Papers by Raid Daud
AIP conference proceedings, 2024
Maǧallaẗ al-handasaẗ, Nov 1, 2022
Journal of Engineering
This study offers numerical simulation results using the ABAQUS/CAE version 2019 finite element c... more This study offers numerical simulation results using the ABAQUS/CAE version 2019 finite element computer application to examine the performance, and residual strength of eight recycle aggregate RC one-way slabs. Six strengthened by NSM CFRP plates were presented to study the impact of several parameters on their structural behavior. The experimental results of four selected slabs under monotonic load, plus one slab under repeated load, were validated numerically. Then the numerical analysis was extended to different parameters investigation, such as the impact of added CFRP length on ultimate load capacity and load-deflection response and the impact of concrete compressive strength value on the structural performance of slabs. This article aims to provide a numerical model for simulating the nonlinear behavior of such slabs, including a trustworthy finite element model approach and constitutive material models. In aspects of load-deflection and cracking patterns, comparisons between...
Civil and environmental engineering, Jun 1, 2024
Ain Shams Engineering Journal, 2021
Abstract This paper presents the effect of non-uniform reinforcement ratio along the beam length ... more Abstract This paper presents the effect of non-uniform reinforcement ratio along the beam length on the flexural behaviour experimentally and numerically. Within the experiment, four reinforced concrete beams each had a different reinforcement ratio. However, three of four beams had a similar reinforcement ratio in the constant moment zone (0.012). Cracking load, load carrying and deflection were monitored through the test. A nonlinear finite element software was implemented to simulate the experimental behaviour. Followed up by a parametric study. It was found that, in reinforced concrete beams, the tension stiffening depends on the concrete area in the tension zone not the reinforcement ratio. FEA predicts the reinforced concrete beams behaviour within a good agreement. Finally, the findings show that, determining variable amount of reinforcement ratio along the beam length will not sacrifice the flexural behaviour, but it will reduce the quantity of the steel reinforcement and the overall cost.
The reliability of bond is crucial to the performance of concrete structures strengthened with ex... more The reliability of bond is crucial to the performance of concrete structures strengthened with externally mounted carbon fibre reinforced polymer (CFRP) plate. This thesis investigates the behaviour of the bond interface of reinforced concrete slabs strengthened with CFRP under cyclic loading using both numerical modelling and experimental methods. The main goals of this research are:(1) To experimentally investigate the static and fatigue behaviour of the interfacial bond between CFRP plate and the concrete substrate in single shear pull-out.(2) To develop reliable numerical simulations in order to understand the post-fatigue nonlinear behaviour of the adhesive interface for CFRP ?concrete bonded joints.(3) Using three dimensional finite element models, explore the nonlinear behaviour of an adhesive layer connecting CFRP to reinforced concrete one-way slabs with different levels of CFRP and different span scenarios under cyclic loading.(4) Through both experimental and numerical mo...
Corrosion of steel bars is considered to be one of the major factors affecting durability of the ... more Corrosion of steel bars is considered to be one of the major factors affecting durability of the concrete structures. In this paper, the bond stress response of corroded and un-corroded embedded bars inside the concrete was assessment experimentally. Twelve cubes were tested experimentally for that purpose. The main parameter of this work was the reinforcement condition, corroded, un-corroded and epoxy coted reinforcement. The corrosion process was executed for 90 days duration. It was found that bond stress for samples subjected to long-term corrosion (for a period of 90 days corrosion) was reduced by approximately 54.4% and the slip was reduced also by a bout 30%. Moreover, the bond stress was reduced by 26% for samples where the reinforcement coated with epoxy. Finally, bond stiffness between the concrete and the reinforcement was deteriorated in the corroded samples more than that in the samples which treated by the epoxy.
The use of spliced reinforcing bars in sustainable concrete members to manage inadequate bars len... more The use of spliced reinforcing bars in sustainable concrete members to manage inadequate bars length is a common practical issue which is may be due to some limitations. The lap splicing means two bars overlapped in parallel with specified length called the splice length in order to provide the required bond between the two bars. The bond between sustainable concrete and spliced steel bars is another important issue. The normal strength sustainable concrete specimens of sizes 1700x150x150 mm with tension reinforcement lap spliced were selected according to testing device length limitations. These members were designed to fail in flexure in order to investigate the lap spliced tension bars effect. The selected lap spliced tension bars were of 10 mm size with smooth and deformed surfaces in order to investigate the surface nature accompanied with the splice nature. The sustainable concrete mechanical properties and mix workability were also studied. This study reveals that the effect ...
Journal of King Saud University - Engineering Sciences, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The reliability of bond is crucial to the performance of concrete structures strengthened with ex... more The reliability of bond is crucial to the performance of concrete structures strengthened with externally mounted CFRP plate. This paper presents a detailed description of a finite element model constructed using ABAQUS 6.10-1, to simulate the behaviour of CFRP-to-concrete bonded joints in single shear pull out tests. Nonlinear finite element analysis with the cohesive surface approach for single shear pull out tests was investigated and validated against existing test results (monotonic and post-fatigue) in order to demonstrate the accuracy of the model. The influence of bond length for different carbon fibre plate stiffness on the ultimate load as well as the de-bonding strain for the post-fatigue analysis was investigated and then compared with existing analytical models. The numerical results suggest that existing analytical models can be nonconservativein estimating the FRP effective bond length in the post-fatigue load regime
Engineering Structures, 2015
ABSTRACT This paper reports the results of an experimental investigation into the static and fati... more ABSTRACT This paper reports the results of an experimental investigation into the static and fatigue behaviour of the interfacial bond between carbon fibre reinforced polymer (CFRP) composite and the concrete substrate. Twenty-four single-shear pull-out tests with two different types of CFRP and different composite plate thicknesses have been carried out. Four additional specimens were tested using different concrete compressive strengths for the sake of comparison. Modes of failure, load–slip relationships, strain profiles of CFRP, interfacial shear stress distributions and interfacial bond stress–slip for monotonic, fatigue and post-fatigue loading have been obtained. The experimental results were used to examine the CFRP stiffness–fatigue life relationship, and CFRP stiffness level–debonding strain relationship. The results indicate that when considering post-fatigue loading regimes, the strain required to cause debonding of the CFRP and the ultimate load capacity of the strengthening system is reduced by the previous cyclic loading. Also, both the ultimate bond strength reduction and fracture energy reduction due to cyclic loading are dependent on the stiffness of the CFRP plate in the bond system for the range of the concrete strengths tested.
Athens Journal of Τechnology & Engineering, 2015
The nonlinear behaviour of an adhesive layer connecting carbon fibre reinforced polymer (CFRP) to... more The nonlinear behaviour of an adhesive layer connecting carbon fibre reinforced polymer (CFRP) to reinforced concrete one way slabs is numerically simulated in the current study. This investigation is aimed at developing as well as validating a three-dimensional finite element model. Numerical results have been compared with those obtained from an earlier experimental study. The FE model was then subjected to the modified fatigue load protocol recommended by FEMA 461. A detailed and accurate 3D FE model of the composite one-way slab was developed using ABAQUS software. A non-linear damage plasticity model is considered for modelling the concrete, and the FE model accounted for the nonlinearity of the concrete under cyclic loading by estimating the stiffness degradation in the concrete for both compression and tension effects. A surface cohesive based model was used to describe the interaction between the CFRP and the concrete slab. For the reinforcement bars, the Bauschinger effect was adopted through the application of the kinematic hardening model under cyclic loading. The FE model was then validated by comparing numerical and experimental values for load-deflection, load-strain in CFRP and load-strain in embedded reinforcement bars. Furthermore, the strain profile of CFRP, slip at interface in monotonic and cyclic loading, and both reduction in the ultimate load and stiffness due to cyclic loading were observed in this study.
Composite Structures, 2017
In this paper, a finite element model using ABAQUS 6.10-1 is developed to simulate the CFRP-to-co... more In this paper, a finite element model using ABAQUS 6.10-1 is developed to simulate the CFRP-to-concrete bonded joint behaviour in single shear pull-out tests. The model adopts the cohesive surface approach and the simulation results are checked against the authors' test results (monotonic and post-fatigue) in order to demonstrate the accuracy of the model. Parametric studies using the validated model were carried out to investigate the effects of varying the bond length, the thickness of FRP, the type of FRP, the concrete strength, and the bond width ratio. The results were then used to assess the various existing design code approaches for predicting the FRP-concrete bond behaviour. The post-fatigue numerical results indicate that the existing design code methods all have significant discrepancies. Based on the work conducted a simple and potentially more accurate model for predicting the debonding strain of CFRP plate in single shear is then presented.
https://www.tandfonline.com/doi/abs/10.1080/153764 by Raid Daud
Nonlinear Finite Element analysis of concrete corb by Raid Daud
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Papers by Raid Daud
https://www.tandfonline.com/doi/abs/10.1080/153764 by Raid Daud
Nonlinear Finite Element analysis of concrete corb by Raid Daud