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Assessing the efficiency of CFRP discrete confinement systems for concrete cylinders

Barros, Joaquim; Ferreira, Débora
Fonte: ASCE Publications Publicador: ASCE Publications
Tipo: Artigo de Revista Científica
ENG; ENG
Relevância na Pesquisa
76.08%
Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section concrete elements confined by distinct arrangements of strips of CFRP sheet are submitted to a direct compression load up to the failure point. The influence of the width of the strip, distance between strips, number of CFRP layers per strip, CFRP stiffness and concrete strength class on the increase of the load carrying capacity and ductility of concrete columns, is evaluated. An analytical model is developed to predict the compressive stress-strain relationship of concrete columns confined by discrete and continuous CFRP arrangements. The main results of the experimental program are presented and analyzed and used to assess the model performance

Near surface mounted CFRP-based technique for the strengthening of concrete structures

Barros, Joaquim; Cruz, Sena; Dias, Salvador; Ferreira, Débora; Fortes, Adriano
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
76.13%
To assess the effectiveness of the Near Surface Mounted (NSM) strengthening technique, an experimental program was carried out involving reinforced concrete (RC) columns and beams. In columns failing in bending the present work shows that the failure strain of the Carbon Fiber Reinforced Polymer (CFRP) laminates can be attained using the NSM technique. Beams failing in bending were also strengthened with CFRP laminates in order to double their load carrying capacity. This goal was attained and maximum strain levels of about 90% of the CFRP failure strain were recorded. Performance of externally bonded reinforcing (EBR) and NMS techniques was compared for strengthening RC beams failing in shear. NMS was much more effective, not only in terms of the increase of the load carrying capacity and deformability at beam failure, but also with respect to the time consuming nature of the corresponding strengthening procedures. To assess the bond behavior of CFRP to concrete, pulloutbending tests were carried out. The influences of bond length and concrete strength on the bond behavior were analyzed

Utilização de fibras de carbono e de fibras de vidro para reforço de vigas de madeira.; Exploitation of carbon fiber and glass fiber to reinforcements of timber beams.

Fiorelli, Juliano
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 19/04/2002 PT
Relevância na Pesquisa
66.3%
A necessidade de recuperação e reforço em estruturas de madeira, concreto e aço exigiu da construção civil uma procura por métodos mais eficientes que pudessem cumprir esse papel. Com este objetivo vários estudos estão sendo realizados utilizando fibras reforçadas com polímeros (FRP). Dentre estas fibras, as que vêm apresentando melhores resultados como reforço para peças estruturais de madeiras são as fibras de carbono e as fibras de vidro. Dentro deste escopo, este trabalho tem como objetivo estudar o comportamento estrutural de vigas de madeira de espécies nacionais reforçadas com fibras de carbono e com fibras de vidro, verificando a eficiência deste reforço e adequando modelos de cálculo para avaliação da resistência e da rigidez das vigas reforçadas, e também verificar a eficiência de uma formulação de adesivos à base de mamona e do adesivo Cascophen, para fixação das respectivas fibras na madeira, em substituição ao adesivo epóxi, normalmente utilizado. Foram efetuados ensaios de vigas de madeira reforçadas com polímeros, em modelo reduzido, e em protótipos, para diversas configurações de geometria e quantidade de fibras utilizadas. Os resultados obtidos indicam uma boa concordância entre os modelos teóricos para avaliar a resistência e a rigidez das vigas reforçadas...

Mecanismos de confinamento em pilares de concreto encamisados com polímeros reforçados com fibras submetidos à flexo-compressão ; Confinement mechanisms in concrete columns wrapped by carbon fiber reinforced polymers subjected to flexural compression

Carrazedo, Ricardo
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 19/12/2005 PT
Relevância na Pesquisa
96.17%
Neste trabalho avaliou-se a influência da forma da seção transversal e da excentricidade do carregamento sobre o efeito de confinamento em pilares de concreto encamisados com polímeros reforçados com fibras (PRF). Para estas avaliações foi utilizada a análise experimental, por meio de ensaios de pilares sob flexo-compressão, e a análise numérica com o método dos elementos finitos. Observou-se que ocorreram reduções significativas dos efeitos de confinamento em pilares de seção quadrada e retangular quando a relação entre o raio de arredondamento dos cantos e o maior lado da seção transversal diminuiu. A influência da relação entre o lado maior e menor, no caso de pilares de seção retangular, não foi tão significativa se comparada ao efeito redutor do raio de arredondamento mencionado anteriormente. Ocorreram ganhos de resistência em todos os pilares ensaiados, indicando que o encamisamento com PRF pode ser utilizado mesmo em situações em que a força de compressão seja aplicada com pequenas excentricidades. O efeito da excentricidade sobre o confinamento dependeu da forma da seção transversal considerada. Em pilares de seção circular a excentricidade reduziu levemente os efeitos de confinamento. Nos pilares de seção quadrada a excentricidade não reduziu significativamente os efeitos de confinamento...

Alternativas para melhoria no desempenho de estruturas de concreto armado reforçadas pela colagem de polímeros reforçados com fibras; Alternatives to improve the performance of reinforced concrete structures post-strengthened through the bonding of fiber reinforced polymers

Garcez, Mônica Regina
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
66.42%
A utilização de Polímeros Reforçados com Fibras (PRF) no reforço de estruturas de concreto armado começou a ser investigada na década de 70 e se consolidou como uma atraente alternativa para utilização em obras civis, principalmente em casos onde ambientes agressivos impedem a utilização de materiais susceptíveis à corrosão, como o aço. Com o passar dos anos, diferentes técnicas de reforço que utilizam sistemas PRF formados com fibras de carbono envolvidas em matriz epoxídica (PRFC) têm sido aplicadas a estruturas que necessitam aumentar recuperar sua capacidade resistente. Apesar dos bons resultados obtidos e das vantagens associadas a estas técnicas, estudos experimentais mostram que a ruptura das estruturas reforçadas freqüentemente acontece de forma prematura, sem o esgotamento da capacidade resistente do PRFC. Apesar dos inúmeros desenvolvimentos positivos referentes à utilização de PRFC em estruturas civis, considera-se que existem diversas possibilidades de avanço, ainda pouco exploradas, que podem favorecer uma utilização mais eficiente, segura e racional dos sistemas PRF. Sendo assim, o principal objetivo deste trabalho é estudar a potencialidade e eficiência de algumas alternativas de emprego da técnica de reforço por colagem de PRF...

Suitability of carbon fiber-reinforced polymers as power cable cores: Galvanic corrosion and thermal stability evaluation

Santos, T. F. A.; Vasconcelos, G. C.; Souza, W. A. de; Costa, M. L.; Botelho, E. C.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 780-788
ENG
Relevância na Pesquisa
106.34%
The increasing demand for electrical energy and the difficulties involved in installing new transmission lines presents a global challenge. Transmission line cables need to conduct more current, which creates the problem of excessive cable sag and limits the distance between towers. Therefore, it is necessary to develop new cables that have low thermal expansion coefficients, low densities, and high resistance to mechanical stress and corrosion. Continuous fiber-reinforced polymers are now widely used in many industries, including electrical utilities, and provide properties that are superior to those of traditional ACSR (aluminum conductor steel reinforced) cables. Although composite core cables show good performance in terms of corrosion, the contact of carbon fibers with aluminum promotes galvanic corrosion, which compromises mechanical performance. In this work, three different fiber coatings were tested (phenol formaldehyde resin, epoxy-based resin, and epoxy resin with polyester braiding), with measurements of the galvanic current. The use of epoxy resin combined with polyester braiding provided the best inhibition of galvanic corrosion. Investigation of thermal stability revealed that use of phenol formaldehyde resin resulted in a higher glass transition temperature. On the other hand...

Caracterização do fresamento de chapas de compósito polímero reforçado com fibras de carbono (PRFC); Characterization of the plates reinforced polymer composite milling with carbon (CFRP) fiber

Francisco Romeo Martins
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/05/2014 PT
Relevância na Pesquisa
66.29%
O objetivo deste trabalho é caracterizar o material composto PRFC (Polímero Reforçado com Fibras de Carbono) em relação ao seu comportamento durante o processo de fresamento cilíndrico tangencial simétrico. Foi usado um método experimental. Uma fresa com oito milímetros de diâmetro e com seis arestas de corte de metal duro ISO K10 foi usada para usinagem placas (PRFC) com 4 mm de espessura. Todo o limite da máquina foi explorado em termos de velocidade de corte que variou entre de 100 em 100 m/min na faixa de 100 a 600 m/min. A profundidade de usinagem (espessura da chapa) foi de 4 mm. Dois avanços por dente da fresa foram utilizados em parte das experiências nos valores de 0,075 e 0,1 mm/rot. Este trabalho se justifica pelo fato de que a utilização de materiais compósitos tem crescido substancialmente e os seus métodos de produção se tornaram mais populares. Estes materiais vêm sendo cada vez mais utilizados em aplicações das mais diversas áreas industriais, tais como: aeroespacial, aviação comercial, indústria naval, automobilística, indústrias de máquinas ferramentas e equipamentos desportivos. Os materiais compósitos (PRFC) são importantes materiais de componentes estruturais, devido às suas propriedades de alta resistência...

Near surface mounted CFRP-based technique for the strengthening of concrete structures

Barros, Joaquim A. O.; Sena-Cruz, José; Dias, Salvador J. E.; Ferreira, Débora R. S. M.; Fortes, Adriano
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2004 ENG
Relevância na Pesquisa
76.13%
To assess the effectiveness of the Near Surface Mounted (NSM) strengthening technique, an experimental program was carried out involving reinforced concrete (RC) columns and beams. In columns failing in bending the present work shows that the failure strain of the Carbon Fiber Reinforced Polymer (CFRP) laminates can be attained using the NSM technique. Beams failing in bending were also strengthened with CFRP laminates in order to double their load carrying capacity. This goal was attained and maximum strain levels of about 90% of the CFRP failure strain were recorded. Performance of externally bonded reinforcing (EBR) and NMS techniques was compared for strengthening RC beams failing in shear. NMS was much more effective, not only in terms of the increase of the load carrying capacity and deformability at beam failure, but also with respect to the time consuming nature of the corresponding strengthening procedures. To assess the bond behavior of CFRP to concrete, pulloutbending tests were carried out. The influences of bond length and concrete strength on the bond behavior were analyzed.; S&P®. Bettor MBT® Portugal. Secil. Nordesfer. Ferseque. Casais. Solusel. VSL. Unibetão (Braga). Cemacom.

Shear Strengthening of RC beams with near-surface-mounted CFRP laminates

Dias, Salvador J. E.; Barros, Joaquim A. O.
Fonte: American Concrete Institute Publicador: American Concrete Institute
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
76.08%
The efficacies of the Near Surface Mounted (NSM) and Externally Bonded Reinforcing (EBR) techniques for the shear strengthening of rectangular cross section RC beams are compared. Both techniques are based on the use of carbon fiber reinforced polymer (CFRP) materials. The NSM was the most effective technique, and was also the easiest and fastest to apply, and assured the lowest fragile failure modes. The performance of the ACI and fib analytical formulations for the EBR shear strengthening was appraised. In general, the contribution of the CFRP systems predicted by the analytical formulations was larger than the values registered experimentally. The capability of the De Lorenzis formulation of predicting the contribution of the NSM technique for the shear strengthening of RC beams was appraised using bond stress and CFRP effective strain values obtained in pullout bending tests. This formulation provided values 61% lower than the values obtained experimentally.

Assessing the effectiveness of embedding CFRP laminates in the near surface for structural strengthening

Barros, Joaquim A. O.; Ferreira, Débora R. S. M.; Fortes, Adriano; Dias, Salvador J. E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
76.13%
The authors of the present work wish to acknowledge the support provided by the S&P, Bettor MBT Portugal, Secil, Nordesfer, Ferseque, Casais, Solusel, VSL, Unibetão (Braga) and the colaboration of Cemacom.; Near Surface Mounted (NSM) is a recent strengthening technique based on bonding Carbon Fiber Reinforced Polymer (CFRP) bars (rods or laminate strips) into pre-cut grooves on the concrete cover of the elements to strength. To assess the effectiveness of the NSM technique, an experimental program is carried out involving reinforced concrete (RC) columns, RC beams and masonry panels. In columns failing in bending the present work shows that the failure strain of the (CFRP) laminates can be attained using the NSM technique. Beams failing in bending are also strengthened with CFRP laminates in order to double their load carrying capacity. This goal was attained and maximum strain levels of about 90% of the CFRP failure strain were recorded in this composite material, revealing that the NSM technique is also very effective to increase the flexural resistance of RC beams. The effectiveness of externally bonded reinforcing (EBR) and NSM techniques to increase the flexural resistance of masonry panels is also assessed. In the EBR technique the CFRP laminates are externally bonded to the concrete joints of the panel...

Near surface mounted CFRP laminates for shear strengthening of concrete beams

Barros, Joaquim A. O.; Dias, Salvador J. E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /03/2006 ENG
Relevância na Pesquisa
76.2%
The authors wish to acknowledge the supports provided by the S&P, BeTTor MBT Portugal, Secil (Unibetão), and the colaboration of Cemacom.; A Near Surface Mounted (NSM) strengthening technique was developed to increase the shear resistance of concrete beams. The NSM technique is based on fixing, by epoxy adhesive, Carbon Fiber Reinforced Polymer (CFRP) laminate strips into pre-cut slits opened in the concrete cover of lateral surfaces of the beams. To assess the efficacy of this technique, an experimental program of four-point bending tests was carried out with reinforced concrete beams failing in shear. Each of the four tested series was composed of five beams: without any shear reinforcement; reinforced with steel stirrups; strengthened with strips of wet lay-up CFRP sheets; and two beams strengthened with NSM precured laminate strips of CFRP, one of them with laminates positioned at 90º and the other with laminates positioned at 45º in relation to the beam axis. Influences of the laminate strip inclination, beam depth and longitudinal tensile steel reinforcement ratio on the efficacy of the strengthening techniques were analyzed. Amongst the CFRP strengthening techniques, the NSM with laminate strips at 45º was the most effective...

Stress-strain model for partial CFRP confined concrete

Ferreira, Débora R. S. M.; Barros, Joaquim A. O.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2008 ENG
Relevância na Pesquisa
76.13%
Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of the partial wrapping technique, circular cross section concrete columns were confined by distinct CFRP arrangements and tested under direct compression. The experimental program was designed to evaluate the influence of the concrete strength class, the stiffness of the wet lay-up CFRP sheet, the distance between strips, the width of the strip, and the number of layers per each strip. The Harajli et al. model was modified in order to predict the compression stress-strain behaviour of reinforced concrete column elements partially and totally confined by CFRP lay-up sheets. The main results of the experimental program are hereby presented and analysed. The model’s performance is assessed using the experimental results.

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 ENG
Relevância na Pesquisa
76.28%
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.

Assessing the efficiency of CFRP discrete confinement systems for concrete column elements

Barros, Joaquim A. O.; Ferreira, Débora R. S. M.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em /04/2008 ENG
Relevância na Pesquisa
76.08%
Concrete columns requiring strengthening intervention always contain a certain percentage of steel hoops. Applying strips of wet lay-up carbon fiber reinforced polymer (CFRP) sheets in-between the existent steel hoops might, therefore, be an appropriate confinement technique with both technical and economic advantages, when full wrapping of a concrete column is taken as a basis of comparison. To assess the effectiveness of this discrete confinement strategy, circular cross section concrete elements confined by distinct arrangements of strips of CFRP sheet are submitted to a direct compression load up to the failure point. The influence of the width of the strip, distance between strips, number of CFRP layers per strip, CFRP stiffness and concrete strength class on the increase of the load carrying capacity and ductility of concrete columns, is evaluated. An analytical model is developed to predict the compressive stress-strain relationship of concrete columns confined by discrete and continuous CFRP arrangements. The main results of the experimental program are presented and analyzed and used to assess the model performance.

Development of high performance fiber reinforced cement composites (HPFRCC) for application as a transition layer of reinforced beams

Ferrari,V. J.; Arquez,A. P.; Hanai,J. B. de; Souza,R. A. de
Fonte: IBRACON - Instituto Brasileiro do Concreto Publicador: IBRACON - Instituto Brasileiro do Concreto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
86.21%
This study presents the development and behavior analysis of high performance fiber reinforced cement composites (HPFRCC). The describedmaterials were specifically developed for application as a transition layer: a repair layer that constitutes the stressed chord of reinforcedconcrete beams strengthened in flexure with carbon fiber reinforced polymers (CFRP). Nineteen different composites were produced by thehybridization process, varying the conventional short steel fiber and steel microfiber (manufactured exclusively for this research) contentsto modify the microstructure of the material, thus enhancing the stress transfer process from the cement matrix to the fibers. To analyze theresponse to flexural loading, the composites underwent three point bending tests in notched prism specimens. The response of the materialwas obtained considering strength and tenacity parameters (flexural and fracture). There was evidence of high performance by the composites with a pseudo-hardening behavior.

Seismic behavior of high-strength concrete columns confined by fiber-reinforced polymer tubes

Ozbakkaloglu, T.; Saatcioglu, M.
Fonte: American Society of Civil Engineers Publicador: American Society of Civil Engineers
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
76.13%
The use of high-strength concrete (HSC) in seismically active regions poses a major concern because of the brittle nature of material. The confinement requirements for HSC columns may be prohibitively stringent when ordinary grade transverse steel reinforcement is used. An alternative to conventional confinement reinforcement is the use of fiber-reinforced polymer (FRP) tubes in the form of stay-in-place formwork which can fulfill multiple functions of: (1) formwork; (2) confinement reinforcement; and (3) protective shell against corrosion, weathering and chemical attacks. The use of stay-in-place FRP formwork is investigated as concrete confinement reinforcement for HSC and normal strength concrete (NSC) columns with circular cross sections. Large-scale specimens with 270 mm circular cross-sections and different concrete strengths were tested under constant axial compression and incrementally increasing lateral deformation reversals. FRP tubes were manufactured from carbon fiber sheets and epoxy resin. The results indicate that inelastic deformability of HSC and NSC columns can be improved significantly by using FRP tubes, beyond the performance level usually expected of comparable columns confined with conventional steel reinforcement.; Togay Ozbakkaloglu and Murat Saatcioglu

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 EN
Relevância na Pesquisa
76.13%
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...

Retrofitting of interior RC beam–column joints using CFRP strengthened SHCC: Cast-in-place solution

Esmaeeli, Esmaeel; Barros, Joaquim A. O.; Sena-Cruz, José; Fasan, Luca; Li Prizzi, Fabio Raimondo; Melo, José; Varum, Humberto
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /04/2015 ENG
Relevância na Pesquisa
76.21%
The effectiveness of a repair strategy, for damaged RC beam–column joints, that combines strain hardening cementitious composite (SHCC) and laminates of carbon fiber reinforced polymers (CFRP laminates) is assessed in the present work. According to this technique, the existing concrete cover in the joint zone of the frame is replaced by a self-compacting SHCC. This thin layer of SHCC is reinforced with CFRP laminates that are bonded into the saw cut grooves. Two full-scale severely damaged interior RC beam–column joints were retrofitted using two different configurations of this technique: (i) applying the strengthening system to only the front and rear faces of the specimen; (ii) jacketing all sides of the elements of the specimen with the strengthening system. The effectiveness of these retrofitting configurations is assessed and compared by evaluating experimentally the hysteretic response, the dissipated energy, the degradation of secant stiffness, the displacement ductility and the failure modes of each repaired specimen, and also using the values of these indicators obtained in the virgin state of the specimens. This comparison revealed that the adopted retrofitting strategies can restore and even enhance the performance of this type of structural elements...

Modelling thermal effects in machining of carbon fiber reinforced polymer composites

Santiuste, Carlos; Díaz Álvarez, José; Soldani, Xavier; Miguélez, Henar
Fonte: SAGE Publicador: SAGE
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em /04/2014 ENG
Relevância na Pesquisa
106.23%
Machining-induced damage is commonly observed when manufacturing components based on carbon fiber reinforced polymer (CFRP) composites. Despite the importance of thermal effects in machining CFRPs, this problem has been poorly analyzed in the literature. Predictive tools are not available for thermal phenomena involved during cutting, while only few experimental studies have been found. In this paper, a three-dimensional (3D) finite element model of orthogonal machining of CFRPs including thermal effects is presented. Predicted thermal and mechanical intralaminar damage showed strong influence of fiber orientation. Thermally affected area was larger than mechanically damaged zone. This fact confirms the importance of accounting for thermal effects when modelling CFRP machining.; The authors acknowledge the financial support for the work to the Ministry of Economy and Competitiveness of Spain under the projects DPI2011-25999 and DPI2010-15123.

Innovative Modular High Performance Lightweight Decks for Accelerated Bridge Construction

Ghasemi, Sahar -
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
76.13%
At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas. The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination...