Predictions of the maximum plate end stresses of imperfect FRP strengthened RC beams: study and analysis

Rabia, Benferhat,Daouadji, Tahar Hassaine,Abderezak, Rabahi Techno-Press 2020 Advances in materials research Vol.9 No.4

A theoretical method to predict the interfacial stresses in the adhesive layer of reinforced concrete beams strengthened with porous FRP plate is presented in this paper. The effect due to porosity is incorporated utilizing a new modified rule of mixture covering the porosity phases. The adherend shear deformations have been included in the present theoretical analyses by assuming a linear shear stress through the thickness of the adherends. Remarkable effect of the porosity has been noted in the results. Indeed, the resulting interfacial stresses concentrations are considerably smaller than those obtained by other models which neglect the porosity effect. It was found that the interfacial stresses are highly concentrated at the end of the FRP plate, the minimization of the latter can be achieved by using porous FRP plate in particular at the end. It is also shown that the interfacial stresses of the RC beam increase with volume fraction of fibers, but decrease with the thickness of the adhesive layer.

Mechanical behavior of RC beams bonded with thin porous FGM plates: Case of fiber concretes based on local materials from the mountains of the Tiaret highlands

Benferhat Rabia,Tahar Hassaine Daouadji,Rabahi Abderezak Techno-Press 2023 Coupled systems mechanics Vol.12 No.3

The objective of this study is to evaluate the effects of adding fibers to concrete and the distribution rate of the porosity on the interfacial stresses of the beams strengthened with various types of functionally graded porous (FGP) plate. Toward this goal, the beams strengthened with FGP plate were considered and subjected to uniform loading. Three types of beams are considered namely RC beam, RC beam reinforced with metal fibers (RCFM) and RC beam reinforced with Alfa fibers (RCFA). From an analytical development, shear and normal interfacial stresses along the length of the FGP plates were obtained. The accuracy and validity of the proposed theoretical formula are confirmed by the others theoretical results. The results showed clearly that adding fibers to concrete and the distribution rate of the porosity have significant influence on the interfacial stresses of the beams strengthened with FGP plates. Finally, parametric studies are carried out to demonstrate the effect of the mechanical properties and thickness variations of FGP plate, concrete and adhesive on interface debonding, we can conclude that, This research is helpful for the understanding on mechanical behavior of the interface and design of the FRP-RC hybrid structures.

Thermo-mechanical behavior of porous FG plate resting on the Winkler-Pasternak foundation

Rabia, Benferhat,Tahar, Hassaine Daouadji,Abderezak, Rabahi Techno-Press 2020 Coupled systems mechanics Vol.9 No.6

The effect of porosity on the thermo-mechanical behavior of simply supported functionally graded plate reposed on the Winkler-Pasternak foundation is investigated analytically in the present paper using new refined hyperbolic shear deformation plate theory. Both even and uneven distribution of porosity are taken into account and the effective properties of FG plates with porosity are defined by theoretical formula with an additional term of porosity. The present formulation is based on a refined higher order shear deformation theory, which is based on four variables and it still accounts for parabolic distribution of the transverse shearing strains and stresses through the thickness of the FG plate and takes into account the various distribution shape of porosity. The elastic foundation is described by the Winkler-Pasternak model. Anew modified power-law formulation is used to describe the material properties of FGM plates in the thickness direction. The closed form solutions are obtained by using Navier technique. The present results are verified in comparison with the published ones in the literature. The results show that the dimensionless and stresses are affected by the porosity volume fraction, constituent volume fraction, and thermal load.

Analysis and sizing of RC beams reinforced by external bonding of imperfect functionally graded plate

Rabia, Benferhat,Daouadji, Tahar Hassaine,Abderezak, Rabahi Techno-Press 2021 Advances in materials research Vol.10 No.2

An analytical method based on the compatibility of deformations and equilibrium of forces is investigated to predict the reinforcement plate area in concrete beams strengthened with Functionally Graded (FG) plates bonded to the tension face of the beams. The models are given for beams having rectangular and T-cross-sections. The effect of porosity that can happen inside FGM materials during their manufacture is also shown. New rules of the mixture that take into account different distribution rates of porosity in FG plates have been developed in this study. A parametric study is conducted to investigate the effect of several parameters such as the ultimate moment, plate stiffness, the distribution rate of the porosity, and compressive strength of the concrete. The results obtained show a significant gain in the reinforcement plate area of the RC beam strengthened with an FG plate relative to another reinforced with FRP plate, which makes it possible to reduce the interfacial stresses and prevents detachment of the reinforcing plate.

Analytical analysis of the interfacial shear stress in RC beams strengthened with prestressed exponentially-varying properties plate

Rabia, Benferhat,Abderezak, Rabahi,Daouadji, Tahar Hassaine,Abbes, Boussad,Belkacem, Adim,Abbes, Fazilay Techno-Press 2018 Advances in materials research Vol.7 No.1

In this paper, a closed-form rigorous solution for interfacial shear stress in simply supported beams strengthened with bonded prestressed E-FGM plates and subjected to an arbitrarily positioned single point load, or two symmetric point loads is developed using linear elastic theory. This improved solution is intended for application to beams made of all kinds of materials bonded with a thin plate, while all existing solutions have been developed focusing on the strengthening of reinforced concrete beams, which allowed the omission of certain terms. The theoretical predictions are compared with other existing solutions. Finally, numerical results from the present analysis are presented to study the effects of various parameters of the beams on the distributions of the interfacial shear stresses. The results of this study indicated that the E-FGM plate strengthening systems are effective in enhancing flexural behavior of the strengthened RC beams.

Effect of porosity in interfacial stress analysis of perfect FGM beams reinforced with a porous functionally graded materials plate

Benferhat Rabia,Tahar Hassaine Daouadji,Rabahi Abderezak 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.3

In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses of FG beam reinforced by porous FGM plates under mechanical loading. The beam is assumed to be isotropic with a constant Poisson’s ratio and power law elastic modulus through the beam thickness. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in graphicals forms. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam, and it is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. The results presented in the paper can serve as a benchmark for future analyses of functionally graded beams strengthened by imperfect varying properties plates. Numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters. The results of this study indicated that the imperfect functionally graded panel strengthening systems are effective in enhancing flexural behavior of the strengthened FGM beams. This research is helpful in understanding the mechanical behaviour of the interface and design of hybrid structures.

Interfacial stresses in porous PFGM-RC hybrid beam

Benferhat Rabia,Hassaine Daouadji Tahar,Rabahi Abderezak Techno-Press 2024 Advances in materials research Vol.13 No.1

This paper presents a careful theoretical investigation into interfacial stresses in RC beams strengthened with externally bonded imperfect FGM plate. In this study, an original model is presented to predict and to determine the stresses concentration at the imperfect FGM end, with the new theory analysis approach. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in forms. It is shown that both the shear and normal stresses at the interface are influenced by the material and geometry parameters of the composite beam, and it is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. The theoretical predictions are compared with other existing solutions. The numerical resolution was finalized by taking into account the physical and geometric properties of materials that may play an important role in reducing the stress values. This research is helpful for the understanding on mechanical behaviour of the interface and design of the PFGM-RC hybrid structures.

Effect of porosity distribution rate for bending analysis of imperfect FGM plates resting on Winkler-Pasternak foundations under various boundary conditions

Aicha, Kablia,Rabia, Benferhat,Daouadji, Tahar Hassaine,Bouzidene, Ahmed Techno-Press 2020 Coupled systems mechanics Vol.9 No.6

Equilibrium equations of a porous FG plate resting on Winkler-Pasternak foundations with various boundary conditions are derived using a new refined shear deformation theory. Different types of porosity distribution rate are considered. Governing equations are obtained including the plate-foundation interaction. This new model meets the nullity of the transverse shear stress at the upper and lower surfaces of the plate. The novel rule of mixture is proposed to describe and approximate material properties of the FG plates with different distribution case of porosity. The validity of this theory is studied by comparing some of the present results with other higher-order theories reported in the literature. Effects of variation of porosity distribution rate, boundary conditions, foundation parameter, power law index, plate aspect ratio, side-to-thickness ratio on the deflections and stresses are all discussed.

Dynamic of behavior for imperfect FGM plates resting on elastic foundation containing various distribution rates of porosity: Analysis and modeling

Kablia, Aicha,Benferhat, Rabia,Tahar, Hassaine Daouadji Techno-Press 2022 Coupled systems mechanics Vol.11 No.5

During the manufacture of FGM plates, defects such as porosities can appear. Those can change the entire behavior of these plates. This paper aims to investigate the free vibration characteristics of porous functionally graded (FG) plates resting on elastic foundations. The Young's modulus of the plate is assumed to vary continuously through the thickness according to a power-law formulation, and the Poisson ratio is held constant. Different types of porosity distribution rates are considered. To examine the accuracy of the present formulation, several comparison studies are investigated. Effects of variation of porosity distribution rate, foundation parameter, power-law index and thickness ratio on the fundamental frequency of plates have been investigated.

Rehabilitation of RC structural elements: Application for continuous beams bonded by composite plate under a prestressing force

Abderezak, Rabahi,Rabia, Benferhat,Daouadji, Tahar Hassaine Techno-Press 2022 Advances in materials research Vol.11 No.2

This paper presents a closed-form higher-order analysis of interfacial shear stresses in RC continuous beams strengthened with bonded prestressed laminates. For retrofitting reinforced concrete continuous beams is to bond fiber reinforced prestressed composite plates to their tensile faces. An important failure mode of such plated beams is the debonding of the composite plates from the concrete due to high level of stress concentration in the adhesive at the ends of the composite plate. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the RC continuous beams strengthened with bonded prestressed laminates. The theoretical predictions are compared with other existing solutions. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate stiffness and the thickness of the laminate where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member.