FRP Reinforcement Research Articles

Temperature induced fast-setting of cement based mineral-impregnated carbon-fiber reinforcements for durable and lightweight construction with textile-reinforced concrete

Developing durable and sustainable mineral-impregnated carbon-fiber (MCF) reinforcement system is today an effective measure to solve common service issues of conventional steel or FRP reinforcement in building sector. This study introduces a novel methodology for the design and realization of fast-setting cement based MCF reinforcements via targeted thermal activation. The process involves impregnating continuous yarns with a micro-sized particle cement suspension utilizing custom-built manufacturing equipment. Subsequently, the impregnated yarns undergo controlled heating at moderate temperatures to accelerate the cure process and strength development. Flexural and tensile performance of the MCFs exhibits progressive improvements with longer curing durations (from 2 to 20 h) and higher temperatures (from 40 °C to 60 °C). Enhanced mechanical properties are attributed to advanced hydration reactions and microstructural densification, as proven by thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), scanning electron microscopy, isothermal calorimetry and micro-computed tomography (μCT). When heating at 60 °C for 20 h, as-produced MCFs demonstrate optimal tensile strength of 2747 MPa and flexural strength of 482 MPa, with exceptional bond with concrete substrate, comparable to conventional FRPs. The proposed post-treatment shows promising potential for significantly enhancing the flexibility of mineral matrix composites, making them suitable for a wide range of industrial and field applications.

Carbon emissions of durable FRP composite structures in civil engineering

Conventional structural materials—concrete and steel—have been producing a substantial amount of carbon emissions to the earth, accounting for over 50 % of industrial emissions worldwide. An urgent call has been made for an alternative structural material with a better environmental impact. In this regard, this work investigated the carbon emissions of durable FRP composite structures in civil engineering. Three typical FRP composite structures were focused, including pedestrian bridges constructed by FRP structural profiles, concrete structures reinforced by FRP rebars, and existing concrete and steel structures strengthened by FRP sheets. Carbon emissions were investigated in terms of the carbon footprints per available dataset. Direct carbon reductions were observed in three FRP composite structures, and also, indirect carbon reductions were discussed, including FRP reinforcement for concrete structures and FRP enclosure for houses. The observed carbon reductions realized by FRP composite structures successfully showcased their great potential in reducing the carbon emissions in civil engineering.

Comparative analysis of the BFRP and steel reinforcement bars under fire conditions

The FRP reinforcement gained importance due to high tensile strength, high durability and ecological friendliness [1–7]. Its usefulness as the internal or Near Surface Mounted reinforcement in bent concrete elements has already been proven. Though, in terms of the compressive behaviour of the bars and concrete elements incorporating them, there are still few experimental and numerical considerations, especially when high temperatures are considered. This article contains further considerations on the performance of concrete columns with BFRP main reinforcement in fire resistance tests on the basis of previously presented authors’ numerical analyses. Comparative analysis in terms of temperatures, deformations and stresses of concrete columns with BFRP and steel main reinforcement in fire resistance tests is presented by the example of two columns, for which also experimental investigations were performed. Also, a comparative analysis of stress-strain relations for BFRP, steel and concrete at temperatures up to 600°C is presented. It can be concluded that BFRP bars’ properties are strongly different when compressive and tensile performance is considered, especially at elevated temperatures. Tensile strength was higher for BFRP than steel at room temperature, but along with temperature growth, it came the other way (at around 600°C). The compressive strength of the BFRP bars was higher than the value for concrete, but only for temperatures lower than 200°C.

Effects of U-wrap anchored doubly FRP strengthened reinforced concrete beams on ductility and serviceability improvements

This paper presents a paradigm shift from the classical thinking that CFRP strengthening increases ultimate capacity only. It addresses a new strengthening technique change that yields significant improvements in ductility and serviceability. A series of eight reinforced concrete beams were cast and tested under four-point bending until failure. The beams were divided into two groups: the control group comprising two beams without any strengthening, and one beam reinforced with one tension layer only. The examined group consisting of four beams having double FRP layers in compression and a single layer in tension, with different anchorage configurations. Additionally, one beam in the examined group had a lower concrete strength. The results demonstrated that the doubly strengthened beams exhibited larger post-cracking stiffness and load capacity compared to the control beams. The anchoring of tension layers and incorporation of compression FRP layers significantly increased ductility of the beams. The utilization of U-wrap anchors successfully shifted the failure mode from sheet debonding to FRP rupture and FRP buckling in the compression zone, effectively maximizing the benefits of the FRP reinforcement. Moreover, the addition of compression FRP layers improved the load distribution and reduced the critical compressive stresses.

Behavior of one-way steel, BFRP, and GFRP reinforced concrete slabs under monotonic and cyclic loadings: Experiments and analyses

This paper experimentally investigated the monotonic and cyclic behaviour of one-way basalt and glass fibre-reinforced polymers (BFRP and GFRP) reinforced concrete (RC) slabs compared with that of traditional steel RC ones. A total of nine 2000×700×100 mm RC slabs, including three BFRP RC (BRC), three GFRP RC (GRC), and three steel RC (SRC) slabs, were tested. The results indicated that the behaviour of BRC and GRC slabs was governed by the elastic characteristic of FRP bars, resulting in a more uniform curvature of the slabs. The behaviour and failure modes of BRC and GRC slabs were comparable with those of SRC slabs. The similarity and difference were characterized by the rupture of FRP bars and the yielding of steel bars. Postcrack stiffness of BRC and GRC slabs was significantly lower than that of SRC slabs and was marginally affected by the effect of cyclic loading. The ultimate loads and ultimate deflections of BRC and GRC slabs were ∼2.0 and 1.6–2.0 times those of SRC slabs, respectively. Concepts of ductility, safety factor, and warning index were introduced and quantified for FRP RC slabs. BRC and GRC slabs had a significantly higher ductility (8.5–10.4) than SRC slabs (5.1–6.2), showing a highly ductile behaviour. SRC slabs had a safety factor of 1.0–1.1, while BRC and GRC slabs had a significantly higher safety factor of 3.8, showing their lower failure probability of BRC and GRC slabs when they are designed at a similar load as SRC slabs. The warning index of SRC slabs was 14.4–30.2, and that of BRC and GRC slabs was 65.1–71.6 and 63.9–86.0, respectively. The strength, ductility, safety factor, recovery, and warning index of BRC and GRC slabs were high, confirming their advanced characteristics. Under cyclic loading, BRC and GRC slabs have significantly larger stiffness degradations (4.4 %–7.2 %/cycle) than SRC slabs (1.62 %−3.2 %/cycle). The results of theoretical analyses showed that the strengths of BRC and GRC slabs can be reasonably predicted. The outcomes indicate the high potential use of FRP reinforcement for slabs in engineering practice.

3D FRP Reinforcement Systems for Concrete Beams: Innovation towards High Performance Concrete Structures.

Despite the advantages of using lightweight and non-corrosive carbon fiber reinforced polymer (CFRP) reinforcements in concrete structures, their widespread adoption has been limited due to concerns regarding the brittle failure of CFRP rupture and its relatively softer load-deflection stiffness. This work offers logical solutions to these two crucial problems: using aggregate coating to strengthen the CFRP-concrete bond and ultimately the load-deflection stiffness, and using CFRP-concrete debonding propagation to create pseudo-ductile behavior. Subsequently, the concrete cracking behavior, the apparent CFRP modulus with aggregates, and the post-peak capacity and deflection of three-dimensional (3D) CFRP-reinforced concrete are all described by equations derived from experiments. These formulas will be helpful in the future design of non-prismatic concrete components for low-impact building projects. The potential of this innovative design scheme in terms of increased capacity and deflections with less concrete material is demonstrated through comparisons between non-prismatic CFRP-reinforced concrete and measured steel reinforced equivalency.

Shear strengthening of reinforced concrete beams completely wrapped by large rupture strain (LRS) FRP

An experimental work on the shear strengthening of reinforced concrete (RC) beams completely wrapped by large rupture strain (LRS) FRP is presented in this paper. A total of 14 three-point bending tests were carried out on simply supported RC beams, with a focus on the impacts of the shear span-to-depth ratio (1.53, 2.25, and 3.01) and FRP reinforcement ratio (0.37 %, 0.75 %, and 1.12 %) on the shear behavior of RC beams strengthened with LRS FRP. For the beams with a median length, the ductility coefficients increased by 81 %, 154 %, and 335 % with the increase in FRP reinforcement ratio. For the long beams, the ductility coefficients increased by 116 %, 286 %, and 470 % as the FRP reinforcement ratio improved. The ductility markedly improved with the increase in shear span-to-depth ratio. PET FRP’s fracture was not found at the ultimate state, and the improvement in mid-span deflection after the peak state was mainly contributed by the shear deformation. The strengthened specimens exhibited a ductile shear failure mode. For the short RC beams, the shear capacity was slightly enhanced, and the ductility was not improved after being strengthened. The strengthened short RC beams still showed a brittle diagonal compression failure mode. The experimental shear contribution of PETT FRP was compared with the prediction of the existing design guidelines. Finally, an effective strain model of PET FRP, including the shear span-to-depth ratio effect, was proposed and verified with the experimental results.

RC beams flexurally strengthened with CFRP sheets combined with FRC layer for mitigating debonding failures

A hybrid strengthening system, comprising a carbon fiber reinforced polymer (CFRP) sheet combined with fiber reinforced concrete (FRC) layer is proposed in this study as a mitigatory solution to brittle debonding problems. Five reinforced concrete (RC) beams, comprising both control cases and those strengthened with the hybrid CFRP-FRC system at various FRP reinforcement ratios, were fabricated and tested to assess the system's effectiveness. A comprehensive finite element (FE) model was also developed to complement the experimental campaign and extend it into a parametric investigation on the effects of FRP reinforcement ratio (ρf), fiber percentage in FRC (vf), and FRC layer thickness (tFRC). Compared with beams strengthened with FRP alone, using the FRC layer increased the ultimate load (Pult.) of FRP-strengthened beams by 29–59%, depending on ρf and vf. The ductility of the hybrid FRP-FRC strengthened beams also increased by more than twice compared to the beams strengthened with only FRP. For the FRP reinforcement ratio (ρf) of 0.18%, use of an FRC layer with vf = 2% yields the highest increase in Pult. and ductility for the hybrid system. Ultimately, the brittle FRP debonding failure was successfully eliminated using the FRC layer, leading to desirable FRP rupture. Built with capabilities to capture material nonlinearity, contact, and debonding phenomena, the FE model predictions excellently matched those of the test results in terms of the beam’s capacity, failure modes as well as load-deflection and load-strain responses.

Study on the hysteretic characteristics of FRP-reinforced concrete shear wall with innovative friction dampers

FRP-reinforced concrete shear walls (FRCWs) are able to achieve satisfactory residual deformation and corrosion resistance compared with steel reinforced concrete walls (SRCWs). However, in the FRCWs, the failure of the plastic hinge region brings great challenges to the post-earthquake repair of the structure. Therefore, this paper designed one SRCW and two FRCWs with innovative friction dampers (FDs) at the feet, and steel truss and steel plate were embedded at the plastic hinge region of the two FRCWs respectively to supplement the weakened shear strength. Then pseudo-static tests were carried out twice before and after repairing the two FRCWs with FDs. Experimental results showed that compared with the SRCW at the same lateral drift, the damage of the FRCW was reduced by installing FDs at the feet, and the energy dissipation capacity was enhanced; the repaired FRCWs with FDs could still have acceptable seismic performance. Subsequently, the Park-Ang damage indices of wall webs of the FRCWs with FDs were calculated, which proved that the FRCWs with FDs could meet the four-level seismic fortification objective. In the end, two orthogonal tests were designed based on the established OpenSees models to evaluate the impact of the damper friction and FRP reinforcement ratio on the seismic behaviours of the FRCWs with FDs. It was recommended to adopt larger longitudinally distributed FRP reinforcement ratio to obtain satisfactory self-centering ability and hysteresis performance of the FRCW with FDs.

Advancements in the Study of FRP-Reinforced Timber Columns under Axial Compression

FRP reinforcement technology, with its numerous outstanding advantages, has been widely applied to the strengthening of timber column structures, making related research of significant social and engineering practical relevance. This paper reviews the research achievements in the axial compression performance of FRP-reinforced timber columns from both domestic and international sources. It analyzes advancements in four aspects: types of FRP, number of FRP layers, the impact of knots, and models of ultimate compressive strength and finite element models. A comprehensive analysis and comparison of existing research shortcomings and unresolved issues are provided. Finally, some references and suggestions for further research and application of FRP-reinforced timber columns are offered.

Experimental study on the seismic performance of GFRP reinforced concrete columns actively confined by AFRP strips

This paper proposes a new type of concrete columns, which are reinforced with GFRP bars and actively confined by Aramid Fiber-Reinforced Polymer (AFRP) strips. FRP reinforcement is a non-corrosive material and has the advantages of having lighter weight, higher tensile strength, and long-term durability as compared to steel reinforcement. Active confinement has advantages over non-confined concrete columns and it is expected that the active confinement in the critical area increases the adhesion between the concrete and the rebars, strengthens the concrete cover portion of the rebars, and increases the shear capacity of the column. The literature does not show a comprehensive examination of the actively confined concrete columns that are reinforced by polymer and steel bars. Six reinforced concrete columns were cast, loaded, and tested under simultaneous application of axial and cyclic loads. Four columns were actively confined by AFRP strips at 10% and 30% of the AFRP ultimate strain in the critical area. Two columns were reinforced with steel bars, and the other two were reinforced with GFRP bars. Also, two columns with steel bars and GFRP bars, but without confinement, were utilized as the control specimens. Experimental results showed that the strain in the cover portion of the actively confined columns was reduced due to the effect of active confinement, and the strength of the concrete core increased. The active confinement increased the adhesion between the concrete and the bars and also reduced crack width, which ultimately resulted in increasing concrete strength, ductility, and energy absorption.

Load-Bearing Capacity of Bended FRP Reinforcement with Various Anchorage Lengths

The research builds upon the analysis of bent glass-fibre-reinforced-polymer reinforcement. The presented work focuses on examining the influence of anchor length on the overall tensile strength of bent FRP rebar. In general, to ensure secure anchoring of the reinforcement in concrete, it is necessary to determine a specific length of the straight section of the rebar beyond the bend, which prevents the reinforcement from being pulled out of the concrete. A total of 27 pieces of bent rebar were tested in the research and divided into four subgroups based on the anchor length beyond the bend. The reference value of the load-carrying capacity of the straight reinforcement was tested on four experimental samples. The research results confirmed that the reduction in tensile strength depends on the anchor length and suggest that the minimum anchorage length stated in the literature should be sufficient; exceeding it does not lead to a significant increase in the load-carrying capacity of the rebar. The research findings expand the Czech Republic’s design knowledge of FRP reinforcement and facilitate the resolution of subsequent phases of the project.

FE Analysis on Size Effect in Torsional Behavior of Rectangular RC Beams with and Without FRP Strengthening

Although torsion is usually considered a secondary consideration in structural design, it can lead to failures, especially in structures with irregular geometry exposed to seismic forces or in unique situations. While some studies have explored the size effect on the torsional behavior of RC beams, none have addressed the impact of reinforcement. This paper investigates the size effect on the torsional behavior of RC beams with varying reinforcement ratios, including both FRP sheets and steel rebars. In this study, the torsional behavior of reinforced concrete (RC) beams with and without FRP strengthening was investigated numerically. Modeling was carried out by Finite element (FE) software ABAQUS and validated using experimental data from literature. The torsional behavior of 24 models with differences in cross-section size and reinforcement ratio were investigated. Concrete damage plasticity, Hashin damage criteria, and von Mises stress were used to investigate the damage in concrete, FRP, and steel, respectively. The cracking torsional moment, ultimate torsional moment, and torque-twist curve of the beams were evaluated and presented. The results indicated the presence of a significant size effect in the torsional strength of beams. After reinforcing the beams with FRP fabrics, the average cracking moment increased by a range of 1.72% to 36% across different groups of beams. An 8.2% increase in ultimate strength is observed with just a 0.4% rise in the FRP strengthening ratio. Post-cracking behavior was seen in 8 models with adequate steel and FRP reinforcement ratio.

Probabilistic analysis of FRP efficacy in seismic risk reduction

Engineers are tasked with the challenging task of evaluating the performance and analyzing the risk of systems in the context of performance-based seismic design. All sources of random uncertainty must be taken into account during the design phase in order to complete this assignment. The performance limit states for a structure must be defined using appropriate procedures that take into consideration the system characteristics describing the structure, the soil, and the loads applied to the structural reactions. The main objective of this study is to conduct an in-depth analysis, both linear and non-linear (Pushover), of seismic vulnerability for a reinforced concrete (RC) structure. This aims to probabilistically evaluate the effectiveness of composite materials, particularly those reinforced with glass and carbon fibers, in reducing seismic risk when used to reinforce structural columns. The outcomes of this study will provide valuable insights into the efficacy of FRP reinforcements in enhancing seismic resistance, regardless of the analytical approach adopted (linear or non-linear). They reveal a seismic risk reduction of 48 % for structures equipped with glass fiber-reinforced columns and 67 % for those with carbon fiber-reinforced columns.

Shear behavior of box‐section concrete beams reinforced by FRP bars and FRP stirrups

AbstractA few research studies are available on the behavior of reinforced concrete (RC) box section beams with fiber‐reinforced polymer bars (FRP) and FRP stirrups. Consequently, the behavior of these beams needs to be investigated. This article studies experimentally, numerically, and analytically the effect of some variables on the behavior of RC box section beams. This article investigates many variables, such as the shear span‐to‐total depth ratio, the flexural FRP reinforcement ratio, and the FRP vertical and horizontal web reinforcement ratio. The experimental program consists of nine simply supported reinforced concrete box section beams. The numerical models using the nonlinear finite element program ANSYS V.15 are carried out. The results are compared to the experimental results using load‐deflection curves, crack patterns, failure loads, and failure modes. The shear capacities based on Egyptian ECP 208‐2019 and ACI 440‐2015 codes are compared to each other and to the experimental results. The findings show an adequate agreement between the experimental, numerical, and analytical results for the range of the studied parameters. The results reveal that increasing the shear span‐to‐depth ratio by 50% decreases the carrying capacity, toughness, and displacement ductility by 2%, 28%, and 12%, respectively. The increase in main FRP reinforcement rebars by 20% increases the carrying capacity and toughness by 59% and 62%, respectively. Increasing vertical FRP stirrups by 79% increases the failure load and toughness by 26% and 15%, respectively, and displacement ductility increases only by 0.8%. The increase in horizontal FRP stirrups by 79% increases the failure load, toughness, and displacement ductility by 33%, 8%, and 4%, respectively. Both Egyptian and American codes are conservative in some cases and unconservative in others, while the numerical results are unconservative.

Near-surface mounted-FRP flexural retrofitting of concrete members using nanomaterial-modified epoxy adhesives

This study, serving as the first of its kind in this scope, investigates the effectiveness of nanomaterial-modified epoxy adhesives (NMEAs) for Near-Surface Mounted (NSM)-FRP flexural retrofitting of concrete. A total of 48 concrete prisms were retrofitted using three different types of FRP reinforcement bars (CFRP, GFRP and BFRP) inserted in grooves sized 8 × 8, 10 × 10 or 12 × 12 mm and bonded to the concrete substrate using either neat epoxy (NE) or NMEAs. NMEAs were developed by incorporating either carbon-based (i.e. CNF, cellulose and graphite) or silicon-based (i.e. silica and MMT clay) nanoparticles into epoxy at 0.1 wt. %, whereas the graphite NMEAs were prepared with more wt.% (i.e. 0.2 and 0.3). SEM and XRD techniques were used to assess the dispersion quality of nanoparticles within the matrix along with the porosity and crystallinity percentages of the NMEAs. Results showed that using silica, clay and graphite NMEAs rather than NE enhanced the retrofitted concrete capacities, whereas a decrease in strength was observed when using CNF- and cellulose-modified epoxies. Moreover, it was found that the specimens bonded with silicon-based NMEAs had, on average, higher capacities than those bonded with carbon-based NMEAs, which, on the other hand, showed more ductile behaviour. Results also suggested that the specimens’ capacities decreased as the wt. % concentration of the nanoparticles (i.e. graphite) increased. Increasing the groove size from 8 × 8 mm to 10 × 10 mm decreased the capacities but enhanced the ductility, whereas increases in both the capacities and ductility were achieved when moving from 8 × 8 mm to 12 × 12 mm.

Universal Bond Models of FRP Reinforcements Externally Bonded and Near-Surface Mounted to RC Elements in Bending.

The use of fibre-reinforced polymer materials (FRPs) for the retrofitting of reinforced concrete (RC) structures has become very popular. However, the main concern for the exploitation of FRPs is their premature debonding failure modes. This paper presents two different universal models for calculating flexed RC elements strengthened with externally bonded and near-surface mounted FRP reinforcements, which were derived by coupling principles of the fracture mechanics of solids and generally accepted assumptions. The first model allows a complete analysis of the behaviour, development, and propagation of rupture of the joint. The main advantages of the proposed model, compared to existing ones, are that it does not require additional bond shear tests to identify missing factors, and it is versatile and suitable for both externally bonded reinforcements (EBR) and near surface mounted (NSM) strengthening techniques. In addition, the concrete-FRP connection is divided into zones and the current phase and length of each zone are determined, allowing for more detailed analysis of the connection at different load stages. The proposed computational model and its derivation focus on the performance of the joint between the two cracks and the distribution of the shear stresses in that joint. The second one requires fewer computations and can be fully exploited when the joint is treated as a unit, without division. The results of the calculations have been validated using the experimental database of 77 RC beams and strengthened with externally bonded and near-surface mounted carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) sheets, plates, strips, and bars taken from 13 different studies. Both the prestress force and the initial stress state before strengthening were evaluated.

Hybrid CFRP-BFRP Rebars for Prestress Concrete Slabs: Abaqus Analysis and Experimental Validation

This study utilizes Abaqus finite element software to analyze concrete slabs reinforced with a novel hybrid of Carbon Fiber Reinforced Polymers (CFRP) and Basalt Fiber Reinforced Polymers (BFRP) rebars known as CBRP rebars. The investigation focuses on assessing the structural performance of these slabs under varying prestressing levels (PL) and FRP reduction factors (FR), along with the prestress index level (PI). The study defines the FR factor as the reduction in the transverse reinforcement area of FRP compared to the control slab. The PI is the ratio of prestressed CBRP rebars to the total FRP reinforcement in the transverse direction, aiming to determine a lower FRP reduction factor without compromising the FRP slabs' design requirements. Three FR values (0.45, 0.37, and 0.29) are considered, with the CBRP tendon tensioned at 35% and 50% of the ultimate strength, including 0.5 and 0.6 of the PI, for validation against experimental test data. The numerical analysis incorporates advanced finite element modeling techniques, integrating material properties, load conditions, and structural parameters to detail the behavior of CBR-reinforced concrete slabs. Various loading scenarios are simulated to evaluate the performance of CBRP rebars under diverse conditions. Comparison with experimental data validates the hybrid reinforcement approach's reliability. The study's findings contribute significantly to understanding the structural performance of concrete slabs reinforced with CBRP rebars. The hybridization of CFRP and BFRP rebars offers a promising alternative for enhancing concrete structure strength while reducing the carbon footprint associated with traditional reinforcement materials. The versatility of CBRP rebars allows customization based on specific structural requirements. Based on the Abaqus numerical analysis and its alignment with experimental data, the study recommends optimizing the CFRP-BFRP ratio to meet structural demands, evaluating long-term performance, and exploring environmental benefits associated with sustainable reinforcement materials. This research advances knowledge in the hybrid fiber-reinforced polymers field, offering insights for engineers and researchers seeking innovative solutions for concrete structure enhancement using Abaqus as a powerful analytical tool.

Experimental Investigation into the Flexural Behaviour of Basalt FRP Reinforced Concrete Beams

This study involved conducting four-point bending tests on three types of rebar-reinforced concrete beam: those reinforced with steel bars, those reinforced using basalt fiber-reinforced polymer rods, and hybrid reinforced concrete beams that used both Basalt fiber-reinforced plastic and reinforcing steel. Various reinforcement ratios and configurations were used to analyze mid-span deflection, flexural capacity, fracture distribution, and Basalt FRP bars strain. The results suggest that using a hybrid reinforcement system that combines Basalt fiber-reinforced plastic and reinforcing steel can improve the transverse rupture strength of rebar-reinforced concrete beam, reduce deflection and cracking, and use the high-strength characteristics of Basalt FRP bars.

Impact response analysis and prediction of FRP-RC beams with varying flexural stiffness: Numerical simulation and modified two-DOF calculation

The damage behavior and simplified calculation of fiber-reinforced polymer reinforced concrete (FRP-RC) beams subjected to impact loading have attracted substantial attention. In this study, a finite element model incorporating strain rate was employed. Based on the model, the progressive damage behavior and nonlinear impact response of FRP-RC beams with varying stiffness under hammer-to-beam mass ratios were examined. The results indicate that in the investigated conditions, the damage mode of FRP-RC beams does not vary with the changes in the tension reinforcement ratio, but is affected by the hammer-to-beam mass ratio. Due to the absence of a yielding stage for FRP bars, a nonlinear alteration occurred in the rebound of the FRP bars’ strain and the beam’s displacement with a redistribution of stress. When the reinforcement ratio varies from 0.32% to 3.37%, the peak displacements, reaction and impact forces vary by 25%-49%, 53%-78%, and 0.1%-1% under different mass ratios, respectively. The reinforcement ratio does not change the relationship between the mass ratio and the curve shape of the impact force time history. Additionally, an improved two-degree-of-freedom model considering the FRP’s elastic brittleness effect and modified contact stiffness scaling factor was developed, their accuracy was verified. However, there are still many inconveniences to applying the two-DOF model in engineering. Consequently, based on the above two-DOF model, explicit formulas considering contact stiffness, bending stiffness, impactor velocity and mass for displacement and impact force response of impacted FRP reinforcement concrete beams were proposed, which greatly facilitates engineering calculations.