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Využití fitness centra pro ovlivnění síly dolních končetin fotbalistů. / Use of fitness center to affect the strength of the lower limbs for football players.Zavičák, Ondřej January 2014 (has links)
Title: Use of fitness center to affect the strength of the lower limbs for football players. Objectives: The aim of thesis is to create an overview for strengthening the lower limbs of football players from lower categories in fitness center. Find information about the strengthening of the lower limbs of football players from performance category and compared with men who go strengthen to the fitness centers. Methods: The paper has been used the literature analysis and carrying out survey which was conducted using interviews. 50 football players of performance category were target group. Results: In this work it was found that 72% football players dedicated strengthening the lower limbs especially in a comprehensive way and not just in fitness centers, as well ass at home and in training. The lower limbs of football players are overwhelmingly strengthened, but at lower categories the quidance of trained coach is missing. The number of reps and sets in training for the lower limbs are rather lower. 60% of footballers train in one set under 10 reps and 84% footballers do under 16 sets in strength training of the lower limbs. Keywords: Lower limbs - football - strength abilities - methodology of the strengthening - exercises application.
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Využití fitness centra pro ovlivnění síly dolních končetin fotbalistů. / Use of fitness center to affect the strength of the lower limbs for football playersZavičák, Ondřej January 2014 (has links)
Title: Use of fitness center to affect the strength of the lower limbs for football players. Objectives: The aim of thesis is to create an overview for strengthening the lower limbs of football players in fitness center. Methods: The paper has been used the literature analysis and carrying out survey which was conducted using interviews. 50 football players were target group performance categories. Results: In this work it was found that football players dedicated strengthening the lower limbs especially in a comprehensive way and not just in fitness centers, as well ass at home and in training. The lower limbs of football players are overwhelmingly strengthened at least in some way. Keywords: Lower limbs - football - strength abilities - methodology of the strengthening - exercises application.
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FRP shear strengthening of reinforced concrete beamsSas, Gabriel January 2011 (has links)
The shear failure mechanisms of flexural reinforced concrete (RC) members is highly complex; its precise details cannot be explained with simple analytical relationships, and are the topic of considerable scientific debate. The studies described and examined the three most used shear theories in the world – the fixed angle truss model (45°TM), the variable angle truss model (VAT), and modified compression field theory (MCFT). These three theories rest on the assumption that a beam loaded in shear behaves as a truss. However, this assumption is applied in different ways in various codes. In this thesis, three major standards, each of which uses a different implementation of these theories (CEN, 2005; ACI-318, 2008; CSA-A23.3, 2009), were used to predict the shear force capacity of a RC railway bridge that was strengthened in flexure with near surface mounted (NSM) carbon fibre reinforced polymers (CFRP) and then tested to failure. The data obtained in this test indicated that the codes underestimated the real shear behaviour of the bridge. There are some accepted reasons for such inaccuracies, namely the use of empirically derived equations in the ACI (2008) and CSA (2009) standards and the omission of the concrete contribution in CEN (2005). Moreover, the NSM reinforcement material used exhibits elastic behaviour until the point of failure; it was found that the use of such materials introduces further decreases the accuracy of the models’ predictions. The strains that developed in the area of the bridge where shear failure was expected were monitored throughout the test using a specially-developed photographic method. The results obtained with this method were promising, especially for research purposes, since it generated reliable data using relatively affordable tools.The use of FRP for shear strengthening introduces further complications to the problem of shear in reinforced concrete members because introduces two new failure modes: debonding at the concrete interface and fibre rupture of the FRP. Extensive research has been carried out on FRP shear strengthening around the world. Much of the data gathered in these studies has been compiled in a database. By analysing this large database, it was found that the effectiveness of FRP shear strengthening is influenced by many factors, including the properties of the FRPs, the FRP strengthening configuration used, the nature of the beam’s cross-section, the shear span to depth ratio, the presence of stirrups, and the nature of the tensile reinforcement. Analysis of this database also demonstrated that most of the studies reported in the literature had focused on investigating the influence of the properties of the FRPs and the different configuration systems, and that the other factors mentioned above have been sparsely investigated if not totally ignored. The strengthening configuration and the amount of fibres influence the failure mode of the FRP and the shear force that it can carry. It appears that the side-bonded and the U-wrapped configurations are most prone to failure by debonding. This is consistent with the findings of various small experimental programs, and was confirmed by analysis of the larger dataset. These findings are relevant because failure of the FRP by debonding is more complex mechanism than is the rupture of the fibres mechanism. As is shown in this thesis, the extent to which the FRP variables (properties and strengthening configuration) can affect the point at which failure occurs and the mode by which it happens is dependent on the quantity of stirrups and tensile reinforcement in the beam, to the position of the load in relation to the size of the cross section (shear span to depth ratio), the type of strengthening configuration, the concrete and FRP properties. For design purposes, it is important to predict the shear failure of FRP shear strengthened beams with as much accuracy as possible. Therefore, a design model for debonding of the shear strengthening of concrete beams with FRP was developed and the limitations of the truss model analogy were highlighted. The fracture mechanics approach was used to analyse the behaviour of the bond between the FRP composites and the concrete. In this model, of the parameters examined, the fracture energy of concrete and the axial rigidity of the FRP are considered to be the most important. The effective strain in the FRP when debonding occurs was determined and the limitations of the anchorage length over the cross section were analysed; ultimately, a simple iterative method for shear debonding was proposed. Since the model’s predictions were considered satisfactory but not really precise, an extensive review of the literature was conducted. All of the significant theoretical models for predicting the shear capacity of FRP strengthened RC beams that have been reported over the years were analysed and commented on, and their predictions were compared to the results recorded in a preliminary experimental database. The predictions of the models that are most widely used in design were compared to the experimental results reported in the database; the model developed by the author was evaluated alongside these more established models. All of the models, including that presented in this thesis, were found to generate inaccurate predictions, but two models have been calibrated so as to provide safe estimates of the FRP shear capacity. Finally a new model for FRP shear strengthening was proposed for use in engineering. The new model was developed on the basis of an analysis of the contents of the database of experimental findings. The model incorporates several design equations adopted from various models and is set up for engineering use. The predictions of the shear force carried by the FRP strengthening material are found to be conservative. / Godkänd; 2011; 20110328 (gabsas); DISPUTATION Ämnesområde: Konstruktionsteknik/Structural Engineering Opponent: Professor Giorgio Monti, University of Rome, Italy Ordförande: Professor Björn Täljsten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 29 april 2011, kl 13.00 Plats: F1031, Luleå tekniska universitet
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Sonderforschungsbereich 528 - Textile Bewehrungen zur bautechnischen Verstärkung und Instandsetzung - Abschlussbericht: Sonderforschungsbereich 528 - Textile Bewehrungen zur bautechnischen Verstärkung und Instandsetzung - Abschlussbericht: gekürzte FassungCurbach, Manfred, Ortlepp, Regine 08 May 2012 (has links)
Nach zwölf Jahren endete am 30.6.2011 die Förderung des Sonderforschungsbereiches 528 durch die Deutsche Forschungsgemeinschaft (DFG). Der Abschlussbericht fasst die zentralen Ergebnisse des Sonderforschungsbereiches auf dem Gebiet der Verstärkung und Instandsetzung mit textilbewehrtem Beton über die gesamte Laufzeit des SFBs zusammen. Dazu berichten die einzelnen Teilprojekte über ihre aktuellen Erkenntnisse aus der letzten Förderperiode.
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Etude expérimentale et numérique des poutres continues en béton armé renforcées ou réparées par collage des matériaux composites / Experimental and numerical study of continuous reinforced concrete beams strengthened or repaired by bonding composite materialsAli, Harith abdullah ali 20 October 2017 (has links)
Le renforcement en flexion des poutres de béton armé par collage externe de matériaux composites s’est révélé être une technique efficace et pratique. Cette thèse présente une étude sur la performance à la flexion des poutres continues en béton armé avec trois travées réparées ou renforcées par collage de tissus en fibres de carbone (CFRP) ou en fibres de verre (GFRP). Le programme expérimental se compose de deux groupes. Le groupe-1 est composé de huit poutres et le groupe-2 est composé de huit poutres. Dans chaque groupe, il y a une poutre de référence, poutre non renforcée. Toutes les poutres ont la même longueur de 9m et la même section de 15x25 (cm). Les essais expérimentaux avec le chargement monotone ont été effectués à l’aide d’une presse de 1000 kN. Les paramètres étudiés sont : effet du renforcement par CFRP et GFRP, épaisseur optimale du renforcement, efficacité de la réparation des poutres endommagées par CFRP et GFRP, comportement mécanique, les modes de rupture des poutres continues en béton armé renforcées. Les essais experimentaux et des calculs par la simulation numérique ont été effectués. Cinq modes de rupture des poutres ont été observés. La résistance maximale d’une poutre peut être améliorée entre 14,8 et 33,0% dans le cas des poutres renforcées par collage de CFRP et entre 7,2 et 11,8% par collage de GFRP. Il existe d’une épaisseur optimale du renforcement dans les trois portées de la poutre. La poutre complètement endommagée peut être réparée à 100%. Le moment de flexion maximal de la poutre endommagée et réparée devient supérieur à celui de la poutre de référence. Une étude numérique, à l'aide de la méthode des éléments finis en utilisant le logiciel ABAQUS, sur les poutres continues en béton armé renforcées ont été également réalisée. / The flexural strengthening of RC beams by external bonding of composite materials has proved to be an efficient and practical technique. This thesis presents a study on the flexural performance of reinforced concrete continuous beams with three spans repaired or strengthened by bonding carbon fiber reinforced polymer (CFRP) or glass fiber reinforced polymer (GFRP). The experimental program consists of two groups. Group-1 consists of eight beams and group-2 consists of eight beams. In each group, there is a reference beam, unreinforced beam. All beams have the same length of 9m and the same section of 15x25 (cm). The experimental tests with the monotonic loading were carried out using a 1000 kN press. The parameters studied are effect of reinforcement by CFRP and GFRP, the optimum thickness of the strengthening, repair efficiency of the beams damaged by CFRP and GFRP, mechanical behavior, the rupture modes of strengthened reinforced concrete beams. Experimental tests and calculations by numerical simulation were carried out. Five modes of the breaking of the beams were observed. The maximum strength of a beam can be improved by 14.8 and 33.0% for beams reinforced by CFRP bonding and between 7.2 and 11.8% by bonding GFRP. There is an optimum thickness of the reinforcement in the three spans of the beam. The fully damaged beam can be repaired at 100%. The maximum bending moment of the damaged and repaired beam becomes greater than that of the reference beam. A numerical study, using the finite element method with the help of ABAQUS software, on strengthening the continuous concrete beams, was also carried out.
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[en] CARBON FIBER REINFORCED POLYMER TORSION STRENGTHENING OF REINFORCED CONCRETE BEAMS / [pt] REFORÇO À TORÇÃO DE VIGAS DE CONCRETO ARMADO COM COMPÓSITOS DE FIBRAS DE CARBONOJULIO JERONIMO HOLTZ SILVA FILHO 27 September 2007 (has links)
[pt] Este estudo teórico-experimental analisa o comportamento
até a ruptura de
vigas de concreto armado reforçadas externamente à torção
com compósitos de
fibras de carbono (CFC). No programa experimental, sete
vigas de concreto
armado, com seção transversal de 20 cm x 40 cm e 420 cm de
comprimento,
com mesma armadura de aço longitudinal e transversal e
concreto com mesma
resistência à compressão, foram ensaiadas até a ruptura.
As vigas testadas
foram divididas em três séries, sendo uma viga de
referência sem reforço, três
vigas com reforço transversal externo e três vigas com
reforço externo
transversal e longitudinal. Para a realização dos ensaios
foi montada uma
estrutura auxiliar de aço capaz de transferir às vigas a
solicitação de torção pura.
No estudo teórico foram desenvolvidas duas formulações. A
primeira formulação,
baseada no modelo da treliça espacial generalizada com
abrandamento de
tensões, apresenta uma sistemática para traçado da curva
momento torçor x
ângulo de torção por unidade de comprimento de vigas de
concreto armado
reforçadas à torção. A segunda formulação, fundamentada no
modelo da
Analogia da Treliça Espacial de acordo com a filosofia de
dimensionamento do
Eurocode 2, apresenta uma sistemática para dimensionamento
de reforço com
CFC . As duas metodologias adotam um modelo para
determinação da
aderência entre o substrato de concreto e o reforço. A
inclusão da aderência nos
modelos desenvolvidos é de grande importância porque em
geral a ruptura do
elemento estrutural ocorre devido ao descolamento do CFC.
Os resultados
experimentais obtidos nos testes das vigas foram
utilizados para validar as duas
formulações teóricas desenvolvidas. Os resultados
experimentais apresentaram
boa aproximação quando comparados com os modelos
propostos. Verificou-se
que todas as vigas reforçadas apresentaram um acréscimo de
resistência à
torção em torno de 40% em relação à viga de referência.
Verificou-se que, após
a fissuração, as vigas reforçadas apresentaram perda de
rigidez inferior à da
viga de referência. Observou-se que o ângulo da fissura
medido
experimentalmente, o ângulo de inclinação calculado pelo
estado de deformação
e o ângulo de inclinação calculado pelo estado de tensão
da viga apresentaram
valores próximos para cada viga. / [en] A theoretical-experimental research on the torsional
behavior up to failure
of reinforced concrete beams strengthened with external
carbon fiber composites
(CFC) was carried out. The experimental study comprises a
series of seven
reinforced concrete beams with the same compressive
strength of concrete
loaded to failure and subjected to torsion. The beams
dimensions were 20 cm x
40 cm x 420 cm. The test specimens had the same internal
steel reinforcement.
The beams were divided in three series: the reference beam
without
strengthening; three beams with the external strengthening
applied transversally
and three beams with the external strengthening applied
transversally and
longitudinally. For the accomplishment of the tests an
auxiliary steel structure
was mounted, capable to transfer to the beams the pure
torsion moment. In the
theoretical study two analytical procedures were
developed. The first formulation,
based on the softened space truss model for torsion,
presents a systematic to
obtain the curve torsion moment x torsion angle per length
unit of the reinforced
concrete beams with CFC torsion strengthening. The second
systematic, based
on the Space Truss Model in accordance with the Eurocode
2, presents the
design of the CFC strengthening. Both methodologies adopt
the Chen and Teng
bond model between concrete and CFC. The consideration of
the bond in the
developed models is very important because the failure of
the concrete members
often occurs from debonding of the CFC. The experimental
results from the
beams tests were used to validate the two analytical
procedures. Good
agreement was obtained with the experimental and
analytical results. For all the
strengthened beams the average values of torsion strength
were increased by
40% when compared to the reference beam. After cracking,
the loss of rigidity in
the strengthened beams was lower then in the reference
beam. The cracking
angle experimentally measured and the strut angles
evaluated by strain state and
stress state presented close values.
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[en] EXPERIMENTAL STUDY OF REINFORCED CONCRETE BEAMS STRENGTHENED FOR SHEAR FORCE WITH CARBON FIBER COMPOSITES / [pt] ESTUDO EXPERIMENTAL DO REFORÇO À FORÇA CORTANTE DE VIGAS DE CONCRETO ARMADO COM COMPÓSITOS DE FIBRAS DE CARBONOLUIS ALBERTO SPAGNOLO JUNIOR 22 July 2008 (has links)
[pt] Neste trabalho é realizado o estudo experimental de oito
vigas de concreto armado de seção T (cm bw=15cm e cm
h=40cm), com 300 cm de comprimento, biapoiadas
e com a mesma armadura longitudinal, reforçadas à força
cortante com compósitos de fibras de carbono (CFC). As
mesmas foram divididas em duas séries de quatro vigas, com
uma viga de referência para cada série, onde a taxa de
armadura transversal interna foi maior para a Série I do
que para a Série II. Para as três vigas reforçadas de cada
série variou-se o número de camadas do reforço em
CFC por meio de estribos em U, os quais foram ancorados
longitudinalmente por meio de faixas desse compósito. A
colagem do CFC foi executada após o surgimento das
primeiras fissuras diagonais no trecho de maior cortante. Os
resultados dos ensaios mostraram que as vigas reforçadas
apresentaram um aumento mínimo de resistência à força
cortante de 36% em relação às respectivas vigas de
referência, e que a ruptura de todas as vigas ocorreu por
tração diagonal, com o descolamento do CFC na região de sua
ancoragem. O modelo cinemático e do ACI-440 (2001)
apresentaram resultados mais próximos aos dos ensaios
realizados para a resistência total da força cortante. O
resultado experimental da parcela da força cortante
resistida pelo CFC apresentou resultados superiores aos
calculados por diversos modelos teóricos, e os resultados
mais consistentes foram os modelos da FIB-Bulletin 14
(2001) e Khalifa e Nanni (2002). A análise de
diversos parâmetros mostrou que o fator de efetividade Vf
do reforço diminui quando a rigidez E(f)P(f) do CFC
aumenta, portanto, há um menor acréscimo de
resistência total à força cortante. / [en] This analysis involves the experimental study of eight
reinforced concrete beams of T section ( cm bw=15cm e
h=40cm), with cm 300cm of length, bisupported and with the
same longitudinal reinforcement, strengthened for shear
force with carbon fiber composites (CFC). They were divided
in two series of four beams, with a reference beam for each
series, where the internal transversal reinforcement ratio
was greater for Serie I than Serie II. For the three
strengthened beams of each series the number of layers of
the reinforcement in CFC made by U stirrup varied, which
were anchored longitudinally by stirrups of this composite.
The CFC glue was done after the first diagonal cracks in
the shear region. The results of the tests showed that the
strengthened beams had a minimum increase of shear force of
36% in relation to the respective reference beams and the
rupture of them occurred due to diagonal tension, with the
CFC debonding in the region of its anchorage. The cinematic
(upper-bound solution) and ACI-440 (2001) model presented
results close to the experimental results for the shear
strength. The experimental result of the shear force parcel
resisted by the CFC presented superior results to the
calculated by diverse theoretical models, and the most
consistent ones were FIB-Bulletin 14 (2001) and Khalifa and
Nanni (2002) models. The analyses of diverse parameters
showed that the strengthening effectiveness Vf decreases
when the rigidity E(f)P(f) of CFC increases, therefore
there is a lesser increase of total strength to the shear
force.
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As interfaces entre o Bolsa Família e a identidade periférica à luz do fortalecimento comunitário / The interfaces between Bolsa família and peripheral identity in the light of community strengtheningLima, Eduardo Sales de 02 September 2016 (has links)
O programa federal de transferência de renda Bolsa-Família foi estudado nesta pesquisa com o objetivo de analisar a identidade local no processo de fortalecimento comunitário dos sujeitos que residem na periferia do município de São Paulo, utilizando como referência o bairro de São Miguel Paulista. Observou-se que na busca pelos direitos sociais básicos, esses sujeitos reagem a outras ações do Estado, as quais lhes negam e até mesmo silenciam a plenitude de experiências sociais e políticas no território. Neste viés, em um processo de gestão social, a renda confere condições básicas para a sobrevivência das famílias ao passo que pode sofisticar a tentativa de tutela e controle sobre as mesmas, levando-as ao silenciamento político e/ou a compactuar com a luta política dentro de limites institucionais nos quais as relações de poder encontram-se consolidadas. Para escutarmos a produção de sentidos a partir das interfaces entre o Bolsa Família e a identidade periférica em uma realidade dialética realizamos entrevistas com bolsistas. Por meio de seus discursos identificamos dispositivos cotidianos de resistência e de sociabilidade. No limite, a transferência de renda associada ao processo de pertencimento ao cotidiano da vizinhança podem impulsionar sentidos relacionados à emancipação individual e coletiva, favorecendo a construção de pontes à participação política / The federal program Bolsa Familia cash transfer was studied in this research in order to analyze the local identity in the community strengthening process of the individuals residing in the outskirts of São Paulo, using as reference the São Miguel Paulista neighborhood. It was observed that in the search for basic social rights, these guys react to other state actions, which they deny and even silence the fullness of social and political experiences in the territory. In this bias, in a social management process, income gives basic conditions for the survival of families while can sophisticate attempting to protection and control over them, leading them to the political silencing and / or condoning the political struggle within institutional boundaries in which power relations are consolidated. To listen to the production of meaning from the interfaces between the Bolsa Família and peripheral identity in a dialectic reality we conducted interviews with bolsistas. Through his speeches we identify everyday devices resistance and sociability. Ultimately, the transfer of income associated with the process of belonging to the neighborhood daily can boost meanings related to individual and collective emancipation, favoring the construction of bridges to political participation
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Reforço de vigas de concreto armado por meio de barras de aço adicionais ou chapas de aço e argamassa de alto desempenho / Rehabilitation of reinforced concrete beams by means of additional steel bars or steel plate and high performance mortarReis, Andréa Prado Abreu 18 June 1998 (has links)
Neste trabalho estuda-se o comportamento de vigas de concreto armado reforçadas mediante duas técnicas distintas de reabilitação: adição de armadura longitudinal no bordo tracionado envolvida com argamassa de alto desempenho com ou sem fibras de aço, ou fixação de chapa de aço, também no bordo tracionado, por meio de argamassa de alto desempenho e conectores de aço. Inicialmente foi efetuado um levantamento dos principais materiais usados em reparo/reforço e dos procedimentos e recomendações indicados na literatura, para a reabilitação de elementos estruturais de concreto armado. Apresentou-se ainda uma síntese dos estudos mais recentes realizados nesta área de pesquisa e os resultados de alguns ensaios de vigas recuperadas realizados por outros pesquisadores. Na seqüência, foram realizados sete ensaios experimentais em vigas de concreto armado com seção transversal \"T\", de tamanho real, para avaliar a eficiência das duas técnicas de reabilitação propostas. De acordo com os resultados obtidos percebe-se que vigas reabilitadas através da adição de fibras de aço na argamassa que envolve a armadura complementar e de conectores metálicos soldados na chapa de aço são eficientes. Além disso, é imprescindível, nas vigas com chapas de aço, realizar uma boa ancoragem desses elementos para evitar a ruptura prematura da peça. Finalmente foi constatado que os resultados experimentais de outros pesquisadores indicam a viabilidade da reabilitação por meio de técnicas semelhantes as empregadas neste trabalho. / This work deals with the behaviour of reinforced concrete beams rehabilitated using two different techniques. One of these techniques consists of the addition of longitudinal reinforcement embedded in a plain or steel fiber reinforced high performance mortar at the tensioned face of the member. The second technique refers to the attachment of a steel plate to the bottom face of the beam, using a high performance mortar and steel connectors. Firstly, it was performed a research about the materials that are most commonly used on repair/strengthening and the recommendations prescribed in the available literature for reinforced concrete members. The work also presents a synthesis of the recent researches in this area, showing the results of some tests carried out by several authors. Next, seven experimental tests were carried out on reinforced concrete T-beams, in full-scale, in order to assess the efficiency of the two techniques mentioned. According to the results obtained on these tests, it can be concluded that beams rehabilitated through addition of steel fibers to the mortar used to cover the complementary reinforcement and metallic connectors welded to the steel plate are efficient. Also, when using steel plate, a good anchorage must be provided to prevent premature failure of the member. Finally, it can be stated that the results obtained by other researchers indicate that the rehabilitation of beams by means of the two techniques presented is feasible.
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Reforço de vigas de concreto armado por meio de cabos externos protendidos / Strengthening of reinforced concrete beams by external prestressed tendonsAlmeida, Tatiana Gesteira Martins de 25 April 2001 (has links)
As patologias apresentadas por algumas estruturas e a necessidade de aumento da capacidade de carga de outras fizeram com que diversas técnicas fossem desenvolvidas para o reforço de vigas de concreto armado. Uma delas é a incorporação e protensão de cabos externos. O grande diferencial desta técnica quando comparada às demais é o seu caráter ativo. Ou seja, por meio da protensão é possível aplicar forças de forma a diminuir o nível de tensões atuantes sobre a estrutura. Neste trabalho, é apresentado um amplo estado-da-arte sobre este tipo de reforço. São descritas algumas obras realizadas com esta técnica e relatados e analisados alguns ensaios em vigas protendidas com cabos externos. Diversos métodos de cálculo de vigas protendidas com cabos não aderentes são apresentados. É mostrado, também, um procedimento para previsão da forma de ruína de vigas protendidas com cabos externos. Foi feito um estudo experimental, ensaiando-se 3 vigas de concreto armado reforçadas por meio da protensão de cordoalhas engraxadas. Os resultados dos ensaios são analisados e comparados com previsões teóricas feitas a partir dos métodos de cálculo estudados e com resultados de ensaios em vigas reforçadas com outras técnicas. Do estudo realizado, foi possível comprovar os benefícios da protensão não só no que se refere à resistência ao momento fletor, mas também ao esforço cortante. / Many techniques for concrete beams strengthening have been developed along the years. Among them, prestressing of external tendons, which presents a major difference when compared to the others: controlled forces can be applied to reduce undesirable stresses in the structure. This work presents a state-of-the-art review on this technique. Some methods proposed to estimate the flexural capacity of beams prestressed with unbonded tendons are reviewed. It is also shown a procedure to predict the failure mode of the beams. Three reinforced concrete beams were strengthened by prestressing of external strands and tested. Results are analyzed and compared with both theoretical predictions and other test results of beams strengthened by alternative techniques. From the research, the benefits of prestressing on improving the flexural capacity and the shear strength of reinforced concrete beams could be confirmed.
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