6,578 research outputs found

    Design formula to evaluate the NSM FRP strips shear strength contribution to a RC beam

    Get PDF
    This paper presents the closing step of a synthesis process aiming at deriving, from a previously developed more complex model, a simple design formula to evaluate the shear strength contribution provided by a system of Near Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) strips to a Reinforced Concrete (RC) beam. The self-contained and ready-to-implement set of analytical equations and logical operations is presented along with the main underlying physical-mechanical principles and assumptions. The formulation proposed is appraised against some of the most recent experimental results and its predictions are also compared with those obtained by the two previous and more sophisticated versions of the same modeling strategy. Monte Carlo simulations are carried out in order to appraise the sensitivity of the NSM shear strength contribution prediction to the value assumed by the input parameters.Fundação para a CiĂȘncia e a Tecnologia (FCT

    Shear strengthening of RC beams by means of NSM FRP strips : constitutive law of a single strip

    Get PDF
    The need to provide a rational explanation to the observed peculiar failure mode affecting the behaviour, at ultimate, of a Reinforced Concrete (RC) beam strengthened in shear by Near Surface Mounted (NSM) Fibre Reinforced Polymer (FRP) strips, led the authors to develop a comprehensive numerical model for simulating the NSM shear strength contribution to RC beams throughout the entire loading process as function of the Critical Diagonal Crack (CDC) opening angle. That model was respectful of equilibrium, ki-nematic compatibility and constitutive laws. Despite its high level of prediction accuracy, taking into account all of the possible failure modes, as well as the interaction among adjacent strips, that model resulted rela-tively complex to be easily implemented in a practitioners-addressed building regulations code. Yet, it can be conveniently simplified into a more user-friendly and closed-form design formula. Crucial point of that sim-plification is the development of a reliable constitutive analytical law providing the single strip strength as function of the imposed end slip. This paper presents the modelling strategy adopted to determine that consti-tutive law, as well as its final analytical expression.The authors of the present work wish to acknowledge the support provided by the Empreiteiros Casais, S&P.., degussa.. Portugal, and Secil (Unibetao, Braga). The study reported in this paper forms a part of the research program SmartReinforcement Carbon fibre laminates for the strengthening and monitoring of reinforced concrete structures supported by ADI-IDEIA, Project no 13-05-04-FDR-00031. This work was also carried out under the auspices of the Italian DPC-ReLuis Project (repertory n. 540), Research Line 8, whose financial support is greatly appreciated

    Parametric studies of the NSM FRP strips shear strength contribution to a RC beam

    Get PDF
    A three dimensional mechanical model was recently developed to simulate the shear strength contribution provided by a system of Near Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) strips to a Reinforced Concrete (RC) beam throughout its loading process. It was developed fulfilling equilibrium, kinematic compatibility and constitutive laws of both materials, concrete and FRP, and local bond between themselves. In the present paper, that model is first appraised on the basis of some of the most recent experimental results and then is applied to carry out parametric studies. The influence of each of the involved parameters on the contribution provided by a system of NSM FRP strips to the shear strength of a RC beam is investigated. The results of those studies are presented along with the main findings.(undefined)The authors of the present work wish to acknowledge the support provided by the “Empreiteiros Casais”, S&P¼, degussa¼ Portugal, and Secil (Unibetão, Braga). The study reported in this paper forms a part of the research program “CUTINEMO” supported by FCT, PTDC/ECM/73099/2006. Also, this work was carried out under the auspices of the Italian DPC-ReLuis Project (repertory n. 540), Research Line 8, whose financial support is greatly appreciated

    Three dimensional mechanical model for simulating the NSM FRP strips shear strength contribution to RC beams

    Get PDF
    Shear strengthening of Reinforced Concrete (RC) beams by means of Near Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) strips is an emerging technique for structural rehabilitation that is gaining increasing interest in the FRP community mainly because of some advantages it provides with respect to the better consolidated technique of the Externally Bonded Reinforcement (EBR). Those advantages encompass, mainly, a better exploitation of material and a higher protection against vandalism along with a relative faster applicability. Yet, the behavior of such NSM FRP strips is extremely complex, as can be gathered by experimental evidence, due to the complex geometry, the non linear mechanical properties of bond, and the scatter affecting the concrete tensile properties along with their non-linearity. In an attempt to provide valuable contribution to a better understanding of their behavior, a three dimensional mechanical model for simulating the shear strength contribution provided by a system of NSM FRPs to a RC beam throughout the loading process was recently developed. Its upgraded version is herein presented along with the main findings. It correctly interprets the experimental evidence taking into account complex phenomena such as the interaction between bond transferred force and concrete fracture along with the interaction between adjacent strips.The authors of the present work wish to acknowledge the support provided by the "Empreiteiros Casais", S&P(R), degussa (R) Portugal, and Secil (Unibetao, Braga). The study reported in this paper forms a part of the research program "SmartReinforcement - Carbon fibre laminates for the strengthening and monitoring of reinforced concrete structures" supported by ADI-IDEIA, Project no. 13-05-04-FDR-00031. Also, this work was carried out under the auspices of the Italian DPC-ReLuis Project (repertory no. 540), Research Line 8, whose financial support is greatly appreciated
    • 

    corecore