Bond Slip Research Articles

Effect of graphene oxide as a nanomaterial on the bond behaviour of engineered cementitious composites by applying RSM modelling and optimization

A crucial aspect of the design approach for bar-reinforced concrete buildings is the proper transfer of loads between the concrete and steel reinforcement via bonding. Bar pull-out tests were done to see how graphene oxide (GO) affected the bond strength, bond energy, and bond stress–slip response of deformed reinforcing bars implanted in engineered cementitious composites (ECC). This was done to improve the bond strength of steel/concrete composites. This article examines the bonding behaviour of steel reinforcing bars in a mixture of GO-modified ECC. The findings of pull-out assessments conducted on two distinct diameters (12 and 16 mm) of reinforcement steel bar inserted in ECC are initially provided. The investigation's findings are then utilised to determine the bond-slip interactions that describes the relations between the ECC mixtures and steel reinforcement bars. According to the experiment results, the introduction of GO as a nano-reinforcement in the ECC mixture had a considerable positive effect on the bar-matrix interactions owing to its bridging function. After 28 days, the bond strength of steel bars with widths of 12 and 16 mm was increased by 54.80% and 26.70%, respectively, when 0.05 wt% of GO was added to 1% of PVA fibre. The response surface methodology (RSM) is employed for developing predictive algorithms, which are then utilised in performing multi-variate optimization on bond-slip parameters, including bond strength, bond slip and bond energy. The acquired actual and predicted findings suggest that the created models are adequate for interpreting the bond performance of reinforcement steel bars in the GO-ECC.

Bond durability of FRP bars and seawater–sea sand–geopolymer concrete: Coupled effects of seawater immersion and sustained load

Fibre reinforced polymer (FRP)-reinforced seawater–sea sand–geopolymer concrete (SSGC) structures combine the advantages of corrosion-free FRP bars in marine environments and the direct utilization of seawater and sea sand, fly ash, and ground granulated blast furnace slag (GGBS), which can lead to a reduction in carbon emissions and promote sustainable development in civil engineering. This study explores the combined effects of seawater immersion (laboratory condition, ∼26 °C) and sustained load (60% ultimate interface bond strength) on the durability of the interface between FRP bars and SSGC by pull-out tests. The test parameters included FRP bar type and immersion duration (60 and 180 days). River sand and freshwater geopolymer concrete (RSGC) were used for comparison. The properties of the SSGC were also studied to reveal the impact on the interface performance. The results showed that the increase in GGBS content reduced the setting time but was beneficial for improving the compressive strength of the concretes at 28 d due to the large amount of calcium ions contained in the GGBS. The increase in Na2SiO3 content increased N-A-S-H, resulting in a dense cementitious material; compressive strength increased, and the axial ultimate strain of concrete decreased. The long-term performances of SSGC and RSGC in a seawater immersion environment were similar and characterized by reduced strength and enhanced brittleness. The bonding strength between the FRP bar–concrete interface decreased due to the decreased concrete strength under seawater immersion. As the immersion time increased, the fibre fractured under the effects of sustained load, leading to an increase in the bond strength degradation. The bond–slip constitutive model was analysed based on existing models.

A RETROFIT SOLUTION FOR UNCODED STEEL RAFTER TO CONCRETE RING BEAM CONNECTIONS

Some building contractors in the Caribbean have been constructing non-coded steel rafter to concrete ring beam connections on low budget residential buildings. These connections may resist failure under normal loading conditions, but critical connections fail under moderate to high loads resulting in partial or full dislodgement of the roof. In this study, the performance of non-coded steel rafter to concrete ring beam designs were analyzed in a finite element program and a retrofit solution for the failed uncoded connections were designed and modeled. Nine versions of the connection were identified and consisted of several variations including mechanically anchoring the rebar to the rafter without welds, using one and two rebars, varying the rebar embedment depth and using 90 degree hooks and straight rebars. A standard, code-compliant, bolted-endplate connection was used as the control for the investigation. The connections were analyzed in “ABAQUS” with a bond slip and damage plasticity model. The maximum load resistances were compared with category 1 hurricane loads for the region. The load capacities of all the connections were found to be lower than the control connection but were still adequate for hurricane category 1 loads, with the exception of the connection in which the rebars were mechanically anchored to the rafter without welds. Connections with welds to the top flange of the rafter were less stiff, experienced larger rafter displacements, inflicted less damage on the concrete ring beam, and required less rebar embedment to prevent pull out failure than the connections to the bottom flange.

Experimental and Numerical Analysis of the Ribbed Reinforced Concrete Fracture Behavior Based on the Mesoscale FE Model

This study presented a meso-model for the fracture analysis of the reinforced concrete (RC) structure. A modeling method of RC meso-structure was proposed, and the rebars were allowed to separate from the concrete. The model was built using the cohesive zone model (CZM). The zero-thickness cohesive elements were adopted to characterize the mechanical behavior of potential fracture surfaces and rebar–concrete interfaces. The constitutive model for concrete was developed by considering the damage relation and friction effect, and the corresponding constitutive for the rebar–concrete interface (especially ribbed rebar) was developed by considering the influence of normal separation on the tangential bond–slip relation. To validate the proposed meso-model, a series of ribbed RC beams with an initial notch was designed and tested by four-point bending loading to obtain different fracture patterns. Through comparison, the developed RC meso-model was validated to simulate the RC structure's fracture behavior appropriately. The influence of the rebar–concrete interface constitutive model on the simulation results was investigated. The investigation results indicate that neglecting normal separation would result in an overestimation of the structure's stiffness and bearing capacity (the peak load was overestimated by more than 10%). Finally, an analysis was conducted on the energy consumption during the failure process of the RC beams. It was found that the proportion of energy consumption during tensile failure of the beam decreased from approximately 86% to 89% in the early stage to approximately 43% to 52% in the later stage, indicating a transition in the beam's failure mode from tensile failure to shear failure.

Nonlinear Semianalytical Prediction of Debonding at the FRP–Generic Material Interface with Mechanical End Anchorages

The full-range debonding process of a fiber-reinforced polymer (FRP)–generic material substrate interface with mechanical end anchorages requires a better understanding. In this study, we developed a nonlinear semianalytical model based on a cohesive crack model to predict the full-range debonding process of such an interface in a single-shear mode, considering the relatively deformed region in the interface as a cohesive zone. Specifically, we produced a double exponential bond–slip constitutive model with residual bonding shear stress and boundary conditions of slip constraints at both anchoring ends. Implicit solutions for the relative slips, bonding shear stresses, and axial forces in the FRP along the bond length, as well as the load–slip responses at the loading end and effective bond length, were obtained using the Chebyshev polynomial approximation strategy. The accuracy of the proposed model was verified using experimental results available in the literature. Then, the evolution of full-range interfacial bonding behavior and load–slip responses for different bond lengths was discussed. Finally, a parametric study highlighting the effect of geometry and material properties on the load–slip response at the loading end was presented.

Early-Age Bond Behavior of Deformed Bars in Concrete Subjected to Bilateral Pressures

In RC structures during construction, the bond behavior of deformed bars in concrete is governed by the age-related concrete strength, the local confining pressure, the bar diameter, and the concrete cover thickness. In this paper, an experimental investigation was performed to quantify the influences of the curing age and the bilateral pressure on the bond behavior of deformed bars in early-age concrete with 204 pull-out specimens for different concrete strengths, bar diameters, and relative concrete cover thicknesses. It was shown that the failure mode was associated greatly with the age-related concrete strength, the concrete cover thickness, and the pressure level, and that the bond strength increased with the pressure level and curing age, whereas the corresponding slip decreased with the curing age. Based on the regression analysis, calculation models were developed to predict the ultimate bond stress and the corresponding slip. A bond–slip model is proposed to describe the bond stress–slip relationship of deformed bars in early-age concrete under bilateral pressures, and the model was verified with the test results.

Refinement simulation of bond-slip performance of deformed reinforced concrete exposed to fire: Parametric analysis

The refined numerical simulation method was used to study the influences of the concrete cover and the diameter of the rebar on the bond-slip properties of deformed reinforced concrete under two fire scenarios. The feasibility and rationality of the refined simulation method were verified by comparison with the experimental results. Subsequently, the influences of the concrete protective layer thickness and the diameter of the rebar on specimen failure pattern, bond failure mechanism, bond-slip curve, and the distribution of the stress and strain for the steel were investigated. The effects of parameters on ultimate, residual bond strength and ultimate slip were mainly discussed. The results show that the failure pattern of the specimen exposure to heat conditions changes from concrete splitting to steel bar pull-out as the concrete cover thickness increases; the shape of the bond-slip curve was affected by the concrete cover thickness, regardless of the fire scenario, rebar diameter and the target temperature. As the rebar diameter increased, the bond strength at high temperatures and after cooling down decreased when the specimen experienced the same temperature. Finally, the formulation for the bond strength and slip at high temperatures and after cooling down was suggested by comparing with the experimental and calculated results, which can take into account the thickness of the concrete protection layer, the diameter of the reinforcement bar, the fire scenario and the temperature.

Steel–concrete bond deterioration in reinforced concrete tension members due to primary cracks

Primary cracks in reinforced concrete tension members lead to the deterioration of the steel–concrete bond. This study aims to investigate this bond deterioration by establishing a novel relationship between the bond force and slips near the cracks. The descending part of this relationship represents the bond deterioration, with its parameters determined by the structural responses. An iterative algorithm is proposed based on this relationship to analyze the bond behaviors of tension members. The effectiveness of the proposed method is validated using reinforced concrete tension members from experiments in the literature. The results demonstrate a gradual decrease in bond forces from local maximum to zero near the cracks, indicating the presence of the descending part of the bond–slip relationship. The length, slope, and characteristic points of the descending part vary with crack spacing and slips at the cracks, leading to nonlinearity in steel strains. In comparison to existing methods assuming constant length or slope, the proposed method accurately predicts these variable parameters, and provide precise estimations of bond force.

Bond behavior of CFRP sheets-to-steel shear joints with different steel surface treatments

The current study focuses on the bond behavior of CFRP sheets-to-steel double-lap shear (DLS) joints with different steel surface treatments. A total of 18 DLS joints are tested in tension. The effects of six different steel surface treatments on the mechanical response of the DLS joints are investigated. The steel surface treatments include power tool polishing with four different sandpapers in grit sizes, grit blasting and pre-coating silane coupling agent. The surface topography and roughness of the steel substrates with different treatments are evaluated from test results, and their relationship with mechanical behavior and failure modes is established qualitatively. The geometric characteristics of the surface are strongly correlated with the average ultimate loads of the DLS joints. Based on the measured load-slip curves, the bond-slip (B-S) relationship is predicted, which removes the effect of the actual deformation of the steel substrates on the slip. Regression analyses of quantifying the B-S relationship are conducted to establish the simplified B-S model applied to the CFRP sheets-to-steel bonded interface, and the effects of different steel surface treatments are considered in this model. The accuracy of the simplified B-S model is verified through comparison with the experimental results.

Experimental Study on Bonding Properties between Finishing Rolled Rebar and Grouting Material

In bearing capacity testing of prestressed concrete pipe piles, grouting material is filled up to the bottom of the pipe pile, which is equipped with a finishing rolled rebar. The reaction force of the reaction beam is transferred to the anchor pile through the bonding force between the finishing rolled rebar and grouting material. Therefore, investigating the bonding properties between the finishing rolled rebar and grouting material is essential to remove barriers to the application of the anchor pile method in bearing capacity testing of the prestressed concrete pipe pile. In this study, the bonding properties of 11 groups of specimens were studied through pull-out tests, and the effects of the cover thickness, diameter, and anchorage length of reinforcement on the bond strength between finishing rolled rebar and grouting material as well as on the bond stress-slip curve were explored. The test results showed that the bond stress-slip curve between finishing rolled rebar and grouting material can be divided into two stages, i.e., slip stage and splitting failure stage. In the slip stage, a linear relationship exists between bond stress and slip amount, and microcracks appear in the grouting material around the finishing rolled rebar. In the splitting failure stage, the slip amount increases rapidly under uplift load. Finally, the grouting material around the finishing rolled rebar forms a failure zone, and splitting failure occurs. The bonding capacity and bond strength between finishing rolled rebar and grouting material increase with the increasing cover thickness of the rebar. The bond strength is the maximum for a relative cover thickness of 3.0, and the difference between the maximum and minimum values is more than 9%. The bonding capacity between rebar and grouting material increases slightly with the increasing rebar diameter, but the bond strength decreases with the diameter, and the difference between the maximum and minimum bond strengths is more than 21%. As the contact area between finishing rolled rebar and grouting material increases, the bonding capacity between them increases with the increasing anchorage length of the rebar. However, the bond strength first increases, then decreases, and finally stabilizes with the increasing anchorage length, and the difference between the maximum and minimum bond strengths exceeds 14.64%.

Effect of multi-scale reinforcement on fracture property of ultra-high performance concrete

This paper aims to achieve multi-scale crack control of concrete by using graphene oxide (GO) and macroscopic steel fiber in combination, and to reveal the multi-scale collaborative reinforcement mechanism of GO and steel fiber. A three-point bending fracture mechanics test was employed to analyze the macroscopic fracture properties of ultra-high performance concrete (UHPC) reinforced by GO, and a single fiber pull-out test was utilized to assess the impact of GO on the fiber–matrix interface properties. The results showed that 0.04% GO reinforced UHPC had the best fracture property, and steel fiber and GO showed good synergistic crack control effect. GO directly acted on controlling the cracking of concrete matrix at the nanoscale, thus improving the fracture energy of UHPC matrix by 14% from 73.08 N/mm to 83.39 N/mm. This micro-scale matrix reinforcement provided by GO further improved the pull-out property of steel fibers, and the pull-out energy dissipation of straight steel fibers and hook-end fibers was increased by 43.7% and 31.5%. A micromechanical prediction model for fracture energy of straight steel fiber UHPC was established, which could construct the quantitative relationship between UHPC fracture energy and micromechanical parameters. The model showed that the initial fiber–matrix bond strength (τ0) and slip hardening coefficient (k0) had a powerful influence on the UHPC fracture energy.

Experimental study on bonding performance of polypropylene fiber modified rubber concrete and deformed steel bar

In order to study the binding properties of deformed steel rods and rubber concrete modified with polypropylene fiber, four groups of bonding specimens were designed with polypropylene fiber volume ratio as a variable. The effect of polypropylene fiber on bond strength and bond slip curve was investigated by drawing test. It was found that the bond strength increased with the increase of polypropylene fiber volume fraction in the range of 0 ~ 1.5 %. Based on the experimental data, the constitutive relationship between deformed steel bar and polypropylene fiber modified rubber concrete was established. It provides a theoretical basis for further research on polypropylene fiber modified rubber concrete.

Bond-slip response of corroded SD bars with recycled coarse aggregate concrete

Recycled aggregate concrete (RAC) has been the subject of numerous research to ensure the efficient use of aggregates made from recycling old concrete by examining various parameters in fresh and hardened phases. The present study investigates the bond-slip response of Recycled coarse aggregate concrete (RCAC) with Super Ductile (SD) reinforcing steel exposed to corrosion with varying degrees. SD rebar category is relatively new compared to the hot-rolled and TMT classes of reinforcing steel. SD has a superior bonding performance with concrete owing to the distinctive rib patterns. RILEM-specified cylindrical pull-out specimens were fabricated with RCA concrete with replacement ratios of (0%, 25%, 50%, 75%, and 100%) and centrally embedded SD bars. Pull-out specimens were immersed in NaCl solution before exposure to impressed current corrosion to achieve desired levels of corrosion. The specimens were tested for failure in a displacement-controlled Pull-out testing universal testing machine (UTM). A set of linear variable displacement transducers (LVDT) recorded the slip of the rebar at both the loaded and unloaded ends. The bond-slip response was used to characterize the overall behavior of the bond mechanism. Predictive models have been suggested for the bond strength of RCAC following corrosion. The results indicate that the bond strength of RCAC is almost similar to that of the natural aggregate concrete (NAC) exposed. The results indicated that both the bond slip and bond degradation hold good and agree with previous models. The findings can help anticipate the performance of structural elements made of recycled coarse aggregate concrete (RCAC) exposed to aggressive environments.

Bond Performance of CFRP Strands to Grouting Admixture for Prestressed Structure and Development of Their Bond-Slip Constitutive Models.

Prestressed concrete structures have witnessed widespread use in building and infrastructure applications during the last two decades due to their high stiffness and strength indices. However, structural failures caused by the corrosion of steel reinforcing bars or strands have proliferated, opening the door for carbon fibre-reinforced polymer (CFRP) strands as an excellent alternative with high corrosion resistance. The bonding interaction between the CFRP strands and concrete is the fundamental parameter in shaping the structural behaviour of CFRP prestressed concrete structures. In this paper, the bonding behaviour between CFRP strands and concrete with grouting admixture is experimentally investigated based on three groups of standard pull-out tests. The bond strength of CFRP strands was systematically studied and compared against steel strands. The untreated CFRP strands exhibited an inefficient bonding strength with the grouting admixture, equivalent to only 5% compared to steel strands of the same diameter. Surface coating with epoxy quartz sand can significantly improve the anchoring efficiency of CFRP strands up to 14 times compared to the untreated strands, which is approximately as efficient as steel strands. Moreover, the bond-slip curves between CFRP strands and concrete were analysed and were found to be different compared to steel strands. Finally, this study proposed bond-slip constitutive models of CFRP strands with better applicability, using an exponentially damped sine function to fit the residual segment of the curve.

Study on Bond Anchorage Behavior of Small-Diameter Rebar Planting under Medium and Low Cycle Fatigue Loads

In this paper, we describe how, through the combination of field testing and finite element simulation, the bonding and anchoring performance of small-diameter rebar under the action of medium and low cycle fatigue load was studied and the corresponding conclusions were obtained: ① Through the test, the performance parameters of the 6 mm and 8 mm rebar planting specimens were obtained after the rebar was subjected to 10,000, 50,000 and 100,000 times of medium and low cycle fatigue loading at depths of 10d, 15d and 20d. The analysis shows that the medium and low cycle fatigue load has a significant effect on the elastic ultimate load, elastic ultimate slip and ultimate slip of the small-diameter rebar planting specimens. With the increase in fatigue loading times, the elastic ultimate load of the rebar specimen decreased continuously, and the elastic ultimate slip and ultimate slip showed an increasing trend. By increasing the anchor depth, the influence of fatigue load on the anchoring performance parameters of the rebar planting specimen can be reduced. Under the influence of the upper ultimate condition of 100,000 times of fatigue loading, the ultimate load and failure mode of the planted bars basically did not change compared with the control specimens without fatigue loading. ② Based on the performance parameters of the rebar planting specimens obtained from the field test, the bond–slip constitutive relationship of the adhesive–rebar interface of the small-diameter rebar planting under the medium and low cycle fatigue load is analyzed and proposed. The F-U relationship of the spring element under the fatigue load is defined to simulate the bond–slip behavior of the adhesive–rebar interface. The finite element simulation results are in good agreement with the field test results. ③ Through a large number of finite element numerical simulation results, the elastic ultimate load calculation formulas of 6 mm and 8 mm diameter rebar planting specimens under medium and low cycle fatigue loads are obtained.

Unconfined bond stress and slip characteristics of steel bars embedded in masonry cement mortars

Reinforcing bars are often embedded into cement mortar layers (bed joints and surface bonded) of masonry structures to enhance their structural performance to various effects. However, there is limited research available on the bond characteristics of steel bars embedded in the masonry mortars. This study was focused on assessing the bond stress and slip characteristics of steel bars anchored within masonry cement mortars. Steel bar embedded masonry cement mortar assemblages were constructed to test them under uniaxial pull-out loading to understand their bond stress and slip characteristics. A double-lap anchorage arrangement was used for these pull-out tests. In total, 72 samples were prepared, incorporating two types of masonry mortars, three steel bar diameters (6 mm, 10 mm and 12 mm) and four anchorage lengths (2.5d, 5d, 7.5d and 10d, where d is the diameter of the bar) to examine their influence on the bonding characteristics. Two types of failure modes were observed (1) pure pull-out failure of steel bars from the mortar and (2) tensile splitting of mortar, depending on the employed mortar types and steel diameters. The bond stress between the steel bars and cement mortars varied between 1.4 MPa and 7.9 MPa for the tested samples. The analytical formulations to predict the bond strength of anchored steel bars within the masonry cement mortars were verified for pull-out and mortar splitting failures to characterise the bond slip characteristics of steel bars anchored in cement mortars.

Experimental investigation on realistic model for local bond stress-slip relationship between ribbed GFRP bars and concrete

Due to the lack of relevant research, the effect of the lateral confinement provided by stirrups and concrete cover on the bond behavior between glass fiber-reinforced polymer (GFRP) bars and concrete is ambiguous, resulting in the lack of a practical bond slip theory of GFRP bars. Therefore, it is impossible to accurately analyze the load response of GFRP-reinforced concrete (RC) structures from the stress level. In this paper, the local bond behavior of ribbed GFRP bars was systematically analyzed by the beam-end tests. The test parameters include concrete strength, stirrup spacing, and concrete cover. In addition, a bond stress-slip model considering the bonding mechanism was proposed on the basis of the beam-end tests and previous research. The results show that, the development of concrete cracks is restricted due to the existence of stirrups, and the specimens tend to fail in pull-out failure with strong confinement of stirrups. With the increase in the lateral confinement level, the failure mode of specimens transits gradually and smoothly from splitting failure to pull-out failure. Meanwhile, the peak slip of specimens with splitting failure also increases, and its maximum value does not exceed the peak slip of the corresponding specimens with pull-out failure. The confining capacity of stirrups and concrete cover was unified by a proposed parameter K. Then, a bond stress-slip model based on parameter K was established to predict the bond behavior of ribbed GFRP bars.

An experimental investigation of the bond performance of BFRP bars with recycled-aggregate concrete of different particle sizes

The pull-out test was performed in this study to investigate the bond performance between basalt fiber reinforced polymer (BFRP) bars and recycled concrete. Three factors were considered: aggregate size (5–10 mm, 11–15 mm, and 16–20 mm), bond anchorage length of bars (3D, 5D, and 7D), and the recycled aggregate replacement rate (0%, 30%, 60%, and 100%). The bond–slip mechanism, failure mode, bond stress distribution, and bond–slip curves were all analysed. Based on the results, it was found that situations with a high recycled aggregate replacement rate, large aggregate particle sizes, or long bond lengths have an increased likelihood of experiencing splitting failure. As the aggregate size increases, the bond strength between the BFRP bars and the concrete would also increase, in ordinary concrete, a 22.54% increase was observed, whereas in recycled concrete, the maximum increase reached 48.20%. The effect would be more pronounced on recycled concrete compared to ordinary concrete, and it would also be more significant in specimens with BFRP bars compared to steel bars. Additionally, the optimal bond anchorage length was determined to be 5D. The bond strength exhibited a trend of decrease followed by an increase as the recycled aggregate replacement rate increased. The maximum reduction of 59.7% in bond strength was observed when the replacement rate of recycled aggregate reached 60%. Moreover, when the replacement rate of recycled aggregate increased to 100%, there was a decrease of 19.05% in bond strength compared to the specimen without recycled aggregates. Based on the experimental test data and existing models, an improved two-stage bond–slip constitutive model was proposed.

Finite Element Analysis of Hysteretic Behavior of Superposed Shear Walls Based on OpenSEES

The superimposed slab shear wall has been found to be more and more applicable in the building construction industry due to its building industrialization superiority. The hysteretic behavior of superimposed slab shear walls accounts for an important part of seismic performance analysis. This paper presents the results of a numerical study to investigate the hysteretic behavior of superimposed slab shear walls. Different calculation methods of the shear capacity of the combined interface and horizontal connection are introduced. The calculated results show that the shear capacity of the combined interface and horizontal connection is much larger than the ultimate shear capacity of a superimposed slab shear wall. Therefore, the bond slip effect of a combined interface and horizontal connection can be ignored in finite element analysis on the premise of it not affecting calculation precision. Three different theoretical analysis models, namely the vertical multi-line element model, bend–shear coupled fiber model and layered shell element model, were established in OpenSEES based on a macro-model and a micro-model. The results show that the calculated results of the vertical multi-line element model and the bend–shear coupled fiber model agree reasonably with the experiment results, whereas the calculated results of the layered shell model gave a relatively larger initial stiffness.

Mesoscale modelling of concrete damage in FRP-concrete debonding failure

It is challenging to simulate fibre-reinforced polymer (FRP)-concrete debonding failure in detail because concrete damage usually occurs with a thin layer of mortar debonding attached to the FRP. This study applied a single-lap shear test with a digital image correlation technique to externally bonded FRP–strengthened concrete elements. An improved random walk algorithm method generated a realistic mesostructure of concrete. The two-dimensional mesoscale finite element model for FRP–strengthened concrete was established. The cohesive interface elements were inserted along all mortar–aggregate interfaces. Concrete damaged plasticity and cohesive zone model were applied to simulate the nonlinear properties of mortar and mortar–aggerate interface, respectively. The experimental and numerical load–displacement curves, strain/stress distribution, and local bond–slip curves were obtained and compared. A numerical parametric study investigated the effects of the aggregate, mortar, and adhesive on debonding failure. The main conclusions are: (1) the initiation and propagation of mortar damage and mortar–aggregate interface cracking in the FRP debonding process were directly conducted by the mesoscale model; (2) the numerical curves showed considerable oscillation, possibly due to the stress concentration near the aggregate boundary when the crack transmitted the aggregate, and the stiffness decreased after cracking was initiated at the mortar–aggregate interface; (3) concrete damage may extend to a depth of 25 mm, indicating that the concrete damage is greater than a thin layer of mortar debonding observed in the test; (4) applying polygonal aggregates, increasing aggregate size and surface mortar thickness, and reducing the adhesive layer thickness improves bond performance.