Dissertations / Theses: 'Normal concrete'

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Saffari-Shooshtari, Nader. "Constant normal stiffness direct shear testing of chalk-concrete interfaces." Thesis, University of Surrey, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328819.

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Plusa, Mariusz. "The influence of wooden fibres on chosen properties on normal contretes." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1063.

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The purpose of work was to show properties of concrete modified with wooden fibres and to compare whem with unmodified concrete in order to show influence of these wooden fibres on chosen properties and to check if using of these types of admixtures is benificial in economical and technical point of view.

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Melo, Weslley Imperiano Gomes de. "Análise dos domínios de deformação de seções retangulares de concreto armado submetidas à flexão composta normal – segundo NBR 6118/14." Universidade Federal da Paraíba, 2015. http://tede.biblioteca.ufpb.br:8080/handle/tede/7698.

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Submitted by Maike Costa (maiksebas@gmail.com) on 2016-01-07T11:50:38Z No. of bitstreams: 1 arquivototal.pdf: 2770765 bytes, checksum: 227f3aba263e8ceeb937ff453f784cd5 (MD5) Made available in DSpace on 2016-01-07T11:50:38Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2770765 bytes, checksum: 227f3aba263e8ceeb937ff453f784cd5 (MD5) Previous issue date: 2015-08-28 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES In order to follow the development occurred in the field of concrete technology, which has permitted the achievement of concrete with increased resistance, brazilian norms ABNT NBR 6118:2014 has incorporated in the latest version in force just over a year, considerations about the concrete of strength classes higher à − 50 limitados à classe − 90. These concretes are more fragile and the constitutive relations for those used to the − 50 class had to be modified to take into account this fact. Taken as fixed parameters to calculate the resistance calculation requests, such as the last bending deformation of concrete, become dependent on its characteristic resistance. This makes the wording used for the design of reinforced concrete sections subject to normal effort and bending moment has to be updated. In this work were developed tables for sizing the flexo - traction and flexo- compression rods and sections of reinforced concrete columns, in accordance with the latest version of NBR 6118. We present the expressions and procedures employed in generating these tables, taking into account the concrete to − 90. It indicates the procedure used to obtain the requests pillars, with which it comes to dimensioning. Classes of − 20 to − 50 the tables are unique to all intermediate classes. − 55 à − 90, each class corresponds to a table. Four arrangements of reinforced were used, and considered three departures from the armor of concrete edge. Are examples of application of the tables. The results were consistent with what was developed. No sentido de acompanhar o desenvolvimento ocorrido no campo da tecnologia do concreto, que tem possibilitado a obtenção de concretos com cada vez maior resistência, a norma brasileira ABNT NBR 6118:2014 incorporou na sua última versão, em vigor há pouco mais de um ano, considerações sobre os concretos das classes de resistência superiores à − 50 limitados à classe − 90. Esses concretos são mais frágeis e as relações constitutivas utilizadas para aqueles até à classe − 50 tiveram que ser modificadas, para levar em conta esse fato. Parâmetros tidos como fixos para o cálculo das solicitações resistentes de cálculo, como por exemplo a deformação última do concreto em flexão, passam a depender da sua resistência característica. Isto faz com que a formulação utilizada para o dimensionamento das seções de concreto armado submetidos a esforço normal e momento fletor tenha que ser atualizada. Neste trabalho foram desenvolvidas tabelas para o dimensionamento a flexo-tração e flexo-compressão de seções de tirantes e pilares de concreto armado, em conformidade com a última versão da NBR 6118. Apresentam-se as expressões e o procedimento empregados na geração destas tabelas, levando em consideração os concretos até − 90. Indica-se o procedimento utilizado para obtenção das solicitações em pilares, com as quais se procede ao dimensionamento. Das classes − 20 à − 50 as tabelas são únicas para todas as classes intermediárias. De − 55 à − 90, a cada classe corresponde uma tabela. Foram utilizadas quatro arranjos de armaduras, e considerados três afastamentos da armadura à borda do concreto. Apresentam-se exemplos de aplicação das tabelas. Os resultados mostraram coerência com o que foi desenvolvido.

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Shayanfar, Mohsen Ali. "Nonlinear finite element analysis of normal and high strength concrete structures." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40000.

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This thesis presents a new hypoelasticity model which was implemented in nonlinear finite formulation to analyze normal and high strength reinforced concrete structures under both monotonically increasing and reversed cyclic loadings. The model includes a new hypoelasticity constitutive relationship utilizing the rotations of material axis through subsequent iterations, employment of both fixed and rotating crack models, compressive strength degradation in post-cracking regime, new uniaxial stress-strain relationships for concrete under monotonically increasing and reversed cyclic loadings, accounting for mesh sensitivity, and utilizing the tensile strength degradation due to extensive internal microcracking of the concrete. The model can account for high nonlinearity of the stress-strain behaviour of concrete in the pre-peak regime, the softening behaviour of concrete in the post-peak regime, the stiffness degradation caused by the extension of microcracks during subsequent unloadings and reloadings and the irrecoverable volume dilatation at high levels of compressive load. The effect of element size on different behavioural aspects of reinforced concrete elements including the load-displacement and load-strain characteristics, crack pattern and ultimate load are discussed along with a comparison with the experimental data where available. Various analyses indicated that the length of the descending branch of the tensile stress-strain curve of concrete defined by the value of the ultimate tensile strain, $ varepsilon sb{ rm tu}$, has a significant effect on the computed results. If the value of $ varepsilon sb{ rm tu}$ is adjusted appropriately according to the element size, it can help eliminate the mesh sensitivity drawback. To adjust an appropriate value for $ varepsilon sb{ rm tu}$, two models have been used: (a) crack band model, as a function of the fracture energy, mesh size and tensile strength of concrete, and (b) a new proposed model as a function of only the element size. The analytical results obtained using the different models are compared with the experimental results; the proposed model gives good agreement. The proposed formula is very simple and can be used for both square and non-square elements. The effect of steel reinforcement details on the general behaviour of the structure and its mode of failure, the criterion for using the rotating crack model versus the fixed crack model, and the importance of compressive strength degradation in the post-crack regime are established using detailed analysis of five shear panels tested by Vecchio and Collins (1982). The effect of a sudden drop of the stress after the tensile strength of concrete has been exceeded on the load-deflection response, the ductility ratio and the crack pattern for two high strength concrete beams are also examined. Further analyses of a squat shear wall and a shear panel are carried out to examine the reliability of the computer program HODA developed in this study for analysis of concrete structures under both monotonic and reversed cyclic loads. Complete response of three structural walls in a low-rise building is studied under monotonically increasing loads until failure using the nonlinear finite elements program HODA. The influence of the tension-stiffening, steel strain-hardening on the load-deflection response and the ultimate load are studied for the case of the rectangular wall. The influence of smeared steel idealization and bar elements idealization on the wall response are also investigated. The ultimate loads of walls are compared with the values calculated using the current CSA Standard CAN3-A23.3-M84. (Abstract shortened by UMI.)

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Saevarsdottir, Thorbjoerg. "The structural, serviceability and durability performance of variable density concrete panels." Thesis, University of Canterbury. Civil Engineering, 2008. http://hdl.handle.net/10092/1237.

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Conventional concrete is a poor insulating material but has good thermal mass, while lightweight concrete provides good insulation at the price of thermal mass. Precast concrete wall systems have not been widely used in residential homes due to poor thermal and acoustic performance, despite being high quality products that are easy to construct. The variable density concrete panel was designed to combine good thermal storage, insulation and high quality precast concrete. It is produced from a single concrete mix which is vibrated to get a lightweight top layer and a normal/heavyweight bottom layer. The lightweight layer is the wall exterior, having low thermal conductivity providing good thermal insulation while the normal/heavyweight layer is the dense wall interior, having high specific heat to provide good thermal mass and sufficient strength for construction handling and to withstand service loads. The intention of this research was to estimate the hardened performance; that is the structural, serviceability and durability performance of the variable density concrete panel. Further developments to the mix design were made where the fresh properties were measured and thermal performance estimated on hardened specimens. Most of the major technical concerns were proved not being as severe as first thought, making the production of variable density concrete panels promising. To ensure that the variable density concrete would stratify, the concrete mix had to have defined fresh properties. Defined rheological ranges gave a good indication of the stratification potential, but the degree of stratification was also found to be dependent on the intensity and time of vibration. Slump flow had to be within a certain range to achieve good stratification but this alone did not guarantee stratification. Variable density concrete was found to have adequate strength capacity both in axial compression and in tension for likely service loads but the strength required to withstand handling loads at early ages was not assessed. The strength of the variable density concrete was found to be affected by several factors such as; degree of stratification, relative strength and thickness of the layers, curing environment and amount of defects. As the stratification of the concrete increased the thermal insulation improved whereas the strength decreased. Warping was found not to significantly affect the serviceability of panels despite differential shrinkage within the element. The amount of warping was mainly related to the degree of stratification. Warping decreased with better stratification as more stress and strain was relieved in the lightweight layer. The lightweight concrete was significantly weaker as well as being less stiff than the structural concrete and therefore creeps to follow the structural concrete. The thermal properties aimed for were generally not reached, but these mixes were not designed to optimise the thermal performance and were tested before the concrete was fully dried. This increased thermal conductivity and therefore reduced the measured R-values. Stratified concrete had good absorption resistance, poor permeability properties and was highly porous. If the concrete was over-vibrated it tended to have a rough surface finish that would require a coating. Delamination of the panels was not assessed in this research but is a likely mode of failure.

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Doh, Jeung-Hwan, and n/a. "Experimental and Theoretical Studies of Normal and High Strength Concrete Wall Panels." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030605.114125.

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The wall design equations available in major codes of practice (e.g. AS3600 and ACI318) are intended for the design of normal strength concrete load bearing walls supported at top and bottom only. These codes fail to recognise any contribution to load capacity from restraints on the side edges. They also fail to give guidance on the applicability of the equations to high strength concrete. Further, they do not consider slender walls. In many situations walls have side edges restrained and are composed of high strength concrete with high slenderness ratios. The recognition of these factors in the codes would result in thinner walls and consequently savings in construction costs. In this thesis, the focus is on the development of a design formula and new design methods for axially loaded reinforced concrete wall panels. The design of walls having side restraints and being composed of high strength concrete is given particular attention. An experimental program has been undertaken to obtain data for the derivation of applicable formulae and to verify the analytical methods developed herein. Note that, the test results and other data available in published literature have also been used to develop the design formula. The formula encompasses effective length, eccentricity and slenderness ratio factors and is proposed for normal and high strength concrete walls simply supported at top and bottom only (one-way) and simply supported on all four sides (two-way). The major portion of the experimental program focuses on a series of normal and high strength concrete walls simply supported at top and bottom only (one-way), and simply supported on all four sides (two-way) with eccentric axial loading. The behaviour of the test panels is noted, particularly the difference between the normal and high strength concrete panels. A Layer Finite Element Method (LFEM) is used as an analytical tool for walls in two-way action. The LFEM gives comparable results to the test data and the proposed design formula. As part of the research, a program named WASTABT has also been developed to implement a more accurate analytical method involving the instability analysis of two-way action walls. WASTABT is proven to be a useful design tool in situations where the walls have (i) various reinforcement ratio in one or two layers; (ii) composed of normal or high strength concrete; (iii) various eccentricity.

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Salzmann, Angela, and n/a. "Damping Characteristics of Reinforced and Prestressed Normal- and High-Strength Concrete Beams." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040430.133844.

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In the last few decades there has been a significant increase in the design strength and performance of different building materials. In particular, new methods, materials and admixtures for the production of concrete have allowed for strengths as high as 100 MPa to be readily available. In addition, the standard manufactured yield strength of reinforcing steel in Australia has increased from 400 MPa to 500 MPa. A perceived design advantage of higher-strength materials is that structural elements can have longer spans and be more slender than previously possible. An emerging problem with slender concrete members is that they can be more vulnerable to loading induced vibration. The damping capacity is an inherent fundamental quantity of all structural concrete members that affects their vibrational response. It is defined as the rate at which a structural member can dissipate the vibrational energy imparted to it. Generally damping capacity measurements, to indicate the integrity of structural members, are taken once the structure is in service. This type of non-destructive testing has been the subject of much research. The published non-destructive testing research on damping capacity is conflicting and a unified method to describe the effect of damage on damping capacity has not yet been proposed. Significantly, there is not one method in the published literature or national design codes, including the Australian Standard AS 3600-2001, available to predict the damping capacity of concrete beam members at the design stage. Further, little research has implemented full-scale testing with a view to developing damping capacity design equations, which is the primary focus of this thesis. To examine the full-range damping behaviour of concrete beams, two categories of testing were proposed. The categories are the 'untested' and 'tested' beam states. These beam states have not been separately investigated in previous work and are considered a major shortcoming of previous research on the damping behaviour of concrete beams. An extensive experimental programme was undertaken to obtain residual deflection and damping capacity data for thirty-one reinforced and ten prestressed concrete beams. The concrete beams had compressive strengths ranging between 23.1 MPa and 90.7 MPa, reinforcement with yield strengths of 400 MPa or 500 MPa, and tensile reinforcement ratios between 0.76% and 2.90%. The full- and half-scale beams tested had lengths of 6.0 m and 2.4 m, respectively. The testing regime consisted of a series of on-off load increments, increasing until failure, designed to induce residual deflections with increasing amounts of internal damage at which damping capacity (logarithmic decrement) was measured. The inconsistencies that were found between the experimental damping capacity of the beams and previous research prompted an initial investigation into the data obtained. It was found that the discrepancies were due to the various interpretations of the method used to extract damping capacity from the free-vibration decay curve. Therefore, a logarithmic decrement calculation method was proposed to ensure consistency and accuracy of the extracted damping capacity data to be used in the subsequent analytical research phase. The experimental test data confirmed that the 'untested' damping capacity of reinforced concrete beams is dependent upon the beam reinforcement ratio and distribution. This quantity was termed the total longitudinal reinforcement distribution. For the prestressed concrete beams, the 'untested' damping capacity was shown to be proportional to the product of the prestressing force and prestressing eccentricity. Separate 'untested' damping capacity equations for reinforced and prestressed concrete beams were developed to reflect these quantities. To account for the variation in damping capacity due to damage in 'tested' beams, a residual deflection mechanism was utilised. The proposed residual deflection mechanism estimates the magnitude of permanent deformation in the beam and attempts to overcome traditional difficulties in calculating the damping capacity during low loading levels. Residual deflection equations, based on the instantaneous deflection data for the current experimental programme, were proposed for both the reinforced and prestressed concrete beams, which in turn were utilised with the proposed 'untested' damping equation to calculate the total damping capacity. The proposed 'untested' damping, residual deflection and total damping capacity equations were compared to published test data and an additional series of test beams. These verification investigations have shown that the proposed equations are reliable and applicable for a range of beam designs, test setups, constituent materials and loading regimes.

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Kodkani, Shilpa. "Interface durability of externally bonded GFRP to normal and high-performance concrete." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3601.

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Thesis (M.S.)--West Virginia University, 2004. Title from document title page. Document formatted into pages; contains xiii, 147 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 141-147).

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15

Doh, Jeung-Hwan. "Experimental and Theoretical Studies of Normal and High Strength Concrete Wall Panels." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/366176.

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The wall design equations available in major codes of practice (e.g. AS3600 and ACI318) are intended for the design of normal strength concrete load bearing walls supported at top and bottom only. These codes fail to recognise any contribution to load capacity from restraints on the side edges. They also fail to give guidance on the applicability of the equations to high strength concrete. Further, they do not consider slender walls. In many situations walls have side edges restrained and are composed of high strength concrete with high slenderness ratios. The recognition of these factors in the codes would result in thinner walls and consequently savings in construction costs. In this thesis, the focus is on the development of a design formula and new design methods for axially loaded reinforced concrete wall panels. The design of walls having side restraints and being composed of high strength concrete is given particular attention. An experimental program has been undertaken to obtain data for the derivation of applicable formulae and to verify the analytical methods developed herein. Note that, the test results and other data available in published literature have also been used to develop the design formula. The formula encompasses effective length, eccentricity and slenderness ratio factors and is proposed for normal and high strength concrete walls simply supported at top and bottom only (one-way) and simply supported on all four sides (two-way). The major portion of the experimental program focuses on a series of normal and high strength concrete walls simply supported at top and bottom only (one-way), and simply supported on all four sides (two-way) with eccentric axial loading. The behaviour of the test panels is noted, particularly the difference between the normal and high strength concrete panels. A Layer Finite Element Method (LFEM) is used as an analytical tool for walls in two-way action. The LFEM gives comparable results to the test data and the proposed design formula. As part of the research, a program named WASTABT has also been developed to implement a more accurate analytical method involving the instability analysis of two-way action walls. WASTABT is proven to be a useful design tool in situations where the walls have (i) various reinforcement ratio in one or two layers; (ii) composed of normal or high strength concrete; (iii) various eccentricity. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) School of Engineering Full Text

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Salzmann, Angela. "Damping Characteristics of Reinforced and Prestressed Normal- and High-Strength Concrete Beams." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/366888.

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In the last few decades there has been a significant increase in the design strength and performance of different building materials. In particular, new methods, materials and admixtures for the production of concrete have allowed for strengths as high as 100 MPa to be readily available. In addition, the standard manufactured yield strength of reinforcing steel in Australia has increased from 400 MPa to 500 MPa. A perceived design advantage of higher-strength materials is that structural elements can have longer spans and be more slender than previously possible. An emerging problem with slender concrete members is that they can be more vulnerable to loading induced vibration. The damping capacity is an inherent fundamental quantity of all structural concrete members that affects their vibrational response. It is defined as the rate at which a structural member can dissipate the vibrational energy imparted to it. Generally damping capacity measurements, to indicate the integrity of structural members, are taken once the structure is in service. This type of non-destructive testing has been the subject of much research. The published non-destructive testing research on damping capacity is conflicting and a unified method to describe the effect of damage on damping capacity has not yet been proposed. Significantly, there is not one method in the published literature or national design codes, including the Australian Standard AS 3600-2001, available to predict the damping capacity of concrete beam members at the design stage. Further, little research has implemented full-scale testing with a view to developing damping capacity design equations, which is the primary focus of this thesis. To examine the full-range damping behaviour of concrete beams, two categories of testing were proposed. The categories are the 'untested' and 'tested' beam states. These beam states have not been separately investigated in previous work and are considered a major shortcoming of previous research on the damping behaviour of concrete beams. An extensive experimental programme was undertaken to obtain residual deflection and damping capacity data for thirty-one reinforced and ten prestressed concrete beams. The concrete beams had compressive strengths ranging between 23.1 MPa and 90.7 MPa, reinforcement with yield strengths of 400 MPa or 500 MPa, and tensile reinforcement ratios between 0.76% and 2.90%. The full- and half-scale beams tested had lengths of 6.0 m and 2.4 m, respectively. The testing regime consisted of a series of on-off load increments, increasing until failure, designed to induce residual deflections with increasing amounts of internal damage at which damping capacity (logarithmic decrement) was measured. The inconsistencies that were found between the experimental damping capacity of the beams and previous research prompted an initial investigation into the data obtained. It was found that the discrepancies were due to the various interpretations of the method used to extract damping capacity from the free-vibration decay curve. Therefore, a logarithmic decrement calculation method was proposed to ensure consistency and accuracy of the extracted damping capacity data to be used in the subsequent analytical research phase. The experimental test data confirmed that the 'untested' damping capacity of reinforced concrete beams is dependent upon the beam reinforcement ratio and distribution. This quantity was termed the total longitudinal reinforcement distribution. For the prestressed concrete beams, the 'untested' damping capacity was shown to be proportional to the product of the prestressing force and prestressing eccentricity. Separate 'untested' damping capacity equations for reinforced and prestressed concrete beams were developed to reflect these quantities. To account for the variation in damping capacity due to damage in 'tested' beams, a residual deflection mechanism was utilised. The proposed residual deflection mechanism estimates the magnitude of permanent deformation in the beam and attempts to overcome traditional difficulties in calculating the damping capacity during low loading levels. Residual deflection equations, based on the instantaneous deflection data for the current experimental programme, were proposed for both the reinforced and prestressed concrete beams, which in turn were utilised with the proposed 'untested' damping equation to calculate the total damping capacity. The proposed 'untested' damping, residual deflection and total damping capacity equations were compared to published test data and an additional series of test beams. These verification investigations have shown that the proposed equations are reliable and applicable for a range of beam designs, test setups, constituent materials and loading regimes. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) School of Engineering Full Text

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Lee, Dong-Jun. "Experimental and Theoretical Studies of Normal and High Strength Concrete Wall Panels with Openings." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366995.

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The simplified wall design formulae specified in the Australian (AS3600) and American (ACI318) concrete standards are intended for the design of normal strength concrete load bearing walls supported at top and bottom only. These practical codes fail to recognise any contribution to load capacity from restraints on all four sides, and do not provide recommendations and design equations for walls with openings (window and door). Also the current code methods are not applicable to the design of walls with high strength concrete (f’c>65MPa) or high slenderness ratios (H/tw>30). In many practical situations wall panels are restrained on all four sides and have openings. In other cases, high strength concrete walls may have reduced their thickness leading to a high slenderness ratio. The recognition and inclusion of such factors lacking in the current codes would result in more reliable and applicable design methods. A total of forty-seven (47) reinforced concrete wall panels were tested in the laboratory in three stages. Seventeen (17) walls with one and two openings in one-way action were tested in Stage one and eighteen (18) identical walls in two-way action were tested in Stage two. In the first two stages, the test panels had slenderness ratios between 30 and 40 and were of higher concrete strengths from 50MPa to 100MPa, and were subjected to a uniformly distributed axial load with an eccentricity of tw/6. In addition to highlighting the experimental set-up, typical crack patterns, failure modes, load- deflection behaviour and ultimate loads were also reported in some detail. Finally twelve (12) wall panels were tested in Stage three to investigate the behaviour of concrete wall panels with various opening configurations including wide window and door type with asymmetric location. The test panels had a constant slenderness ratio of 30 and a concrete strength of 65MPa. The same eccentric loading was applied and the panels were tested in both one- and two-way action. Utilising these test results, an empirical formula predicting the ultimate load of walls with openings was proposed. A favourable comparison between the predicted results and the test data (including the present and other experimental test results) indicates that the proposed formula is accurate and reliable for use in design. A numerical study was also undertaken to verify the effectiveness of the Layered Finite Element Method (LFEM) in predicting the failure characteristics of reinforced concrete walls with openings. The LFEM was used to model, six (6) normal strength concrete walls tested by Saheb and Desayi and thirty-five (35) concrete wall panels with openings tested in this research. The ultimate loads, load-deflection responses up to failure, deflected shapes and crack patterns predicted by the LFEM were compared favourably to the experimental observations. The comparative study also confirmed that the LEFM is a reliable and effective numerical modelling technique for determining ultimate load capacity of high strength concrete walls with high slenderness ratio and various opening configurations. Upon verification, the LFEM was then used as an effective tool to undertake three parametric studies, on a wide range of opening configurations, slenderness ratios and concrete strengths. The purpose of these parametric studies was threefold: (1) to provide missing data that were not covered by the code methods and existing empirical formulae due to their limited scope; (2) to conduct LFEM simulations which helped to reduce the number of labour intensive and very costly laboratory tests; (3) to validate the performance of the proposed formula in predicting the load carrying capacity of wall panels with openings. In total, 20, 64 and 108 wall models were analysed respectively for three parametric studies. The study confirms the accuracy and reliability of both the LFEM and the proposed formula. To this end, both the LFEM and the proposed formula can be used as an effective tool for the analysis and design of normal and high strength concrete walls with openings and high slenderness ratios performing in both one-and two- way action. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) Griffith School of Engineering Science, Environment, Engineering and Technology Full Text

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Júnior, Odinir Klein. "Pilares de concreto armado em situação de incêndio submetidos à flexão normal composta." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-17082011-154210/.

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Segundo a legislação brasileira, as estruturas de concreto armado devem ser verificadas em situação de incêndio, de modo a assegurar a capacidade portante para permitir a fuga dos usuários e o combate ao fogo com segurança e minimizar a propagação do incêndio para outros compartimentos. Para estruturas de concreto armado, especial atenção deve ser dada aos pilares. A redução da capacidade portante desses elementos é significativa em situação de incêndio e seu colapso pode resultar na instabilidade global da estrutura em certos casos. O cálculo do tempo de resistência ao fogo de pilares de concreto armado, em fase de projeto, é feito normalmente usando métodos simplificados dados pelas normas técnicas. Esses métodos possuem campos de validade limitados e podem apresentar resultados excessivamente seguros (antieconômicos) e em alguns casos contra a segurança. Neste trabalho foi desenvolvida uma ferramenta computacional para o cálculo do tempo de resistência ao fogo de pilares de concreto armado em situação de incêndio, dados os campos de temperaturas simétricos na seção transversal em função do tempo de exposição ao incêndio-padrão. O cálculo do pilar foi baseado no método da estimativa da curvatura dado pelo Eurocode 2 (EN 1992-1-2:2004). A seção transversal foi discretizada em elementos (concreto e aço), na qual as deformações térmicas e as propriedades termomecânicas de cada elemento foram calculadas de acordo com sua temperatura. O método da estimativa da curvatura permite ainda considerar os efeitos da não linearidade geométrica, que geralmente se tornam importantes devido à redução da rigidez do pilar sob temperaturas elevadas. Foram modelados pilares sob flexão normal composta considerando a seção transversal aquecida de forma simétrica. Os resultados do programa foram comparados a resultados de ensaios de laboratórios internacionais, com o objetivo de validar as hipóteses de cálculo adotadas. According to Brazilian Codes, reinforced concrete structures must be verified under high temperatures, in order to assure the load bearing capacity to allow the safe evacuation of the users and the fire fighting and to reduce the fire spread to other compartments. For reinforced concrete structures, the columns must be analyzed carefully. The significant reduction in the load bearing capacity of reinforced concrete columns in fire can lead to collapse, which could result in global instability of the structure in some cases. The calculation of the fire resistance time of reinforced concrete columns, in the design phase, is usually done by means of simplified methods given by the standards. These methods are very limited and can result in excessively safe solutions (uneconomical) or unsafe solutions in some cases. A computational tool was developed for calculating the fire resistance time of reinforced concrete columns in fire, given symmetrical temperature fields in cross section as a function of exposure time to standard fire. The calculation method was developed using the method based on estimation of curvature given by Eurocode 2 (EN 1992-1-2:2004). The cross section was divided into elements (concrete and steel), in which the thermal strain and thermomechanical properties of each element were calculated according to its temperature. The mechanical behavior of the column under uniaxial bending considered the geometrically nonlinear effects of the structure, which generally become important due to reduced stiffness of the column at elevated temperatures. The results of the numerical analysis and experimental results of full-scale laboratory fire tests on concrete columns performed by international researchers were compared in order to validate the main hypothesis adopted.

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Shamsai, Mohammad. "Prefabricated cage system for reinforcing concrete members." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1141744526.

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Luo, Lie, and 罗冽. "Uni-axial behavior of normal-strength concrete filled steel tubular columns with external confinement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49618210.

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This thesis proposes two forms of external confinement for concrete filled steel tubular (CFST) columns. The confinement efficiency is studied by examining the axial strength enhancement and ductility improvement of the CFST columns with external confinement. Due to the heavy demand of confining steel to restore the column ductility in seismic regions, it is more efficient to confine these columns by hollow steel tube to form CFST column. Compared with transverse reinforcing steel, steel tube provides a stronger and more uniform confining pressure to the concrete core, and reduces the steel congestion problem for better concrete placing quality. The CFST columns are therefore characterised by higher strength, ductility and large energy absorption before failure. However, a major shortcoming of CFST columns is the imperfect steelconcrete interface bonding occurred at the elastic stage as steel dilates more than concrete in compression. This adversely affects the confining effect and decreases the elastic modulus. To resolve the problem, it is proposed in this thesis to use external steel confinement in the forms of rings and ties to restrict the dilation of steel tube. For verification, a series of uni-axial compression test was performed on some CFST columns with external steel rings and ties. From the results, it was found that the external steel rings could improve both the axial strength and stiffness of the CFST columns significantly. However, the steel ties could not improve either the axial strength or elastic stiffness significantly. The confining efficiency was then investigated by comparing the strength of these confined-CFST columns with the reinforced concrete (RC) columns counterparts with the same concrete and steel volume. It is evident that the axial strength of CFST columns is much higher than the RC columns, which suggests that the application of CFST columns can utilise less construction materials and reduce the demolition waste. A theoretical model is also proposed for predicting the axial strength of ring-confined CFST columns. Comparison between the predicted results and the test results obtained by the author and other researchers shows that the proposed model gives good estimation for both unconfined and confined CFST columns. published_or_final_version Civil Engineering Master Master of Philosophy

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Kaufmann, Walter Hans Jakob. "Strength and deformations of structural concrete subjected to in-plane shear and normal forces /." Zurich, 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12711.

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Peng, Jun, and 彭軍. "Effects of strain gradient on maximun concrete stress and flexural capacity of normal-strength RC members." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085787.

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Peng, Jun, and 彭军. "Strain gradient effects on flexural strength and ductility design of normal-strength RC beams and columns." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329630.

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The stress-strain characteristics of concrete developed in flexure is very important for flexural strength design of reinforced concrete (RC) members. In current RC design codes, the stress-strain curve of concrete developed in flexure is obtained by scaling down the uni-axial stress-strain curve to account for the strain gradient effect. Therefore, the maximum concrete stress that can be developed under flexure is smaller than its uni-axial strength, and the use of which always underestimates the flexural strength of RC beams and columns even though the safety factors for materials are taken as unity. Furthermore, the value of strength underestimation was different for RC beams and columns, which indicates that the extent of strain gradient will affect the maximum concrete stress and stress-strain curve developed under flexure. To investigate the maximum concrete stress, 29 column specimens were fabricated and tested in this study. They were divided into 9 groups, each of which was poured from the same batch of concrete and contained specimens with identical cross-section properties. In each group, one specimen was tested under concentric load while the rest was/were subjected to eccentric or horizontal load. To study the strain gradient effects, the ratio of the maximum concrete compressive stress developed in the eccentrically/horizontally loaded specimens to the maximum uni-axial compressive stress developed in the counterpart concentrically loaded specimens, denoted by k3, is determined based on axial force and moment equilibriums. Subsequently, the concrete stress block parameters and the equivalent rectangular concrete stress block parameters are determined. It is found that the ratios of the maximum and equivalent concrete stress to uni-axial cylinder strength, denoted respectively by k3 and , depend significantly on strain gradient, while that of the depth of stress block to neutral axis depth, denoted by , remains relatively constant with strain gradient. Design equations are proposed to relate and  with strain gradient for strength calculation, whose applicability is verified by comparing the strengths of RC beams and columns tested by various researchers with their theoretical strengths predicted by the proposed parameters and those evaluated based on provisions of RC codes. Based on the test results, the stress-strain curve of normal-strength concrete (NSC) developed under strain gradient is derived using least-square method by minimising the errors between the theoretical axial load and moment and the respective measured values. Two formulas are developed to derive the flexural stress-strain curve, whose applicability is verified by comparing the predicted strength with those measured by other researchers. Lastly, the application of the proposed stress-block parameters and stress-strain curve of NSC will be illustrated by developing some charts for flexural strength design of NSC beams and columns. The application will further be extended to develop strength-ductility charts for NSC beams and columns, which enable simultaneous design of strength and ductility. By adopting the proposed design charts, the flexural strength design, as well as that of the plastic hinge forming mechanism during extreme events, will be more accurate. The resulting design will be safer, more environmentally friendly and cost effective. published_or_final_version Civil Engineering Doctoral Doctor of Philosophy

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Peng, Jun. "Effects of strain gradient on maximun concrete stress and flexural capacity of normal-strength RC members." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085787.

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Desai, Satish Balkrishna. "Shear resistance at normal and high temperatures of reinforced concrete members with links and central bars." Thesis, City University London, 1995. http://openaccess.city.ac.uk/7734/.

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This report, in its earlier part, reviews some important aspects of research and development in the design of reinforced concrete members against shear. This review includes a study of the background of design method for shear resistance given in the British Standard code of practice and a comparison of this method with the methods recommended by the Eurocode and the American code of practice for concrete structures. Based on this study, the contributions to shear resistance of a member afforded by concrete, the tension steel and the links are identified. The influence of these constituents on the modes of transfer of shear has been investigated, in order to examine the method for estimating the overall shear resistance of the member. A test programme is reported, concerning horizontal steel at the centre of the cross-section as an alternative form of shear reinforcement. Tests on some fifty beam specimens were carried out, allowing for variation in the main parameters; for example, the span of beams, the strength of concrete and the amount of tension steel. Also, some beams did not have any shear reinforcement and some were provided with central bars, some with links and some with the combination of central bar and links. A design method has been derived on the basis of these tests, for estimating the contribution of central steel to the shear resistance of beams. This method has been verified with the help of measurement of stresses in the web steel, using strain gauges fixed on the reinforcement of two of the test beams. A similar design method is proposed for using central steel to enhance the punching shear resistance of slabs, based on the results of tests on fifteen slab specimens, allowing for variations in thickness of slabs, the strength of concrete and the amount of central steel. The design methods for beams and slabs have been examined with the help of a finite element computer program capable of using the non-linear properties of structural materials. Finally, the normal temperature design rules for beams have been modified and a method is proposed for design of beams exposed to high temperatures. This method has been verified on the basis of fire exposure tests on ten beam specimens provided with differing amount and type of web steel and with gauges for measurement of temperatures inside, the beams.

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Runguphan, Theerawat. "Investigation on the use of burnt colliery spoil as aggregate in low to normal strength concrete." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609568.

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Haach, Vladimir Guilherme. "Análise teórico-experimental da influência da força normal em nós de pórtico externos de concreto armado." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-26072005-161151/.

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Os nós de pórtico são locais de mudança de direção do eixo da estrutura, logo são regiões descontínuas, ou seja, as hipóteses de Bernoulli de deformações lineares ao longo da seção transversal não são válidas. Sendo assim os métodos convencionais de dimensionamento não se aplicam a esta região. Além disso, são regiões problemáticas também do ponto de vista construtivo, por apresentarem geralmente uma alta taxa de armadura em dimensões reduzidas. Diversas são as variáveis que influenciam o comportamento dos nós de pórtico externos, dentre elas está a força normal aplicada no pilar. Esta variável foi observada por diversos pesquisadores (Parker & Bullman, 1997; Scott et al., 1999; Hwang & Lee, 1999; Bakir & Boduroglu, 2002; Hegger et al., 2003), porém com grandes divergências de opiniões sobre sua influência na ligação. Desta forma, este trabalho visa analisar a influência da força normal no comportamento de nós de pórtico externos de concreto armado. Neste sentido é apresentada uma extensa pesquisa bibliográfica abordando trabalhos experimentais e modelos teóricos propostos para o dimensionamento dos nós (bielas e tirantes). Inserindo-se no contexto é analisada a influência da força normal nos nós de pórtico externos por meio da análise experimental de quatro ligações sujeitas a diferentes níveis de força normal, da comparação com os modelos teóricos apresentados e da simulação numérica do nó de pórtico com o aplicativo ABAQUS, utilizando como ferramenta básica o método dos elementos finitos (MEF) The joints are points where the structures axes swerving, therefore they are discontinuous regions, it means, Bernoullis hypotheses of linear deformations over the section are not valid. Consequently the conventional methods of design are not applied to this region. Moreover, the joints are also problematic regions to build, for generally presenting one high reinforcement ratio in reduced geometricals dimensions. The normal force applied in the column is one among several variables that influence exterior joints behavior. This variable was observed by many researchers (Parker & Bullman, 1997; Scott et al., 1999; Hwang & Lee, 1999; Bakir & Boduroglu, 2002; Hegger et al., 2003), however with divergences of opinions on its influence in the connection. So, this work aims to analyze the influence of the normal force in reinforcement concrete exterior joint behavior. In this way an extensive literature review is presented approaching experimental works and proposed theoretical models for the joint design (strut an ties). Inserting the research on the context, the influence of the normal force in exterior joints was done through experimental analysis of four connections with different levels of normal force, comparisons with the theoretical models presented and numerical simulation of the joint using finite elements method (FEM) packages at the software ABAQUS

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Pires, Susana de Lima 1973. "Análise de pilares de concreto armado submetidos à flexão normal composta considerando as não-linearidades física e geométrica." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257731.

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Orientador: Maria Cecília Amorim Teixeira da Silva Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo Made available in DSpace on 2018-08-17T07:55:36Z (GMT). No. of bitstreams: 1 Pires_SusanadeLima_M.pdf: 919425 bytes, checksum: d13d24300a7bb026a2c9352fd83b1c35 (MD5) Previous issue date: 2006 Resumo: Este trabalho apresenta um modelo numérico para o estudo de pilares isolados de concreto armado submetidos à flexão normal composta onde as não linearidades física e geométrica são levadas em conta de maneira rigorosa. O procedimento numérico desenvolvido para o cálculo dos deslocamentos é baseado no Método dos Elementos Finitos. Para a inclusão das não linearidades física e geométrica é utilizado o Método de Newton-Raphson Modificado que é um procedimento iterativo para a determinação de raízes de funções não lineares. A relação tensão-deformação do concreto é representada pelo diagrama parábola-retângulo. O aço é considerado um material elastoplástico perfeito. É admitida perfeita aderência entre o concreto e o aço. São desenvolvidos algoritmos para o dimensionamento de pilares e para o estudo da estabilidade do pilar. É desenvolvido um programa de computador utilizando os algoritmos mencionados acima. A eficiência do programa é verificada por meio da comparação com trabalhos experimentais e com o programa comercial CAD/TQS. Os resultados do dimensionamento feito com o programa proposto apresentaram boa concordância com os dados experimentais selecionados. Finalmente é feito um estudo comparativo entre os resultados do dimensionamento de pilares feito pelo programa elaborado, com os resultados obtidos pelas simplificações admitidas pela Norma Brasileira NBR 6118/2003. Esta comparação mostra que, para os exemplos apresentados, a NBR 6118/2003 superestima o dimensionamento de pilares esbeltos realizados através dos métodos simplificados. Para pilares com índice de esbeltez superiores a 90, a norma está certa em impedir o dimensionamento com os métodos simplificados pois podem apresentar resultados contra a segurança. Os efeitos causados pela deformação lenta não foram incluídos neste trabalho Abstract: This work presents a numerical model for the study of reinforced concrete columns subjected to combined axial load and bending where the geometric and material nonlinearities are rigorously considered. The numerical procedure developed to calculate the displacements is based on the Finite Element Method. An iterative procedure for the determination of roots of nonlinear functions, the Modified Newton-Raphson Method, is used for including nonlinearities. The parabolic-rectangular diagram is adopted as the concrete stress-strain relationship. The steel is considered a perfect elastoplastic material, and a perfect concrete-to-steel bond is admitted. Algorithms are developed for dimensioning and studying the stability of columns. A computer program is developed using the algorithms mentioned above. The efficiency of the program is verified against available experimental data and commercial programs such as CAD/TQS. The values obtained from the program have presented good agreement with experimental data. Finally a comparative study is made among the results of the designed columns with values obtained from Brazilian Code NBR 6118/2003 approaches. This comparison shows that, for the presented examples, NBR 6118/2003 overestimates the slender columns design when using the approaches, and for columns with slenderness index over 90 the code is correct in preventing the design through the simplified methods, for it can lead to unsafe results. The effects caused by the creep are not enclosed in this work Mestrado Estruturas Mestre em Engenharia Civil

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Persson, Axel, and Rikhard Rautjärvi. "Dimensionering av pelare och balkar i ett bostadshus med UHPC, respektive NC : En jämförelsestudie ur aspekten, en hållbar design." Thesis, Högskolan i Halmstad, Akademin för företagande, innovation och hållbarhet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-45327.

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It is a well-known problem that concrete needs to be made more efficient and that it is the large consumption of cement that is the major contributing factor to the nearby need. There is a zero vision of a climate-neutral concrete where all CO2 emissions in the life cycle of the concrete are to be reset by 2050. It is a question of improving, above all, the process of handling CO2 in the production of cement. This study tackles CO2 emissions from the concrete from a holistic perspective, by exploring optimization possibilities when implementing a newly developed concrete in residential buildings, called Ultra High Performance Concrete (UHPC). While it should be a better alternative for the climate, it should also require less material consumption and be more cost-effective in order to create a competitive alternative to the conventional alternative today, called Normal Concrete (NC). UHPC is during a development phase regarding optimization opportunities and it has been proven in several studies to be able to relate better to a sustainable design, based on a total life cycle progression. This applies above all to large and robust bridge structures where large volume differences are available. The idea behind this study is to highlight the question of whether there is an opportunity to get similar results in the construction of less robust components in residential buildings, since the problem with the mix design for UHPC has been the overall high cost in relation to NC. In recent years, this cost has been reduced and now there are opportunities to effectively introduce UHPC into another segment.In this study, columns and beams were dimensioned in a residential NC building and a residential UHPC building with ETABS (CSI 2019). Furthermore, the components of the buildings were compared, based on the aspect of a sustainable design from a total LCA. What was investigated were the differences in total material consumption, CO2 emissions, and costs.The study showed that the UHPC components were better based on all aspects after its total LCA. The total cement consumption was larger, but the building received at the same time an estimated double the lifespan of the NC- building. The total material consumption in the form of total component volumes became smaller, the total annual CO2 emissions became smaller and the total annual costs became smaller as well. Det är ett välkänt problem att betong behöver klimateffektiviseras och att det är den storacementkonsumtionen som är den stora bidragande faktorn till det närliggande behovet. Detfinns en nollvision om en klimatneutral betong där alla CO2- utsläpp under betongenslivscykel (LCA), ska nollställas fram till år 2050. Det är en fråga om att framför allt förbättraprocessen gällande hantering av CO2 vid produktion av cement. Den här studien angriperCO2- utsläppen från betongen ur ett helhetsperspektiv, genom att undersökaoptimeringsmöjligheter vid implementering av en nyutvecklad betong i bostadshus, kalladUltra High Performance Concrete (UHPC). Samtidigt som den ska vara ett bättre alternativför klimatet, ska den också kräva mindre materialåtgång och vara mer kostnadseffektiv föratt kunna skapa ett konkurrenskraftigt alternativ till det konventionella alternativet idag,kallad Normal Concrete (NC). UHPC är under en optimeringsfas och den har bevisats i flerastudier kunna förhålla sig bättre till en hållbar design, utifrån en total LCA. Det gäller framförallt stora och robusta brokonstruktioner där stora volymskillnader är disponibla. Tankenmed den här studien är att lyfta fram frågan om det finns möjlighet att få liknande resultatvid byggnation av mindre robusta komponenter i bostadshus, i ju med att problemet medmix-designen för UHPC, har varit den generella höga kostnaden i förhållande till NC. Påsenare år har den kostnaden kunnat reduceras och nu finns möjligheterna att effektivtkunna införa UHPC till ytterligare ett segment.I studien jämfördes pelare och balkar i ett UHPC- hus med motsvarande komponenter i ettNC- hus utifrån aspekten en hållbar design, ur en total LCA. Husen dimensionerades i ETABS(CSI 2019) utefter samma förutsättningar med hänsyn till kravet på bärförförmågorna. Detutgjorde skillnader hos volymerna på komponenterna, som således påvisade hurmaterialåtgången förändrades. CO2- utsläppen och kostnaderna påverkades avbetongkompositionerna och skillnaderna hos de materiella egenskaperna av respektivebetongtyp. I slutändan redovisades vilken betongtyp som genererade minsta och störstaårliga CO2- utsläpp och kostnader.Resultatet visade att UHPC- komponenterna minskade den totala betongåtgången underbyggprocessen med 27,1%, samt minskade armeringsåtgången med 12,0%, men attcementåtgången nästan fördubblades och motsvarade en ökning på 99,4%. CO2- utsläppenvart således betydligt större efter byggprocessen, men i förhållande till ett totaltlivcykelförlopp, minskade de totala årliga utsläppen med 18,8%. Det fanns en kritisk punktdär UHPC- komponenterna måste ha en LCA på minst 97,5 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala CO2- utsläpp.Kostnaderna vart också betydligt större för UHPC- komponenterna efter byggprocessen,men efter en total LCA, minskade de totala kostnaderna med 39,0%. Det fanns en kritiskpunkt, där LCA- förloppet måste uppgå till minst 73,2 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala kostnader.Enligt det framtagna resultatet fanns det goda möjligheter för pelare och balkar i UHPChuset att förhålla sig bättre utifrån en hållbar design, än vad motsvarande komponenter förNC- huset gjorde, efter en total LCA. Pelare och balkar i bostadshus kan bli ett nytt segmentatt introducera UHPC till, även om pålitligheten för studien är begränsad av betydelsefullafelkällor och tillgängliga kunskaper inom området för närvarande.

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Taillet, Elodie. "Caractérisation des discontinuités dans des ouvrages massifs en béton par la diagraphie électrique de résistivité." Thèse, Université de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/128.

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Résumé : Le vieillissement des ouvrages en béton est une préoccupation majeure affectant la pérennité et l’efficacité des structures. Le maître d’ouvrage se doit de maintenir les fonctions d’usage de la structure tout en gardant une gestion économique efficace. L’objectif final de ces travaux de recherche est, donc de pouvoir renseigner sur l’état global de fissuration de la structure afin d’aider le maître d’ouvrage à respecter ses engagements. Dans cette optique, cette thèse développe une nouvelle technique aidant à la quantification de l’état des ouvrages massifs en béton. Elle s’appuie, pour cela, sur la méthode non-destructive de résistivité électrique en surface, connue pour sa sensibilité face à des facteurs révélateurs d’une altération. Toutefois, à cause de sa dépendance entre la profondeur d’investigation et la résolution, la méthode ne peut pas garantir de l’état global d’un ouvrage. De ce fait, il a été décidé d’utiliser la résistivité électrique via des forages préexistants dans la structure (diagraphie électrique). L’outil utilisé est une sonde en dispositif normal réservée jusqu’à présent pour la prospection pétrolière et hydrogéologique. En plus d’une prospection en profondeur via le forage, cette sonde peut acquérir des informations sur un rayon de 3.2m autour du forage. Cependant, à mesure que le volume de béton sondé augmente, la résolution décroit. La difficulté est donc de pouvoir exploiter les capacités de prospection de la sonde tout en sachant que la résolution faillit. Il s’agit de contourner le problème en maîtrisant les concepts de la diagraphie et son nouveau milieu d’application. Cette thèse est basée sur une première approche numérique permettant d’apporter des corrections sur les données de terrain et de déterminer la sensibilité de l’outil face à de l’endommagement d’ouverture plurimillimétrique à centimétrique. Ceci est validé par des mesures réalisées sur une écluse de la Voie Maritime du Saint-Laurent. Une étude numérique de la réponse de l’outil en fonction des paramètres de fissure tels que l’ouverture, le contraste entre la résistivité de la discontinuité et du béton, et l’extension est réalisée. Elle permet de construire une base de données afin de développer une méthode pour la caractérisation de l’endommagement. Cette méthode s’appuie sur ces réponses diagraphiques pour retrouver les paramètres de fissure recherchés (problème inverse). Nous procédons tout d’abord par une analyse préliminaire se basant sur un croisement des informations apportées par les différentes électrodes de la sonde puis nous optimisons les résultats par la méthode de recuit simulé. La méthode, ainsi développée est ensuite appliquée à un deuxième ouvrage pour en déterminer l’état interne. Ces travaux détectent plusieurs zones endommagées et caractérisent l’une d’elles par une ouverture centimétrique et une extension comprise entre 1.6m et 3.2m. Ces travaux prometteurs, attestent d’un premier diagnostic interne des ouvrages massifs en béton, un enjeu qui restait sans réponses satisfaisantes jusqu’à maintenant. // Abstract : The aging of concrete structures is a major problem affecting their sustainability and their efficiency. The owner must maintain the structure serviceability and provide cost-effective management. The goal of this work is to provide detailed information about the state of cracking inside the structure in order to assist the owner to meet its commitments. In this context, this thesis develops a new technology to assess the condition of mass concrete structures. It relies on a non-destructive method based on electrical resistivity measured from surface, known for its sensitivity to factors associated with concrete deterioration. However, because of its dependence between the investigation depth and the resolution, the method cannot assess the overall state of a structure. Therefore, it was decided to use the electrical resistivity through preexisting boreholes in the structure (electrical logging). The tool used is a normal probe, which has been traditionally used for oil and hydrogeological exploration. In addition to the investigation in depth via boreholes, this probe can get information over a radius of 3.2m around the borehole. However, as the probing volume of concrete increases, the resolution decreases. Difficulty is to use the exploration abilities of the tool, knowing that the resolution is limited. This is to get around the problem by mastering logging concepts and its new application environment. This thesis is based on a first numerical approach to make corrections on field data and to determine the tool sensitivity with regard to the multi-millimeter and centimeter crack size damage. This was validated with measurements made on a full-size lock located on the St. Lawrence Seaway. A numerical study of the tool response versus the discontinuities parameters such as the crack aperture, the resistivity contrast between the discontinuity and the concrete, and the extension was done. It allowed building a database used to develop a method for the characterization of the damage. This method is based on the tool responses to find the crack parameters (inverse problem). First, we proceed with a preliminary analysis based on a cross of information provided by the different electrodes of the probe then we optimize the results by the method of simulated annealing. The characterization method is applied to another structure to quantify its internal state. These studies detect several damaged areas and characterize one of them by a centimeter aperture and an extension between 1.6m and 3.2m. This work attest to a first internal diagnosis of massive concrete structures, an issue that remained without satisfactory answers so far.

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Zangeneh, Kamali Abbas. "Shear Strength of Reinforced Concrete Beams subjected to Blast Loading : Non-linear Dynamic Analysis." Thesis, KTH, Bro- och stålbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104241.

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The experimental investigations performed on the behaviour of reinforce concrete elements subjected to blast loading have revealed that the shear mechanisms and ductility play important roles in the overall response and failure mode of such structures. The main aim of this master thesis is to study the possibility of using finite element method as a tool for predicting the dynamic response of blast loaded reinforced concrete beams and evaluation of their shear strength. In this study, the commercial software, ABAQUS/Explicit has been used by implementing appropriate constitutive material models in order to consider the material nonlinearity, stiffness degradation and strain rate effects. The results of some blast loaded tested beams have been used for verification and calibration of the model. As a secondary objective, the calibrated model used to study the influence of some important factors on the shear strength of reinforced concrete beams and investigate their effects on the failure mode. The results used as a reference and compared with the calculations according to some design codes for blast resistance design. The results of the present research show that the implemented nonlinear finite element model successfully simulates the dynamic responses including displacement/reaction force time histories and induced damage patterns of blast tested beams with reasonable accuracy. The results of performed parametric study confirm that the ductility play important role in the failure behaviour of studied beams. The numerical simulations show that dynamic response of a soft element is more ductile than the stiffer one and the shear forces are thereby limited. Thus, although a soft element fails by large deformations in flexure, a stiff element may experience a brittle shear failure mode for the same load intensity. The comparison between the results of numerical analysis and design codes calculation show that the American approach in shear design of reinforced concrete elements subjected to blast loading is relatively conservative, similar to static design approach and do not consider the effect of ductility in the shear design procedure. On the contrary, the procedure that Swedish guideline implemented somehow considers the effect of ductility on the shear strength of reinforced concrete elements subjected to impulsive loads. Further research should involve the using the developed finite element model as a tool in order to theoretically study the dynamic response of blast loaded reinforced concrete elements and their failure modes. The results of numerical simulations can be used as a reference to derive simplified computational methods for practical design purposes.

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Bian, Jian. "Ultimate flexural limit states analysis of prestressed concrete sleeper." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/63660/1/Jian_Bian_Thesis.pdf.

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Railway is one of the most important, reliable and widely used means of transportation, carrying freight, passengers, minerals, grains, etc. Thus, research on railway tracks is extremely important for the development of railway engineering and technologies. The safe operation of a railway track is based on the railway track structure that includes rails, fasteners, pads, sleepers, ballast, subballast and formation. Sleepers are very important components of the entire structure and may be made of timber, concrete, steel or synthetic materials. Concrete sleepers were first installed around the middle of last century and currently are installed in great numbers around the world. Consequently, the design of concrete sleepers has a direct impact on the safe operation of railways. The "permissible stress" method is currently most commonly used to design sleepers. However, the permissible stress principle does not consider the ultimate strength of materials, probabilities of actual loads, and the risks associated with failure, all of which could lead to the conclusion of cost-ineffectiveness and over design of current prestressed concrete sleepers. Recently the limit states design method, which appeared in the last century and has been already applied in the design of buildings, bridges, etc, is proposed as a better method for the design of prestressed concrete sleepers. The limit states design has significant advantages compared to the permissible stress design, such as the utilisation of the full strength of the member, and a rational analysis of the probabilities related to sleeper strength and applied loads. This research aims to apply the ultimate limit states design to the prestressed concrete sleeper, namely to obtain the load factors of both static and dynamic loads for the ultimate limit states design equations. However, the sleepers in rail tracks require different safety levels for different types of tracks, which mean the different types of tracks have different load factors of limit states design equations. Therefore, the core tasks of this research are to find the load factors of the static component and dynamic component of loads on track and the strength reduction factor of the sleeper bending strength for the ultimate limit states design equations for four main types of tracks, i.e., heavy haul, freight, medium speed passenger and high speed passenger tracks. To find those factors, the multiple samples of static loads, dynamic loads and their distributions are needed. In the four types of tracks, the heavy haul track has the measured data from Braeside Line (A heavy haul line in Central Queensland), and the distributions of both static and dynamic loads can be found from these data. The other three types of tracks have no measured data from sites and the experimental data are hardly available. In order to generate the data samples and obtain their distributions, the computer based simulations were employed and assumed the wheel-track impacts as induced by different sizes of wheel flats. A valid simulation package named DTrack was firstly employed to generate the dynamic loads for the freight and medium speed passenger tracks. However, DTrack is only valid for the tracks which carry low or medium speed vehicles. Therefore, a 3-D finite element (FE) model was then established for the wheel-track impact analysis of the high speed track. This FE model has been validated by comparing its simulation results with the DTrack simulation results, and with the results from traditional theoretical calculations based on the case of heavy haul track. Furthermore, the dynamic load data of the high speed track were obtained from the FE model and the distributions of both static and dynamic loads were extracted accordingly. All derived distributions of loads were fitted by appropriate functions. Through extrapolating those distributions, the important parameters of distributions for the static load induced sleeper bending moment and the extreme wheel-rail impact force induced sleeper dynamic bending moments and finally, the load factors, were obtained. Eventually, the load factors were obtained by the limit states design calibration based on reliability analyses with the derived distributions. After that, a sensitivity analysis was performed and the reliability of the achieved limit states design equations was confirmed. It has been found that the limit states design can be effectively applied to railway concrete sleepers. This research significantly contributes to railway engineering and the track safety area. It helps to decrease the failure and risks of track structure and accidents; better determines the load range for existing sleepers in track; better rates the strength of concrete sleepers to support bigger impact and loads on railway track; increases the reliability of the concrete sleepers and hugely saves investments on railway industries. Based on this research, many other bodies of research can be promoted in the future. Firstly, it has been found that the 3-D FE model is suitable for the study of track loadings and track structure vibrations. Secondly, the equations for serviceability and damageability limit states can be developed based on the concepts of limit states design equations of concrete sleepers obtained in this research, which are for the ultimate limit states.

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Yehya, Mohamad. "Propriétés de transfert dans le béton par imagerie neutronique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI103/document.

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Pour les structures de génie civil avec un rôle d’étanchéité, lors d’un accident grave, la perméabilité du béton est une question clé. Les mesures de perméabilités actuelles ne permettent d'avoir que des grandeurs moyennes (structurelles) qui ne conviennent pas pour des éprouvettes hétérogènes (fissures et/ou armatures). La compréhension des détails de l'écoulement des fluides est cruciale en raison des implications sur les voies préférentielles (interface acier/béton, fissures, etc.). Le but de cette thèse est de proposer une nouvelle méthodologie et de tester un nouveau dispositif expérimental par imagerie neutronique à la ligne de faisceaux D50 à l’Institut Laue Langevin à Grenoble. Le test consiste à injecter de l’eau normale (H2O), sous haute pression, dans un échantillon de béton coulé et saturé en eau lourde (D2O), afin de suivre la progression d’un front d’eau dans le temps par différence d’atténuation entre ces deux eaux. Une campagne expérimentale a été lancée sur des éprouvettes de béton sous différentes configurations (béton sain, béton fissuré et béton avec une armature) et des mesures de perméabilité locale dans les singularités (zone fissurée, interface armature-béton, etc.) ont été faites. Les essais ont montré que les mesures classiques de perméabilité sont sous-estimées et les écoulements dans le béton sont contrôlés par les défauts For civil engineering structures, especially containment buildings during a severe accident, the permeability of concrete is a key issue. Current permeability measurements allow only average (structural) magnitudes, which are not suitable for heterogeneous samples (cracks and/or reinforcements). Understanding the details of fluid flow is crucial because of the implications of preferred pathways (steel/concrete interface, cracks, etc.). The aim of this thesis is to propose a new methodology, and to test a new experimental setup, using neutron imaging at the D50 beam line at the Institute Laue Langevin in Grenoble to measure flow directly. The test consists of injecting normal water (H2O) under high pressure, into a concrete sample casted and saturated with heavy water (D2O), in order to follow the evolution of a waterfront over time by difference of attenuation between these two waters. An experimental campaign was launched on concrete specimens in different configurations (proper concrete, cracked concrete and concrete with reinforcement) and measurements of local permeability in singularities (cracked zone, reinforcement-concrete interface, etc.) were done. Tests have shown that classical permeability measurements are underestimated and flows in concrete are controlled by defects

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Osorio, Gomez Laura Isabel. "Behavior of synthetic fiber-reinforced concrete circular columns under cyclic flexure and constant axial load." Mémoire, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1435.

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La ductilité et la capacité à dissiper de l'énergie sont deux qualités très importantes pour les éléments structuraux des structures situées dans les régions sismiques comme l'est du Canada. Soulignons que Montréal occupe la deuxieme place en ce qui a trait au risque sismique au Canada. De plus, la réduction des coûts de maintenance des infrastructures est un sujet d'intérêt pour les propriétaries alors que ces derniers doivent en tout temps garantir la sécurité des usagers. Or, le béton renforcé avec des fibres synthétiques semble être un matériau qui remplit ces caractéristiques. Pourtant, son utilisation est actuellement limitée aux éléments non structuraux ou structuraux mais non principaux. Afin de généraliser l'utilisation du béton fibre dans le domaine structural, il faut continuer à produire et à analyser des données expérimentales qui permettront de valider et d'améliorer les prescriptions de design et les modèles analytiques actuels pour la conception des éléments en béton armé avec des fibres dans les zones sismiques. Dans ce contexte, six poteaux circulaires à grande-échelle ont été testés sous une charge axiale constante (25% de Agf'c) et en flexion cyclique. Trois poteaux ont été confectionnés en béton normal (BN) et les trois autres en béton renforcé avec des fibres synthétiques (BRFS). La résistance à la compression du béton spécifiée à 28 jours pour les spécimens était de 30 MPa. Le volume de fibres synthétiques en polypropylène-polyéthylène utilisé a été de 1%. Les trois poteaux en BN étaient renforcés par une armature transversale constituée d'une spirale ayant un pas de 42, 75 et 100 mm respectivement. Ces trois spécimens ont été comparés avec des spécimens similaires en BRFS. Les résultats montrent que la présence des fibres synthétiques dans la matrice de béton améliore le comportement ductile et la capacité a dissiper de l'énergie des spécimens. Il a été observé que cette amélioration n'est pas directement proportionnelle à la quantité d'armature transversale. Toutefois, l'utilisation du béton fibre semble rendre possible une réduction de l'armature transversale tout en conservant un aussi bon sinon un meilleur comportement.

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Malakoski, Joice. "Pilares esbeltos de concreto armado com seção variável." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-22022018-152222/.

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São descritas as recomendações da Norma Brasileira NBR-6118/1978 e do Código Modelo do Comité Euro-internacional du Béton CEB-1990 para a verificação da estabilidade de pilares esbeltos de concreto armado com seção variável submetidos à flexão normal composta, empregando-se a teoria do método geral. Para a obtenção dos momentos de segunda ordem são descritos os métodos de Engesser-Vianello e da integração numérica das curvaturas das seções transversais ao longo do pilar. Para a determinação do momento fletor absorvido pelas seções em função da curvatura proveniente da flexão do pilar sob a ação de uma força normal, desenvolvem-se as expressões para seções retangulares e circulares (cheias e vazadas) com base nas relações de tensão-deformação dos materiais segundo a norma e o código supracitados. Apresenta-se também um programa para microcomputador, elaborado em linguagem PASCAL, destinado à verificação da estabilidade de pilares com opção de adoção dos critérios da NBR-6118/1978 ou do CEB-1190. Não foram abordados os efeitos decorrentes de vibrações, fazendo-se apenas a descrição dos métodos de consideração dos efeitos decorrentes da deformação lenta. The recommendations of Brazilian Code NBR-6118/1978 and Comité Euro-Internacional du Béton Model Code CEB-1990 are described, for stability verification of concrete slender columns with variable cross sections, subjected to axial load and bending moment, using the exact method. To obtain the second order bending moments, the Engesser-Vianello method and the numeric integration of the cross section curvatures along the longitudinal axial of column method are described. To obtain of bending moment supported by the cross sections due to curvature resultant of the column flexure under axialload, expressions for rectangular and circular (full and hollow) cross sections are developed, using stress-strain relations for materials proposed by model codes above mentioned. It\'s also presented a software written in PASCAL language for microcomputer and destined to column stability verification, with option to adopt the NBR-6118/1978 or CEB-1990 model code recommendations. Effects due to vibrations were nor included. Methods to take in account creep effects were described.

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Kašparů, Jakub. "Statické řešení betonového komínu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226418.

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The goal of this Master´s thesis is a review of a reinforced concrete chimney´s stack and a foundation design based on a combination of M+N load. Two bar models (by ČSN and EN) and one shall model were created to analyze internal forces. The fine element software SCIA ENGINEERING was used to create the models. The loads taken into consideration - for analysis include self weight, lining, temperature, wind, and Karman vortex. The stack was horizontally divided by several cuts which were investigated. The stack and foundation were designed by an algorithm created in the program MS EXCEL. The piles were designed in the program GEO 5. Drawings include - drawings of shapes and drawings of the reinforcement of specifics part of chimney.

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Clément, Jean-Luc. "Interface acier-beton et comportement des structures en beton arme : caracterisation, modelisation." Paris 6, 1987. http://www.theses.fr/1987PA066153.

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Developpement d'un modele prenant en compte l'influence d'une contrainte de confinement sur la forme des lois tangentielles d'adherence acier-beton. Comparaison par calculs aux elements finis de deux approches: plasticite, et calcul continu en deplacements, avec un modele d'endommagement pour le beton. Application de la deuxieme methode au calcul d'une poutre precontrainte

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Nascimento, Alessandro Lugli. "Análise de estabilidade de contenções, via MEF, considerando a interação solo-estrutura." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-30052012-122749/.

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Este trabalho tem a finalidade de estudar a influência da parede de concreto na análise de estabilidade de contenções atirantadas bem como discutir sobre segurança nestas análises. Para isto foram elaborados modelos em estado plano de deformação por meio do método dos elementos finitos, MEF, para análise. A parede de concreto foi modelada com variações de rigidez e modelos reológico, com o fim de se entender sua influência no fator de segurança. Por fim foi realizado um breve estudo sobre a utilização dos métodos estatísticos na análise de estabilidade de contenções. This work has the purpose of study the influence of the concrete wall in the stability analysis of tieback retaining walls and to discuss these safety analysis. Models were developed using plane strain state via the finite element method, FEM, for analysis. The concrete wall was modeled with variations of stiffness and rheological models, in order to bore its influence on the safety factor. Finally a brief study was conducted on the use of statistical methods in stability analysis of retaining walls.

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Taillet, Elodie. "Caractérisation des discontinuités dans des ouvrages massifs en béton par la diagraphie électrique de résistivité." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00982066.

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Les discontinuités sont préjudiciables à la pérennité des structures en béton. Les méthodes non-destructives sont bien développées pour l'étude des altérations en surface, mais peu de techniques sont adaptées à la caractérisation de défauts dans la masse. Dans cette thèse, des mesures de résistivité électrique sont réalisées pour l'étude des discontinuités (fissures, joints, interfaces) au sein des ouvrages massifs en béton par l'intermédiaire des forages préexistants. La technique utilisée est la diagraphie électrique de résistivité en dispositif normal. Une première approche numérique (éléments finis) permet d'appréhender les corrections à apporter sur les mesures. Puis l'étude des paramètres d'ouverture, de contraste entre la résistivité de la discontinuité et du béton, et d'extension permet de proposer une méthode d'inversion des mesures pour la caractérisation de l'endommagement. Des essais sur des ouvrages hydrauliques sont réalisés afin de définir la méthodologie de mesure sur site. Les mesures sont ensuite confrontées à la méthode d'inversion pour la valider.

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Yahya, Norrul Azmi. "Strategies for mitigation of the failure of concrete pedestals supporting bridge girder bearings." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/105498/1/Norrul%20Azmi_Yahya_Thesis.pdf.

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This thesis explains on the numerical study of localized damage mechanism in concrete pedestals supporting bridge girder bearings. It examined the structural response of concrete pedestals dealing with complex contact interaction behaviour between steel bearing plate and concrete. Three dimensional nonlinear explicit finite element micro models of concrete pedestals were analyzed with various pedestal heights, edge clearance distances, loading geometries, confinement reinforcements and loading eccentricities. Also included are few mitigation strategies had been proposed to minimize the effect of localized failure and therefore which can then improve the structural performance of concrete pedestals.

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41

Cabral, Larissa Marques Cunha. "Análise comparativa do módulo de elasticidade calculado segundo diferentes normas." Universidade Católica de Pernambuco, 2014. http://www.unicap.br/tede//tde_busca/arquivo.php?codArquivo=1053.

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O trabalho em questão estuda o comportamento e adequação do diagrama de dosagem do concreto com relação ao módulo de elasticidade estático e dinâmico. Além disso, compara os modelos de previsão do módulo de elasticidade estático baseados na resistência à compressão das normas americana, alemã, européia, fib e a brasileira ABNT NBR 6118 (2014) - Projeto de Estruturas de Concreto: procedimento. Foram produzidos dois concretos com consistências distintas; uma plástica e outra flúida (auto adensável). Foram desenvolvidos três traços para cada consistência, totalizando assim seis traços. Essas dosagens tiveram como variáveis a relação água/cimento e o consumo de cimento; o abatimento foi mantido constante. Uma análise comparativa entre os resultados experimentais com os valores previstos por algumas normas foi realizada, avaliando o nível de precisão das mesmas. A ACI 318 (2014) foi a norma que teve seus resultados mais próximos em relação a NBR 6118 (2014). Já as normas EUROCODE 2 (2004) e DIN 1045 apresentaram resultados semelhantes. E a norma fib CEB 2010, apresentou valores superestimados em relação às demais normas. Assim, é possível afirmar que a determinação do módulo de elasticidade do concreto se mostrou coerente com os materiais e dosagens utilizadas. Contudo, é uma variável muito sensível à composição do traço, mesmo quando mantidos os materiais. A resistência à compressão é uma das variáveis que interfere nos resultados. Entretanto, tem também grande influência a variação da natureza dos agregados graúdos e a relação pasta/agregado graúdo, por exemplo. O módulo dinâmico através de ondas ultrassônicas, também foi medido e comparado com o módulo estático, mostrando-se uma opção rápida e não destrutiva de avaliar o módulo de elasticidade do concreto. The work involved studying the behavior and adjustment of dosage diagram of concrete with respect to static and dynamic elastic modulus. Furthermore, it compares the models of the static elastic modulus based on the compressive strength, German, European, American and Brazilian ABNT NBR 6118 (2014) prediction - Design of Concrete Structures: procedure. Two concrete were produced with different consistency; plastic and other fluid (selfcompacting). Three traits were developed for each consistency, totaling six traits. These dosages were as varying the water / cement and cement consumption; the rebate was kept constant. A comparative analysis of the experimental results with those predicted by some standards was carried out to evaluate the level of accuracy of the same. ACI 318 (2014) was the standard that had their closest results compared to NBR 6118 (2014). Have the Eurocode and DIN 1045 standards -2 showed similar results. And the standard fib CEB - 2010, showed overestimated values in relation to other standards. Thus, we can say that the determination of elasticity of the concrete module proved consistent with the materials and dosages used. However, it is very sensitive to the composition of the trace variable, even when kept the materials. The compressive strength is one of the variables that affect the results. However, it also has great influence to change the nature of the coarse aggregate and the relative folder / coarse aggregate, for example. The dynamic ultrasonic waves through the module was also measured and compared with the static module, showing a rapid and non-destructive option to evaluate the modulus of elasticity of the concrete.

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Poletto, Fernanda Alves Basílio. "Análise da fluência em vigas de concreto armado simplesmente apoiadas usando o método dos elementos finitos." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1591.

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A fluência é um fenômeno de grande importância no concreto armado. Apesar de ser apontada como a causa de diversas patologias em estruturas, seus efeitos ainda são considerados de forma simplificada pelos projetistas estruturais. Além de estudar o fenômeno em estruturas de concreto armado e sua consideração atual utilizada na análise de estruturas, este trabalho compara as deformações de vigas simplesmente apoiadas de concreto armado, obtidas de forma analítica, e em ensaios experimentais com os resultados de simulações pelo Método dos Elementos Finitos (MEF). Os valores de deformações e deslocamentos calculados de forma analítica foram obtidos a partir de recomendações da Norma Brasileira NBR 6118 (2014) e do Código Modelo Simplificado CEB-FIP (1990), e os resultados experimentais foram extraídos de ensaios disponíveis na literatura. As simulações são realizadas no programa ANSYS Workbench, utilizando o elemento tridimensional SOLID 186 e a simetria das vigas. Posteriormente são realizadas análises de convergência utilizando o elemento bidimensional PLANE 183. Conclui-se ao final que as análises através do MEF são qualitativa e quantitativamente eficazes para estimativa dessa não linearidade e que o método de obtenção dos coeficientes de fluência utilizados é suficientemente preciso. Reinforced concrete creep is a phenomenon of great importance. Despite being appointed as the main cause of several pathologies, its effects are yet considered in a simplified way by the structural designers. In addition to studying the phenomenon in reinforced concrete structures and its current account used in the structural analysis, this paper compares creep strains at simply supported reinforced concrete beams in analytical and in experimental forms with the finite element method (FEM) simulation results. The strains and deflections obtained through the analytical form were calculated with the Brazilian code NBR 6118 (2014) recommendations and the simplified method from CEB-FIP 90 and the experimental results were extracted from tests available in the literature. Finite element simulations are performed using ANSYS Workbench software, using its 3D SOLID 186 elements and the structure symmetry. Analyzes of convergence using 2D PLANE 183 elements are held as well. At the end, it is concluded that FEM analyses are quantitative and qualitative efficient for the estimation of this non-linearity and that the method utilized to obtain the creep coefficients values is sufficiently accurate.

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Rabello, Fernando Toppan. "Análise comparativa de normas para a punção em lajes de concreto armado." reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/94391.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Civil, Florianópolis, 2010 Made available in DSpace on 2012-10-25T09:23:30Z (GMT). No. of bitstreams: 1 277178.pdf: 2596674 bytes, checksum: 7b424249f57fe66c5b708a4dfad48446 (MD5) Os sistemas estruturais usados em pavimentos de concreto armado, em que as lajes se apóiam diretamente sobre os pilares, sem o uso de vigas, têm, entre suas características, a existência de tensões concentradas elevadas nas ligações laje-pilar, tensões estas que podem até levar à ruína. A esse efeito dá-se o nome de punção. Como a ruptura das ligações por punção é do tipo frágil, sem aviso, é extremamente importante que seja feita a verificação da resistência da ligação. As crescentes inovações técnicas e a análise dos critérios normativos propostos pelo ACI 318/08, BS 8110/97, NBR 6118/03 e EUROCODE 2/04 para o dimensionamento ao esforço de punção em lajes lisas de concreto armado são as diretrizes da elaboração do presente estudo. Dentro deste cenário, o objetivo desta dissertação é avaliar a acessibilidade, aplicabilidade, limitações e economia destes critérios por meio da comparação de resultados obtidos na análise de pilares internos em três configurações diferentes de lajes, variando suas espessuras. Foram analisados os seguintes parâmetros: a) para laje sem armadura de punção, compararam-se as relações entre tensões resistentes e solicitantes; as máximas reações que podem ser aplicadas à laje; a proporcionalidade do efeito dos momentos em relação a uma carga simétrica; excentricidades médias em relação às reações máximas suportadas pela Norma Britânica e um coeficiente estipulado para simular o efeito dos momentos fletores supondo-se uma carga de reação simétrica. B) para lajes com armadura de punção, compararam-se as relações entre tensões resistentes e solicitantes e o consumo de armadura de punção necessária segundo as recomendações de cada norma. The structural systems in reinforced concrete, where the slab is directly supported by the columns, without the use of beams, has, among its aspects, the existence of great tensions distributed in small areas, which can lead the structure to collapse. This effect is called punching shear. As the punching shear collapse occurs without warning, it is of extreme importance that the slab-column resistance verification is made. The increasing technical innovations and analysis of normative criteria proposed by ACI 318/08, BS 8110/97, NBR 6118/03 and EUROCODE 2 / 04 for punching analysis in flat slabs of reinforced concrete are the guidelines of this study. In this scenario, the main objective of this work is to evaluate these punching shear design procedures in terms of accessibility, applicability, limitations and economy, comparing the results obtained on analysis of a internal column in three different slabs configurations, varying their thicknesses. The following parameters had been analyzed and compared, as the recommendations of each code: a) for slabs without links, the relation between the resisted and applied tension, the maximum actions that can be applied, the representativeness of the unbalanced moment to the load reaction, and a increase coefficient to consider the effects of unbalanced moments; b) for slabs with links, the relation between resisted and applied tension and the armor consumption necessary to resist the loads for each case had been compared, according the recommendations of each code.

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Bergami, Mara Lúcia. "Diretrizes para a gestão da qualidade do processo de projeto em empresas de pré-fabricados baseado na norma NBR ISO 9001:2000." Universidade Federal de São Carlos, 2009. https://repositorio.ufscar.br/handle/ufscar/4648.

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Made available in DSpace on 2016-06-02T20:09:12Z (GMT). No. of bitstreams: 1 2773.pdf: 2245845 bytes, checksum: 2fc3e08d73e5f205613b996050003eb8 (MD5) Previous issue date: 2009-02-19 The project process is critical so that be achieved the objectives of quality for constructive prefabricated concrete. The correct development of a project process, from the program systematization of quality management, promote to the efficacy of the entire production project. Thus, this dissertation has the objective to propose guidelines for effective implementation of project requirements established by section 7.3 and others sections related to the project process, referenced in standard NBR ISO 9001:2000 to manufacture companies of prefabricated concrete. These guidelines were established from the review of literature and of the explorative case study, accomplished in three manufacture companies of prefabricated concrete, where through a preliminary questionnaire and observation, we can collect data that identify the attention points for quality management of process project. To achieve the objectives above, were investigated aspects such as: the project relevance to the concrete prefabs industry, the method of project coordination in prefab and the impact of non-conformance projects for the production process (production and setting prefabricated project). O processo de projeto mostra-se crítico para que possam ser atingidos os objetivos da qualidade dos sistemas construtivos em pré-fabricados de concreto. O desenvolvimento adequado de um processo de projetos a partir da sistematização de um programa de gestão da qualidade contribui para a eficácia de todo o processo de produção. Partindo desse contexto, a presente dissertação tem como objetivo propor diretrizes para implementação eficaz dos requisitos de projeto estabelecidos pela seção 7.3 e demais seções relacionadas ao processo de projeto referenciados na norma NBR ISO 9001:2000 em empresas produtoras de pré-fabricados de concreto. Tais diretrizes foram estabelecidas a partir da revisão da literatura e de estudo de caso exploratório realizado junto a três empresas produtoras de pré-fabricados de concreto, onde por meio de um questionário semi-estruturado e de observação de campo foi possível coletar dados que permitiram identificar os pontos de atenção para gestão da qualidade do processo de projeto. Para atingir os objetivos supracitados foram investigados aspectos tais como: a relevância dos projetos para a indústria de pré-fabricados em concreto, a metodologia de coordenação de projeto em empresas de pré-fabricados e o impacto da não-qualidade dos projetos para o processo produtivo (produção e montagem de pré-fabricados).

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Rodrigues, Marcelo Paixao Pinto. "Flexão normal composta em seções retangulares de concreto armado em situação de incêndio." Universidade Federal de Minas Gerais, 2009. http://hdl.handle.net/1843/PASA-7TGG5H.

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This work presents a general structural design method for reinforced concrete elements subjected to fire according to the Brazilian Standard ABNT NBR 15200:2004. The developed method evaluates reinforced concrete rectangular cross-sections subjected to compound flexure for different fire resistance required times specified by the BrazilianStandard ABNT NBR 14432:2000. The temperature distribution along the elements cross-section considering the non-linearity was obtained using the program THERSYS, a three-dimensional temperature distribution simulation system for buildings subjected to fires that uses the finite element method and which was developed at the Structural Engineering Department from the Federal University of Minas Gerais. An algorithm was implemented using the Visual Basic programminglanguage within the MS Excel spreadsheet environment to design rectangular reinforced concrete sections with symmetrical steel bar arrangement at normal temperatures (i.e., 20ºC). Electronic spreadsheets were developed to calculate and draw interactivediagrams of (axial force) x (bending moment) at 20ºC, for each fire resistance required time specified by the Brazilian standard (i.e., 30, 60, 90 e 120 minutes) and also for a structure which had been previously exposed to fire and cooled down back to 20ºC. Este trabalho apresenta um método geral de cálculo de acordo com a norma brasileira ABNT NBR 15200:2004, capaz de avaliar se uma seção retangular de concreto armado com armadura qualquer resiste à flexão normal composta quando submetida a incêndios com diversos tempos requeridos de resistência ao fogo (TRRF), preconizados pela ABNT NBR 14432:2000. A distribuição de temperatura na seção é rigorosamentecalculada, levando-se em consideração todas as não-linearidades envolvidas. Para tanto, fez-se uso do programa THERSYS Sistema para simulação via método dos elementos finitos da distribuição 3D de temperatura em estruturas em situação de incêndio, desenvolvido no Departamento de Engenharia de Estruturas da Universidade Federal de Minas Gerais. Implementou-se um algoritmo na linguagem de Programação Visual Basic dentro do ambiente MS Excel para o dimensionamento de seções retangulares de concreto armado submetidas à flexão normal composta com armadura simétrica à temperatura ambiente. Desenvolveram-se planilhas eletrônicas que calculam e desenham as curvas de interação (força normal) x (momento fletor) de cálculo para a temperatura ambiente, para os quatro tempos requeridos de resistência ao fogo preconizados em norma (TRRF 30, 60, 90 e 120 minutos) e para uma estrutura que tenha sido submetida a uma situação de incêndio e já tenha sido resfriada até a temperatura ambiente, ou seja, 20ºC.

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Lidmila, Ladislav. "Rekonstrukce mostu v Ledči nad Sázavou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409797.

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Diploma thesis deals with reconstruction of old beam bridge in town Ledeč nad Sázavou. Three variants of reconsttruction were done. Detailed structural design report was done to one of them, streithening with post-tensioning. Calculation of load effect was solved with finite elemet method via software on grillage model. Construction was checked on ultimate limit state and serviceability limit state. Necessary drawings were elaborated to chosen method.

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Kwasny, Jacek. "Influence of mix composition on engineering properties of normal and lightweight self-compacting concretes." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602356.

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The overall solid packing see mix design method of Brouwers and Radix was modified by developing an optimisation tool, facilitating the proportioning normal weight SCCs (NWSCCs) and L WSCCs. The method comprised two concepts: filling the voids within the loosely packed aggregate fraction with appropriate paste and comparing the overall particle size distribution (PSD) of solids in the mix with the model PSD. To implement this method, the influence of supplementary cementitious materials (SCMs), fillers and chemical admixtures on the paste properties was investigated; moreover, physical properties and packing of normal and lightweight aggregates (L W As) were studied. The influence of two L WAs, three superplasticisers and three SCMs/fillers on the fresh properties and compressive strength of LWSCCs was evaluated, followed by a detailed study on L WAs and SCMs/fillers effect on engineering and durability properties of L WSCCs. The proposed mix design modification yielded highly flowable, strong and durable L WSCCs for structural precast applications. Successful LWSCCs required carefully optimised paste composition and paste/aggregate content. L W As water absorption characteristics and cement-superplasticiser compatibility strongly influenced workability and workability retention of LWSCCs. The effect of aggregate composition and aggregate/paste content on fresh, hardened and durability properties of structural NWSCCs was studied. The proposed mix design allowed manufacturing NWSCCs with moderate workability, high strength and paste content lower than typically reported. Most of NWSCCs properties correlated with the average spacing between the aggregate particles, allowing for engineering of NWSCC properties by its adjustment.

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Ribeiro, Kleyser. "Diagramas para verificação de pilares retangulares em concreto armado submetidos à flexão composta normal." reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/95091.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Civil, Florianópolis, 2011 Made available in DSpace on 2012-10-25T20:32:12Z (GMT). No. of bitstreams: 1 289075.pdf: 5812474 bytes, checksum: f37f6ac44e9bf683be185670dbc9e6b2 (MD5) Neste trabalho, apresentam-se tabelas e diagramas para a verificação de de esbeltez até noventa. Além da verificação da capacidade portante da seção transversal, as tabelas e os diagramas desenvolvidos realizam a verificação da estabilidade dos pilares, sendo agrupados em diferentes níveis de esbeltez, considerando-se a não-linearidade física e a ãolinearidade geométrica. Apresenta-se uma revisão bibliográfica dos principais trabalhos nacionais e internacionais acerca do tema, incluindo-se uma comparação entre a norma brasileira (ABNT NBR 6118: 2007) e a norma européia (EN 1992: 2004). Para a construção dos diagramas, foram desenvolvidos algoritmos computacionais e implementados na linguagem REALbasic. Em todo o trabalho, foi adotado o método geral, em razão de sua precisão, sendo que os programas executam os procedimentos iterativos relativos à obtenção da relação momento-curvatura e ao cálculo dos efeitos de segunda ordem. Ao final, são apresentados exemplos de aplicação e comentários acerca da utilização das tabelas e dos diagramas, concluindo-se que o uso destes pode ser útil tanto aos projetistas quanto aos estudantes da área de engenharia civil, seja nas etapas de verificação ou prédimensionamento, pois podem ser encontrados resultados mais econômicos que os obtidos por métodos aproximados, respeitando-se as condições de segurança da norma. This dissertation presents tables and diagrams for the verification of rectangular cross-section columns in reinforced concrete, with slender ratio up to 90. In addition to checking the bearing capacity of the crosssection, the tables and diagrams developed also check column stability, grouped into different levels of slender ratio, considering physical and geometric non-linearities. The review of the literature presents national and international works on the issue, including a comparison between the Brazilian Code (ABNT NBR 6118: 2007) and the European Code (EN 1992: 2004). For the construction of diagrams, computational algorithms were developed and implemented in REALbasic. The general method was adopted throughout the work due to its accuracy. The programs perform iterative procedures regarding the obtaining of moment-curvature relationships and second-order effect calculations. In the end of the dissertation, application examples and comments on the use of tables and diagrams are presented, concluding that the use of such tools may be useful to both engineers and students of Civil Engineering in verification or preliminary design stages, as they can obtain more economic results than results obtained by approximation methods, while respecting safety conditions in the Brazilian Code.

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Melo, Carlos Eduardo Luna de. "Análise experimental e numérica de pilares birrotulados de concreto armado submetidos a flexo-compressão normal." reponame:Repositório Institucional da UnB, 2009. http://repositorio.unb.br/handle/10482/9077.

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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2009. Submitted by Luiza Moreira Camargo (luizaamc@gmail.com) on 2011-07-06T15:15:24Z No. of bitstreams: 1 2009_CarlosEduardoLunadeMelo.pdf: 14414751 bytes, checksum: 9cd48908da60899bdb0ec6f3eb2f6797 (MD5) Approved for entry into archive by Elna Araújo(elna@bce.unb.br) on 2011-07-14T23:53:35Z (GMT) No. of bitstreams: 1 2009_CarlosEduardoLunadeMelo.pdf: 14414751 bytes, checksum: 9cd48908da60899bdb0ec6f3eb2f6797 (MD5) Made available in DSpace on 2011-07-14T23:53:35Z (GMT). No. of bitstreams: 1 2009_CarlosEduardoLunadeMelo.pdf: 14414751 bytes, checksum: 9cd48908da60899bdb0ec6f3eb2f6797 (MD5) Trata-se de um estudo experimental e numérico do comportamento até a ruína de pilares birrotulados de concreto armado submetidos a flexo-compressão normal. Foram ensaiados 24 pilares, sendo 10 com 3,0 m, 7 com 2,5 m e 7 com 2,0 m de altura. Os pilares possuíam seção transversal de 250 mm x 120 mm, resistência do concreto em torno de 40 MPa, e taxa geométrica de armadura longitudinal de 1,57 %. A principal variável foi a excentricidade da força aplicada na direção de menor inércia da seção transversal. Resultados de forças últimas e tipos de ruína, fissuração, deslocamentos horizontais, deformações do concreto e da armadura são apresentados e analisados, juntamente com as estimativas calculadas por dois programas computacionais adaptados para o tipo de ensaio realizado. Os pilares com força centrada apresentaram ruína brusca com ruptura do concreto na região central dos pilares, com um pilar apresentando ruína na região do consolo. Os demais pilares apresentaram ruína por flexo-compressão na região central dos pilares. O sistema de ensaio mostrou-se adequado, sendo recomendado para ensaios futuros. Uma curva de tendência de forma exponencial para a força última relativa (υ = Fu/(bhfc)) em função da excentricidade relativa (e/h) foi determinada, apresentando um bom ajuste aos resultados dos pilares analisados. Os resultados numéricos estimados pelos programas se aproximaram bem dos resultados experimentais, sendo adequada a sua utilização na verificação de elementos birrotulados submetidos a flexão composta normal, possuindo pelo menos um eixo de simetria. Foram determinadas funções de forma polinomiais do terceiro grau para a determinação da força de ruína de pilares com índices de esbeltez de 92,7, 71,5 e 52,2 e taxas mecânicas de armadura iguais a 0,196 e 0,131. Os métodos aproximados para a determinação dos efeitos de segunda ordem da ABNT NBR 6118:2003 apresentaram excelentes resultados de estimativa da força última em relação à força última experimental, apresentando uma relação Fu/Fu,NBR próxima à unidade. Os métodos aproximados do ACI 318:2002 e MC-CEB (1990) apresentaram resultados subestimados de resistência dos pilares, em relação aos pilares testados. _________________________________________________________________________________ ABSTRACT This work presents experimental and numerical studies of reinforced concrete columns under combined axial load and bending. Experimental analyses were conducted in twenty four specimens, with dimensions classified as: ten with three meters height, seven with two and a half meters height, and seven with two meters height. The analyzed columns had rectangular cross sections, with dimensions of 250 x 120 mm. All the specimens had a concrete strength under compression of approximately 40 MPa, with a longitudinal reinforcement ratio of 1.57 %. The load eccentricity, applied at the minor inertia direction, was considered as the major variable in the experiments. Results of ultimate loads, failure types, cracking distribution, horizontal displacements, concrete and reinforcement strains are presented and analyzed, along with results obtained with two computer programs, with modified parameters matching the conducted tests. Fragile failures were observed in the columns under compression. In the remaining specimens, concrete rupture with a combined axial load and bending occurred at the mid span. The test setup was proven to be adequate and it is recommended for future studies. An exponential estimative for the ultimate relative load was achieved, being a function of the relative eccentricity, providing a good agreement with the analyzed results. Numerical results achieved with the computer programs provide a good estimative of the experimental values and are recommended for analyses of structural elements having at least one symmetry axis, under combined axial load and bending. Polynomial approximations of the third degree for the ultimate load of columns with slenderness ratios of 92.7, 71.5 and 52.5, with reinforcement ratios of 0.196 and 0.131 were established. Simplified methods of second order analysis of design code ABNT NBR 6118:2003 present a good estimative of the ultimate load, providing ratios close the unity when compared to experimental values, while approximate methods of ACI 318:2002 and MCCEB (1990) codes underestimate these values.

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Quispe, Enciso Marco Antonio, and Rajkovic Luis Felipe Terry. "Análisis comparativo del diseño sismorresistente de una edificación de concreto armado de 7 pisos en lima empleando la Norma E030 (versión 2016 vs versión 2003)." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2017. http://hdl.handle.net/10757/621899.

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Realiza el análisis y diseño de 3 edificaciones de características similares; la primera, con la versión anterior de la norma sismorresistente E030 (2003); la segunda, teniendo la edificación en la zona 4 con la norma vigente E030 (2016); la tercera también con la norma vigente pero con la diferencia de que la edificación se encontrará en la zona 3. Luego se procederá a realizar los diseños de los elementos principales de las 3 edificaciones para luego realizar el cálculo de las dimensiones de placas, columnas, vigas, y el acero que estas tendrán en cada edificación. El propósito es saber qué influencia tienen los cambios que presenta la versión de la norma E030 actual (2016) en volumen y cantidad de acero y concreto para las edificaciones analizadas. Para la evaluación de los 3 casos, se realizará un análisis comparativo de los aspectos más importantes como fuerza basal, momentos, derivas, dimensiones y cuantías. Es decir se analizará si los cambios en la norma sismorresistente implican grandes variaciones en estos factores. Al final, se realizará un análisis de materiales de concreto y acero de cada estructura diseñada anteriormente para tener una idea del porcentaje en que pueden variar los costos del casco de una edificación al diseñarse con la versión de la norma 2016, con diferente zonificación del proyecto, respecto a la versión de la norma 2003.

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Dissertations / Theses on the topic 'Normal concrete'

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