http://depot.umc.edu.dz/handle/123456789/6139 2026-05-01T02:26:03Z 2026-05-01T02:26:03Z Khene, Ahmed Chikh, Nasr-Eddine http://depot.umc.edu.dz/handle/123456789/14807 2026-01-19T09:28:12Z 2023-06-24T00:00:00Z

Contribution à l’étude du renforcement des éléments fléchis par NSM-PRFC. Khene, Ahmed; Chikh, Nasr-Eddine In recent years, carbon fiber reinforced polymers (CFRP) have gained increasing interest in the strengthening of structural members. This trend is due to the specific properties of CFRP, which contribute significantly to the strength and ductility of the reinforced elements. However, debonding results in the loss of the bond between the CFRP laminates and the concrete substrate at an early stage, leading to brittle failure at limited load levels and would prevent the composite materials from reaching their full strength capacity. The phenomenon of premature debonding of FRPs has been proven and confirmed by several researchers and is the main drawback of the EBR (Externally Bonded Reinforcement) technique. In this research work, we opted to use a new technique for strengthening of reinforced concrete beams with composite materials, namely the NSM (Near Surface Mounted) technique. The NSM technique consists of inserting strips of carbon fiber reinforced polymer (CFRP) laminate into slots previously made in the concrete cover of the elements to be strengthened. First, an experimental study was performed on reinforced concrete beams strengthened with CFRP using the NSM and EBR techniques for comparison. Several parameters were taken into consideration, including the rate of reinforcement, the anchorage length, the surface condition of the CFRPs, the type of reinforcement, the reinforcement technique and the hybrid reinforcement configuration. The experimental results showed the effectiveness of carbon fiber reinforced polymers in improving the structural behavior of the beams, a clear improvement of the bearing capacity was observed. Subsequently, a numerical study was investigated in depth to fully understand the behavior of reinforced concrete beams strengthened by NSM-CFRP. The computational code used in this study for the numerical modeling is the ATENA 2D finite element software. The results of the numerical models developed have a good agreement with the experimental results. At this stage, the validated numerical models can be used for a parametric study. At the end, this research work was concluded with a parametric study through several strengthening simulations with different parameters influencing the behavior of reinforced concrete beams strengthened by the NSM technique. The parametric study also gave interesting results regarding the effectiveness of the NSM strengthening technique using composite materials.

2023-06-24T00:00:00Z Zaioune, Hiba Mezhoud, Samy http://depot.umc.edu.dz/handle/123456789/14585 2025-03-20T08:08:16Z 2025-02-26T00:00:00Z

Contribution à l’étude de comportement des consoles courtes en béton armé renforcées ou réparées par matériaux composites. Zaioune, Hiba; Mezhoud, Samy The present research provides a comprehensive investigation of the performance of reinforced concrete (RC) corbels that have been reinforced with carbon fiber reinforced polymer (CFRP) under different loading conditions. The study combines both experimental and numerical analysis to investigate the impact of monotonic, cyclic, and seismic loading on the behavior of RC corbels strengthened with CFRP. The research examines the crucial factors that influence the behavior of corbels, such as the number of CFRP layers, the compressive strength of the concrete, and the presence of horizontal reinforcing stirrups. Numerical results obtained under monotonic loading show that augmenting the thickness of CFRP layers has a substantial impact on both the shear strength and stiffness of the corbels, resulting in a 123% increase, although it may reduce their ductility. Increased concrete compressive strength significantly enhances the loadbearing capacity and stiffness. Incorporating horizontal stirrups significantly improves the shear capacity, ductility, and distribution of cracks. Under cyclic loading, the experimental analysis shows distinct phases of elastic and plastic deformation in both the steel reinforcement and CFRP strips. The behavior of the RC corbel exhibit elastic cycles in the beginning, followed by substantial reversible deformation and eventual pinching effects caused by localized damage. The main cause of failure in CFRP-strengthened corbels is the crushing of diagonal concrete struts and the delamination of CFRP strips. Abaqus numerical models effectively capture the behavior and and failure mechanisms of reinforced concrete corbels subjected to both monotonic and cyclic loading. Nevertheless, the models have a tendency to overestimate the amount of deformation that occurs under cyclic loading. This might be attributed to the difficulties in accurately predicting shear deformation and the slippage of reinforcement. Furthermore, the numerical analysis conducted under both reversed and non-reversed cyclic loading clearly shows that the use of CFRP strengthening greatly enhances the cyclic performance, load carrying capacity, and stiffness of RC corbels when compared to unstrengthened specimens, especially when the shear span-to-effective depth ratios are optimized, increasing the number of CFRP layers, increasing the concrete compressive strength, and including horizontal reinforcement stirrups. Moreover, the study determines that the impacts of factors such as the quantity of CFRP layers, the compressive strength of concrete, and the presence of horizontal reinforcing stirrups remain comparable in both monotonic and cyclic loading conditions. Nevertheless, CFRP strengthening exhibits much greater efficiency when subjected to monotonic loading compared to cyclic loading. The numerical simulation findings demonstrate that CFRP strengthening typically improves the seismic performance of RC corbels. However, the efficiency of this strengthening method differs depending on the specific seismic factors and reinforcement configurations. The use of both vertically and horizontally wrapped and combined CFRP strips yielded optimal outcomes under certain earthquake conditions. Nevertheless, inadequately designed CFRP strengthening techniques could compromise the performance of RC corbels, emphasizing the need for designing these reinforcements according to precise seismic characteristics. In addition, the external strengthening's efficiency is less noticeable when subjected to seismic excitation compared to its performance under monotonic and cyclic loading.

2025-02-26T00:00:00Z Chibani, Nawel Beroual, Ahmed http://depot.umc.edu.dz/handle/123456789/14460 2024-05-08T10:22:42Z 2022-01-01T00:00:00Z

Elaboration d’un béton autoplaçant pour le renforcement et la réparation des ouvrages en béton arme. Chibani, Nawel; Beroual, Ahmed To develop methodologies to improve the quality of repairs, which leads to durable repair, it is necessary all components of repaired system must be considered. The choice of repair material must be compatible with the concrete to be repaired, in particular, the dimensional compatibility criteria are essential to avoid deboning of the repair layer on the one hand and on the other hand the quality of adhesion between the repair material and its support (substrate). Taking into account that the main pathologies of cement-based adherent repairs result from cracking due to dimensional variations. Also, the roughness and wetness of the surface of the substrates significantly affect the adhesion with the repair. To answer the objective of this study, a simulation by the repair technique applied to an ordinary concrete substrate (BO) and using as repair material three types of concretes: two self-compacting concretes of different resistance (30 and 40MPa), namely (BAP30) and (BAP40), and a vibrated concrete (BOV) of resistance (30Mpa) is taken as reference concrete. The bond evaluation test is based on the splitting tensile test protocol (indirect tensile). To determine the adhesion and bond quality, as well as the mode of rupture for each composite (Repair/Substrate). Overall, the results obtained show that, .the fabricated self-compacting (BAPs) give advantages for use as repair materials. The use of self-compacting (BAP) improves the performance of the repaired system. Excellent adhesion quality obtained by (BAP40) and (BAP30), compared to ordinary vibrated concrete (BOV). Repair by (BAP30) and (BAP40) developed an adaptation capacity by shrinkage favorable to the repaired system. The (BAP30) presents dimensional variations nearest and the (BAP40) slightly less to those of (BO), and Therefore Adequate deformational compatibility, by the use of self-compacting concrete for the cement-based repair. These results contribute to obtaining a durable repair.

2022-01-01T00:00:00Z Barour, Sabiha Zergua, Abdesselam http://depot.umc.edu.dz/handle/123456789/14205 2023-10-17T10:31:04Z 2022-07-18T00:00:00Z

Étude du renforcement des poutres vis –à –vis des efforts de cisaillement. Barour, Sabiha; Zergua, Abdesselam This thesis deals with the non-linear analysis of the behaviour of beams, reinforced with composite materials, with respect to shear forces. The modelling is carried out using the general purpose finite element program ANSYS©. Several three-dimensional non-linear models have been developed. These models are obtained by taking into account the mechanical and geometrical properties of the different components of the studied beams.The elements 'SOLID 65'; 'LINK180'; 'SHELL181' and 'SOLID185' were used to model, the concrete; the steel reinforcement; the fibre reinforced polymers (FRP) and the steel plate supports, respectively. The resulting models were validated by comparison with experimental results. Then a parametric study, notably the configuration and quantity of reinforcements, the geometry of the beams, was carried out, followed by a comparison of the numerical results with experimental results of the literature and the various structural codes such as ACI (American Concrete Institute) and FIB (International Federation of Structural Concrete). Consistent and satisfactory results were observed regarding the beam's load-bearing capacity, deformations, failure modes, cracks distribution and evolution. It was concluded that the models obtained are reliable, predicting adequately the response and behaviour of the tested beams. They are also capable of simulating the entire history of the beam up to failure.

2022-07-18T00:00:00Z