Shear resistance analytical evaluation for RC beams with transverse reinforcement with two different inclinations

Colajanni, Piero; Pagnotta, Salvatore; Recupero, Antonino; Spinella, Nino

doi:10.1617/s11527-020-1452-8

Cited by 11 publications

(9 citation statements)

References 18 publications

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“…Colajanni et al [22] proposed a model based on the stress field approach, able to assess the shear capacity of RC members having transverse reinforcement arranged with two different inclinations. Here, that model is modified to be applied in the case of RC beams retrofitted with FRP reinforcement inclined in any direction.…”

Section: Design-oriented Modelmentioning

confidence: 99%

“…The proposed model also represents the extension of a model based on the stress field approach, able to assess shear strength of retrofitted RC beams with vertically-oriented FRP reinforcement only [23]. On the basis of the same assumption of the models proposed in [22,24], shear capacity of a strengthened RC beam can be assessed by means of three different equations, obtained by calculating the vertical equilibrium of beam segments, identified via three different sections parallel to stress field directions of concrete strut, steel stirrups, and FRP reinforcement, respectively (Figure 1). By doing so, each of the three equilibrium equations, which are given below, depends only on two stress fields, and can be easily solved: A f b s f are the nondimensional stresses and the mechanical ratios of FRP reinforcement and steel stirrups, respectively, ffu is the nominal rupture stress of the fiber, R the strain and stress "effective" coefficient (effective strain fe= fu R, effective stress ffe=ffu R=Ef fe), and r is the reduction factor of the efficiency of the steel stirrups.…”

Section: Design-oriented Modelmentioning

confidence: 99%

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Influence of the Effectiveness Factors in Assessing the Shear Capacity of Rc Beams Strengthened With FRP

Colajanni¹,

Pagnotta²

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Shear failure of RC beams strengthened with composite textiles is often affected by the different failure modes characterizing the FRP reinforcement. The most relevant analytical models for evaluating the shear capacity of RC beams strengthened with FRP take into account these failure modes by introducing an effectiveness factor "R", which reduces the ultimate FRP tensile stress. Moreover, the interaction between stirrups and FRP reinforcement leads to a reduced efficiency of the transverse steel reinforcement due to the brittle failure of composite textile which hinders the yielding of all the stirrups involved by critical crack. In this regard, some analytical models introduce an effectiveness factor "r", aiming at reducing the yielding stress of stirrups. The procedures to calculate the above two parameters represent the main differences characterizing most of analytical models, significantly influencing their results. For this reason, the present paper focuses on the comparison of the different procedures to assess the effectiveness factors, proposing a new procedure for each effectiveness factor by modification of already existing formulations. Influence of the arrangement of composite reinforcement on the efficacy of stirrups, affected by brittle failure of FRP, is considered by means of the ratio between effective strain of composite to yielding strain of steel. The proposed procedures are employed in a design-oriented analytical model able to calculate the shear strength of RC beams retrofitted with FRP reinforcement arranged in any direction. The model is formulated aiming at representing an extension of EN1992 shear model to beams strengthened with FRP. The efficacy of the proposed procedures is assessed by comparing the experimental results against the predictions obtained via the design-oriented model and the above-mentioned analytical models.

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Section: Design-oriented Modelmentioning

confidence: 99%

Section: Design-oriented Modelmentioning

confidence: 99%

Influence of the Effectiveness Factors in Assessing the Shear Capacity of Rc Beams Strengthened With FRP

Colajanni¹,

Pagnotta²

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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“…Shear failure in RC members is one of the most critical and undesired failure phenomena. Beams and columns of existing RC Moment Resisting Frames (MRFs) usually do not satisfy the current code requirements regarding shear strength; thus, often it becomes necessary to strengthen the existing RC structural member in order to protect it from unwanted shear failure [1,2].…”

Section: Introductionmentioning

confidence: 99%

Influence of Cross-Section Shape and FRP Reinforcement Layout on Shear Capacity of Strengthened RC Beams

2022

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The evaluation of the shear capacity of an FRP-strengthened reinforced-concrete beam is challenging due to the complex interaction between different contributions provided by the concrete, steel stirrup and FRP reinforcement. The shape of the beam and the FRP inclination can have paramount importance that is not often recognized by the models that are suggested by codes. The interaction among different resisting mechanisms has a significant effect on the shear capacity of beams, since it can cause a reduction in the efficiency of some resisting mechanisms. A comparative study of the performance in the shear resistance assessment provided by three models with six different effectiveness factors (R) is performed, considering different cross-section shapes, FRP wrapping schemes, inclination and anchorage systems. The results revealed that the cross-section shape, the FRP inclination and the efficiency of the FRP anchorages have a significant effect on the shear strength of beams. The analysis results show that the three models are able to provide an accurate average estimation of shear strength (but with a coefficient of variation up to 0.35) when FRP reinforcement orthogonal to the beam axis is considered, while a significant underestimation (up to 19%) affected the results for inclined FRP reinforcement. Moreover, all the models underestimated the resistance of beams with a T section.

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Section: Introductionmentioning

confidence: 99%

“…Retrofitting of existing RC frame structures by strengthening members such as beams and columns is among the commonly adopted strategies to improve the seismic capacity of existing buildings subjected to seismic actions [1][2][3]. Different approaches are available nowadays and each method provides different capacity improvement depending on the mechanical behavior of the confining device [3]. For example, Fiber Reinforced Polymers (FRP) sheets provide to the columns passive confining mechanism [4][5][6][7][8][9], and steel jackets provide semiactive or active confinement [8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

The Role of the Sustained Loads on the Bearing Capacity of Reinforced Concrete Columns Retrofitted by Steel Jackets

Ferrotto¹,

Pradhan²,

Cavaleri³

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Strengthening of reinforced concrete structures by steel jackets is a common retrofitting technique widely used in engineering practice. In most cases, reinforced concrete columns are strengthened under service loads while the columns are subjected to a certain amount of compressive stress caused by gravitational loads. In such cases, the bearing capacity for strengthened columns can be different from that obtained without existing stresses. In this paper, the effect of sustained loads in the prediction of the bearing capacity for strengthened columns is assessed by experimental, numerical, and analytical approaches. The results of the investigation revealed that the level of sustained loads at the moment of strengthening reduces the bearing capacity of columns, influencing the overall performances of retrofitted structures.

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Shear resistance analytical evaluation for RC beams with transverse reinforcement with two different inclinations

Cited by 11 publications

References 18 publications

Influence of the Effectiveness Factors in Assessing the Shear Capacity of Rc Beams Strengthened With FRP

Influence of the Effectiveness Factors in Assessing the Shear Capacity of Rc Beams Strengthened With FRP

Influence of Cross-Section Shape and FRP Reinforcement Layout on Shear Capacity of Strengthened RC Beams

The Role of the Sustained Loads on the Bearing Capacity of Reinforced Concrete Columns Retrofitted by Steel Jackets

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