Deflection analysis of reinforced concrete beams strengthened with carbon fibre reinforced polymer under long-term load action

International Journal of Polymer Science

et al. 2018

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The present study focuses on a prediction of crack width and load-carrying capacity of flexural reinforced concrete (RC) elements strengthened with fibre-reinforced polymer (FRP) reinforcements. Most studies on cracking phenomena of FRP-strengthened RC structures are directed to empirical corrections of crack-spacing formula given by design norms. Contrary to the design norms, a crack model presented in this paper is based on fracture mechanics of solids and is applied for direct calculation of flexural crack parameters. At the ultimate stage of crack propagation, the load-carrying capacity of the element is achieved; therefore, it is assumed that the load-carrying capacity can be estimated according to the ultimate crack depth (directly measuring concrete's compressive zone height). An experimental program is presented to verify the accuracy of the proposed model, taking into account anchorage and initial strain effects. The proposed analytical crack model can be used for more precise predictions of flexural crack propagation and load-carrying capacity.

Section: Introductionmentioning

confidence: 99%

Crack Width and Load-Carrying Capacity of RC Elements Strengthened with FRP

Šlaitas

International Journal of Polymer Science

et al. 2018

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“…Experimental researches (Marčiukaitis et al 2007;Skuturna et al 2008;Daugevičius et al 2012;Skuturna, Valivonis 2014, 2015 show that flexural stiffness increases due to the increased depth of the neutral axis. However, thin CFRP plates do not change the crosssection of the strengthened element.…”

Section: Introductionmentioning

confidence: 99%

Rc Beams Strengthened With Hpfrcc: Experimental and Numerical Results

Journal of Civil Engineering and Management

Skuturna

et al. 2016

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Abstract. The study analyses the behaviour of reinforced concrete beams strengthened with high-performance fibrereinforced cementitious composite (HPFRCC). Six beams were divided into two equal groups and strengthened. In total, nine beams were tested, including three control beams that were not strengthened. Control beams were over-reinforced. The beams of the first group were strengthened in the compressed part while those of the second group were strengthened in the compressed and tensioned parts of the section. The experimental results of all tested beams were compared with numerical results. The positive and negative effects of strengthening the resistance and serviceability of the beams were experimentally determined. The obtained results showed that the load-carrying capacity of all strengthened beams increased and their deflections decreased; however, crack width in the beams of the second group increased while that of the beams of the first group decreased. The width of cracks increased because the number of cracks decreased. The findings of this study show a comparison of strains, deflections, cracking and load-carrying capacity and indicate that strengthening changed the failure of the beams.

“…The description of the investigated strengthened beams was presented in the previous articles (Daugevičius et al, 2012;Daugevičius & Valivonis, 2013). Four beams were chosen for the numerical analysis.…”

Section: The Investigated Elementsmentioning

confidence: 99%

“…The aim of the present work is to investigate the long-term behaviour of the strengthened beams by using the finite element analysis program. The results of the numerical analysis can be compared with the experimentally obtained data (Daugevičius, Valivonis, & Marčiukaitis, 2012;Daugevičius & Valivonis, 2013). For performing the numerical analysis the FEA program TNO DIANA (version 9.6) developed by TNO DIANA (the user manual by Jonna Manie and Wijtze Pieter Kikstra) is used.…”

Section: Introductionmentioning

confidence: 99%

The numerical analysis of the long-term behaviour of the reinforced concrete beams strengthened with carbon fiber reinforced polymer: Deflection

Modern Building Materials, Structures and Techniques (MBMST)

Skuturna

2019

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The numerical analysis of the reinforced concrete beams strengthened with CFRP is presented. The beams previously tested experimentally under long-term loading are selected for numerical simulation. The numerical modelling is performed by evaluating the beam’s work at various stages: the work stage before the long-term loading period, the work stage under the long-term load action, the work stage when the external load is removed and the work stage until failure. The work stages of all modelled beams are described in more detail. To analyse the behaviour of beams at different work stages, the numerical modelling using the phase analysis is performed. Different finite element groups are evaluated in each phase of analysis. The external load is increased, maintained and reduced. The finite elements of the CFRP layer are activated at a certain work stage for evaluating the strengthening effect. To assess the accuracy of the numerical analysis, each beam is modelled from the finite elements of various sizes. The paper presents the process of the numerical modelling and the predicted deflections. The numerically predicted deflections are compared with the deflections of the experimental study. The modelling of the behaviour of the strengthened beams has shown that the nature of the long-term deflection differs from that obtained in the experiment. The increment of the numerically predicted deflection decreases gradually over the long-term period. Meanwhile, the experimental long-term deflection increment is characterised by the sharp increase and decrease at the start of the long-term period. This contradiction shows that the experimental long-term deflections are greater. However, over time, the numerical model deflections may reach and exceed the experimental deflections due to steady increase. The smaller size of the finite elements causes the increase in the cracking moment and the higher moment when the yielding of the tensioned reinforcement occurs. However, the cracking moment obtained by the numerical modelling is much higher than that obtained by the experimental modelling. However, when the yielding strength of the tensile reinforcement is reached, the considered moment is smaller than the experimental one.