The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform

Barros, Joaquim A. O. - One of the best experts on this subject based on the ideXlab platform.

  • Assessing the effectiveness of a NSM-CFRP flexural strengthening arrangements for continuous RC slabs by experimental and numerical research
    International Institute for FRP in Construction (IIFC), 2014
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    A program formed by continuous slab strips strengthened in flexure with near surface mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) laminates was carried out, and the obtained results showed the possibility of increasing significantly the load carrying capacity of these elements, maintaining high levels of ductility. The experimental program is formed by slab strips of two equal span lengths, and has the main purpose of exploring the potentialities of distinct NSM flexural strengthening configurations for the increase of the load carrying capacity of this type of structures. In the present work two types of strengthening arrangements were investigated, one with CFRP laminates exclusively applied at the intermediate support, H series (Hogging Region), and the other with laminates applied at both Hogging and sagging Regions (HS series). For assessing the predictive performance of a FEM-based computer program (FEMIX V4.0), the experimental results are compared with values predicted by this software. Then, a parametric study with 144 numerical models is carried out to investigate the influence of the strengthening arrangement and CFRP percentage in terms of moment redistribution and rotational capacities of continuous RC slab strips flexurally strengthened by the NSM technique. The obtained results are presented and analyzed in this paper.Fundação para a Ciência e a Tecnologia (FCT)The first author acknowledges the financial support of FCT (PhD Grant number SFRH/BD/69818/2010) and the National Council for Scientific and Technological Development (CNPq) –Brazil (GDE 200953/2007-9

  • NSM technique to increase the load carrying capacity of continuous RC slabs
    Elsevier, 2013
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    This work presents and analysis the results of an ongoing research project on the use of the near surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) laminates for the increase of the load carrying capacity of statically indeterminate (two spans) reinforced concrete (RC) slabs. The test program consisted of seventeen slab strips, grouped in two series that are different on the adopted strengthening scheme: H series, where H is the notation to identify the slabs strengthened with NSM CFRP laminates exclusively applied in the Hogging Region; HS series, where HS is the notation to identify the slabs strengthened with NSM CFRP laminates applied in both Hogging and sagging Regions. The program includes six unstrengthened reference RC slab strips, and eleven strengthened with CFRP NSM configurations designed to increase in 25% or 50% the load carrying capacity of the corresponding reference RC slabs. An extensive monitoring system was applied in the constituent materials, in the critical Regions of the tested slabs, in order to collect information for the discussion about the effectiveness of NSM technique in terms of load carrying and moment redistribution capacity. The strengthening procedures adopted in the laboratory tests followed, as much as possible, the real strengthening practice for this type of interventions. The obtained results show that the proposed technique is able to increase significantly the load carrying capacity of statically indeterminate RC slabs, even for those with relatively high steel reinforcement ratios. The load carrying capacity of the strengthened slabs was limited by its shear capacity or by the detachment of the strengthened concrete cover layer. At failure of the strengthened slabs, the longitudinal steel bars at intermediate support (Hogging Region) and at loaded sections (sagging Regions) have already yielded, and the deflection was quite large. However, for some strengthening configurations, the CFRP laminates led to a decrease of the moment redistribution capacity of the slabs.Fundação para a Ciência e a Tecnologia (FCT

  • Reforço à flexão de faixas de laje contínuas de BA utilizando laminados de carbono aplicados segundo a técnica NSM
    Instituto Brasileiro do Concreto (IBRACON), 2012
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    Um programa experimental foi realizado para avaliar a eficácia da técnica “Near Surface Mounted” (NSM) para reforço à flexão de elementos contínuos de betão armado (BA), em termos de capacidade de carga, redistribuição de momentos e ductilidade. O programa experimental é composto por 17 faixas de lajes de dois tramos, divididas em dois grupos de acordo com a configuração de reforço: Grupo H, composto por lajes reforçadas com laminados de CFRP aplicados segundo a técnica NSM na região de momento negativo; Grupo HS, constituído por lajes reforçadas com laminados de CFRP em ambas as regiões de momentos negativos e positivos. Este trabalho tem por objetivo verificar a possibilidade de aumentar a capacidade de carga das faixas de lajes em 25% e 50%, mantendo níveis de redistribuição de momentos de 15%, 30% e 45%. O programa experimental é descrito e os resultados obtidos são apresentados e analisados neste trabalho.An experimental program was carried out to assess the effectiveness of the Near Surface Mounted (NSM) technique for the flexural strengthening of continuous reinforced concrete (RC) slabs, in terms of load carrying, moment redistribution and ductility capacities. The experimental program consisted of seventeen two span slab strips, grouped in two series depending on the strengthening scheme: H series, where H is the notation to identify the slabs strengthened with NSM CFRP laminates exclusively applied in the Hogging Region; HS series, where HS is the notation to identify the slabs strengthened with NSM CFRP laminates applied in both Hogging and sagging Regions. This work aims to verify the possibility of increasing the load carrying capacity of the slab strips in 25% and 50%, maintaining moment redistribution levels of 15%, 30% and 45%. The experimental program is described and the obtained results are presented and analyzed in this pape

  • Assessment of the effectiveness of NSM-CFRP flexural strengthening configuration for continuous RC slabs
    Czech Concrete Society, 2011
    Co-Authors: Breveglieri Matteo, Dalfré Gláucia, Barros, Joaquim A. O., Aprile Alessandra
    Abstract:

    The experimental programs for the flexural strengthening of reinforced concrete (RC) structures using the Near Surface Mounted (NSM) technique with Fiber Reinforced Polymer (FRP) laminates were, in general, conducted with simply supported beams. Therefore, there is a lack of experimental and theoretical studies on the moment redistribution of statically indeterminate RC elements strengthened with NSM technique. This work explores the influence of the amount of FRP in terms of load carrying capacity, ductility and moment redistribution capacity of continuous RC slab strips. In this way, two span slab strips strengthened in the Hogging Region were tested. The obtained results were used to assess the predictive performance of a finite element model in the simulation of the nonlinear behavior of the tested slabs. Finally, a parametric study is carried out to investigate the influence of the strengthening arrangement and FRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique.Fundação para a Ciência e a Tecnologia (FCT) - CUTINEMO - Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures” PTDC/ECM/73099/200

Dalfré Gláucia - One of the best experts on this subject based on the ideXlab platform.

  • Assessing the effectiveness of a NSM-CFRP flexural strengthening arrangements for continuous RC slabs by experimental and numerical research
    International Institute for FRP in Construction (IIFC), 2014
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    A program formed by continuous slab strips strengthened in flexure with near surface mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) laminates was carried out, and the obtained results showed the possibility of increasing significantly the load carrying capacity of these elements, maintaining high levels of ductility. The experimental program is formed by slab strips of two equal span lengths, and has the main purpose of exploring the potentialities of distinct NSM flexural strengthening configurations for the increase of the load carrying capacity of this type of structures. In the present work two types of strengthening arrangements were investigated, one with CFRP laminates exclusively applied at the intermediate support, H series (Hogging Region), and the other with laminates applied at both Hogging and sagging Regions (HS series). For assessing the predictive performance of a FEM-based computer program (FEMIX V4.0), the experimental results are compared with values predicted by this software. Then, a parametric study with 144 numerical models is carried out to investigate the influence of the strengthening arrangement and CFRP percentage in terms of moment redistribution and rotational capacities of continuous RC slab strips flexurally strengthened by the NSM technique. The obtained results are presented and analyzed in this paper.Fundação para a Ciência e a Tecnologia (FCT)The first author acknowledges the financial support of FCT (PhD Grant number SFRH/BD/69818/2010) and the National Council for Scientific and Technological Development (CNPq) –Brazil (GDE 200953/2007-9

  • Flexural and shear strengthening of RC elements
    2013
    Co-Authors: Dalfré Gláucia
    Abstract:

    Tese de doutoramento em Engenharia CivilIn a recent experimental program dealing with the Near Surface Mounted (NSM) technique for the flexural strengthening of continuous reinforced concrete (RC) slabs strips, the increase of load carrying and the moment redistribution was lower than the expected values. This experimental program was analysed in depth in this thesis and it was concluded that more efficient flexural strengthening arrangements can be applied if carbon fibre reinforced polymer (CFRP) laminates (of rectangular cross section) are applied not only in the intermediate support (Hogging Region), but also in the positive bending moment zones (sagging Regions). Thus, an experimental and a numerical research program were carried out, and it was verified the possibility of increasing the load carrying capacity in 25% and 50%, maintaining a relatively high level of moment redistribution, when correct NSM flexural strengthening arrangements are used. For assessing the predictive performance of a FEM-based computer program, the experimental tests were simulated by considering the nonlinear relevant aspects of the intervening materials. After has been concluded about the capability of this model to simulate the behaviour of this type of structures, a parametric study was carried out to investigate the influence of the strengthening arrangement and CFRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique. Additionally, to predict the load-deflection response of this type of structures up to its collapse, an analytical model was developed and its performance was appraised by using the data obtained from the experimental program. This model is based on the flexibility method and requires the knowledge of the flexural stiffness of the representative cross sections of the structure, which can be determined from the moment-curvature relationship of these sections. The increase of the load carrying capacity of the strengthened slabs can, however, can be limited by the formation of a shear failure crack in the Hogging Region. To avoid the occurrence of this brittle failure mode, a new technique, designated Embedded Trough Section (ETS) was developed, and its effectiveness was appraised by testing two series of RC beams of different cross section. Finally, the most relevant conclusions extracted from the present study are presented, and further research developments are suggested.Num programa experimental recentemente realizado sobre o reforço à flexão de faixas de laje contínuas de betão armado (BA) reforçadas segundo a técnica NSM (Near Surface Mounted, nomenclatura inglesa), o aumento da capacidade de carga e de redistribuição de momento foi inferior ao esperado. Este programa experimental foi analisado em profundidade nesta tese e foi concluído que existem configurações de reforço à flexão mais eficientes que podem ser utilizadas se laminados de fibra de carbono (CFRP) forem aplicados não só na região de apoio central (momento negativo), mas também na região de momentos positivos. Nesse sentido, um programa experimental e numérico foi levado a cabo, e verificou-se a possibilidade de aumentar a capacidade resistente em 25% e 50%, mantendo um nível de redistribuição de momentos relativamente elevada, quando se usam sistemas de reforço NSM adequados. Para avaliar a capacidade de previsão um software baseado no Método dos Elementos Finitos (MEF), os resultados experimentais foram simulados considerando os aspectos mais relevantes do comportamento não-linear dos materiais intervenientes. Após a conclusão deste estudo sobre a capacidade de simulação do comportamento deste tipo de estruturas com este modelo, foi realizado um estudo paramétrico para investigar a influência da disposição do reforço e da percentagem de CFRP na capacidade de carga e capacidade de redistribuição de momento em faixas de laje contínuas reforçadas segundo a técnica NSM. Além disso, um modelo analítico foi desenvolvido para prever a relação força-flecha deste tipo de estruturas até o seu colapso e o seu desempenho foi avaliado usando os dados obtidos no programa experimental. Este modelo é baseado no método de flexibilidade e pressupõe o conhecimento da rigidez à flexão das secções transversais representativas da estrutura, a qual pode ser determinada a partir da relação momento-curvatura destas secções. O aumento da capacidade de carga pode, no entanto, ser comprometido pela formação de fendas de corte junto aos apoios centrais dos elementos estruturais reforçados. Para evitar a ocorrência deste tipo de rotura frágil, uma nova técnica de reforço, designada por Embedded Trough Section (ETS, na nomenclatura inglesa) foi desenvolvida, e a sua eficácia foi avaliada por meio de ensaios de duas séries de vigas com diferentes seções transversais. Finalmente, as principais conclusões extraídas da investigação desenvolvida ao longo deste trabalho são apresentadas, e desenvolvimentos futuros são sugeridos

  • NSM technique to increase the load carrying capacity of continuous RC slabs
    Elsevier, 2013
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    This work presents and analysis the results of an ongoing research project on the use of the near surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) laminates for the increase of the load carrying capacity of statically indeterminate (two spans) reinforced concrete (RC) slabs. The test program consisted of seventeen slab strips, grouped in two series that are different on the adopted strengthening scheme: H series, where H is the notation to identify the slabs strengthened with NSM CFRP laminates exclusively applied in the Hogging Region; HS series, where HS is the notation to identify the slabs strengthened with NSM CFRP laminates applied in both Hogging and sagging Regions. The program includes six unstrengthened reference RC slab strips, and eleven strengthened with CFRP NSM configurations designed to increase in 25% or 50% the load carrying capacity of the corresponding reference RC slabs. An extensive monitoring system was applied in the constituent materials, in the critical Regions of the tested slabs, in order to collect information for the discussion about the effectiveness of NSM technique in terms of load carrying and moment redistribution capacity. The strengthening procedures adopted in the laboratory tests followed, as much as possible, the real strengthening practice for this type of interventions. The obtained results show that the proposed technique is able to increase significantly the load carrying capacity of statically indeterminate RC slabs, even for those with relatively high steel reinforcement ratios. The load carrying capacity of the strengthened slabs was limited by its shear capacity or by the detachment of the strengthened concrete cover layer. At failure of the strengthened slabs, the longitudinal steel bars at intermediate support (Hogging Region) and at loaded sections (sagging Regions) have already yielded, and the deflection was quite large. However, for some strengthening configurations, the CFRP laminates led to a decrease of the moment redistribution capacity of the slabs.Fundação para a Ciência e a Tecnologia (FCT

  • Reforço à flexão de faixas de laje contínuas de BA utilizando laminados de carbono aplicados segundo a técnica NSM
    Instituto Brasileiro do Concreto (IBRACON), 2012
    Co-Authors: Dalfré Gláucia, Barros, Joaquim A. O.
    Abstract:

    Um programa experimental foi realizado para avaliar a eficácia da técnica “Near Surface Mounted” (NSM) para reforço à flexão de elementos contínuos de betão armado (BA), em termos de capacidade de carga, redistribuição de momentos e ductilidade. O programa experimental é composto por 17 faixas de lajes de dois tramos, divididas em dois grupos de acordo com a configuração de reforço: Grupo H, composto por lajes reforçadas com laminados de CFRP aplicados segundo a técnica NSM na região de momento negativo; Grupo HS, constituído por lajes reforçadas com laminados de CFRP em ambas as regiões de momentos negativos e positivos. Este trabalho tem por objetivo verificar a possibilidade de aumentar a capacidade de carga das faixas de lajes em 25% e 50%, mantendo níveis de redistribuição de momentos de 15%, 30% e 45%. O programa experimental é descrito e os resultados obtidos são apresentados e analisados neste trabalho.An experimental program was carried out to assess the effectiveness of the Near Surface Mounted (NSM) technique for the flexural strengthening of continuous reinforced concrete (RC) slabs, in terms of load carrying, moment redistribution and ductility capacities. The experimental program consisted of seventeen two span slab strips, grouped in two series depending on the strengthening scheme: H series, where H is the notation to identify the slabs strengthened with NSM CFRP laminates exclusively applied in the Hogging Region; HS series, where HS is the notation to identify the slabs strengthened with NSM CFRP laminates applied in both Hogging and sagging Regions. This work aims to verify the possibility of increasing the load carrying capacity of the slab strips in 25% and 50%, maintaining moment redistribution levels of 15%, 30% and 45%. The experimental program is described and the obtained results are presented and analyzed in this pape

  • Assessment of the effectiveness of NSM-CFRP flexural strengthening configuration for continuous RC slabs
    Czech Concrete Society, 2011
    Co-Authors: Breveglieri Matteo, Dalfré Gláucia, Barros, Joaquim A. O., Aprile Alessandra
    Abstract:

    The experimental programs for the flexural strengthening of reinforced concrete (RC) structures using the Near Surface Mounted (NSM) technique with Fiber Reinforced Polymer (FRP) laminates were, in general, conducted with simply supported beams. Therefore, there is a lack of experimental and theoretical studies on the moment redistribution of statically indeterminate RC elements strengthened with NSM technique. This work explores the influence of the amount of FRP in terms of load carrying capacity, ductility and moment redistribution capacity of continuous RC slab strips. In this way, two span slab strips strengthened in the Hogging Region were tested. The obtained results were used to assess the predictive performance of a finite element model in the simulation of the nonlinear behavior of the tested slabs. Finally, a parametric study is carried out to investigate the influence of the strengthening arrangement and FRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique.Fundação para a Ciência e a Tecnologia (FCT) - CUTINEMO - Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures” PTDC/ECM/73099/200

Al Khalil, Jwan Ahmad - One of the best experts on this subject based on the ideXlab platform.

  • STRUCTURAL RESPONSE OF FLEXURE-DEFICIENT REINFORCED CONCRETE CONTINUOUS SLABS STRENGTHENED WITH COMPOSITES
    Scholarworks@UAEU, 2015
    Co-Authors: Al Khalil, Jwan Ahmad
    Abstract:

    Accidental reduction in the amount of steel in continuous reinforced concrete (RC) floor slabs is a typical problem that might occur due to an error in design, unclear drawings, or overlooked verification of reinforcement prior to concrete casting. Existence of such deficiencies would compromise the load capacity and serviceability of RC floor slabs. This research examines the effectiveness of using fiber-reinforced polymers (FRP) to improve the structural response of flexure-deficient continuous RC slab strips. The study comprised experimental testing and finite element (FE) modeling. Sixteen two-span RC slab strips, 400 x 125 x 3800 mm each, were tested. Test parameters included the deficiency location, strengthening regime, and amount of FRP. The unstrengthened slab strip deficient in the sagging Region had 22% lower load capacity and 64% higher deflection-based ductility index compared with those of its counterpart deficient in the Hogging Region. Strengthening with FRP improved the load capacity and stiffness of the deficient slab strips. The FRP strengthening tended to decrease the ductility index of the slab strips deficient in the sagging Regions. Conversely, the ductility index of the slab strips deficient in the Hogging Region tended to increase after strengthening. The strength gain caused by strengthening was in the range 29% to 69% for the slab strips deficient in the sagging Regions and 14% to 44% for those deficient in the Hogging Region. Increasing the amount of FRP resulted in an increase in the load capacity but the additional strength gain was, generally, not proportional to the added amount of FRP. Increasing the amount of FRP had, typically, less significant effect on the load capacity of the slabs deficient in the Hogging Region than in the sagging Region. vii Strengthening of deficient Regions reduced the moment redistribution ratios. The ratios further decreased as the amount of FRP in the deficient Region increased. A maximum moment redistribution ratio of +32% was recorded for the strengthened slab strips. The FE models developed in this study predicted the nonlinear structural response of the tested continuous RC slab strips with a hig

  • Structural Response of Flexure-Deficient Reinforced Concrete Continuous Slabs Strengthened With Composites
    Scholarworks@UAEU, 2015
    Co-Authors: Al Khalil, Jwan Ahmad
    Abstract:

    Accidental reduction in the amount of steel in continuous reinforced concrete (RC) floor slab is a typical problem that might occur due to an error in design, unclear drawings, or overlooked verification of reinforcement prior to concrete casting. Existence of such deficiencies would compromise the load capacity and serviceability of RC floor slab. This research examines the effectiveness of using fiber-reinforced polymers (FRP) to improve the structural response of flexure-deficient continuous RC slab strips. The study comprised experimental testing and finite elements (FE) modeling. Sixteen two-span RC slap strips, 400 x 125 x 3800 mm each, were tested. Test parameters included the deficiency location, strengthening regime, and amount of FRP. The unstrengthened slab strip deficient in the sagging Region had 22% lower load capacity and 64% higher deflection-based ductility index compared with those of its counterpart deficient in the Hogging Region. Strengthening with FRP improved the load capacity and stiffness of the deficient slab strips. The FRP strengthening tended to decrease the ductility index of the slab strips deficient in the sagging Regions. Conversely, the ductility index of the slab strips deficient in the Hogging Region tended to increase after strengthening. The strength gain caused by strengthening was in the range 29% to 69% for the slab strips deficient in the sagging Regions and 14% to 44% for those deficient in the Hogging Region. Increasing the amount of FRP resulted in an increase in the load capacity but the additional strength gain was, generally, not proportional to the added amount of FRP. Increasing the amount of FRP had, typically, less significant effect on the load capacity of the slabs deficient in the Hogging Region than in the sagging Region. Strengthening of deficient Regions reduced the moment redistribution ratios. The ratios further decreased as the amount of FRP in the deficient Region increased. A maximum moment redistribution ratio of +32% was recorded for the strengthened slab strips. The FE model developed in this study predicted the nonlinear structural response of the tested continuous RC slab strips with a high level of accuracy. The numerical and experimental results were in good agreement

Alshawa, Jafer Husni - One of the best experts on this subject based on the ideXlab platform.

  • FLEXURAL STRENGTHENING OF ONE-WAY CONTINUOUS REINFORCED CONCRETE SLABS WITH CUTOFFS IN SAGGING AND Hogging RegionS Jafer Husni
    Scholarworks@UAEU, 2014
    Co-Authors: Alshawa, Jafer Husni
    Abstract:

    Installation of cutouts in existing reinforced concrete (RC) floor slabs to accommodate utility services reduces the slab load capacity and ductility. This research examines the effectiveness of using near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) reinforcement to improve the flexural response of continuous RC slabs with cutouts. The study comprised experimental testing and analytical modeling. A total of eleven two-span RC slab strips, 400 x 125 x 3800 mm each, were tested. Test parameters included the location of the cutout, and amount and distribution of the NSM-CFRP reinforcement between the sagging and Hogging Regions. Installation of a cutout in the sagging Region reduced the load capacity and ductility index by 27% and 12%, respectively. When the cutout was installed in the Hogging Region, a 23% reduction in both load capacity and ductility index was recorded. The NSM-CFRP strengthening fully restored the original load capacity of all deficient specimens, except one specimen with a cutout in the Hogging Region where only 90% of the original load capacity was restored. The enhancement in load capacity due to strengthening was in the range of 53% to 81% for the specimens with a cutout in the sagging Region and 18% to 54% for the specimens with a cutout in the Hogging Region. The ductility index of the specimens strengthened in the sagging Region only was, on average, 16% lower than that of the control specimen, whereas for the specimens strengthened in the Hogging Region only, the ductility index was almost the same as that of the control slab. For the specimens heavily strengthened in both sagging and Hogging Regions, the ductility index was on average 40% lower vii than that of the control slab. A maximum moment redistribution ratio of 26% was recorded for the continuous RC slabs strengthened with NSM-CFRP. An analytical model that can predict the load capacity of two-span RC slab strips containing cutouts and strengthened with NSM-CFRP has been introduced. The ratio of the predicted to measured load capacity was in the range of 0.74 to 1.02 with an average of 0.85, standard deviation of 0.09, and coefficient of variation of 10%

  • Flexural Strengthening of One-Way Continuous Reinforced Concrete Slabs with Cutoffs in Sagging and Hogging Regions
    Scholarworks@UAEU, 2014
    Co-Authors: Alshawa, Jafer Husni
    Abstract:

    Installation of cutouts in existing reinforced concrete (CR) floor slabs to accommodate utility services reduces the slab load capacity and ductility. This research examines the effectiveness of using near-surface-mounted (NSM) carbon fiber reinforced polymer (CFRP) reinforcement to improve the flexural response of continuous RC slabs with cutouts. The study comprised experimental testing and analytical modeling. A total of eleven two-span RC slabs strips, 400 x 125 x 3800mm each were tested. Test parameters included the location of the cutouts, and amount and distribution of the NSM-CFRP reinforcement between the sagging and Hogging Regions. Installation of a cutout in the sagging Region reduced the load capacity and ductility index by 27% and 12% respectively. When the cutout was installed in the Hogging Region, a 23% of reduction in both load capacity and ductility index was recorded. The NSM-CFRP strengthening fully restored the original load capacity of all deficient specimens, expect one specimen with a cutout in the Hogging Region where only 90% of the original load capacity was restored. The enhancement in load capacity due to strengthening was in the range of 53% to 81% for the specimens with cutout in the Hogging Region. The ductility index of the specimens strengthened in the sagging Region only was, on average, 16% lower than that of the control specimen, whereas for the specimens strengthened in the Hogging Region only, the ductility index was almost the same as that of the control slab. For the specimens heavily strengthened in both sagging and Hogging Regions, the ductility index was on average 40% lower than that of the control slab. A maximum moment redistribution ratio of 26% was recorded for the continuous RC slabs strengthened with NSM-CFRP. An analytical model that can predict the load capacity of two-span RC slab strips containing cutouts and strengthened with NSM-CFRP has been introduced. The ratio of the predicted to measured load capacity was in the range of 0.74 to 1.02 with an average of 0.85, standard deviation of 0.09, and coefficient of variation of 10%

Aprile Alessandra - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of effectiveness of NSM-CFRP flexural strengthening configurations for continuous RC slabs
    Czech Concrete Society ČBS Servis, 2011
    Co-Authors: Breveglieri Matteo, Dalfré G. M., Barros J. A. O., Aprile Alessandra
    Abstract:

    The experimental programs for the flexural strengthening of reinforced concrete (RC) structures using the Near Surface Mounted (NSM) technique with Fiber Reinforced Polymer (FRP) laminates were, in general, conducted with simply supported beams. Therefore, there is a lack of experimental and theoretical studies on the moment redistribution of statically indeterminate RC elements strengthened with NSM technique. This work explores the influence of the amount of FRP in terms of load carrying capacity, ductility and moment redistribution capacity of continuous RC slab strips. In this way, two span slab strips strengthened in the Hogging Region were tested. The obtained results were used to assess the predictive performance of a finite element model in the simulation of the nonlinear behavior of the tested slabs. Finally, a parametric study is carried out to investigate the influence of the strengthening arrangement and FRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique

  • Assessment of the effectiveness of NSM-CFRP flexural strengthening configuration for continuous RC slabs
    Czech Concrete Society, 2011
    Co-Authors: Breveglieri Matteo, Dalfré Gláucia, Barros, Joaquim A. O., Aprile Alessandra
    Abstract:

    The experimental programs for the flexural strengthening of reinforced concrete (RC) structures using the Near Surface Mounted (NSM) technique with Fiber Reinforced Polymer (FRP) laminates were, in general, conducted with simply supported beams. Therefore, there is a lack of experimental and theoretical studies on the moment redistribution of statically indeterminate RC elements strengthened with NSM technique. This work explores the influence of the amount of FRP in terms of load carrying capacity, ductility and moment redistribution capacity of continuous RC slab strips. In this way, two span slab strips strengthened in the Hogging Region were tested. The obtained results were used to assess the predictive performance of a finite element model in the simulation of the nonlinear behavior of the tested slabs. Finally, a parametric study is carried out to investigate the influence of the strengthening arrangement and FRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique.Fundação para a Ciência e a Tecnologia (FCT) - CUTINEMO - Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures” PTDC/ECM/73099/200