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CFRP - Confined reinforced concrete elements subjected to cyclic compressive loading

Ferreira, Débora; Barros, Joaquim; Varma, Rajendra
Fonte: American Concrete Institute Publicador: American Concrete Institute
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.60384%
The effectiveness of discrete and continuous CFRP wrapping arrangements for reinforced concrete (RC) short column subjected to monotonic and cyclic compressive loading is assessed in this work. The experimental program is composed of four series of RC columns with discrete wrapping arrangements and one series of full wrapped RC columns. Each series is composed of a monotonic and a cyclic test. Strain gauges were installed along the height of each column to measure the strain field in the CFRP during the test. The variation of the stiffness of the unloading and reloading branches of each loading cycle was determined. A constitutive model to simulate FRP-confined RC concrete elements subjected to cyclic compressive loading was developed and implemented into a computer program based on the finite element method. This model was appraised with the data obtained from the carried out experimental program.

Estudo de métodos e medidas auxiliares para o controle da resistência à carbonatação de concretos estruturais de cimento Portland.; Study of auxiliary methods and measurements to control carbonation resistance of Portland cement structural concrete.

Cafange, Daniele Maria Pilla Junqueira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/11/2010 Português
Relevância na Pesquisa
36.857632%
A durabilidade das estruturas de concreto armado deve ser alcançada, entre outros fatores, pela adequação do concreto frente ao meio ambiente para proteger as armaduras pelas características da camada de cobrimento. Assim, concretos precisam ser corretamente especificados no projeto estrutural e ter a sua qualidade controlada durante a produção e aplicação. Pela ABNT NBR 6118 (2007), os concretos passaram a ser especificados por classes de fck associadas a outras variáveis de dosagem e produção, como relação água/cimento máxima e consumo mínimo de cimento por metro cúbico. Mas, continuam invariavelmente controlados apenas por ensaios de abatimento no estado fresco e de resistência à compressão (fcj), para desforma ou verificação do fck (28 dias, nas obras comuns). Logo, a propriedade em uso para controlar indiretamente a resistência à carbonatação do concreto deveria ser o fcj, já que os concretos se diferenciam, de fato, é pelos materiais constituintes, método de dosagem e pela variabilidade de produção. Mas, na prática o controle da resistência à carbonatação dos concretos vem ocorrendo apenas pela especificação e aceitação do fck e uma das razões para isto pode ser a falta de métodos mais avançados para a predição de propriedades físicas mais complexas...

Concreto ultraleve® estrutural com pérolas de EPS: caracterização do material e estudo de sua aplicação em lajes; Structural ultra lightweight concrete with EPS beads: material characterization and study of its use in slabs

Catoia, Thiago
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/10/2012 Português
Relevância na Pesquisa
36.857632%
A utilização de concreto leve decorre especialmente dos benefícios promovidos pela redução da massa específica do material, tais como menores esforços nas estruturas, economia com fôrmas e cimbramento, além de diminuição dos custos com transporte e montagem de construções pré-fabricadas. Atualmente, além das questões técnicas e econômicas, a escolha dos materiais de construção deve levar em conta os aspectos ambientais. Portanto, o uso de poliestireno expandido (EPS) na produção de concreto pode abrir portas para o emprego de resíduos de materiais dessa natureza, e ainda usufruir de sua baixa massa específica nas aplicações estruturais. Este trabalho teve como objetivo determinar as principais características do concreto leve com pérolas (esferas) de EPS, também conhecido como Concreto Ultraleve® ou Concreflex®, características essas necessárias para projetar elementos estruturais, e analisar o comportamento de lajes produzidas com esse novo material. Mais especificamente, foram determinadas características mecânicas, tais como: resistência à compressão, módulo de elasticidade e resistência à tração, na compressão diametral e na flexão, além de características de deformação de longo prazo...

Avaliação da aderência entre o concreto e o sistema de reforço com fibra de carbono; Evaluation of the adhesion between concrete and strengthening system with carbon fiber

Marcio Vinicius Marini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/04/2011 Português
Relevância na Pesquisa
36.857632%
O reforço de estruturas de concreto armado ou protendido têm sido necessário na construção civil devido às falhas causadas por erros em projetos e execuções de obras, corrosões de armaduras, reabilitação após incêndios ou mudanças na utilização das estruturas projetadas. Os métodos convencionais para reforço de estruturas de concreto estão relacionados ao reforço pela adição de barras de aço e de concreto na estrutura ou, ainda, pela instalação de chapas de aço. O uso de fibras de carbono para reforços estruturais é recente, apresentando vantagens em relação aos métodos tradicionais, tais como: fácil manuseio na aplicação, alta aderência entre as fibras de carbono e o concreto e aumento na resistência à corrosão. Sendo assim, o objetivo deste trabalho é avaliar a aderência entre o sistema de reforço com as fibras de carbono e concretos com resistência à compressão de 15 MPa, 40 MPa e 60 MPa. A aderência concreto/fibra foi avaliada por meio de ensaios pull-out em pequenas placas de concreto com fibras de carbono aplicada superficialmente. Do concreto, foram obtidos resultados de sua porosidade e rugosidade; por meio de estereomicroscópia, foram avaliadas características como a textura superficial. Os resultados demonstraram que os concretos com menor relação água/cimento (a/c)...

Strength and durability characteristics of polymer-modified carbon fiber concrete

Torgal, Fernando Pacheco; Gonzalez, J.; Jalali, Said
Fonte: International Community on Polymers in Concrete (ICPIC) Publicador: International Community on Polymers in Concrete (ICPIC)
Tipo: Conferência ou Objeto de Conferência
Publicado em 12/02/2010 Português
Relevância na Pesquisa
46.754785%
Carbon-fiber concrete (CFC) materials are gaining momentum due to the reduction of carbon fiber cost and also to the sensing performance of carbon fiber reinforced concrete based structures. For carbon fiber concrete electrical resistance increases with tensile stress and decreases upon compression. Therefore CFC can act as self-monitoring strain sensor. Nevertheless, fiber incorporation is responsible for a loss in concrete workability, and also for a slightly compression strength reduction related to an increase in air content. Although shortterm mechanical properties of these materials are well documented, durability issues still need further investigations efforts. This paper reports some results on the strength and durability characteristics of several concrete mixtures made with different polymer and carbon fiber addition percentage. Results show that carbon fiber addition decreases strength and increases water penetration under pressure and also increases chloride diffusion, while the polymer addition reduces water penetration and concrete permeability.

Study of the compressive strength of concrete block prisms : stack and running bond

Mohamad, Gihad; Lourenço, Paulo B.; Roman, Humberto R.
Fonte: Brazilian Concrete Institute (IBRACON) Publicador: Brazilian Concrete Institute (IBRACON)
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
46.529814%
The main goal of this work is to investigate the nonlinear behavior of concrete block masonry prisms under compression, with an emphasis in the prism deformability and the failure modes. A total of 18 stack-bonded prisms have been tested, using hollow blocks of a single geometry and two different mortar types. To investigate the effect of vertical joints, the bond pattern – stack and running bond – in the prism was varied, by using half units. Finite element analysis of hollow masonry prisms was done utilizing a commercial non-linear finite element code DIANA. The numerical simulation were carried out using non-linear two dimensional 8-node elements and the biaxial stress state material was modeled by a combination of the yield conditions of Rankine and Drucker-Prager. The numerical and experimental results were compared to validate the ability to predict deformation and peak load. The results show that an analytical model cannot be formulated without understanding the interaction between block and mortar. It was observed that: the non-linearities of the masonry correspond to an increase in the lateral strain due to extensive cracking of the material and a progressive increase in the ratio between lateral and axial strains.; the cracks in the three block stacked prisms constructed with a stronger mortar were vertical on both sides; the prisms constructed with a weaker mortar had...

13th International Congress on Polymers in Concrete

Aguiar, J. L. Barroso de, ed. lit.; Jalali, Said, ed. lit.; Camões, Aires, ed. lit; Ferreira, Rui Miguel, ed. lit.; International Congress on Polymers in Concrete, 13, Madeira, 2010
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /02/2010 Português
Relevância na Pesquisa
46.80796%
The 13th International Congress on Polymers in Concrete 2010 (13th ICPIC 2010) follows a series of 12 earlier successful congresses, which has been started in London in 1975. These congresses, being held every three years, played a key role in disseminating R&D findings between researchers, academics, industrials and students. The 13th ICPIC was again a forum to exchange knowledge and most recent research findings among participants. It represented a contribution to the development of this important subject. The 13th ICPIC was held in Funchal, capital of Madeira Islands, Portugal. 120 participants coming from thirty different countries presented and discussed about 100 contributions submitted to the congress. The main topics covered had been: (a) Concrete-Polymer Composites (Micro and nanostructure, Ecological aspects, Properties, Test methods and Applications), (b) Interface Zone Polymer/Concrete (Micro and nanostructure, Penetration process, Adhesion strength, Durability and Test methods), (c) Coatings and Crack Injection (Adhesion strength, Permeability, Durability, Test methods and Applications), and (d) Concrete Rehabilitation (Innovations, Durability, Test methods and Case studies). Nowadays, the field “polymers in concrete” is rather consolidated in the construction industry. The future of polymers in concrete will be oriented to take full benefit of the synergic actions between these organic and mineral materials...

Design and testing elevated steel fibre reinforced self-compacting concrete slabs

Barros, Joaquim A. O.; Salehian, Hamidreza; Pires, Miguel; Gonçalves, Delfina
Fonte: International Conference BEFIB2012 – Fibre reinforced concrete Publicador: International Conference BEFIB2012 – Fibre reinforced concrete
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 Português
Relevância na Pesquisa
46.729355%
The use of steel fibres for the reinforcement of concrete structures is as competitive as higher is the support redundancy, and as many stress components develop in the structure. Slabs supported on piles or columns (here designated by elevated slabs) are this type of structures, where the statically indeterminate degree is dependent on the number of columns/piles, and five stress components are installed, three of which lead to membrane force and bending moment components, and the other two out-of-plane stresses generate the shear force components. When using relatively high content of steel fibres (1 to 1.5% in volume) of large aspect ratio (65 to 80), steel fibre reinforced concrete (SFRC) of quite significant post-crack residual tensile strength can be built, able of providing an ultimate moment much higher than its cracking moment. The benefits guaranteed by the fibre reinforcement at the cross section level are amplified at the structural level due to the stress redistribution provided by the support redundancy character of this type of structures, and by the reinforcement mechanisms assured by fibres bridging the cracks, leading to an ultimate load carrying capacity for the SFRSC slab that is much larger than the load at crack initiation. Adding the benefits of fibre reinforcement to those derived from the self-consolidating character of a self-compacting concrete (SCC)...

Assessment of fibre orientation and distribution in steel fibre reinforced self-compacting concrete panels

Abrishambaf, Amin; Barros, Joaquim A. O.; Cunha, Vitor M. C. F.; Cunha, F. N. M.
Fonte: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities Publicador: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 Português
Relevância na Pesquisa
46.6573%
The benefits of adding fibres to concrete lie, mostly, in improving the post-cracking behaviour, since its ability to transfer stresses across cracked sections is substantially increased. The post-cracking strength is dependent not only on the fibre geometry, mechanical performance and fibre/matrix interface properties, but also on the fibre orientation and distribution. Previous works have shown that in self-compacting concrete matrices, there is a preferential fibre alignment according to the concrete’s flow in the fresh state. Having in mind that fibres are more efficient if they are oriented according the principal tensile stresses, a preferential fibre alignment on a certain direction could either enhance or diminish the material and the structural performance of this composite. In this paper, it is investigated the influence of the fibre orientation and distribution on the post-cracking behaviour of the steel fibre reinforced self-compacting concrete (SFRSCC). To perform this evaluation, SFRSCC panels were casted from their centre point. Two self-compacting mixtures were prepared using the same base mix proportions. For each SFRSCC panel cylindrical specimens were extracted and the post-cracking behaviour was assessed from a crack width controlled splitting tensile test.

Interfacial bond behaviour of GFRP bar in self-compacting fiber reinforced concrete

Mazaheripour, H.; Barros, Joaquim A. O.; Soltanzadeh, Fatemeh; Gonçalves, Delfina
Fonte: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities Publicador: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 Português
Relevância na Pesquisa
46.529814%
In an ongoing research project, discrete steel fibers are being used in a self-compacting concrete (SFRSCC) to replace completely steel stirrups for pre-fabricated beams reinforced longitudinally with pre-stressed glass fiber reinforced polymer (GFRP) and steel bars. To take the advantages of the non-corrodible character and high tensile strength of GFRP bars, the minimum SFRSCC cover needs to be determined in order to assure the adequate bond performance between these bars and the surrounding SFRSCC. Since bond of the longitudinal bars has a relevant impact on the cracking behavior of RC elements (crack opening and crack spacing), an extensive experimental program composed of pullout bending tests was carried out where the influence of the following parameters was assessed in terms of bond behavior: GFRP bar diameter, surface characteristics of the GFRP bars, bond length, SFRSCC cover thickness. The local bond law was derived from inverse analysis and it was used to define the slip mode of the constitutive law adopted for interface finite elements. These interface finite elements were used to assess the crack opening and crack spacing on SFRSCC beams flexurally reinforced with GFRP bars. This paper resumes the experimental program...

A design model for fibre reinforced concrete bending elements with longitudinal pre-stressed steel and FRP bars

Taheri, Mahsa; Barros, Joaquim A. O.; Salehian, Hamidreza
Fonte: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities Publicador: 8th RILEM International Symposium on Fibre Reinforced Concrete: challenges and opportunities
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 Português
Relevância na Pesquisa
46.69772%
A close form solution to calculate the moment-curvature and load-deflection response of strain-softening and strain-hardening fibre reinforced concrete (FRC) elements failing in bending and reinforced longitudinally with pre-stressed steel and fibre reinforce polymer (FRP) bars is presented. This hybrid reinforcement is used for the development of high durable pre-fabricated and cost competitive beams. Pre-stressed FRP bars are applied with the minimum concrete cover, in order to take into account the benefits derived from the relatively high tensile strength of these bars and their immunity to corrosion. Pre-stressed steel bars, with a larger concrete cover have the purpose of providing the necessary ductility and assure the resistance of the beam in case of a fire occurrence. To replace completely the steel stirrups, a high performance fibre reinforced concrete is used. The predictive performance of the model is assessed by taking advantage of FEMIX, a FEM-based computer program. The model is finally utilized in a parametric study in order to evaluate the impact of post-cracking performance of FRC and applied pre-stress percentage on structural performance of FRC beams.

Prediction of compressive strength of concrete containing fly ash using data mining techniques; Techniki zgłȩbiania danych w prognozowaniu wytrzymałości na ściskanie betonu z dodatkiem popiołu lotnego

Martins, Francisco F.; Camões, Aires
Fonte: Foundation Cement, Lime, Concrete Publicador: Foundation Cement, Lime, Concrete
Tipo: Artigo de Revista Científica
Publicado em /02/2013 Português
Relevância na Pesquisa
46.775674%
The concrete compressive strength is the most used mechanical property in the design of concrete structures. Therefore, the use of rational models to its prediction, to simulate the effects of its different constituents and its properties can play an important role in the achievement of the safety-economy required. Models to forecast the concrete compressive strength have already been presented before by some researchers. However, the comparison of different rational models and the application of models to predict the importance of the different constituents in the concrete behaviour have not yet been approached. Therefore, developing these models will be necessary namely to take into account the quality, i.e. the activity, of the most used mineral addition in concrete: fly ash. This study compared different Data Mining techniques to predict the compressive strength of fly ash concrete along time. The presented models are able to learn the complex relationships between several variables like the uniaxial compressive strength, the different concrete compounds and its mix design, the different properties of the fly ash used and the relative influence of its.

Contribuição ao estudo da aderência de barras de aço em concreto autoadensável reforçado com fibras metálicas; Contribution to the study of adhesion of steel bar in self compacting concrete reinforced with fibers

Tojal, Thaise Lima
Fonte: Universidade Federal de Alagoas; BR; Estruturas; Programa de Pós-Graduação em Engenharia Civil; UFAL Publicador: Universidade Federal de Alagoas; BR; Estruturas; Programa de Pós-Graduação em Engenharia Civil; UFAL
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
36.88589%
One of the conditions of existence assigned to the concrete as a building material is the adhesion between the concrete and steel. This adhesion has been the subject of several research studies that give rise to models that mathematically describe the behavior of adhesion; present testing techniques and in analysis of the influence of different factors that affect the concrete-steel adhesion. With the technological advancement of the concrete there were some special concrete compositions which contain chemical additives and minerals, and fiber, as is the case of self compacting concrete and concrete reinforced with fibers. These special concretes have shown different behavior compared to conventional concrete, contributing to an improved system of steel-concrete adhesion. Thus, this study used the pullout test of a steel bar of a massive concrete, following the standard model of RILEM-CEB-FIP (1973) known as Pull Out Test (Steel Reinforced Bond Test) were used conventional concrete, self compacting concrete and self compacting concrete with the addition of 1% steel fibers and steel bars used were 10mm and 16mm od diameter. The analyses were based on curves that describe the behavior of the loss of adhesion between the concrete and steel...

Estudo Experimental de Pavimentos de Concreto: Influência da Posição da Barra de Transferência e do Tipo de Concreto; Experimental Study of Concrete Pavement: Influence of Position of Bar Transfer and Type of Concrete

SILVA, Juliano Rodrigues da
Fonte: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias Publicador: Universidade Federal de Goiás; BR; UFG; Mestrado em Engenharia Civil; Engenharias
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
36.876187%
This work presents an experimental study of the behavior of transverse joints in unreinforced concrete slabs under elastic support. Due to the tensions caused by loads and volumetric variations in the slab, transverse joints when badly executed can cause a efficiency reduction in the shear transfer, thus reducing the useful life of the concrete pavement. To have a better efficiency in the shear transfer in joints of concrete pavements, 500 mm transfer bars are used with bar diameters varying from 10 mm to 32 mm. These bars are positioned at midheight of the sawed joints spaced at every 300 mm. This research seeks to verify the influence of the positioning of the transfer bars and the influence of different types of concrete on sawed joints of concrete pavements. Three different types of unreinforced concrete were used: conventional concrete, steel fiber concrete and self-compacting concrete. The experimental program consisted of the application of static monotonic loading in nine concrete plates, simulating concrete pavements, with dimensions 2200 mm x 600 mm, with a sawed joint at midlength supported by an elastic rubber layer. The experimental results showed that joints with transfer bars performed much better than those joints without transfer bars and that bars located at midheight perform better than those bars positioned at 45 mm from the base. The concrete types were quite different...

Análise de ligação entre o substrato de concreto antigo e concreto auto adensável com lançamento subaquático; Analysis of the connection between the substrate of old concrete and self-compacting concrete casting underwater

Mendes, Henry Silvério
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
Português
Relevância na Pesquisa
36.857632%
O objetivo deste trabalho é apresentar os resultados do estudo da ligação entre um substrato e o concreto auto-adensável com lançamento subaquático simulando a realização de reparos em estruturas de concreto submersas em diversas aplicações. Para tanto foram utilizadas amostras de concreto “antigo” provenientes de estruturas extraídas da Usina Hidrelétrica de Itumbiara no estado de Goiás, que foram considerados substratos, o concreto utilizado no presente trabalho segue os parâmetros de dosagens estabelecidos na pesquisa concluída em 2003 pelo laboratório de Furnas Centrais Elétricas e foi ajustado aos materiais (brita e areia) encontrados na região de Uberlândia do Estado de Minas Gerais. Os resultados obtidos são provenientes de testemunhos das juntas verticais e horizontais dos corpos-de-prova prismáticos concretados com substratos e mantidos submersos e extraídos após um ano, portanto, a hidratação quase completa. As análises relativas ao processo de lançamento do concreto indicam que é totalmente viável sua produção para pequenas aplicações. A visibilidade durante a concretagem foi dificultada pelo aumento de turbidez da água produzida pelo concreto, portanto deve-se diminuir a presença de um fluxo de água direto no concreto. As análises foram por comparação entre os resultados dos testemunhos e dos corpos-de-prova. Foi observado um aumento da resistência em relação direta ao diâmetro do testemunho. Nos testemunhos de 50 mm x 100 mm obteve-se um coeficiente de variação de 9% dando ao concreto uma variabilidade baixa. Os testemunhos compostos de concreto submerso e substrato de concreto (com junta inclinada) obtiveram uma resistência com valor 84% em relação os corpos-de-prova. A resistência à tração por compressão diametral dos testemunhos correspondeu a 54% do valor de referência. Também pode ser verificada a interface entre substrato e concreto após a ruptura. __________________________________________________________________________________________ ABSTRACT; The objective of this paper is to present the results of the connection between a substrate and self-compacting concrete with underwater launch simulating the repairs to concrete structures submerged in various applications. Therefore...

Rectangular Stress Block for High-Strength Concrete

Ozbakkaloglu, T.; Saatcioglu, M.
Fonte: Amer Concrete Inst Publicador: Amer Concrete Inst
Tipo: Artigo de Revista Científica
Publicado em //2004 Português
Relevância na Pesquisa
46.754785%
The use of high-strength concrete (HSC), with strengths reaching 130 MPa, has increased in recent years due to its superior performance and strength. Structures are designed and built using HSC, especially in columns of multistory buildings. The rectangular stress block specified in the ACI 318-02 Building Code for design of reinforced concrete elements was developed, however, on the basis of normal-strength concrete column tests. The applicability of the ACI rectangular stress block to higher-strength concretes becomes questionable, especially for members under high levels of axial compression. A new rectangular stress block is introduced in this paper for a wide range of concrete strengths between 20 and 130 MPa. The proposed stress block is verified against available test data. Column strengths computed using the stress block show good agreement with those recorded experimentally.; Togay Ozbakkaloglu and Murat Saatcioglu; © Copyright 2004, American Concrete Institute

Seismic behavior and design of reinforced concrete columns confined with FRP stay-in-place formwork

Saatcioglu, M.; Ozbakkaloglu, T.; Elnabelsy, G.
Fonte: Amer Concrete Inst Publicador: Amer Concrete Inst
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
Relevância na Pesquisa
46.754785%
One of the applications of fiber-reinforced polymers (FRP) in building and bridge construction is stay-in-place formwork. FRP stay-in-place formwork, in the form of preformed tubes, provides easy form assembly protection of steel reinforcement and concrete against corrosion and chemical attacks while also improving the strength and ductility of structural elements in earthquakeresistant construction. Seismic performance of FRP tubes in building and bridge columns has been investigated through tests of large-scale specimens under simulated seismic loading. The experimental program consisted of tests of circular and square columns confined with carbon FRP (CFRP) tubes. The results indicate that the use of CFRP tubes increases column inelastic deformability significantly. Bridge columns under low levels of axial compression exhibit inelastic drift capacities in excess of 4% before failing in flexural tension due to the rupturing of longitudinal reinforcement. Building columns under higher levels of axial compression show drift capacities in excess of 8% when the behavior is governed by confined concrete. These observations and experimental results were used to develop a displacement-based design procedure for concrete confinement for FRP-encased concrete columns. The paper presents an overview of the experimental program and the design approach developed.; http://www.concrete.org/PUBS/JOURNALS/OLJDetails.asp?Home=SP&ID=20245; M. Saatcioglu...

The discrete rigid body rotation of reinforced concrete beams using partial interaction and shear friction theory.

Haskett, Matthew Henry Thomas
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010 Português
Relevância na Pesquisa
36.870613%
In reinforced concrete members, two types of deformations exist: deformations due to curvature distribution and deformation due to discrete localised conditions such as cracks. The latter is the subject of this thesis, which presents a new approach for evaluating the discrete moment-rotation relationship of reinforced concrete members. This thesis is a collection of submitted, accepted or published papers from internationally recognised Journals, where the titles of Chapters 1 through 13 reflect the titles of the Journal papers. Each chapter takes the following format: the key theory and results from each journal paper are presented in a short synopsis, after which the journal paper is presented in full. This provides the reader, if desired, with the ability to understand the research in full by only reading the synopses of each chapter. In Chapter 1, the peripheral areas of shear friction theory, partial interaction theory and rigid body displacement are combined to quantify the moment-rotation response of any reinforced concrete member. It is discussed how partial interaction theory is used to model the behaviour of the reinforcement, shear friction theory the behaviour of the concrete, and that both these behaviours are combined through a rigid body displacement profile. This rigid body rotation approach is a structural mechanics model...

Experimental Study of the Influence of Bond on the Flexural Behaviour of Concrete Beams Pre-tensioned with AFRPs

Lees, Burgoyne C.J. Janet M
Fonte: The American Concrete Institute Publicador: The American Concrete Institute
Tipo: Article; not applicable
Português
Relevância na Pesquisa
46.729355%
This is the accepted version of the original publication available at http://www.concrete.org/Publications/ACIMaterialsJournal/ACIJournalSearch.aspx?m=details&ID=671; An experimental program was formulated to investigate the flexural behaviour of concrete prestressed with aramid fibre reinforced plastic tendons (AFRPs). The particular focus was the influence of the bond between an AFRP tendon and concrete on the flexural response of a beam. In the main test series pre-tensioned concrete beams were cast using either one of two types of AFRP tendons or steel tendons. The influence of bond was studied by testing beams with fully-bonded tendons, unbonded tendons or partially-bonded tendons. It was found that, although the fully-bonded beams had a high ultimate load capacity, only limited rotation occurred prior to failure. In contrast, large rotations were noted in the unbonded beams but the strengths of these members were significantly (25%) lower than those of the fully-bonded beams. The only beams that achieved both a high rotation capacity and a high ultimate load capacity were the beams with partially-bonded tendons. It is suggested that the use of partially-bonded tendons could provide the basis of a new design method for concrete beams prestressed with FRPs.

Analysis of Concrete Beams with Partially Bonded Composite Reinforcement

Lees, Janet M.; Burgoyne, C. J.
Fonte: American Concrete Institute Publicador: American Concrete Institute
Tipo: Article; accepted version
Português
Relevância na Pesquisa
46.60384%
This is the accepted version of the original publication available at http://www.concrete.org/PUBS/JOURNALS/AbstractDetails.asp?ID=854.; Beams prestressed with partially bonded fiber-reinforced plastic (FRP) tendons have high strength and rotation capacity but cannot be modeled by conventional techniques. Herein, it is assumed that all deformation takes place at cracks between rigid bodies. By setting up appropriate compatibility and equilibrium equations, the behavior at a single crack can be modeled, which then allows predictions to be made as to which of four possible events will occur next. These lead either to beam failure, or to changes in the geometry that can be analyzed using the same techniques. Comparisons are made with test results, and reasonable agreement is shown.; http://www.concrete.org/PUBS/JOURNALS/AbstractDetails.asp?ID=854