Proposed FE Model Research Articles

Experimental and numerical investigations on shear behavior of RC beams strengthened with U-wrapped PET FRP

This paper reports the investigations of experimental and numerical programs on the shear performance of U-shaped Polyethylene Terephthalate (PET) FRP-retrofitted RC beams. Twelve RC beams were fabricated and tested under monotonic three-point loading with the test parameters being FRP strip width and shear span-to-effective depth ratio. A comprehensive analysis and investigation were conducted in terms of the failure modes, shear load–deflection responses, shear capacities, the strain evolution of FRP and stirrups, and the interaction of shear contributions among FRP, stirrups and concrete. Larger debonding strains were observed for PET FRP. Five design guidelines and two models available in the literature were assessed against the measured PET FRP shear contribution. A modified model of the shear contribution for PET FRP was developed and verified by the test results. Finally, a finite element model was established to further understand the shear performance of retrofitted beams, in which the bond-slip relationship between concrete and FRP was considered. The FE model was validated by comparing the test and FE results. The proposed FE model could accurately capture the propagation of shear critical cracks and FRP debonding failure for the specimens with medium and large shear spans.

Effect of evolutionary anisotropic hardening on the prediction of deformation and forming load in incremental sheet forming simulation

The incremental sheet forming (ISF) process typically accompanies large plastic strain without fracture exceeding uniform elongation or ultimate tensile strength (UTS) in the uniaxial tensile test. Therefore, ISF features improved formability compared to the conventional stamping process. Meanwhile, numerous studies have focused on modeling and simulation of formability in ISF where anisotropic yield function is one of the key constitutive laws for predicting sheet deformation. However, the conventional yield function is defined based on anisotropy of initial yielding, while the ISF modeling requires the deformation behavior at large strains beyond the UTS. In this study, an evolutionary anisotropic plasticity model is investigated based on Hill's 48 yield function combined with the non-associated flow rule; i.e., e-NAFR Hill's 48. The e-NAFR Hill's 48 model is implemented to the vectorized user-defined material subroutine in the commercial finite element software ABAQUS/Explicit. Then, the proposed FE model is applied to the forming of truncated cone, pyramid, and clover shaped single point incremental forming (SPIF) of an aluminum alloy 6014-T4 sheet. The simulated part profile, thickness variation, and forming force are compared with those of experiments. The evolutionary constitutive model shows an average accuracy of 99.15% in thickness prediction and 94.22% accuracy in forming force, demonstrating the importance of evolutionary sheet anisotropy in the SPIF process.

Compressive behaviour of circular steel tube confined reinforced concrete (STCRC) columns considering shrinkage and creep

Thin-walled steel tube confined reinforced concrete (STCRC) columns are increasingly used in high-rise and heavily loaded structures. One concern is whether concrete shrinkage affects the load resistance of STCRC columns, as the confinement to the concrete may become less effective when the concrete shrinks. This paper presents ultimate tests on STCRC columns after subjected to 490-day-sustained-loading or 490-day-shrinkage. The compression tests are conducted on specimens with different steel ratios, reinforcement ratios, concrete strengths and steel-concrete interfacial bonding conditions, or with long-term load first applied at different concrete ages. The sustained load history and the shrinkage effects on the short-term axial stiffness, ultimate strength, and peak strain of STCRC columns are investigated. The development of confinement effects and the tube's axial stiffness contribution after shrinkage and creep history are compared against those test results without experiencing shrinkage or long-term load history. A non-linear finite element model is finally developed for the ultimate response prediction of STCRC columns with the consideration of the creep and shrinkage history, and its accuracy is compared against the test data. The results show that concrete shrinkage and creep significantly affect the occurrence and development of the confinement effects, but not the confining pressure at the peak load. The axial stiffness and peak strain of STCRC columns are sensitive to time effects, while the ultimate strength is not. Under service loading, the tube's contribution to the axial stiffness of STCRC columns is negligible due to concrete shrinkage, while at the ultimate strength limit state condition, the column compression resistance is barely influenced by shrinkage and creep effects. The proposed FE model achieves reasonable accuracy in evaluating the ultimate responses of STCRC columns considering the shrinkage and creep effects.

A new robust equation for shear strength of GFRP-RC deep beams using hybrid experimental and synthetic data based-FE quasi-static analysis procedure

The main objective of this article is to propose a new, more robust, and comprehensive design equation for Glass-Fiber-Reinforced-Polymer (GFRP) reinforced concrete (RC) Deep Beams (DBs). The investigation is based on a numerical model using Quasi-Static Two-Dimensional FE simulation of GFRP-RC DBs. The numerical model is validated by calibrating four parameters (concrete dilatation angle ψ, concrete tensile strength fct, fracture energy Gf, mesh size) against data from ten full-scale experiments on GFRP-RC DBs available in the literature. Additionally, a numerical parametric study based on a full factorial design with 5 factors (and between 2 and 5 modalities) is conducted using the validated quasi-static FE model, which includes 360 large-scale GFRP-RC DBs. The impacts of primary design variables on the concrete contribution Vc to the shear capacity of GFRP-RC DBs are assessed. The effects of various geometrical and mechanical variables, such as cross-sectional dimensions (width b × height H), concrete compressive strength grade (fc), GFRP properties (modulus Ef, and strength ffu), GFRP reinforcement ratio (ρf), and shear span to depth ratios (a/df), are examined to understand the shear behavior of GFRP-RC DBs.The numerical simulations demonstrate that the proposed FE model accurately captures the behavior of GFRP-RC DBs. Building upon these findings, a new shear design equation is proposed for DBs, and its accuracy and robustness are compared with five established international design codes (ACI-440.1R-15, ISIS-Canada, CAN/CSA-S806-12, JSCE-1997, and BS-8110). The existing design codes significantly underestimate the concrete contribution to shear capacity, leading to uneconomical designs. In contrast, the new design equation provides a fair prediction of Vc, with a standard error of 7.734 % and 20.84 % compared to the FE and experimental datasets, respectively. This represents a substantial improvement over the existing design guides.

Prediction of post-fire seismic performance of reinforced concrete frames

Due to the importance of evaluating the seismic behavior of structures after a fire, a numerical study was conducted on RC frames using the detailed finite element method. The simulation process consists of two separate steps. The first step is heat transfer analysis to estimate heat distribution in the various elements of RC frames, and the second step is evaluating the post-fire seismic performance of the frames using thermal–mechanical analysis. The test specimens used to verify the proposed FE model include two RC frames with different beam-column bending capacity ratios, which are in two different conditions, including the specimens at ambient temperature as control specimens and fired specimens inside of the furnace chamber. In the heat transfer analysis step, the sensitivity of responses to two effective parameters, including the moisture content and the emissivity of the concrete surface has been investigated. In the post-fire analysis, among the various models presented for the post-fire behavior of concrete, three stress–strain models were selected for cyclic analysis of RC frames and the results were compared with the test data. Also, the bond-slip behavior of the concrete-steel interface has been simulated using the equivalent springs technique. It was seen from the comparison of the numerical results with the test data, that the proposed model accurately estimates the resistance and the dissipated energy of frames in each cycle. In addition, parametric studies showed that every 30 min increase in the fire duration based on the ISO 834 standard curve causes a 10% decrease in post-fire seismic resistance compared to the control specimen.

Experimental testing and structural analysis of composite tile – reinforced concrete domes

Conventional formworks for concrete curved shells either are expensive, complex and wasteful or have formal restrictions. Using tile vaults (also known as timbrel, Guastavino, thin-tile or Catalan vaults) as stay-in-place formwork for concrete shells could significantly reduce construction costs and material waste. Tile vaults only require formwork at the boundaries and provide a high formal flexibility.The combination of masonry and reinforced concrete creates a new type of composite structure that needs experimental validation and new structural analysis models to deal with the specific features of the system. This paper presents experimental research on the component materials, load tests on doubly-curved, full-scale prototypes and the definition of a reliable Finite Element structural model for the analysis of the proposed hybrid structure.The experimental research has involved the characterisation of the bricks, mortar, concrete and reinforcement composing the proposed system in order to provide the material properties to be considered in the structural analysis. The construction and testing of two composite sail domes in the laboratory have allowed the validation of the proposed FE model by comparing its predictions with the collapse mechanisms, damage, ultimate loads and load–displacement curves obtained experimentally.

The shear strength of existing non-seismic RC beam-column joints strengthened with CFRP Sheets: Numerical and analytical study

A key part of RC structure seismic performance is the effective distribution of earthquake forces across all resistance elements through reinforced concrete (RC) beam-column (B-C) joints. By virtue of their ease of implementation and convenient material properties, Carbon-Fiber-Reinforced Polymers (CFRP) are highly utilized for strengthening existing structures with inadequate reinforcement or insufficient confinement. Previous experimental research revealed that debonding failure widely occurs on CFRP shear-strengthened B-C joints. The experimental research as well showed the value of column axial load makes a great contribution to such joint’s failure mode. Using CFRP U-jacketing to strengthen non-seismically B-C joints, this article presents a non-linear, two-dimensional FE model for investigating shear behavior. The developed FE model considered the adhesive layer between CFRP sheets and concrete to capture the debonding and a bond-slip model was implemented between concrete-to-CFRP sheets using connector elements. The FE results were verified versus experimental works from literature to prove the proposed FE model's accuracy with appreciate to load-deformation relation and failure modes. Depending on the verified FE model, a parametric study on shear-strengthened RC B-C joints with CFRP U-jacketing with free and fixed ends was performed below monotonic loading. In the existing study, several parameters, including column-to-beam flexural strength ratio (over strength ratio), concrete strength, and value of column axial load, were investigated on the structure's strength and ductility. Using the developed strut-and-tie model (STM), new design equations were proposed to calculate strengthened RC B-C joint's shear strength using CFRP. The proposed equations incorporate the interfacial bond among concrete and CFRP effect, as well CFRP sheet end boundary (free or fixed). The developed design equation’s ability to estimate shear strengths of strengthened B-C joints with CFRP was verified through experimental works and FE results. It was evident from verification results that the produced design equations were compatible with experimental and FE model results.

Experimental and numerical investigations on the mode I delamination growth behavior of reinforced laminates via a ZPI (Z-pin pre-hole insertion) technique

This paper proposes a low-in-plane damage ZPI (Z-pin pre-hole insertion) process. The delamination growth behavior and the influence of Z-pin insertion density on the mode I interlaminar fracture toughness of laminate was explored experimentally and numerically. Meanwhile, Z-pin pull-out and shear tests were conducted in order to provide accurate data for the DCB simulation test. What’s more, an infinite-focus microscope was used to scan the specimen’s defect caused by the ZPI process. It can be found that the ZPI process can lead to less Z-pin inclination, fibre breaking, and crack initiation at the bonded interface. The DCB test results show that the load-displacement curve can be distinguished into four stages for the pinned specimen. In addition, a specimen pinned with a higher Z-pin volume fraction to more suitable for increasing the G IC. The simulation results show that the simulated maximum load and the G IC of the specimen are 286.63 N and 940.06 J·m−2, with a 0.56% and 10.10% error from the experimental result, indicating that the proposed FE model is validated by comparing the predictions with the experimental results. These results can provide some guidance for fabricating the reinforced laminates via the ZPI process.

Dynamic Finite Element Model Based on Timoshenko Beam Theory for Simulating High-Speed Nonlinear Helical Springs

Helical springs with nonlinear geometric parameters nowadays have shown great advantages over classical linear springs, especially due to their superior performance in diminishing dynamic responses in high-speed situations. However, existing studies are mostly available for springs with linear properties, and the sole FE spring models using solid elements occupy significant computational resources. This study presents an FE spring model based on Timoshenko beam theory, which allows for high-speed dynamic simulations of nonlinear springs using a beehive valve spring sample. The dynamic results are also compared with the results of the FE model using solid elements and the results of the engine head test and indicate that the proposed FE model can accurately predict dynamic spring forces and the phenomenon of coil clash when simulating the beehive spring at engine speeds of both 5600 and 8000 RPM. The results also indicate that rapid coil impact brings significant spike forces. It should also be noted that the FE spring model using beam elements displays sufficient accuracy in predicting the dynamic responses of nonlinear springs while occupying much fewer computational resources than the FE model using solid elements.

Nonlinear Finite Element Analysis of High-strength Reinforced Concrete Beams with Severely Disturbed Regions

The inclusion of D-regions within a reinforced-concrete member may affect largely the general behavior of the structure. Different techniques and approaches were proposed to control the behaviour of D-regions, such as the shear-friction approach and the STM model. Such proposals may not be applicable for all types of Dregions. The current work presents a nonlinear finite element model using the ANSYS software, that is adopted to study three types of D-regions, which are dapped ends, deep beams with openings and beams with loaded openings. The results revealed that the proposed FE model predicted adequately the effects of the inclusion of D-regions in RC beams. It is found that reducing the hanger or the nib reinforcement of a dapped end by 25% resulted in reducing capacity by 15% and 32%, respectively. Also, the results showed that for these deficiently reinforced dapped ends, reducing a/d ratio from 1.5 to 0.75 improved capacity by 23% and 36%. For the deficiently shearreinforced flanged deep beams, it was found that the inclusion of large openings within the shear span resulted in a capacity drop by (41-49) %. An enhancement of 23% was obtained when using stirrups of 12mm on both sides of the openings. Moreover, it is confirmed that the optimum location of the openings is under the diagonal path. Furthermore, it has been concluded that for loaded openings, the use of T-rolled sections within the bottom chord of the opening yielded an enhancement of 23% relative to the rhombus-shaped configuration. KEYWORDS: Dapped ends, T-deep beams with openings, Loaded openings, Hanger reinforcement.

Modelling on stress redistribution around broken fibers for fiber reinforced plastic with poor fiber distribution uniformity

AbstractIn order to calculate stress redistribution after a fiber breaking for unidirectional fiber reinforced plastic (FRP) with practically poor fiber distribution uniformity, a new and efficient FE model is developed with high computation efficiency. Based on the proposed FE model, the stress concentration factor (SCF) of intact fibers around a broken fiber is investigated for unidirectional FRP. It is observed that the SCF depends heavily on the local fiber volume ratio (FVR), and a modified analytical SCF model is proposed which takes into account the variation of local FVR. It is proved that the modified analytical SCF model can provide SCF values with much better accuracy for FRP with poor fiber distribution uniformity. The modified analytical SCF model would be very useful for accurate prediction of progressive fiber breaking in FRP.

Numerical investigations on the damage tolerance of adhesively bonded pultruded GFRP joints with adhesion defects

Adhesive bonding has gained increasing acceptance in joining pultruded glass fiber reinforced polymer (GFRP) sections. However, one of the major issues hindering the widespread application of adhesive bonding in building and construction industries is the difficulty in predicting the mechanical behavior of the joints in the presence of adhesion defects. This paper investigates the damage tolerance of the adhesively bonded pultruded GFRP double-strap joints under quasi-static tensile loading using finite element analysis. Defects of various locations (along the bond length), sizes, and numbers were embedded within the bondline. A two-dimensional (2D) stress analysis was conducted to assess the effects of the bondline defects on the out-of-plane displacement, stress distribution, and peak stresses of the joints. Three-dimensional (3D) progressive damage models were further developed to predict residual joint capacity and provide insights into the effects of the adhesion defects on the damage mechanism of the joints. The progressive damage model uses the cohesive zone model (CZM) to simulate progressive interlaminar damage within the adherends as well as adhesive-FRP interface debonding. The proposed FE model was validated with published experimental data, and an excellent correlation was found between experimental and numerical results. The validated model was then used in a parametric study to assess the effects of design parameters such as adhesive types (from highly brittle to highly ductile) and joint geometry (adhesive chamfering, adherend chamfering, and recessing) on the damage tolerance of adhesively bonded joints. This paper also reports a comparative study on the damage tolerance between GFRP double-strap, single-strap, and single-step joints. The stress analysis results revealed that the presence of the bondline defects could increase the out-of-plane displacement of the adherends and the peak shear and peel stresses at the overlap ends. High-stress concentrations were also observed in regions adjacent to the defect extremities. The double-strap joints exhibited better damage tolerance than the single-strap and single-step lap joints. The damage tolerance of the joints can be improved by using stress-reduction methods such as adhesive chamfering, adherend chamfering, and recessing.

Investigation of thermal behaviour of structural steel S235N under laser cutting process: Experimental, analytical, and numerical studies

Laser cutting represents an appealing solution for high machining speed and precision in steel constructions. To control the efficiency of laser cutting, the effects of laser heating must be understood; and to investigate thermal effects on a steel workpiece, a methodological approach for analytical modeling of laser cutting heat source is proposed herein. The proposed model takes into account laser source geometry variation along the cut edge thickness. Given the complexity of the analyzed process, there is no accurate mathematical formulation capable of modelling both heat flux and temperature distribution. Therefore, to model heat flux with an accurate temperature distribution field and both calibrate and validate solid phases of a cut specimen, the paper proposes a modified heat source based on a Gaussian distribution. The study focuses on mild structural steel S235N and relevant commonly used laser cutting parameters for structural applications. More precisely, the model allows the laser cutting process to be simulated as a function of laser beam diameter, cutting speed, laser power and element thickness. Thus, to simulate the thermal process by means of a proper heat source, a model was implemented in the FE software Abaqus. Model parameters were both calibrated and validated through experimental results provided by online monitoring of laser cutting process with a thermal camera and location of microconstituents. In particular, the temperature profiles obtained from the proposed FE model, exhibit a good agreement with experimental results. Finally, the distribution of microconstituents along the depth agrees with predicted temperature profiles.

Oligodendrocyte tethering effect on hyperelastic 3D response of axons in white matter

A novel finite element model is proposed to study the mechanical response of axons embedded in extracellular matrix when subjected to tensile loads under purely non-affine kinematic boundary conditions. Ogden hyperelastic material model describes the axons and the extracellular matrix material characterizations. Two axon-glia tethering scenarios in white matter are studied a single oligodendrocyte (single-OL) with multiple connections a multi-oligodendrocyte (multi-OL) one. In the multi-OL tethering configuration, resultant forces are randomly oriented as distributed glial cells arbitrarily wrap around axons in their immediate vicinity. In the single-OL setup, a centrally located oligodendrocyte myelinates multiple axons nearby. Tethering forces are directed towards this oligodendrocyte, resulting in greater directionality and farther-reaching stress distribution. The oligodendrocyte connections to axons are represented by a spring-dashpot model. The material properties of myelin served as the upper limit for the parameterization of the oligodendrocyte stiffness (“K"). The proposed FE models enable realization of connection mechanisms and their influence on axonal stiffness to determine resultant stress states accurately. Root mean square deviation analysis of stress-strain plots of different connection scenarios reveal an increasing axonal stiffness with increasing tethering, indicating the role of oligodendrocytes in stress redistribution. In single-OL submodel, for the same number of connections per axons, RMSD values increased as “K" (the oligodendrocyte spring stiffness) values were set higher. RMSD calculations reveal that for a “K" value, single-OL model yielded slightly stiffer models compared to multi-OL. The current study also addresses the potential geometrical limitations of multi-OL model by randomizing and adding connections to ensure greater responsiveness. Cyclic bending stresses noticed in both submodels suggest the risk of axonal damage accumulation and repeated load failure.

Aggregate interlock in fractured concrete mesoscale models: a novel finite element modelling approach

Aggregate interlock is a stress transfer mechanism in cracked concrete. After concrete cracks under tensile loading, crack interfaces can experience significant slip deformation due to the applied crack kinematics. Upon rising slip along crack interfaces, aggregate interlock stresses are generated which transfer shear stress and normal stress. Many experimental programmes and analytical expressions have been developed for several decades. However, a finite element model considering realistic crack surfaces was still not developed. The complexity of developing a FE model lies due to the mesoscopic nature of the problem. In this study, concrete mesoscale models were employed to generate realistic cracked concrete surfaces. Uniaxial tensile fracture propagation in concrete mesoscale models were achieved using Zero-thickness cohesive elements approach. Once cracked concrete FE models are developed, validation of the proposed FE models was conducted against two experimental campaigns. The study comprises the evaluation of the surface roughness index of the cracked concrete surfaces. The FE model predicts secondary cracking under low initial crack widths and mixed mode angles. FE predictions were further compared with Walraven’s simplified formulae, Bažant’s rough crack model, Cavagnis’s aggregate interlock formulae and contact density model and consistence agreement was observed. Finally, strengths and weaknesses of the proposed FE modelling approach for aggregate interlock was discussed and further implementations were also highlighted.

Accurate thermal-induced structural failure analysis under incompressible conditions

In this work, the performance of the mixed 3-field displacement/deviatoric-strain/pressure (u/e/p) finite element is examined for nonlinear thermo-mechanical structural applications under incompressible behavior. The proposed FE model increases the solution accuracy in terms of strains and stresses, guaranteeing mesh-objective results in nonlinear analyses. Structural failure is modelled with J2-plasticity and J2-damage constitutive laws, introducing the isochoric behavior, typical of metals, in the material response. The solution of the coupled thermal and mechanical problems follows a staggered scheme and temperature dependent material properties are introduced to study the effect of the thermal coupling in the mechanical problem. This FE approach is applicable with any interpolation basis: triangles, quadrilaterals, tetrahedras, hexahedras and prisms.A set of numerical benchmark problems is proposed to examine the influence of the enhanced accuracy of the proposed model in thermally-induced structural failure analyses in incompressible conditions. The study includes the comparison of the u/e/p and u/p FE formulations, where the effect of the thermal coupling in the problem is investigated. The superior performance of the 3-field formulation with regard to the evaluation of collapse mechanisms, failure loads, mechanical dissipation and numerical stability in incompressible situations is shown.

Numerical evaluation for the effective slab width of continuous composite beams

Basic beam bending theory and the effective width concept are commonly used in the design and analysis of steel–concrete composite beams to evaluate deflections, stresses, and strengths. The shear-lag effect is partially accountedfor by adopting a reduced “effective” slab width rather than the actual slab width. Besides the precise numerical values obtained via numerical analysis of a composite beam, Code provisions should provide a simplified practical techniquefor calculating effective slab width that is both simple and precise. Current design codes propose effective width values that are essentially a function of the beam span, ignoring the effects of other essential factors. Finite element analysis of continuous composite beams is a complex task, as large numbers of contacts and meshing elements are required to catch all the physical phenomena; this leads to potential convergence difficulties using a general static analysis. In this paper, several 3D numerical simulations of a composite continuous beam are conducted using the RIKS method available in ABAQUS. Comparisons to available experimental results are used to validate the proposed FE model. Then, the so-validated numerical model is utilized to perform a parametrical study to assess the effect of the longitudinal reinforcement at the hogging moment region and the influence of the concrete slab width on the effective width evaluation. Finally, the proposed finite element model and EC4 specification results are compared to draft a useable design guide.

Vibrational study of FG skew sandwich plates having geometric distortions

An innovative composite material called functionally graded material (FGM) has gained a lot of interest in various engineering applications. This work aims to carry out vibrational study of FG skew sandwich plates having geometric distortions. It is performed using Higher Order Zigzag Theory and dimensionless frequencies are obtained. Using this theory fulfil the criteria of continuous transverse shear stress at inter-laminar junctions and zero at the top and bottom surface of the plate. It thus eliminates the necessity of factor for shear correction. The material properties follow the power law variation. The frequencies are obtained using code for the proposed FE model and are confirmed with those from the previous studies. New findings are put forth which can be used as reference for future studies in similar field.

Performance Assessment of Reinforced Concrete Frame under Close‐In Blast Loading

The need for assessing and retrofitting structures increased with time as terrorism‐induced explosion trends rose with time. This paper presents a numerical investigation on performance assessment of a two‐story, one‐bay seismic resistant reinforced concrete framed building under close‐in blast loading. ANSYS AUTODYN, an explicit nonlinear finite element software program, was used for 3D model development and analysis. The experimental results reported in the literature were used to validate proposed FE models. Furthermore, parametric studies on close‐in explosive story‐to‐story locations and charge masses were performed on both conventional and seismically detailed RC framed structures. FEA results showed that a decrease in scaled distance raised effective plastic strain and damage index values. Furthermore, simultaneous use of close‐spaced transverse steel reinforcement spacing in mid‐height and ends of reinforced concrete columns is found to be effective in reducing both effective plastic strains and damage index values.

Bond Behaviour of Near-Surface Mounted Strips in RC Beams-Experimental Investigation and Numerical Simulations.

This paper presents an investigation of the bond mechanism between carbon fibre reinforced polymer (CFRP) laminates, concrete and steel in the near-surface mounted (NSM) CFRP-strengthened reinforced concrete (RC) beam-bond tests. The experimental program consisting of thirty modified concrete beams flexurally strengthened with NSM CFRP strips was published in. The effects of five parameters and their interactions on the ultimate load carrying capacities and the associated bond mechanisms of the beams are investigated in this paper with consideration of the following investigated parameters: beam span, beam depth, longitudinal tensile steel reinforcement ratio, the bond length of the CFRP strips and compressive concrete strength. The longitudinal steel reinforcement was cut at the beam mid-span in four beams to investigate a better assessment of the influence of the steel reinforcement ratio on the bond behaviour of CFRP to concrete bond behaviour. The numerical analysis implemented in this paper is based on a nonlinear micromechanical finite element model (FEM) that was used for investigation of the flexural behaviour of NSM CFRP-strengthened members. The 3D model based on advanced CFRP to concrete bond responses was introduced to modelling of tested specimens. The FEM procedure presents the orthotropic behaviour of the CFRP strips and the bond response between the CFRP and concrete. Comparison of the experimental and numerical results revealed an excellent agreement that confirms the suitability of the proposed FE model.