Fiber Reinforced Polymer Layers Research Articles

Detecting Internal Defects in FRP-Reinforced Concrete Structures through the Integration of Infrared Thermography and Deep Learning.

This study represents a significant advancement in structural health monitoring by integrating infrared thermography (IRT) with cutting-edge deep learning techniques, specifically through the use of the Mask R-CNN neural network. This approach targets the precise detection and segmentation of hidden defects within the interfacial layers of Fiber-Reinforced Polymer (FRP)-reinforced concrete structures. Employing a dual RGB and thermal camera setup, we captured and meticulously aligned image data, which were then annotated for semantic segmentation to train the deep learning model. The fusion of the RGB and thermal imaging significantly enhanced the model's capabilities, achieving an average accuracy of 96.28% across a 5-fold cross-validation. The model demonstrated robust performance, consistently identifying true negatives with an average specificity of 96.78% and maintaining high precision at 96.42% in accurately delineating damaged areas. It also showed a high recall rate of 96.91%, effectively recognizing almost all actual cases of damage, which is crucial for the maintenance of structural integrity. The balanced precision and recall culminated in an average F1-score of 96.78%, highlighting the model's effectiveness in comprehensive damage assessment. Overall, this synergistic approach of combining IRT and deep learning provides a powerful tool for the automated inspection and preservation of critical infrastructure components.

Axial compression test on strengthening concrete cylinders by Fe-SMA/FRP-HDPE tube and rubber concrete cladding layer

This paper proposed a new method to strengthen and repair concrete columns, which combined active and passive confinement. The method involved the use of iron-based shape memory alloy (Fe-SMA) strips to quickly exert active confinement to these columns, followed by the use of fiber-reinforced polymer (FRP) and high-density polyethylene (HDPE) tubes as external passive confinement to improve the load-bearing capacity, durability, and ductility of concrete columns. Rubber concrete that performs high energy consumption and certain strength was used as the cladding layer to improve the impact resistance of the concrete column. This paper explored the effect of this method on the bearing capacity performance of concrete columns through axial compression tests and set three test variables, including different net-spacing of Fe-SMA, different FRP wrapping forms, and different FRP layers. The test outcomes showed that all three test variables obviously improved the load-bearing capacity and ductility of concrete columns, peculiarly when applying active confinement. Eventually, this paper proposed a theoretical model to predict the peak compressive strength of the specimen, which can provide a reference for designing this active-passive confinement strengthening method.

Degree of bending of FRP-reinforced tubular X-joints in offshore jacket-type structures under in-plane bending moment

In offshore jacket structures, the stress within the chord thickness of tubular joints arises from both membrane and bending stresses. The Degree of Bending (DoB)—the ratio of bending stress to the total stress—is key to evaluating these joints' fatigue resistance. This study delves into the DoB in tubular X-joints reinforced with fiber-reinforced polymer (FRP) subjected to in-plane bending moment. It begins by validating finite element (FE) analysis accuracy through comparison with existing theoretical and experimental evidence. Following this, the analysis of 166 joints was conducted to examine how variations in FRP characteristics (such as type, layer count, and layout) and the joints' dimensionless geometric factors influence the DoB and its ratio in reinforced joints compared to their unreinforced counterparts. Findings indicate that FRP layers enhance fatigue resistance by lowering hot spot stresses on the chord's inner and outer surfaces and elevating the DoB value by up to 26.16%. Consequently, the study introduces a parametric formula for calculating the DoB in FRP-reinforced tubular X-joints under an in-plane bending moment. This development is significant, as there was no existing parametric formula for determining DoB in FRP-reinforced joints. The proposed formula stands out for its high determination coefficient and minimal error, effectively addressing a notable gap in the field.

Strength, durability and finite element analysis of hybrid jute/basalt fiber reinforced polymer confined concrete column under axial compression

Implementing retrofitting measures for a civil structure may guarantee its ongoing safety and operation, while also extending its lifespan. The present investigation focused on the examination of compressive axial loads on concrete columns that were confined by natural fiber reinforced polymer (FRP). In particular, concrete cylinders confined with jute and basalt fiber epoxy composites were evaluated for their strength and durability. Various strength tests were conducted on unconfined and, jute, basalt, and hybrid jute-basalt FRP confined concrete cylinders with varying thicknesses of the FRP layers. Effectiveness of these natural FRP systems in providing external confinement to concrete columns in various environmental conditions were investigated, including exposure to acidic, alkaline, seawater, and potable water environments. Test results demonstrated that external confinement with hybrid FRP wraps, i.e. with both jute and basalt fibers, enhanced the load-bearing and energy absorption capacities by 63.64 % and 287 %, respectively. The confinement effectiveness of FRP wrapped specimens were 213 %, 164 %, 166 % and 163 % respectively compared to the unconfined specimens after exposure to acidic, alkaline, seawater and potable water environments. These impressive outcomes may be ascribed to the intrinsic rigidity of hybrid fibers. Furthermore, a finite element analysis (FEA) model of FRP confined concrete columns was performed using ABAQUS software calibrated with the experimental data. A close agreement between the experimental results and the adopted numerical model was observed. The outcome of the study suggests that the confinement with natural FRP can be used as a prominent retrofitting technique for columns in a variety of environments which can thus enhance the durability and sustainability of civil constructions.

Factors affecting axial and lateral load transfer of hollow fibre-reinforced polymer piles in soft clay

ABSTRACT The growing interest in the long-term performance of pile foundations and their ability to resist the negative effects of water exposure and aggressive environmental conditions has led to considering non-corrosive materials such as fibre-reinforced polymer (FRP). The most common applications are light-bearing structures in waterfront environments, while applications for larger structures have not been widely accepted in industry due to the lack of long-term records and design guidelines available. In this study, a numerical model using the finite element method was developed to simulate small-scale load tests of hollow carbon-fibre reinforced polymer (CFRP) and glass-fibre reinforced polymer (GFRP) piles in soft clay. The findings of this research indicate that the number of FRP layers impacts loading behaviour significantly, while inner tube soil height has a reasonable influence on axial load response and fibre orientation has a minor effect under lateral load conditions.

Integrated behavioural analysis of FRP-confined circular columns using FEM and machine learning

This study investigates the structural behaviour of double-skin columns, introducing novel double-skin double filled tubular (DSDFT) columns, which utilise double steel tubes and concrete to enhance the load-carrying capacity and ductility beyond conventional double-skin hollow tubular (DSHT) columns, employing a combination of finite element model (FEM) and machine learning (ML) techniques. A total of 48 columns (DSHT+DSDFT) were created to examine the impact of various parameters, such as double steel tube configurations, thickness of fibre-reinforced polymer (FRP) layer, type of FRP material, and steel tube diameter, on the load-carrying capacity and ductility of the columns. The results were validated against the experimental findings to ensure their accuracy. Key findings highlight the advantages of the DSDFT configuration. Compared to the DSHT columns, the DSDFT columns exhibited remarkable 19.54 % to 101.21 % increases in the load-carrying capacity, demonstrating improved ductility and load-bearing capabilities. Thicker FRP layers enhanced the load-carrying capacity up to 15 %, however at the expense of the reduced axial strain. It was also observed that glass FRP wrapping displayed 25 % superior ultimate axial strain than aramid FRP wrapping. Four different ML models were assessed to predict the axial load-carrying capacity of the columns, with long short-term memory (LSTM) and bidirectional LSTM models emerging as superior choices indicating exceptional predictive capabilities. This interdisciplinary approach offers valuable insights into designing and optimising confined column systems. It sheds light on both double-tube and single-tube configurations, propelling advancements in structural engineering practices for new constructions and retrofitting. Further, it lays out a blueprint for maximising the performance of the confined columns under the axial compression.

Structural Behaviour of FRP-Reinforced Tubular T-Joint Subjected to Combined In-Plane Bending and Axial Load

In this study, 90 finite-element models are used to explore the behaviour of fibre-reinforced polymer (FRP) reinforced joints under combined in-plane bending (IPB) and axial load (AX). The effects of joint geometry, FRP layer count, and AX levels of the chord or brace are considered. Three typical failure modes are observed: chord plastic failure, brace plastic failure, and brace buckling failure. Increasing the number of FRP layers can ensure that failure is chord-related failure in a ductility manner rather than the unexpectedly brace-related brittle failure. Depending on the stress distribution of fibres, FRP reinforcement can restrict the deformation of joints subjected to complex loading patterns. Moreover, added FRP layers efficiently reduce the effect of brace AX on the IPB resistance. Finally, a modified strength equation is established, including the influence of FRP reinforcement, chord AX, and brace AX.

Effect of CNT film interleaves on the flexural properties and strength after impact of CFRP composites

Abstract Carbon nanotubes (CNTs), with their high strength, modulus, and large aspect ratio, have emerged as a frontrunner in nano-reinforcements. In this study, CNT films (CNTFs) were inserted between carbon fiber-reinforced polymer (CFRP) prepregs and were cured together to form interleaved composite laminates. The influence of CNTF interleaves on the flexural and interlaminar properties of fiber-reinforced polymer (FRP) laminates is investigated. Three different types of FRP specimens were tested, namely, 0CNTs-CFRP, 2CNTs-CFRP, and 4CNTs-CFRP. The surface and internal damage characteristics and mechanism of CNTF were analyzed using scanning electron microscopy and computed tomography testing methods. The results showed that the flexural strength of 0° CNTs-CFRP beams increased by 3.79 and 14.34% for 2CNTs-CFRP and 4CNTs-CFRP, respectively, while the flexural modulus increased by 7.33 and 13.76%, respectively. It was also found that the damage area and overall deformation after impact with the energy of 5 J was reduced in the CNTF interleaved composite beams. This work has confirmed that the mechanical properties of FRP laminates can be improved by conveniently inserting CNTF during stacking prepregs in the manufacturing process. However, there is a reduction in the flexure after impact properties of the CNTF-CFRP composites, suggesting that the interface between CNTF and FRP layers should be optimized for high residual strength.

A Constitutive Model for Circular and Square Cross-Section Concrete Confined with Aramid FRP Laminates

Fiber-reinforced polymer (FRP) has been used for seismic retrofitting and structural reinforcement over recent decades. Numerous researchers have created stress–strain models based on experimental data to predict the mechanical properties of FRP-confined concrete. In this study, circular and square cross-section specimens with different design concrete strength were prepared, and the compressive strength of the specimens confined with different layers of aramid FRP (AFRP) were measured in compressive tests. A constitutive model was proposed to simulate the uniaxial compressive stress–strain relationship of the AFRP-confined concrete, which was derived from the Mohr–Coulomb failure envelope theory, and the corresponding axial strain was determined from the regression analysis. The internal friction angle of the proposed constitutive model was determined for the cylindrical concrete specimens confined with one and two layers of AFRP. The compressive strength of one and two layers of AFRP-confined concrete specimens were used to obtain the parameters of the constitutive model; the absolute average error between experimental and predicted compressive strength was 7.01%. Then, the constitutive model was used to predict the strength of a three-layer AFRP-confined concrete specimen, and the absolute average error was 4.95%. The cross-sectional shape coefficient of the square concrete specimen was obtained analytically. Substituting the cross-sectional shape coefficient into the proposed constitutive model, the average absolute error of the square cross-section concrete specimen was about 3.84%. The results indicated that the proposed constitutive model can predict the compressive strength of circular and square cross-section concrete specimens confined with AFRP.

Behavior of grouted splice sleeve connection using FRP sheet

Most existing studies on grouted splice connections have focused on the bond behavior between connected steel rebars and conventional steel or iron sleeves. These research findings cannot properly predict the bond behavior and performance of the grouted splice connections, particularly when a new splice device, such as fiber reinforced polymer (FRP) materials, are adopted. The main purpose of this study is to investigate the feasibility of the proposed grouted splice sleeve connection (GSSC) using sheet materials of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP). A total of 45 GSSC specimens with various rebar embedded lengths and different polymer sleeve materials were tested to failure under incremental axial pull-out load to evaluate the bond performance of the connected steel rebars in confined grout provided by the FRP sleeves. To evaluate the confinement effect of FRP sleeves on the tensile strength of the grouted connection, an analytical model was developed. The pull-out test results showed that the rebar embedded length was the major parameter affecting the average tensile strength of the GSSC. Also, the effects of mechanical properties of FRP sheets, such as the number of FRP layers and type of FRP sheets, contributed to the tensile strength of the GSSC sleeves that allow the transmission of tensile load between rebars through the medium of grout, aluminum tube, and FRP sheets. The analytical model that incorporates the confinement effects predicted well the experimental ultimate tensile strength of GSSC connections.

Monotonic and cyclic axial compressive responses of concrete specimens externally confined with different types of FRP composites: experimental and analytical investigations

The main objective of this study was to investigate the monotonic and cyclic axial stress versus strain response of the concrete confined with different types of fiber reinforced polymer (FRP) composites such as cotton fiber rope reinforced polymer (CFRRP), glass fiber reinforced polymer (GFRP) composites and carbon fiber reinforced polymer (CFRP) composites. Another objective was to investigate the applicability of existing ultimate strength models to predict the ultimate strength of concrete confined with CFRRP, GFRP and CFRP composites. For this, a total number of 28 concrete cylinders were cast, strengthened and tested under pure axial compression. The concrete cylinders were strengthened with two and four layers of FRPs. The experimental results indicate that all kinds of FRPs are very useful to alter the ultimate strength and strain of the confined concrete. The highest increase in ultimate strength was recorded for CFRP composite confined specimens and the highest increase in ultimate strain was observed for CFRRP composite confined specimens. Further, both ultimate strength and ultimate strains are found higher in the case of cyclic loads compared with the monotonic load. In general, the stress versus strain curves of cotton fiber rope and glass FRPs are found trilinear. Whereas, stress versus strain curves of CFRP confined specimens are observed to be bilinear. Existing ultimate strength models developed for CFRRP and CFRP composites are found well accurate to predict the ultimate strengths of CFRRP and CFRP confined concrete specimens tested in this study.

Influence of GFRP Confining Tube Parameters in Double-Skin Tubular Short Columns under Axial Loading

Abstract Composite construction with steel and concrete has become a widespread solution in modern construction practices because of its inherent properties such as high strength-to-weight ratio, good corrosion resistance, and high stiffness. Concrete-filled fiber-reinforced polymer (FRP) steel double-skin tubular compression members as vertical load–carrying members in buildings helps in optimizing the advantages of three materials: steel, concrete, and FRP. This study investigates the axial compressive behavior of short, concrete-filled glass fiber–reinforced polymer (GFRP) steel double-skin tubular (GSDST) columns and concrete-filled GFRP tubular (CFFT) columns. Parameters such as the number of FRP layers, hollow section ratio (HSR), variation of diameter of the inner steel tube, and the angle of orientation of the fibers have been examined in this investigation. The experimental study was carried out by performing a monotonic axial compressive loading condition. Three different angles of fiber orientation, 0° along the hoop direction, 45°, and 0°/90° with respect to the axis of the column, were adopted in this study. The ultimate load-carrying capacity, axial displacement, axial and horizontal strains, and failure modes were observed. The experimental results indicate that the structural performance of GSDST columns is significantly influenced by GFRP tube thickness, inner steel-tube diameter, and fiber-orientation angle. Maximum displacement was observed in the specimens with high HSR, thus showing a ductile characteristic in the axial load-displacement behavior. The load-carrying ability of the specimens decreased as the HSR increased. The load-carrying capacity of the specimens increased with the increase in outer GFRP tube thickness. This study demonstrates that GFRP tubes can be used efficiently in the construction field as vertical load–carrying components by enhancing the axial behavior of FRP steel double-skin tubular columns.

EXPERIMENTAL STUDY ON AXIAL STRENGTH AND PURE BENDING RESPONSE OF FWSCT-JACKETED SRC CIRCULAR COLUMNS

A novel composite shell system called FWSCT (FRP-wrapped steel corrugated tube) is composed of steel corrugated tube and fiber reinforced polymer (FRP). A series of experiments have been conducted to investigate the mechanical performance of FWSCT applied to steel-reinforced concrete (SRC) circular columns. This paper introduces the development of FWSCT, and the experimental programs on the FWSCT-jacketed SRC circular columns under uniaxial compression and pure bending. A total of 48 small-size FWSCT-jacketed SRC column cylinders were loaded axially, and the other five large-size circular column specimens were tested under four-point bending. Test parameters include the type of shaped steel, steel tube confinement, and the FWSCTs with various FRP layers and orientations. The experimental results were used to identify the mechanical contribution of various FWSCTs to the column strength and as the database for model development and numerical simulation for FWSCT-jacketed columns. Test results have validated the confinement effect and failure mechanism of the FWSCT applied on SRC columns.

Uniaxial compressive behaviour of a FRP standing support made of mine wastes

Twenty-seven specimens were tested to investigate the uniaxial compression behaviour of an innovative standing support for underground space applications. The innovative standing support consisted of an external fibre reinforced polymer (FRP) jacket and the infill column made of cementitious grout, tailings and coal wash rejects. Effects of the FRP layers number and water to the cementitious grout (w/g) ratio were evaluated. Test results indicated that lower w/g ratios produced stronger infill columns. With FRP confinement, the standing support demonstrated strain-hardening loading characteristics with a significant improvement in both strength and ductility. The highest strength and strain of the specimens achieved was 58.4 MPa and 11.8% respectively. Compared with the unconfined specimens, the confinement with four FRP layers increased the specimen strength and associated strain up to 3.6 and 27.0 times respectively. A correlation between the compressive strength of the infill material and the ultrasonic pulse velocity was also investigated. Furthermore, a simple design-oriented model was proposed to predict the peak strength and the corresponding strain of the innovative standing support.

Seismic behavior of RC square columns strengthened with LRS FRP under high axial load ratio

A new type of fiber-reinforced polymer (FRP) with a tensile rupture strain of more than 5% was used for the seismic retrofitting of reinforced concrete (RC) square columns in this paper. A control column and 9 FRP-wrapped RC square columns were prepared with different number of FRP layers and FRP types. The seismic performance was comprehensively discussed and analyzed in terms of the failure modes, hysteretic behaviors, cumulative energy dissipation and FRP strain evolution. Experimental results showed that the ductility of specimens had a remarkable improvement as the confinement stiffness increased. Moreover, the buckling of longitudinal bars was restricted and postponed. Numerical analysis was conducted in OpenSees to further research the seismic performance of specimens based on an LRS FRP-confined concrete model and a reinforcing bar buckling model considering FRP confining effect. The simulated results were in close agreement with the experimental results. Parametric analysis was also conducted to investigate the influence of the FRP wrapping thickness, axial compression ratio and longitudinal reinforcement ratio on the seismic performance.

Damage and restoration of historical urban walls: literature review and case of studies

Within this work, the causes of collapses and damages occurred in masonry artefacts have been evaluated to properly identify suitable monitoring and restoration methods. In this regard, a comprehensive literature review has been performed. Based on the results, the moisture has found to be a critical parameter, which affects the structural health of masonry artefacts. Diverse non-destructive methods were employed to measure the moisture and monitor the materials involved: the Infrared Thermography, the Electrical Resistivity Tomography and the Ground Penetrating Radar, the Laser Scanning and Digital Terrestrial Photogrammetry, the Global Navigation Satellite Systems, the Unilateral Nuclear Magnetic Resonance, the Laser-Induced Fluorescence technique, the Acoustic Imaging and the Acoustic Tomography, the Geographic Information System and on-site survey process as well as computer modeling of the structure with specific FEM software. Finally, the implementation of tie-beams, Fiber Reinforced Polymers layers, ventilation, draining systems, and high-quality materials are proposed as solutions for controlling the moisture effect and retrofitting.

Bio-based sandwich beams made of paper honeycomb cores and flax FRP facings: Flexural and shear characteristics

Sandwich composite panels have been used in construction as building envelopes and cladding systems. The sandwich composite used today are mainly made of conventional synthetic foam cores and synthetic fiber-reinforced polymer (FRP) facings, typically made of glass or carbon fibers and synthetic polymers. With increasing environmental consciousness, it is important to develop sustainable building materials to replace conventional building materials with more sustainable materials such as bio-based fibers and polymers. There is lack of studies on sandwich composites made of bio-based materials for both core and facings. In this study, 18 sandwich beam specimens (1200 mm long and 100 mm wide) made of flax FRP facings and 75 mm thick paper honeycomb core were fabricated and tested under three-point bending. The parameters of the tests were facing thickness (1, 2 and 3 layers of flax FRP) and core types (hollow and foam-filled). It was found that the paper honeycomb has comparable performance with lighter weight to other synthetic counterparts and foam-filling was effective in improving the performance of the core and sandwich beams. In addition, as the nonlinear behavior of the specimens was evident, a new analytical model was developed based on the material nonlinearity of both facings and core materials to predict the test data and perform a parametric study. Overall, the bio-based sandwich system showed substantial potential to be used for building applications with much less environmental footprints in comparison with other synthetic counterparts.

Machine learning models for predicting concrete beams shear strength externally bonded with FRP

This paper focuses on preparing a database that covers a wide range of experimental data encompassing all the variations in concrete design and fiber reinforced polymer (FRP) composition in reinforced concrete (RC) beams. Artificial intelligence technique is applied to develop 10 machine learning models for estimating the shear capacity of RC beams strengthened in shear using FRP. This study is unique in the sense that it covers the largest data regarding T-beams available in literature so far and is not limited to a particular beam cross section or FRP composition. A comparison among several design guidelines is done to evaluate the efficiency of the guidelines as well as the models developed in shear capacity estimation of FRP retrofitted RC beams. The results reveal that the ensemble learning models developed in this paper namely, random forest, CatBoost and XGBoost give the highest precision in estimating shear capacity of the FRP retrofitted RC beams. For rectangular beams the R2 and MAE values from CatBoost are 0.871 and 0.214 kN, respectively whereas those for XGBoost are 0.870 and 0.202 kN, respectively. The R2 and MAE values for T-beams using random forest are 0.897 and 0.128 kN, respectively and those using CatBoost are found to be 0.899 and 0.127 kN, respectively. The most significant input feature by Shapley Additive exPlanations is found to be the effective depth for the rectangular beams whereas height of FRP layers in the case of T-beams. The proposed ensemble models in this paper are proved to be superior to the existing mechanics-driven models currently being used for design practices.

Cyclically loaded elliptical FRP-confined concrete: Behavioral characteristics and modeling

The previous studies on elliptical concrete confined with fiber-reinforced polymer (FRP) are mainly concerned with their monotonic compressive responses. By contrast, no research has been focused on their performance under cyclic axial loading. Motivated by this research gap, the behavioral characteristics of cyclically compressed elliptical FRP-confined concrete (FCC) were investigated in this research. The experimental parameters included the aspect ratio varying between 1.0 (circular section), 1.3, 1.7 and 2.0, the number of FRP layers, and the loading pattern (monotonic loading or two schemes of cyclic loading). The results revealed that plastic strains and stress degradation in elliptical FCC were confinement-independent parameters, regardless of confinement efficiency (affected by sectional geometry) and confinement level (governed by FRP thickness). This was similar to the case of cyclically loaded rectangular FCC (characterized by depth-to-width ratio). Moreover, the mechanism of non-uniform hoop strain distribution was dominated by two aspects, namely curvature radius-induced varying confinement stiffness and concrete cracking-induced strain localization. In contrast, the cyclic loading had a marginal effect on this distribution. Based on the monotonic model (considered as envelope curve) for elliptical FCC and the hysteretic rules originally for circular FCC, the complete compressive behavior of cyclically loaded elliptical FCC could be modeled with favorable accuracy.

Nano filler incorporated epoxy based natural hybrid fiber confinement of concrete systems: Effect of fiber layers and nano filler addition

The utilization of environment friendly materials in the construction industry is essential for sustainable development. For the purpose of strengthening and retrofitting concrete structures, fiber reinforced polymer (FRP) composites have been predominantly used. In the area of structural strengthening, as an alternative to synthetic fiber reinforced composites, the application of natural fiber reinforced composites is of immense interest. This study discusses the mechanical properties of externally strengthened concrete cylinders using a natural hybrid fiber system with two layers of sisal fiber sheets followed by 1 to 3 layers of basalt fiber sheets. In addition, the effect of multi walled carbon nanotubes (MWCNT) incorporation in the epoxy matrix from 0.5 to 1.5 wt%, on the various properties are analyzed. The inclusion of MWCNT in the epoxy matrix improved the overall performance of the FRP significantly. The results show that there is substantial improvement in mechanical properties up to 1 wt% MWCNT content in composites, beyond which it is reduced due to agglomeration of nanofiller. The MWCNT incorporated epoxy based five layered hybrid sisal basalt FRP confined specimens showed an improvement of 114% and 427% in peak strength and strain values under axial compressive strength tests. Moreover, the axial compressive behavior, stress–strain response, energy absorption and ductility characteristics of the confined column specimens were evaluated. The major focus of the study is to assess the influence of basalt FRP layers on the ultimate load carrying capacity and performance of hybrid sisal basalt FRP (HSBFRP) confined specimens. Statistical analysis of variance (ANOVA) was carried out and revealed that the number of FRP layers and addition of MWCNT in epoxy significantly affect the overall performance. The addition of basalt fiber layers in hybrid sisal basalt FRP systems is found to improve the load carrying capacity and energy absorption characteristics of confined specimens. Therefore, HSBFRP confinement can be used in areas where moderate strength and greater ductility is commanded.