Curvature ductility of confined HSC beams

Bouzid Haytham,Idriss Rouaz,Sahnoune Ahmed,Benferhat Rabia,Tahar Hassaine Daouadji 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.6

Tahar Hassaine Daouadji2,4 The present paper investigates the curvature ductility of confined reinforced concrete (RC) beams with normal (NSC) and high strength concrete (HSC). For the purpose of predicting the curvature ductility factor, an analytical model was developed based on the equilibrium of internal forces of confined concrete and reinforcement. In this context, the curvatures were calculated at first yielding of tension reinforcement and at ultimate when the confined concrete strain reaches the ultimate value. To best simulate the situation of confined RC beams in flexure, a modified version of an ancient confined concrete model was adopted for this study. In order to show the accuracy of the proposed model, an experimental database was collected from the literature. The statistical comparison between experimental and predicted results showed that the proposed model has a good performance. Then, the data generated from the validated theoretical model were used to train the artificial neural network (ANN) prediction model. The R² values for theoretical and experimental results are equal to 0.98 and 0.95, respectively which proves the high performance of the ANN model. Finally, a parametric study was implemented to analyze the effect of different parameters on the curvature ductility factor using theoretical and ANN models. The results are similar to those extracted from experiments, where the concrete strength, the compression reinforcement ratio, the yield strength, and the volumetric ratio of transverse reinforcement have a positive effect. In contrast, the ratio and the yield strength of tension reinforcement have a negative effect.

Bending analysis of an imperfect FGM plates under hygro-thermo-mechanical loading with analytical validation

Daouadji, Tahar Hassaine,Adim, Belkacem,Benferhat, Rabia Techno-Press 2016 Advances in materials research Vol.5 No.1

Flexural bending analysis of perfect and imperfect functionally graded materials plates under hygro-thermo-mechanical loading are investigated in this present paper. Due to technical problems during FGM fabrication, porosities and micro-voids can be created inside FGM samples which may lead to the reduction in density and strength of materials. In this investigation, the FGM plates are assumed to have even and uneven distributions of porosities over the plate cross-section. The modified rule of mixture is used to approximate material properties of the FGM plates including the porosity volume fraction. In order the elastic coefficients, thermal coefficient and moisture expansion coefficient of the plate are assumed to be graded in the thickness direction. The elastic foundation is modeled as two-parameter Pasternak foundation. The equilibrium equations are given and a number of examples are solved to illustrate bending response of Metal-Ceramic plates subjected to hygro-thermo-mechanical effects and resting on elastic foundations. The influences played by many parameters are investigated.

Hyperstatic steel structure strengthened with prestressed carbon/glass hybrid laminated plate

Tahar, Hassaine Daouadji,Abderezak, Rabahi,Rabia, Benferhat Techno-Press 2021 Coupled systems mechanics Vol.10 No.5

This paper presents a careful theoretical investigation into interfacial shear stresses in steel beam strengthened with prestressed carbon/glass hybrid laminated plate. A closed-form rigorous solution for interfacial shear stress in steel beams strengthened with bonded prestressed carbon/glass hybrid laminated plates and subjected to a uniformly distributed load, is developed using linear elastic theory and including the variation in fiber volume fraction of carbon/glass hybrid laminated. The results show that there exists a high concentration of shear stress at the ends of the laminate, which might result in premature failure of the strengthening scheme at these locations. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate and adhesive stiffness, the proportions and volume fraction of the fiber of carbon/glass hybrid laminated, the thickness of the laminate and the effect of prestressing where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member. This solution is intended for application to beams made of all kinds of materials bonded with a thin composite plate. This research is helpful for the understanding on mechanical behaviour of the interface and design of such structures.

New approach of composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate: Analysis and modeling

Hassaine Daouadji Tahar,Bensatallah Tayeb,Rabahi Abderezak,Abdelouahed Tounsi 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.3

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.

A new model for adhesive shear stress in damaged RC cantilever beam strengthened by composite plate taking into account the effect of creep and shrinkage

Hassaine Daouadji Tahar,Rabahi Abderezak,Benferhat Rabia 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.5

In this paper, a closed-form solution for interfacial stresses in reinforced concrete damaged cantilever beam strengthened by bonded composite plate including the effect of the adherent shear deformations, the creep and shrinkage effect is presented. In such plated beams, tensile forces develop in the bonded plate, and these have to be transferred to the original beam via interfacial shear stresses. Consequently, debonding failure may occur at the plate ends due to a combination of high shear interfacial stress. The analysis is based on the deformation compatibility approach where the shear stress is assumed to be invariant across the adhesive layer thickness. In this study, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the concrete beam and the bonded plate. The influence of creep and shrinkage effect relative to the time of the casting, and the time of the loading of the RC damaged cantilever beams is taken into account. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of interfacial stress distributions.

Bending analysis of an imperfect advanced composite plates resting on the elastic foundations

Daouadji, Tahar Hassaine,Benferhat, Rabia,Adim, Belkacem Techno-Press 2016 Coupled systems mechanics Vol.5 No.3

A two new high-order shear deformation theory for bending analysis is presented for a simply supported, functionally graded plate with porosities resting on an elastic foundation. This porosities may possibly occur inside the functionally graded materials (FGMs) during their fabrication, while material properties varying to a simple power-law distribution along the thickness direction. Unlike other theories, there are only four unknown functions involved, as compared to five in other shear deformation theories. The theories presented are variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. It is established that the volume fraction of porosity significantly affect the mechanical behavior of thick function ally graded plates. The validity of the two new theories is shown by comparing the present results with other higher-order theories. The influence of material parameter, the volume fraction of porosity and the thickness ratio on the behavior mechanical P-FGM plate are represented by numerical examples.

Theoretical analysis of composite beams under uniformly distributed load

Daouadji, Tahar Hassaine,Adim, Belkacem Techno-Press 2016 Advances in materials research Vol.5 No.1

The bending problem of a functionally graded cantilever beam subjected to uniformly distributed load is investigated. The material properties of the functionally graded beam are assumed to vary continuously through the thickness, according to a power-law distribution of the volume fraction of the constituents. First, the partial differential equation, which is satisfied by the stress functions for the axisymmetric deformation problem is derived. Then, stress functions are obtained by proper manipulation. A practical example is presented to show the application of the method.

Elastic analysis effect of adhesive layer characteristics in steel beam strengthened with a fiber-reinforced polymer plates

Tahar Hassaine Daouadji,Lazreg Hadji,Mohamed Ait Amar Meziane,Hadj Bekki 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.1

In this paper, the problem of interfacial stresses in steel beams strengthened with a fiber reinforced polymer plates is analyzed using linear elastic theory. The analysis is based on the deformation compatibility approach developed by Tounsi (2006) where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The analysis provides efficient calculations for both shear and normal interfacial stresses in steel beams strengthened with composite plates, and accounts for various effects of Poisson’s ratio and Young’s modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi (2006). 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 steel beam and bonded plate. The paper is concluded with a summary and recommendations for the design of the strengthened beam.

Flexural behaviour of steel beams reinforced by carbon fibre reinforced polymer: Experimental and numerical study

Hassaine Daouadji Tahar,Abbes Boussad,Rabahi Abderezak,Benferhat Rabia,Abbes Fazilay,Adim Belkacem 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.4

The paper presents the results of an experimental and numerical programme to characterize the behaviour of steel beams reinforcement by composite plates. Important failure mode of such plated beams is the debonding of the composite plates from the steel beam due to high level of stress concentration in the adhesive at the ends of the composite plate. In this new research, an experimental and numerical finite element study is presented to calculate the stresses in the sika carbodur and sika wrap reinforced steel beam under mechanical loading. The main objective of the experimental program was the evaluation of the force transfer mechanism, the increase of the load capacity of the steel beam and the flexural stiffness. It also validated different analytical and numerical models for the analysis of sika carbodur and sika wrap reinforced steel beams. In particular, a finite element model validated with respect to the experimental data and in relation to the analytical approach is presented. Experimental and numerical results from the present analysis are presented in order to show the advantages of the present solution over existing ones and to reconcile debonding stresses with strengthening quality.

Analytical solution of nonlinear cylindrical bending for functionally graded plates

Daouadji, Tahar Hassaine,Hadji, Lazreg Techno-Press 2015 Geomechanics & engineering Vol.9 No.5

This article considers the problems of cylindrical bending of functionally graded plates in which material properties vary through the thickness. The variation of the material properties follows two power-law distributions in terms of the volume fractions of constituents. In addition, this paper considers orthotropic materials rather than isotropic materials. The traction-free condition on the top surface is replaced with the condition of uniform load applied on the top surface. Numerical results are presented to show the effect of the material distribution on the deflections and stresses. Results show that, all other parameters remaining the same, the studied quantities (stress, deflection) of P-FGM and E-FGM plates are always proportional to those of homogeneous isotropic plates. Therefore, one can predict the behaviour of P-FGM and E-FGM plates knowing that of similar homogeneous plates.