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Externally bonded fiber-reinforced polymer (EB-FRP) laminates have become popular for strengthening existing reinforced concrete (RC) structures. However, the high tensile strength of the FRP laminate is often not fully utilized due to premature debonding failure of the FRP-to-concrete interface, typically occurring in a thin layer beneath the bond interface. Numerical simulations have gained significant attention as a supplement to experimental tests, as they have the ability to provide valuable insights into the debonding process. However, most existing numerical models for EB-FRP joint debonding are unable to explicitly consider cracks within different concrete phases [i.e., mortar and interfacial transition (ITZ)], or precisely capture the corresponding failure mechanisms involving mortar cracking, ITZ debonding, and kinking. This study proposes a novel mesoscale phase field model for concrete, which is capable of accurately modeling complex failure behaviors, including mixed-mode fracture in both the mortar and ITZ, as well as friction on cracked surfaces. The ITZ is regularized using an auxiliary interface phase field and then the overall mixed-mode failure behaviors in both the mortar and ITZ are modeled using a unified damage phase field. To validate the proposed mesoscale model, three pull-off tests of FRP-to-concrete bonded joints, which have been well reported in the existing literature, are simulated. Moreover, the model is used to investigate the effects of adhesion and the FRP laminate on the debonding behavior of the FRP-to-concrete joints. [ABSTRACT FROM AUTHOR]

This paper aimed to study the compatibility between E-glass of chemical resistance (ECR-glass) fibers and the polymer matrix and the influence of different matrix types on the durability performance of ECR-glass fiber–reinforced polymer (GFRP) bars in a marine concrete environment. Two types of matrices, epoxy and vinyl ester, were employed to fabricate GFRP bars, which were then subjected to accelerated exposure by immersion in a simulated seawater sea-sand concrete (SWSSC) pore solution. The degradation performance and damage mechanism were thoroughly investigated. The results indicated that hydrolytic degradation of the cured epoxy and vinyl matrices and subsequent chemical etching to glass fibers are the primary damage mechanisms affecting GFRP bars in the SWSSC environment. Based on these mechanisms, two damage models were proposed: a chemical etching-based model and a hydroxyl ion diffusion-based model. These models enabled the prediction of the residual tensile strength of GFRP bars in the SWSSC pore solution environment at different temperatures. The accuracy of the proposed models was validated through comparisons with experimental data. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the seismic behavior of polyethylene naphthalate (PEN) fiber–reinforced polymer (FRP)-jacketed circular reinforced-concrete (RC) columns. A total of seven specimens were tested under constant axial load and cyclic lateral load. The key parameters studied were the thickness (one, two, and three layers) and type (PEN FRP and CFRP) of FRP jacket. Test results indicated that the control column failed by buckling of the longitudinal reinforcement and shortage of ductility, while concrete spalling and bar buckling were effectively inhibited by the application of external FRP jacket. It is also observed that PEN FRP-jacketed specimens had more additional strain capacity compared with CFRP-jacketed specimens at the final condition. The additional strain capacity can serve as a safety reserve for structures and make PEN FRP more suitable for strengthening large or noncircular columns. Furthermore, it is found that 1-ply PEN FRP and 1-ply CFRP had a similar strengthening effect and thus the design of PEN FRP-strengthened column can simply refer to the design method of CFRP-strengthened columns in current codes. Different FRP thickness and types had marginal impact on the hysteretic curves of the specimens, which was attributed to the low axial load ratio (0.15) and high slenderness ratio (5.25) adopted in this paper. Finally, based on a cyclic stress–strain model for longitudinal reinforcement, including buckling effect, developed by the authors in a previous study, the test columns were simulated by the Open System for Earthquake Engineering Simulation (OpenSee)s to achieve an in-depth understanding of the experimental findings and associated strengthening mechanisms. Further parametric analyses showed that considering bar buckling played a significant role in accurately predicting the hysteretic response of FRP-jacketed columns. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to investigate the influence of FRP confinement on the buckling behavior of longitudinal steel reinforcing bars (rebars) in RC columns subjected to monotonic and cyclic axial compression. Test results of 12 FRP-confined RC columns and 12 FRP-confined plain concrete columns (control specimens) are presented with particular attention to the evolution of strains in the longitudinal steel rebars and the FRP jacket as the load increases. For an FRP-confined RC column subjected to monotonic axial compression, the contribution of longitudinal steel rebars to the overall axial load carried by the column was deduced by subtracting the contribution of the FRP-confined plain concrete from the total axial load. The test results showed that the compressive stress-strain response of longitudinal steel rebars in FRP-confined RC columns follows that from tensile testing before the axial stress reduces gradually due to the onset of buckling deformation. Significant interactions were found to exist between FRP confinement and the buckling of longitudinal steel rebars. This interaction should be carefully considered when formulating constitutive laws for both the longitudinal steel rebars and the FRP-confined concrete for use in theoretical modeling. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) rods have been increasingly used in grouted ground anchors due to their high strength-to-weight ratio, excellent corrosion resistance, and convenience in incorporating the fiber sensing technology. To establish their pull-out capacity, FRP rods are usually embedded within a grouted steel tube and then subjected to pull-out in the laboratory. The aim of this paper is to develop a numerical method for predicting the nonlinear pull-out response of FRP rods embedded in steel tubes filled with cement grout. In the method, the cement grout is assumed to be subject to simple shear, the local interfacial bond stress–slip model of the bar-to-grout interface is represented by a piece-wise curve comprising elastic, softening, and frictional stages, and the unloading effect is also taken into account. A set of two second-order ordinary differential equations are derived in terms of the displacements of the FRP rod and steel tube and solved analytically to formulate the element transfer matrix. When the thickness of the steel tube approaches infinity, this method can be applied to the problem of FRP rods embedded in rock. Based on the developed numerical method, the interfacial bond properties and snapback phenomenon are analyzed. After the method is validated by comparisons with four sets of experimental data, the effects of the radius and length of FRP rods, the local peak bond stress and the residual frictional strength on the maximum pull-out load are evaluated in a quantitative manner. [ABSTRACT FROM AUTHOR]

Highlights: [•] The pull-out response of grouted FRP rods in steel tubes is analytically modeled. [•] The interfacial bond-slip model is incorporated into the analysis. [•] Different boundary conditions are considered in the analysis. [•] The solutions can be applied to the problem of FRP rods embedded in rock. [Copyright &y& Elsevier]

This paper presents a nonlinear local bond-slip model for fiber reinforced polymer (FRP) laminates externally bonded to concrete at elevated temperature for future use in the theoretical modeling of fire resistance of FRP-strengthened concrete structures. The model is an extension of an existing two-parameter bond-slip model for FRP-to-concrete interfaces at ambient temperature. The two key parameters employed in the proposed bond-slip model, the interfacial fracture energy, , and the interfacial brittleness index, , were determined using existing shear test data of FRP-to-concrete bonded joints at elevated temperature. In the interpretation of test data, the influences of temperature-induced thermal stress and temperature-induced bond degradation are properly accounted for. As may be expected, the interfacial fracture energy, , is found to be almost constant initially and then starts to decrease when the temperature approaches the glass transition temperature of the bonding adhesive; the interfacial brittleness index, , exhibits a similar trend. The proposed temperature-dependent bond-slip model is shown to closely represent the test data upon which it is based, despite the large scatter of the test data. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an experimental study on the seismic retrofit of reinforced concrete (RC) square columns with polyethylene terephthalate (PET) fibre reinforced polymer (FRP) composites, which is a new type of FRP with a larger tensile capacity compared to conventional FRPs. Test results of six PET FRP jacketed specimens are presented and compared with those of a specimen with high strength aramid FRP (HS AFRP) and two reference specimens. Hysteretic responses and failure modes of the specimens under a constant axial load and cyclic lateral loads, as well as the responses of the internal steel reinforcement and the FRP jackets are discussed in detail. The contributions of shear deformation and fixed end rotation due to the slip of longitudinal steel bars to the lateral displacement of columns are also investigated. The results show that PET FRP is a promising alternative to conventional FRPs for the seismic retrofit of RC columns. It improves the displacement ductility of RC columns significantly and does not rupture at the ultimate limit state. Future studies should examine a wider range of geometry and material properties and they should also be concerned with a systematic and direct comparison between specimens jacketed with PET FRP and conventional FRP with equivalent jacket stiffness. [Copyright &y& Elsevier]

This paper presents the results of an experimental study on the behavior of concrete confined by fiber reinforced polymer (FRP) jackets with a large rupture strain (LRS). The FRP composites considered herein are formed by embedding polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) fibers in a suitable epoxy resin matrix. The PEN and PET fibers are usually made from recycled materials (e.g., PET bottles) and have a strain capacity greater than 5%. They are ideal for use in seismic retrofit applications where increases in ductility and energy absorption capacity are of prime concern. The present study has two specific objectives: (1) to develop a good understanding of the compressive stress-strain behavior of concrete confined with LRS FRP; and (2) to examine whether existing confinement models developed for conventional FRPs are applicable to LRS FRPs. As the existing models have been developed and verified mainly based on test data for CFRP and GFRP, which have a jacket hoop rupture strain of less than 2%, their accuracy in the hoop/lateral strain range beyond 2% is unclear. Results presented in this paper indicate that the two LRS FRPs made from PEN and PET fibers possess a bilinear tensile stress-strain relationship, which has a significant effect on the axial compressive stress-strain behavior of FRP-confined concrete. A recent confinement model for conventional FRPs is compared with the present test results, indicating that the model significantly overestimates the ultimate axial strain. A modified version of the model is then presented to provide more accurate predictions of the test results. [ABSTRACT FROM AUTHOR]

• Novel forms of tubular members made of FRP grid reinforced UHPC are developed. • Behavior of FRP-UHPC tubular beams under bending is briefly introduced. • Behavior of FRP-UHPC tubular columns under axial compression is presented. • A connection system for FRP-UHPC plates is developed and verified. In this short communication, a series of novel forms of tubular members made of fiber-reinforced polymer (FRP) grid reinforced ultra-high-performance concrete (UHPC) (referred to as "FRP-UHPC tubular members") are developed. FRP-UHPC tubular members have excellent mechanical properties, and their excellent performances are demonstrated through three preliminary studies: i) behavior of FRP-UHPC tubular beams under bending; ii) behavior of FRP-UHPC tubular columns under axial compression; and iii) behavior of FRP-UHPC plates with a novel grouting sleeve connection system under bending. The experimental programs and results are briefed in the paper. The proposed FRP-UHPC tubular members are attractive in various structural applications such as pipelines, bridge box girders, permanent formwork of beams/columns, especially in marine environments (e.g., floating structures). [ABSTRACT FROM AUTHOR]

• The debonding of epoxy-to-concrete interface with the presence of water is studied using the atomistic approach. • The interfacial chemical bonds (Ca–O, Ca–N and H-bond) is reduced by water presence. • Water molecules can fill in the interfacial voids and enlarge the interfacial space. • The fracture position may transfer from the internal of epoxy to the interface with the water presence. • The epoxy C S H interaction and the load transfer of water molecules are weakened. In this study, molecular models are developed to investigate the water-induced bond degradation of the epoxy–concrete interface. Concrete is simulated using the C S H binder. The results indicate that the interfacial chemical bonds, including Ca–O, Ca–N, and H-bond, are reduced due to the existence of water at the interface. Two different roles of water molecules are characterized in the interfacial structure, including the filling and enlarging roles. The water presence degrades the interfacial bond strength and accelerates the interface debonding process, attributed to the weakened interaction between the epoxy and the C S H and the weakened load transfer of water molecules. The fracture position is transferred from the internal epoxy to the interface between the epoxy and the C S H. These atomic-level findings facilitate a better understanding of the interfacial deterioration of epoxy-bonded systems, e.g., fiber-reinforced polymer (FRP)-strengthened concrete structures with water presence at the interface. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP)-retrofitted steel structures in service are likely to experience significant temperature variations due to seasonal and diurnal service temperature changes. Even without the material system degradation, such temperature variations may influence the intermediate crack-induced (IC) debonding mechanism in FRP-retrofitted steel structures, mainly due to the interfacial thermal stress induced by the different thermal expansion coefficients of the FRP plate and the substrate steel. This paper presents a closed-form analytical solution for the full-range debonding process of an FRP-retrofitted notched steel beam under combined thermal and mechanical loading. A bilinear bond-slip relationship is used for describing the non-linear property of the bonding layer. The effects of thermal stress on the interfacial stress distribution, the IC debonding load and the stress intensity factor (SIF) at the notch are examined for the FRP-retrofitted steel beam at various service temperatures. The analytical solution is verified through the comparison between analytical and finite element (FE) results. Parametric investigations have indicated that a temperature decrease may lead to a reduced IC debonding load while an increased SIF, and vice versa. Such effect is more significant when a thicker and stiffener FRP plate is applied to retrofit the steel beam. [ABSTRACT FROM AUTHOR]

In this study, Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) panels with Fiber-Reinforced Polymer (FRP) reinforcement (i.e., FRP bars and girds) were proposed for the construction of sustainable marine structures. Based on four-pointed bending tests, the mechanical performance of FRP-reinforced UHS-ECC [with 2% polyethylene (PE) fibers] and FRP-reinforced ultra-high-strength concrete (UHSC, without fibers) panels were investigated and compared to understand the composite action between UHS-ECC and FRP. Compared with the FRP-reinforced UHSC panel, the FRP-reinforced UHS-ECC panel showed significantly higher ultimate load (139-173% higher), stiffness, and deformation capacity. It was also found that the use of seawater as the raw material had almost no effect on the mechanical performance of FRP-reinforced UHS-ECC (UHSC) panels. An analytical investigation was conducted to predict the load capacities of the tested panels, and the prediction error was acceptable. For FRP-reinforced UHS-ECC (UHSC) panels, it was revealed that using UHS-ECC to replace UHSC improved the stress transfer and deformation compatibility with FRP because the multiple cracking behavior of UHS-ECC lowered the crack-induced shear stress concentration along the FRP reinforcement. The developed FRP-reinforced UHS-ECC system showed great potential in the construction of durable and sustainable marine infrastructure. • FRP-reinforced UHS-ECC panel was developed and investigated for the first time. • The load capacity of the UHS-ECC panel was 139–173% higher than that of the UHSC panel with the same reinforcement. • Using UHS-ECC to replace UHSC significantly improved the effective strain of FRP. • The multiple cracking behavior of UHS-ECC improved the stress transfer and deformation compatibility with FRP. • The load capacities of the developed panels were predicted by an analytical approach. [ABSTRACT FROM AUTHOR]

• A novel connection based on FRP bars and steel grouting sleeves has been developed for prefabrication construction. • Flexural tests were conducted to clarify the effects of the connection mode and reinforcing fiber type. • Composite plates always failed outside the connection zone. • The horse tooth connection led to a better ductility of the composites plates than the staggered connection mode. Fiber reinforced polymer (FRP) bars have been proposed for use in ultra-high performance concrete (UHPC) as the reinforcement to mitigate/avoid the post-peak strain softening of UHPC under tension and to reduce the fiber dosage used in UHPC. The so-formed FRP-reinforced UHPC plates could be adopted for both structural strengthening and constructing novel structural elements. In this paper, a novel connection based on FRP bars and steel grouting sleeves has been developed for prefabrication construction of FRP bar-reinforced UHPC structures. Flexural tests were conducted to gain understandings of the effects of the connection mode (the staggered connection and the horse tooth connection) and reinforcing fiber type (polyethylene (PE) fibers and steel fibers) in the UHPC on the flexural behavior of connected FRP bar-reinforced-UHPC composite plates. The test results revealed that the proposed connection system is reliable since the composite plates always failed outside the connection zone, and most of the crack opening displacements at the interface of the connection are smaller than 0.2 mm at ultimate. The connection mode and the fiber type had little influence on the first cracking load and the initial bending stiffness of the FRP bar-reinforced UHPC plates, while the horse tooth connection led to a better ductility of the composites plates than the staggered connection mode. At given tolerable deflection of 1/200 span (about 5 mm), the longitudinal strains developed in the CFRP bars were about 2000 με for all specimens. [ABSTRACT FROM AUTHOR]

• Plate-end debonding failure of FRP-strengthened steel beams under combined mechanical/thermal loading was analyzed. • Coupled mixed-mode cohesive zone modeling approach was adopted in the theoretical model. • The theoretically predicted full-range debonding process was validated by finite element analysis. • Effects of various design parameters on the plate-end debonding failure were clarified. Fiber-reinforced polymer (FRP) strengthened steel beams may experience significant temperature variation during their service life. Because of the different coefficients of thermal expansion (CTEs) of FRP and steel materials, thermal stresses can be generated by temperature variation at the FRP-to-steel interface and consequently influence the plate-end debonding mechanism. Therefore, an accurate prediction of the debonding failure of FRP-strengthened steel beams under combined mechanical and thermal loading is of great importance for the strengthening design. This paper proposes a closed-form analytical solution based on a coupled mixed-mode cohesive zone model (CZM) (i.e., with the consideration of Mode-I and Mode-II mixity), to analyze the effect of thermal stress on the debonding failure of FRP-strengthened steel beams. An excellent agreement has been achieved between the analytical solution and the finite element (FE) modeling in terms of interfacial full-range debonding behavior. Further parametric studies were conducted and indicated that the thermal stresses induced by elevated temperatures tend to reduce the plate-end debonding load and such effect becomes more significant when a thicker FRP plate is adopted. [ABSTRACT FROM AUTHOR]

• Calibrating the concrete damage plasticity model by both the active confinement pressure approach and the confinement stiffness approach. • Deducing the concrete plastic flow from LRS FRP-confined concrete columns as a function of confinement stiffness. • Incorporating geometrical effects in the determination of the plastic dilation angle. In concrete columns confined with large rupture strain (LRS) fiber-reinforced polymers (FRPs), the LRS FRPs enhance the strength and ductility of concrete columns with the same mechanism as conventional FRPs by rendering passive lateral confinement pressure. However, LRS FRPs exhibit a strain capacity much larger than that of conventional FRPs. Notably, LRS FRPs have a bilinear material stiffness instead of the linear stiffness in conventional FRPs. Therefore, under axial compression, concrete confined by LRS FRPs will bear a different load path compared to that confined by conventional FRPs. This difference must be considered for finite element analysis (FEA) of LRS FRP-confined columns especially when the confinement pressure is non-uniform. To this aim, 23 samples of non-circular LRS FRP-confined concrete columns under axial monotonic compression were tested and analyzed. The variable test parameters are the aspect ratio (i.e., the depth (longer side) and width (shorter side) of the cross-sections）, the number of LRS FRP layers, and the type of LRS FRPs. For FEA, the concrete damage plasticity module (CDPM) was calibrated by both the active confinement pressure approach and the confinement stiffness approach. The active confinement pressure approach shows that the concrete plastic flow of LRS FRP-confined concrete is dominated by the secondary stiffness of the LRS FRP jacket. For the confinement stiffness approach, the concrete plastic flow is deduced from the compressive cyclic tests of cylindrical columns confined by LRS FRP jackets as a function of confinement stiffness. Results showed that the plastic dilation angle of concrete confined by LRS FRPs changes almost three times faster than that for concrete confined by conventional FRPs. The geometrical effects are included in the obtained plastic dilation angle so that a new plastic dilation angle model becomes feasible for the FEA of non-circular LRS FRP-confined concrete columns. Utilizing this new plastic dilation angle model enables the proposed plastic damage model to capture the stress strain behavior of the non-circular columns. Moreover, the non-uniformity of plastic flow on sections is captured reasonably. [ABSTRACT FROM AUTHOR]

In this study, a novel form of tubular permanent formwork that is made of ultra-high-performance concrete (UHPC) internally reinforced with fiber-reinforced polymer (FRP) micro-bars (herein referred to as FRP-UHPC tubular permanent formwork or simply FRP-UHPC tubular column) is developed. The axial compression test results of FRP-UHPC tubular columns with and without in-filled concrete are presented and discussed. Effects of the FRP micro-bar spiral pitch, the steel fiber addition in the UHPC, the tube thickness and the presence of external FRP confinment are investigated. The test results confirmed that the FRP-UHPC tubular columns have an excellent compressive strength, and the strength and ductility of existing concrete columns jacketed with an FRP-UHPC composite tube are substantially enhanced due to the confinement and axial contribution of the FRP-UHPC tube. The proposed FRP micro-bar-reinforced UHPC composite tubes are attractive in structural applications as pipelines or permanent formworks for columns, as well as external jackets (can be prefabricated in the form of two halves of composites tubes) for strengthening deteriorated reinforced concrete columns. [ABSTRACT FROM AUTHOR]

• Bond behavior of FRP-to-concrete interface between two adjacent cracks under thermal and mechanical loadings was considered. • A closed-form solution of the debonding process due to the presence of thermal loading was proposed. • The effects of thermal loading on local and global behaviors of the bond interface between two adjacent cracks were examined. • Thermal loading was numerically simulated by an FE model and the results were compared with the proposed analytical solution. Externally bonded fiber-reinforced polymer (FRP) composites have been widely used for the strengthening and repairing of reinforced concrete (RC) beams. Existing studies have denstrated that the full-range behavior and the associated debonding mechanism of the FRP-to-concrete interface between two adjacent cracks in the FRP-plated RC beam are different from those of the pull-off bonded joint. Moreover, the bond behavior between the FRP and the concrete may be affected by interfacial thermal stresses induced by the service temperature variations (i.e., the thermal loadings). Based on a fully reversible bilinear bond-slip model, this paper presents an analytical study to investigate the full-range deformation behavior of the FRP-to-concrete interface between two adjacent cracks under combined mechanical and thermal loadings. The analytical results have indicated that the thermal loadings may significantly influence the full-range deformation behavior and the axial stress distribution of the FRP plate, although the material properties of concrete, adhesive, and FRP are assumed to be not affected by the service temperature variations. A temperature increase leads to an increase in the ultimate load of the bond interface and vice versa. A finite element (FE) model with different considerations of the bondline damage is developed to verify the proposed analytical solution. The reliability of the proposed analytical solution is then validated by the comparisons between the analytical results and the corresponding predictions provided by the FE model. [ABSTRACT FROM AUTHOR]

Precast concrete sandwich panel (PCSPs), consisting of two reinforced concrete (RC) wythes (i.e., interior and exterior), a core insulation layer and connectors, can help to improve the building energy efficiency. This study is concerned with the fire and post-fire residual performance of an innovative PCSP system, in which fiber-reinforced polymer (FRP) reinforced geopolymer concrete is used as the two wythes and FRP tubes are used as the connectors. Six PCSP specimens were fabricated and five of them were tested under one-side fire exposure. The experimental parameters included the concrete type (geopolymer and conventional concrete), the reinforcement type (basalt FRP reinforcement and steel reinforcement), the connector type (plate-type and hexagonal tubular type), and the RC wythe thickness. After the fire exposure, all the specimens were tested under concentric loading to evaluate their residual axial load capacity. In addition, numerical analysis was conducted to facilitate a better understanding on the experienced temperature field of the PCSPs. It was found that the PCSPs with geopolymer concrete exhibited a decrease of the axial load capacity by 88.5% after 4 h one-side fire exposure while they performed better than that with conventional concrete. Besides, the reinforcement type, RC wythe thickness and the connector type are key factors influencing the post-fire structural performance of the PCSPs. [ABSTRACT FROM AUTHOR]

Large rupture strain (LRS) fiber-reinforced polymers (FRP) composites with an elongation greater than 5% offer an attractive solution for seismic strengthening of reinforced concrete (RC) columns. For a quick and reliable design of LRS FRP-strengthened RC columns, this paper presents a simplified plasticity damage model for LRS FRP-confined concrete under cyclic axial compression. This model consists of two parts: (a) a recent monotonic LRS FRP-confined concrete model developed by the authors' group as an envelope curve and (b) a simplified linear plasticity damage cyclic rule for predicting unloading and reloading paths. To solve the cyclic model deviation induced by concrete softening under a large axial strain, a pseudo-plastic strain was proposed, based on which the damage degradation of FRP-confined concrete can be quantified. The model comparisons show that although the proposed model sacrificed some precision when directly applied for the cyclic axial compressive behavior of FRP-confined concrete, it can give similarly accurate predictions as a complex model does for the behavior of conventional or LRS FRP-jacketed RC columns under a combined axial load and cyclic lateral load. Thus, this simplified plasticity damage model serves as a promising basic model for simulation of the seismic performance of FRP-strengthened structures. [ABSTRACT FROM AUTHOR]

• Full-range behavior of the bonded joint with a limited bond length was analyzed. • Thermal loading effects on local and global performance of the bonded joint were studied. • The solution was used to calibrate interfacial fracture energy from bonded joint tests. Concrete structures strengthened with externally bonded fiber-reinforced polymer (FRP) composites are likely to experience significant temperature variations (i.e., thermal loadings) due to daily and seasonal temperature changes or possible fire exposure during service life. Such thermal loadings may lead to changes in the mechanical properties of components (including FRP, bonding adhesive and concrete substrate) and induce interfacial thermal stress due to the thermal incompatibility between FRP and concrete. A limited bond length is usually adopted to investigate the bond behavior (e.g., the local bond-slip characteristics) of the FRP-to-concrete interface under temperature variations. This paper presents an analytical study for the first time to predict the full-range deformation behavior of a mechanically loaded FRP-to-concrete bonded joint with a limited bond length under temperature variations. The solution is in a closed-form manner and has enabled isolation of the interfacial thermal stress effect from the temperature-induced changes of material properties, thereby leading to an accurate calibration of the bond-slip characteristics and the interfacial fracture energy. The closed-form analytical solution has been verified by comparing the analytical predictions with the existing experimental and numerical results in the literature. To further understand the mechanism of the FRP-to-concrete interface under combined thermal and mechanical loadings, the effects of thermal stress and bond length on the interfacial responses and the full-range deformation behavior of the FRP-to-concrete interface are comprehensibly analyzed. [ABSTRACT FROM AUTHOR]