fixed ends. The difference between predicted and measured results was due to a limitation in pressure sensor range and test specimen construction for the free end model and fixed end model, respectively.
The results show effects of pallet deck stiffness and packaging stiffness on SIFs with percentage changes ranging from 2 to 26% (absolute value of change) for all three end conditions. The sensitivity study concluded that changing both pallet deck stiffness and packaging stiffness more significantly influenced the SIFs than bearing areas.Ph. D.
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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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Lee, Jung Hoon. "Local buckling behaviour and design of cold-formed steel compression members at elevated temperatures." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15972/.
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The importance of fire safety design has been realised due to the ever increasing loss of properties and lives caused by structural failures during fires. In recognition of the importance of fire safety design, extensive research has been undertaken in the field of fire safety of buildings and structures especially over the last couple of decades. In the same period, the development of fire safety engineering principles has brought significant reduction to the cost of fire protection. However the past fire research on steel structures has been limited to heavier, hot-rolled structural steel members and thus the structural behaviour of light gauge cold-formed steel members under fire conditions is not well understood. Since cold-formed steel structures have been commonly used for numerous applications and their use has increased rapidly in the last decade, the fire safety of cold-formed steel structural members has become an important issue. The current design standards for steel structures have simply included a list of reduction factors for the yield strength and elasticity modulus of hot-rolled steels without any detailed design procedures. It is not known whether these reduction factors are applicable to the commonly used thin, high strength steels in Australia. Further, the local buckling effects dominate the structural behaviour of light gauge cold-formed steel members. Therefore an extensive research program was undertaken at the Queensland University of Technology to investigate the local buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. The first phase of this research program included 189 tensile coupon tests including three steel grades and six thicknesses to obtain the accurate yield strength and elasticity modulus values at elevated temperatures because the deterioration of the mechanical properties is the major parameter in the structural design under fire conditions. The results obtained from the tensile tests were used to predict the ultimate strength of cold-formed steel members. An appropriate stress-strain model was also developed by considering the inelastic mechanical characteristics. The second phase of this research was based on a series of more than 120 laboratory experiments and corresponding numerical analyses on cold-formed steel compression members to investigate the local bucking behaviour of the unstiffened flange elements, stiffened web elements and stiffened web and flange elements at elevated temperatures up to 800°C. The conventional effective design rules were first simply modified considering the reduced mechanical properties obtained from the tensile coupon tests and their adequacy was studied using the experimental and numerical results. It was found that the simply modified effective width design rules were adequate for low strength steel members and yet was not adequate for high strength cold-formed steel members due to the severe reduction of the ultimate strength in the post buckling strength range and the severe reduction ratio of the elasticity modulus to the yield strength at elevated temperatures. Due to the inadequacy of the current design rules, the theoretical, semi-empirical and empirical effective width design rules were developed to accurately predict the ultimate strength of cold-formed steel compression members subject to local buckling effects at elevated temperatures. The accuracy of these new design methods was verified by comparing their predictions with a variety of experimental and numerical results. This thesis presents the details of extensive experimental and numerical studies undertaken in this research program and the results including comparison with simply modified effective width design rules. It also describes the advanced finite element models of cold-formed steel compression members developed in this research including the appropriate mechanical properties, initial imperfections, residual stresses and other significant factors. Finally, it presents the details of the new design methods proposed for the cold-formed steel compression members subject to local buckling effects at elevated temperatures.
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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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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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Trinca, Alex Julio. "Influencia da dimensão do corpo-de-prova no ensaio destrutuvo de compressão paralela as fibras e no ensaio não-destrutivo utilizando ultra-som." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257144.
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Orientador: Raquel GonçalvesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Resumo: é praticamente toda exportada em sua forma in natura sem que a ela seja agregado valor de beneficiamento. Um dos problemas enfrentados pela indústria moveleira é o fato da madeira não ser submetida à classificação, dificultando a elaboração de projetos e a certificação da qualidade do móvel confeccionado a partir deste material. Nesse contexto as empresas moveleiras brasileiras buscam parâmetros para composição e certificação de seu produto, sendo atualmente a norma brasileira ¿Projeto de Estruturas de Madeira¿ ¿ NBR 7190/97, o único instrumento norteador para a caracterização de propriedades da madeira. No entanto, nesse setor as dificuldades para a obtenção de corpos-de-prova nas dimensões especificadas por esse texto normativo têm gerado dúvidas quanto aos resultados de caracterização de propriedades, de maneira que este trabalho teve como objetivo principal verificar se os valores do módulo de elasticidade e da tensão de ruptura no ensaio de compressão paralela às fibras podem ser considerados estatisticamente equivalentes, desde que sejam mantidas a proporcionalidade da dimensão do corpo-de-prova. Para isso adotou-se, como alternativa ao corpo-de-prova proposto pela NBR 7190/97, a dimensão 0,03 m x 0,03 m x 0,09 m. Os ensaios foram realizados utilizando-se 7 diferentes espécies de madeira com densidades variadas, buscando-se, com essa amostragem, a generalização dos resultados. Como objetivo secundário se buscou avaliar a influência das dimensões do corpo-de-prova e da freqüência do transdutor na velocidade de propagação de ondas de ultra-som na direção longitudinal. As espécies adotadas foram: Cerejeira (Torresea sp), Perobinha (Paratecoma peroba) , Cabreúva-vermelha (Myroxylon peruiferum), Angico-preto (Anadenanthera macrocarpa), Garapeira (Apuleia leiocarpa), Eucalipto grandis ( Eucalyptus grandis) e Pinus elliotti (Pinus elliottii). Todos os corpos-de-prova foram ensaiados com aproximadamente 12% de umidade e os ensaios foram realizados em ambiente controlado (21° C ± 1°C). Os resultados permitiram concluir que a hipótese foi verdadeira para todas as espécies estudadas quando se considera a tensão de ruptura
Abstract: Most of the exported wood in Brazil is unprocessed, without any aggregated value. To change this scenario technology for wood processing and qualification are required. One of the problems faced by the furniture industry refers to the non classification of the wood, which cause difficulties to projects elaboration and quality certification of the furniture made from this material. In this context the Brazilian Industries of furniture seek for parameters to certificate its products, and the NBR 7190/97 standard ¿Project of Structures of Wood " is, nowadays, the only instrument for the characterization of wood properties. However, for the furniture industry it is very difficult to obtaining the dimensions specified by the standard. This research had as main objective to verify if the means values of the modulus of elasticity and rupture in compression parallel to the grain can be considerate statistically equal, when smaller specimen are used, if the proportionality is maintained. For that it was adopted, as alternative to the specimen proposed by NBR 7190/97, the dimension 0.03 x 0.03 x 0.09 m. For the experiments there were used 7 different species with varied densities. The secondary objective was to evaluate the influence of the specimen size and of the transducer frequency in the speed of ultrasound wave propagation in the longitudinal direction. The adopted species were: Cerejeira (Amburana cearensis), Perobinha (Paratecoma peroba), Cabreúva vermelha (Myroxylon peruiferum), Angico-preto (Anadenanthera macrocarpa), Garapeira (Apulleia leiocarpa), Eucalyptus grandis, (Eucalyptus grandis) and Pinus ellioti (Pinus elliottii). All specimens were tested with approximately 12% moisture content and were accomplished in controlled atmosphere (21° C ± 1°C). The results allowed concluding that the hypothesis was true for all the studied species when the rupture in compression parallel to the grain was considered. For the module of elasticity this hypothesis was not confirmed for two species, from the seven evaluated (garapeira e eucalipto). Although, the mean difference between the results obtained in the tests using both specimens size was 10%, smaller then the maximum allowed variability in mechanical tests (18%). For the ultrasonic velocity propagation four species did not presents statistical variation with the modification of the size of the specimens - cerejeira, garapeira, pinus and eucalyptus while for the perobinha, angico and cabreúva the ultrasonic wave velocity propagation could not be considered statistically equal when the dimension of the specimens was modify. On average (considering all the studied species) the relationship among the ultrasonic wave velocity propagation (VLL) in normalized specimen and in proposed specimen was 0.99, being respectively the maximum and the lower relationships of 1.02 and 0.93. The velocity of wave propagation presents larger variations for values of length of wave percolation/wave length (L/?) up to 3, being more constant above that limit. It was also possible to verify, for the studied species, that the velocity of wave propagation increases with the increase of the transducer frequency. Key words: modulus of elasticity of wood; compression strength parallel to the fiber; ultrasonic wave velocity; dynamic constant
Mestrado
Construções Rurais e Ambiencia
Mestre em Engenharia Agrícola
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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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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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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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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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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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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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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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Kuchař, Martin. "Stanovení modulu pružnosti zdiva ve směru ložné spáry." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227159.
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The determination of strain properties of masonry in the direction parallel to bed joints is a fundamental pre-requisite for designing structures, where masonry is subjected to horizontal stresses (e. g. strengthening with prestressing). The diploma thesis summarized techniques of determination of masonry modulus of elasticity presented in available literature. The goal is to suggest suitable methodology of determination of masonry modulus in direction parallel to the bed joints. In the practical part of the diploma thesis is that methodology verified by experimental test and results of tests are analyzed and discussed.
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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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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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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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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.
Full textAbstract:
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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Trindade, Fábio Maciel de Oliveira da. "PROPRIEDADES MECÂNICAS DE CONCRETOS COM DIFERENTES CIMENTOS PORTLAND E COM CINZA DE CASCA DE ARROZ NATURAL E MOÍDA." Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/7789.
Full textAbstract:
Due to high rates of emissions of carbon dioxide released in cement production, an
alternative to minimize this pollution is the use of rice husk ash in concrete as partial cement
replacement. This research aims to investigate the technical feasibility, and the mechanical
properties of the use of rice husk ash in concrete for structural purposes. Rice husk ash content
to 15% by mass replacement of cement CPII-Z and CPIV were used in natural state and ground
in a ball mill and compared with the reference concrete, with three water/binder relationships:
0.45; 0.55 and 0.65. Mechanical strength tests by axial compression and diametral compression
at ages 28 and 91 days and elasticity modulus at 28 days were performed. The 28 days results
indicated axial compression strength, modulus of elasticity and diametrical compression
strength below the reference at 91 days and the concrete results with mineral admixtures were
similar to the reference concrete. The mixtures containing CPII-Z, presented higher axial
compressive strength than CPIV, because the higher cement consumption compared with the
CPII-Z with the same w/b relationship. This fact coupled with the presence of high levels of fly
ash, classifies cement CPIV with resistance to higher environmental aggressiveness, which
represents more durability and useful life. It was found that mixtures containing CCAN reduced
axial compressive and diametral strength compared with CCAM, because of the smaller
chemical reactivity and bigger particles of CCAN compared with ground rice husk ash. These
differences between the mixtures were not relevant, being about 10% and consumption of about
20 kg/m³ in relation to the same w/b compared with mixtures of CCAM for the two cement
types. In conclusion, the results of the tests show that there is technical feasibility for the use of
natural rice husk ash in structural concrete due to the differences observed with the ground
mixtures were negligible. The values obtained in the tests were satisfactory for natural rice husk
ash and ground rice husk ash with sligth advantage for the latter compared to first one, because
both developed axial compressive and diametral strength and elasticity modulus similar to the
reference concretes. These results reveal the greater sustainability to the concrete utilizing
agriculture by-products, contributing to reducing the pollutants emissions and the global
warming, due to decreased use of clinker in the mixtures.Devido às altas taxas de emissão de dióxido de carbono liberado na produção do cimento, uma alternativa para minimizar esta poluição é o uso parcial de cinza de casca de arroz no concreto em substituição ao cimento. Esta pesquisa teve o objetivo de investigar a viabilidade técnica, quanto às propriedades mecânicas do emprego de cinza de casca de arroz natural (sem moagem) e moída, em concretos para fins estruturais. Foram utilizadas cinza de casca de arroz com teor de 15% em substituição em massa de cimento CPII-Z e CPIV, nas formas moída em moinho de bolas e natural (sem beneficiamento), e comparadas com o concreto de referência, com três relações água/aglomerante: 0,45; 0,55; e 0,65. Foram executados os ensaios de resistência por compressão axial e compressão diametral nas idades de 28 e 91 dias e módulo de elasticidade aos 28 dias. Os resultados aos 28 dias indicaram resistências axiais, módulo de elasticidade e resistência por compressão diametral inferiores ao de referência; aos 91 dias, os resultados dos concretos com adições minerais foram semelhantes ao concreto de referência. As misturas com cimento CPII-Z apresentaram resistências à compressão axial superiores com CPIV, este com consumo de cimento maior nas relações a/ag do que o anterior. Tal fato, aliado com a presença de altos teores de cinza volante, classifica o cimento CPIV com maior resistência à agressividade ambiental de agentes deletérios como cloretos e carbonatação, o que representa maior durabilidade frente aos agentes agressivos. Também foi constatado que as misturas com CCAN tiveram menores resistências mecânicas comparadas com CCAM, em razão de a CCAN possuir partículas maiores e reatividade química menor do que a cinza moída. Estas diferenças entre os dois tipos de misturas não se revelaram significativas, ficando em aproximadamente 10%, e consumo, em torno de 20 kg/m³ em igualdade de relação a/ag se comparadas com as misturas de CCAM para os dois tipos de cimentos. Como conclusão, os resultados obtidos nos ensaios revelam que existe viabilidade técnica para o emprego de cinza de casca de arroz natural no emprego em concreto estrutural, em razão de as diferenças constatadas com as misturas com CCA moída terem sido pouco significativas. Os valores obtidos nos ensaios foram bastante próximos, tanto para cinza de casca de arroz natural como moída, com vantagem para esta última, pois ambas desenvolveram resistências à compressão axial, módulos de elasticidade e resistências por compressão diametral similares ao concreto de referência. Estes resultados contribuem para conferir maior sustentabilidade ao concreto pelo aproveitamento de subprodutos da agricultura, contribuindo para diminuir a emissão de poluentes na atmosfera e o efeito estufa, devido à diminuição do uso de clínquer nas misturas.
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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.
Full textAbstract:
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.
Full textAbstract:
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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Bert, Stephen M. "Using Maturity to Predict Girder Camber." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32852.
Full textAbstract:
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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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.
Full textAbstract:
Made available in DSpace on 2014-07-29T15:03:32Z (GMT). No. of bitstreams: 1
dissertacaoDanilo.pdf: 2147690 bytes, checksum: c918dd24c275d43fcca4fc1283e857a6 (MD5)
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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Bartoň, Vojtěch. "Metodika zkoušek historických cihel a zdiva." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409950.
Full textAbstract:
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.
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Wang, Xin. "Elasticity of Lipid Membrane Leaflets: Determining Pivotal Plane and Tilt Modulus in Computer Simulations." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/960.
Full textAbstract:
This thesis introduces a novel protocol to measure two elastic quantities of lipid membranes, the pivotal plane of a single leaflet and the lipid tilt modulus. The key setup relies on the simulation of a buckled membrane, a configuration that had been previously proposed to measure a membrane's bending rigidity. Since this method solely depends on the geometrical analysis of the membrane shape, and can hence even be applied to existing simulation trajectories of buckled membranes, it can provide two additional physical quantities at no extra simulation cost. Due to the high precision of its result, many technical subtleties are considered throughout the derivation, pertaining for instance to higher order corrections due to Poisson ratio effects. This calculation, as shown in this thesis, can be used to provide both a reference for other study as well as deeper insight into the nature of lipid models, especially the limitation of the coarse-grained ones.
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Hirsch, Sebastian. "Compression-sensitive Magnetic Resonance Elastography." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17205.
Full textAbstract:
Diese Arbeit stellt das Konzept der kompressionssensitiven Magnetresonanzelastographie vor. Kompressionssensitive MRE analysiert die Ausbreitung von Kompressionswellen und liefert dadurch Erkenntnisse über die Kompressionseigenschaften eines Mediums auf Grundlage eines poroelastischen Modells. Anomalien bei der Regulation des Gewebedrucks stehen in Zusammenhang mit verschiedenen Krankheitsbildern, wie Normaldruck-Hydrozephalus und Pfortader-Hypertonie. Statischer Druck spielt als Porendruck eine zentrale Rolle in den poroelastischen Wellengleichungen; die kompressionssensitive MRE könnte daher ein nichtinvasives Diagnoseinstrument darstellen, das die durch konventionelle Scherwellen-Elastographie gewonnenen Informationen um weitere Aspekte ergänzt. Diese Arbeit beschreibt die Entwicklung einer schnellen Singleshot-EPI-Bildgebungssequenz, mit deren Hilfe die durch propagierende Druckwellen hervorgerufene volumetrische Verzerrung quantifiziert werden kann. Die Validierung der kompressionssensitiven MRE erfolgte an verschiedenen Systemen: an porösen Gelphantomen, an der menschlichen Lunge in zwei Atemzuständen, in einer ex-vivo Schafsleber bei unterschiedlichen hydrostatischen Drücken und schließlich am menschlichen Gehirn. Die Ergebnisse belegen, dass die Stärke der induzierten volumetrischen Verzerrung sensitiv gegenüber Druckänderungen ist, wohingegen die Scherverzerrung keine derartige Abhängigkeit aufweist. In einer weiteren Studie wurde intrinsische Pulsation des menschlichen Hirns anstelle einer externen Vibrationsquelle ausgenutzt. Dabei erzeugte die arterielle Pulswelle eine kurze lokale Expansion des Hirnparenchyms; in der sich anschließenden diastolischen Phase erfolgte eine langsame Rückkehr zum Ausgangszustand. Aus den gemessenen volumetrischen Verzerrungen wurden durch Inversion der Druckwellengleichung numerische Werte für den Druckwellenmodul M berechnet; Rauschen wurde als primäre Ursache für die systematische Unterschätzung von M identifiziert.This thesis introduces the concept of compression-sensitive Magnetic Resonance Elastography. Compression-sensitive MRE detects the propagation of pressure waves, providing insight into the compressibility of a material based on a poroelastic tissue model. Poroelastic models incorporate compressibility through interaction of compartments, even as each individual compartment remains incompressible. Hydrostatic tissue pressure abnormalities are associated with a number of diseases, such as normal pressure hydrocephalus or hepatic portal hypertension. Since pore pressure plays a central role in the poroelastic wave equations, compression-sensitive MRE could potentially serve as a diagnostic tool, providing information complimentary to shear-wave MRE data. This thesis describes the development of a fast single-shot EPI MR sequence capable of quantifying volumetric strain induced by external vibrations. Compression-sensitive MRE was validated in porous gel phantoms, in the human lung at two different respiratory states, in an ex vivo sheep liver at varying levels of hydrostatic pressure, and finally in human liver and brain. Results illustrate that compression-sensitive MRE is capable of quantifying volumetric strain in phantoms and in human organs. It was found that volumetric strain was sensitive toward pressure changes associated with different physiological states, whereas shear strain remained constant. In an additional study, pulsation of the human brain, driven by the heart cycle, was used as the actuation source instead of the external vibration generator. Results indicate local expansion of brain parenchyma upon the arrival of the arterial pulse wave, followed by a slow return to the initial state during the diastolic phase. Numerical values for the pressure wave modulus M were calculated from measured volumetric strain through inversion of the pressure wave equation. Measurement noise was identified as the primary effect causing a severe underestimation of M.
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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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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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Waghorn, Matthew J. "Effect of initial stand spacing and breed on dynamic modulus of elasticity of Pinus radiata." Thesis, University of Canterbury. Forestry, 2006. http://hdl.handle.net/10092/1129.
Full textAbstract:
Wood stiffness or modulus of elasticity (MOE) is one of the most important wood properties for solid timber applications, and as such, the efficacy of wood use, especially for structural timber is strongly related to MOE. MOE in Pinus radiata is highly variable and poorly understood. In this study, the effect of initial stand spacing and breed on outerwood MOE and the vertical distribution of MOE of Pinus radiata was assessed. Understanding positive or negative influences of growth caused by initial stand spacing and genetic material on MOE is appealing because it could enable us to better comprehend how forest growers could adapt silvicultural operations to the demands of wood processing. Physical characteristics of different breeds and propagation methods of Pinus radiata were assessed at a variety of initial stand spacings. Stem diameter, crown height, stem slenderness and branch size were all heavily influenced by stand spacing. Breed had a marginally significant influence on diameter and stem slenderness. Internode length was not affected by stand spacing, but showed sizeable differences, especially between the long internode 870 breed and the remaining growth and form (GF) breeds. Outerwood MOE was significantly (P<0.0001) influenced by stand spacing and breed, but not their interaction (P>0.05). MOE scaled positively with stand spacing. MOE increased by 39% from 5.4 GPa at 209 stems ha-1 to 7.5 GPa at 2551 stems ha-1. The majority of this increase (33%) occurred between 209 and 835 stems ha-1. Physiologically aged cuttings of greater maturation status exhibited greater MOE, with the three-year-old cuttings being stiffer than the one-year-old cuttings, seedlings from the 870, 268 and 850 series, by 15, 17, 22 and 27%, respectively. Stem slenderness exhibited the strongest significant (P<0.0001) relationship with MOE (r2=0.49), followed by green crown height (r2=0.46) and diameter (r2=0.44). Stem slenderness and green crown height had a direct influence on MOE that explained 53% of the variance in MOE. MOE was also significantly (P<0.0001) influenced by spacing and breed when using the resonance technique to assess whole stem MOE. The vertical distribution of MOE showed that the lowest portion of the stem (bolt 1) was approximately 30% less stiff than bolts 2 and 3. After the greatest MOE value had been obtained at bolt 3, MOE gently declined to the top of the measured stem. Variation of MOE within trees was significant (58%) at the high stockings of 1457 and 2551 stems ha-1, but somewhat lower (36%) at the lower stockings. The 870 breed was approximately 8% and 16% stiffer than the 268 and 850 breeding series respectively, across all stockings, with the three-year-old cuttings being 7% stiffer than the one-year-old cuttings. At stockings of 481 stems ha-1 and less, the proportional height at which MOE was greatest within a tree was between 25% and 50% of stem height. At stockings above 481 stems ha-1 the proportional height at which maximum MOE was obtained was between 15% and 40% of stem height. Bolt slenderness was found to be the most significant factor impacting on MOE of the bolt. Regression of critical buckling height against diameter at ground level yielded a scaling exponent of 0.55, which was lower than the scaling exponent of 0.67 predicted with constant density-specific stiffness. There was a tendency for some bolts with lower mean diameter to display significantly higher safety margins than bolts with higher mean diameter, suggesting that the largest bolts, which occur at the base of tree, are the point of most likely critical failure.
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Torres, Donna Schulz 1972. "Effects of modulus of elasticity of collagen sponges on their cell-mediated contraction in vitro." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50056.
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Adem, Hana Hussin. "Modulus of Elasticity Based Method for Estimating the Vertical Movement of Natural Unsaturated Expansive Soils." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31910.
Full textAbstract:
Expansive soils are widely distributed in arid and semi-arid regions around the world and are typically found in a state of unsaturated condition. These soils are constituted of the clay mineral montmorillonite that is highly active and contributes significantly to volume changes of soils due to variations in the natural water content conditions. The volume changes of expansive soils often cause damage to lightly loaded structures. The costs associated with the damage to lightly loaded structures constructed on expansive soils in the United States alone were estimated as $2.3 billion per year in 1973, which increased to $13 billion per year by 2009. In other words, these damages have increased more than five fold during the last four decades. Similar trends in damages were also reported in other countries (e.g., Australia, China, France, Saudi Arabia, United Kingdom, etc.).
Numerous methods have been proposed in the literature over the past 50 years for the prediction of the volume change movement of expansive soils. However, the focus of these methods has been towards estimating the maximum potential heave, which occurs when soils attain the saturation condition. The results of heave estimation considering saturated soil conditions are not always useful in engineering practice. This is because most of damages due to expansive soils often occur prior to reaching the saturation condition. A reliable design of structures on expansive soils is likely if the anticipated soil movements in the field can be reliably estimated over time, taking into account the influence of environmental factors. Limited studies are reported in the literature during the past decade in this direction to estimate/predict the expansive soil movements over time. The existing methods, however, suffer from the need to run expensive and time consuming tests. In addition, verification of these studies for different natural expansive soils has been rather limited.
A simple approach, which is referred to as a modulus of elasticity based method (MEBM), is proposed in this study for the prediction of the heave/shrinkage movements of natural expansive soils over time. The proposed MEBM is based on a simplified constitutive relationship used for the first time to estimate the vertical soil movements with respect to time in terms of the matric suction variations and the corresponding values of the modulus of elasticity. The finite element program VADOSE/W (Geo-Slope 2007) for simulating the soil-atmospheric interactions is used as a tool to estimate the changes in matric suction over time. A semi-empirical model that was originally proposed by Vanapalli and Oh (2010) for fine-grained soils has been investigated and extended for unsaturated expansive soils to estimate the variation of the modulus of elasticity with respect to matric suction in the constitutive relationship of the proposed method. The MEBM has been tested for its validity in five case studies from the literature for a wide variety of site and environmental conditions, from Canada, China, and the United States. For each case study, factors influencing the volume change behavior of soils, such as climate conditions, soil cracks, lawn irrigation, and cover type (pavement, vegetation), are successfully modeled over the period of each simulation. The proposed MEBM provides good predictions of soil movements with respect to time for all the case studies. The MEBM is simple and efficient for the prediction of vertical movements of natural expansive soils underlying lightly loaded structures.
In addition, a new dimensionless model is also proposed, based on the dimensional analysis approach, for the estimation of the modulus of elasticity which can also be used in the constitutive relationship of the MEBM. The dimensional model is rigorous and takes into account the most significant influencing parameters such as matric suction, net confining stress, initial void ratio, and degree of saturation. This model provides a comprehensive characterization of the modulus of elasticity of expansive soils under unsaturated conditions for different scenarios of loading conditions (i.e., both lightly and heavily loaded structures).
The results of the present study are encouraging for proposing guidelines based on further investigations and research studies for the rational design of pavements, shallow and deep foundations placed on/in expansive soils using the mechanics of unsaturated soils.
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Gao, Liang. "Ultrasound Elasticity Imaging of Human Posterior Tibial Tendon." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338897.
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Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, it could be used to quantify the severity of tendonosis and help determine the appropriate treatment. Ultrasound elasticity imaging (UEI) is a real-time, noninvasive technique to objectively measure mechanical properties in soft tissue. It consists of acquiring a sequence of ultrasound frames and applying speckle tracking to estimate displacement and strain at each pixel. The goals of my dissertation were to 1) use acoustic simulations to investigate the performance of UEI during tendon deformation with different geometries; 2) develop and validate UEI as a potentially noninvasive technique for quantifying tendon mechanical properties in human cadaver experiments; 3) design a platform for UEI to measure mechanical properties of the PTT in vivo and determine whether there are detectable and quantifiable differences between healthy and diseased tendons. First, ultrasound simulations of tendon deformation were performed using an acoustic modeling program. The effects of different tendon geometries (cylinder and curved cylinder) on the performance of UEI were investigated. Modeling results indicated that UEI accurately estimated the strain in the cylinder geometry, but underestimated in the curved cylinder. The simulation also predicted that the out-of-the-plane motion of the PTT would cause a non-uniform strain pattern within incompressible homogeneous isotropic material. However, to average within a small region of interest determined by principal component analysis (PCA) would improve the estimation. Next, UEI was performed on five human cadaver feet mounted in a materials testing system (MTS) while the PTT was attached to a force actuator. A portable ultrasound scanner collected 2D data during loading cycles. Young's modulus was calculated from the strain, loading force and cross sectional area of the PTT. Average Young's modulus for the five tendons was (0.45±0.16GPa) using UEI. This was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52±0.18GPa). We also calculated the scaling factor (0.12±0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the human PTT. Finally, we built a custom ankle inversion platform for in vivo imaging of human subjects (eight healthy volunteers and nine advanced PTTD patients). We found non-linear elastic properties of the PTTD, which could be quantified by the slope between the elastic modulus (E) and the inversion force (F). This slope (ΔE/ΔF), or Non-linear Elasticity Parameter (NEP), was significantly different for the two groups: 0.16±0.20 MPa/N for healthy tendons and 0.45±0.43 MPa/N for PTTD tendons. A receiver operating characteristic (ROC) curve revealed an area under the curve (AUC) of 0.83±0.07, which indicated that the classifier system is valid. In summary, the acoustic modeling, cadaveric studies, and in vivo experiments together demonstrated that UEI accurately quantifies tendon mechanical properties. As a valuable clinical tool, UEI also has the potential to help guide treatment decisions for advanced PTTD and other tendinopathies.
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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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Zoric, Branislav. "Modelling the influence of stocking on longitudinal and radial variation in wood properties of Pinus radiata on a warm Northland site." Thesis, University of Canterbury. School of Forestry, 2009. http://hdl.handle.net/10092/2564.
Full textAbstract:
The objective of this study was to determine how final stocking influences tree growth and radial and longitudinal variation in wood properties at a Pinus radiata D. Don plantation located at one of the warmest forest sites in New Zealand, Forsyth Downs forest in Northland. This thesis addressed both the effect of stocking on stand basal area, height, diameter and branch diameter and the effect of stocking on wood properties microfibril angle (MFA), module of elasticity and density. Finally, how ring width influences wood properties and whether this variable accounts for the treatment effects was investigated.
Stocking, height and ring number and all interactions between these variables significantly affected ring width. Ring width by itself was significant as a predictor of density, but when it was combined with other class level variables it was insignificant (i.e. does not account for treatment effects), and it did not add anything to a model with only class effects. There was a significant impact of ring number on density while ring width was insignificant in the same model.
MFA was significantly affected by ring width, height and ring number in the tree, and all interactions, apart from the three way interaction, but not by stocking. Ring width was significant in the MFA model both by itself and when it was combined with other variables. Ring width accounted for the stocking effect.
The best model of MOE included the class level effects of stocking, height and ring number within the tree, and all interactions between these variables, and ring width, as a continuous variable. While there was a significant effect between stockings this was relatively weak compared to the other main effects. Ring width largely accounted for the effect of stocking, but not that of ring number, or height.
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Hermawan, Vera. "Experimental techniques to determine the Young's Modulus of the trachea thesis submitted in partial fulfilment of the degree of Master of Engineering, Auckland University of Technology, September 2004." Full thesis. Abstract, 2004.
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