A 1D finite element model for the flexural behaviour of RC beams strengthened with MF-FRP strips

Martinelli, Enzo; Napoli, Annalisa; Nunziata, Bruno; Realfonzo, Roberto

doi:10.1016/j.compstruct.2013.07.058

Cited by 11 publications

(7 citation statements)

References 20 publications

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“…All its relevant properties can be defined in terms of the compressive strength, f c , and an ultimate axial strain ε cu = 0.0035 is assumed as a conventional value for the concrete crushing condition ( [20]); • An elastic response of concrete in tension is assumed, up to the unidirectional tensile strength, f ct , which can be determined as a function of f c ( [20]). Then, a power law is assumed for simulating a softening branch, which corresponds to the well-known tension-stiffening effect ( [27]); • A trilinear elastic-hardening-plastic law is adopted for reinforcing steel bars. It allows the simulation of the linear behavior up to yielding stress f y , a hardening branch up to the ultimate tensile strength, f s,u , which is kept constant up to a conventional value of the ultimate strain of ε s,u = 0.06;…”

Section: Fett Rech Prüfenmentioning

confidence: 99%

Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling

et al. 2014

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This paper presents a study on the load carrying capacity of reinforced concrete (RC) beams strengthened with externally bonded (EB) carbon fiber reinforced polymer (CFRP) strips prestressed up to 0.6% in strain. At the strip ends, the innovative gradient anchorage is used instead of conventional mechanical fasteners. This method, based on the epoxy resin's ability to rapidly cure under high temperatures, foresees a sector-wise heating followed by a gradual decrease of the initial prestress force towards the strip ends. The experimental investigation shows a promising structural behavior, resulting in high strip tensile strains, eventually almost reaching tensile failure of the composite strip. Additionally, ductility when considering deflection at steel yielding and at ultimate load is satisfying, too. From a practical point of view, it is demonstrated that premature strip grinding in the anchorage zone is not beneficial. In addition, a non-commercial 1D finite element code has been enlarged to an EB reinforcement with prestressed composite strips. A bilinear bond stress-slip relation obtained in earlier investigations is introduced as an additional failure criterion to the code. The numerical code is able to almost perfectly predict the Polymers 2014, 6 115 overall structural behavior. Furthermore, the calculations are used for comparison purposes between an initially unstressed and a prestressed externally bonded composite reinforcement. The increase in cracking and yielding load, as well as differences in structural stiffness are apparent.

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Section: Fett Rech Prüfenmentioning

confidence: 99%

Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling

et al. 2014

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“…Such a model, deeply described in [12], is based on a discrete connection between the RC beam and the FRP strip, and can be potentially used for analyzing other similar modeling problems, such as those related to the external reinforcement of masonry or wood members.…”

Section: Outline Of the Proposed 1d-fe Modelmentioning

confidence: 99%

“…Details about the model formulation are omitted herein for the sake of brevity and can be found in [12]. …”

Section: Assumptions and Formulation Of The Finite Elementmentioning

confidence: 99%

“…It is highlighted that in the numerical analyses, the values of ε sh , ε su and ultimate strength (f t ) were always assumed equal to 0.003, 0.07 and 1.20 f y , respectively, where f y is the yield strength of longitudinal steel rebars. More details about the considered stress-strain laws can be found in [12]. Figure 6, instead, shows the bearing stress-interface slip (σ f -s) relationships employed to simulate the response of the connecting devices, i.e., of shot or screwed fasteners.…”

Section: Nonlinear Analysis Proceduresmentioning

confidence: 99%

“…Thus, the authors have recently developed a novel FE model which is based on the explicit assumption of discrete connection between concrete and FRP. Such a model, already detailed and validated in Martinelli et al [12], is used in this study to simulate experimental tests available in the literature and relative to MF-FRP-strengthened RC beams and one-way slabs; most of these tests are included in a more general database published by Brown et al [4].…”

Section: Introductionmentioning

confidence: 99%

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RC Beams Strengthened with Mechanically Fastened Composites: Experimental Results and Numerical Modeling

et al. 2014

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Abstract:The use of mechanically-fastened fiber-reinforced polymer (MF-FRP) systems has recently emerged as a competitive solution for the flexural strengthening of reinforced concrete (RC) beams and slabs. An overview of the experimental research has proven the effectiveness and the potentiality of the MF-FRP technique which is particularly suitable for emergency repairs or when the speed of installation and immediacy of use are imperative. A finite-element (FE) model has been recently developed by the authors with the aim to simulate the behavior of RC beams strengthened in bending by MF-FRP laminates; such a model has also been validated by using a wide experimental database collected from the literature. By following the previous study, the FE model and the assembled database are considered herein with the aim of better exploring the influence of some specific aspects on the structural response of MF-FRP strengthened members, such as the bearing stress-slip relationship assumed for the FRP-concrete interface, the stress-strain law considered for reinforcing steel rebars and the cracking process in RC members resulting in the well-known tension stiffening effect. The considerations drawn from this study will be useful to researchers for the calibration of criteria and design rules for strengthening RC beams through MF-FRP laminates.

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Ceroni¹,

Pecce²,

Carloni³

et al. 2015

Design Procedures for the Use of Composites in Strengthening of Reinforced Concrete Structures

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This chapter gives an overview on the state-of-the-art about verifications of reinforced concrete structures using Externally Bonded (EB) Fibre Reinforced Polymers (FRP) under particular loading condition. Focus is mainly put on flexural strengthening, nowadays the most common application field for composite materials in structural engineering. The items discussed in this chapter are:\ud Serviceability limit states;\ud Fatigue behaviour;\ud Effects of fire and high temperature;\ud Long term behaviour;\ud Anchoring systems;\ud Mechanically Fastened Systems

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A 1D finite element model for the flexural behaviour of RC beams strengthened with MF-FRP strips

Cited by 11 publications

References 20 publications

Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling

Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling

RC Beams Strengthened with Mechanically Fastened Composites: Experimental Results and Numerical Modeling

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