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This paper presents an overview and discusses the applications of fibre reinforced polymer (FRP) bars as reinforcement in civil engineering structures. Following a discussion of the science underpinning their use, selected case studies where FRP reinforcement has been used are presented. The use of FRP reinforcement is rapidly gaining pace and may replace the traditional steel due to its enhanced properties and cost‐effectiveness. In addition, FRP reinforcement offers an effective solution to the problem of steel durability in aggressive environments and where the magnetic or electrical properties of steel are undesirable.

This study aims to conduct an experimental study and finite element model (FEM) to investigate the flexural behavior of heat-damaged beams strengthened/repaired by hybrid fiber-reinforced polymers (HFRP).

Two groups of beams of (150 × 250 × 1,200) mm were cast, strengthened and repaired using different configurations of HFRP and tested under four-point loadings. The first group was kept at room temperature, while the second group was exposed to a temperature of 400°C.

It was found that using multiple layers of carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) enhanced the strength more than a single layer. Also, the order of two layers of FRP showed no effect on flexural behavior of beams. Using a three-layer scheme (attaching the GFRP first and followed by two layers of CFRP) exhibited increase in ultimate load more than the scheme attached by CFRP first. Furthermore, the scheme HGC (heated beam repaired with glass and carbon, in sequence) allowed to achieve residual flexural capacity of specimen exposed to 400°C. Typical flexural failure was observed in control and heat-damaged beams, whereas the strengthened/repaired beams failed by cover separation and FRP debonding, however, specimen repaired with two layers of GFRP failed by FRP rupture. The FEM results showed good agreement with experimental results.

Few researchers have studied the effects of HFRP on strengthening and repair of heated, damaged reinforced concrete (RC) beams. This paper investigates, both experimentally and analytically, the performance of externally strengthened and repaired RC beams, in flexure, with different FRP configurations of CFRP and GFRP.

Covering a fiber-reinforced concrete column (fiber reinforced plastic (FRP)) improves the performance of the column primarily. The purpose of this paper is to investigate the behavior of small FRP concrete columns that are subject to axial pressure loading, in order to study the effect of many parameters on the effectiveness of FRP couplings on circular and square concrete columns.

These parameters include the shape of the browser (circular and square), whole core and cavity, square radius of square columns, concrete strength (low strength, normal and high), type of FRP (carbon and glass) and number of FRP (1–3) layers. The effective fibrillation failure strain was investigated and the effect of effective lateral occlusion pressure.

The results of the test showed that the FRP-coated columns improved significantly the final conditions of both the circular and square samples compared to the unrestricted columns; however, improvement of square samples was not as prominent as improvement in circular samples. The results indicated that many parameters significantly affected the behavior of FRP-confined columns. A new model for predicting compressive force and the corresponding strain of FRP is presented. A good relationship is obtained between the proposed equations and the current experimental results.

The average hoop strain in FRP wraps at rupture in FRP-confined concrete specimens can be much lower than that given by tensile coupon tests, meaning the theoretical assumption that the FRP-confined concrete cylinder ruptures when the FRP material tensile strength attained at its maximum is not suitable. Based on this observation, the effective peak strength and corresponding strain formula for FRP concrete confined columns must be based on the effective hoop rupture strain composite materials.

Fibre reinforced polymer (FRP) bars are made of innovative materials and establishment of the fire resistance of FRP reinforced concrete (RC) is necessary for their widespread application. Experimental behaviours of Carbon FRP (CFRP) and Glass FRP (GFRP) bar RC beams at elevated temperatures have been investigated in this paper. Data are presented from fire tests of six simply supported beams that were fabricated using normal-weight concrete. The effects of varying load levels and FRP bar type were studied. The beams were designed over-reinforced and were tested in a floor furnace. A steel bar reinforced beam was used as control specimen. A rebar temperature of 500°C was selected as failure criterion for the beam. Non-linear temperature distribution across the beam cross section was observed. Temperature rise in the compression concrete was found insignificant and its mechanical properties were nearly unaffected. All beams met the failure criterion of critical rebar temperature of 500°C. The stiffness reduction in the GFRP and steel RC beams was nearly the same at elevated temperatures and was independent of load levels and/or bar modulus. The CFRP bar reinforced beams showed better stiffness characteristics compared to other beams.

This study aims to use carbon fiber-reinforced polymer (CFRP) laminates to strengthen the compression flange of structural I-beam so as to avoid local failure of compression flange and to take a load to its full capacity. Light weight beam (LB) 100 at 5.1 kg/m and LB 115 at 8.1 kg/m are used for this purpose. The compression flange of a beam is well prepared to ensure a rust-free surface so as to achieve proper bonding between the flange and fiber sheet to avoid de-bonding at the time of testing. A flange of the beam is strengthened using CFRP sheets applied to it with the help of adhesive. The beam with CFRP is cured in air for 48 h before testing. Experiments are performed in a loading frame of 100 T capacity. Results show that the load carrying capacity of the strengthened beam increased by 25-30 per cent compared to the control beam (non-strengthened), and the local failure of the compression flange due to the applied load is totally avoided. The elastic behavior of the strengthened beam is also increased compared to the non-strengthened beam, which gives a higher yield point.

Different methods exist for strengthening various structures. Use of CFRP appears to be an excellent solution. Vast research has been conducted on the use of CFRP for strengthening and retrofitting of steel structures. The load carrying capacities of steel beams can be increased by strengthening their compression flange by using CFRP and avoiding the local failure of beams at early stages.

The load carrying capacity of a beam strengthened with CFRP increased by 25-30 per cent compared to the non-strengthened beam. In addition, the elastic behavior of the strengthened beam is also improved.

The compression flange of the steel beam is strengthened using different layers of CFRP strips to avoid the local failure, and its deflection is observed using linear variable deformation transducer.

Composite materials are effective alternatives for rehabilitating critical members of offshore platforms, bridges, and other structures. The structural response of composite reinforcement greatly depends on the orientation of fibres in the composite material. Joints are the most critical part of tubular structures. Various existing studies have identified optimal reinforcement orientations for a single load component, but none has addressed the combined load case, even though most practical loads are multiplanar.

This study investigates the optimal orientation of composite reinforcement for reducing stress concentration factors (SCF) of tubular KT-joints. The joint reinforcement was modelled and simulated using ANSYS. A parametric study was carried out to determine the effect of the orientations of reinforcement in the interface region on SCF at every 15° offset along the weld toe using linear extrapolation of principal stresses. The impact of orientation for uniplanar and multiplanar loads was investigated, and a general result about optimum orientation was inferred.

It was found that the maximum decrease of SCF is achieved by orienting the fibres of composite reinforcement along the maximum SCF. Notably, the optimal direction for any load configuration was consistently orthogonal to the weld toe of the chord-brace interface. As such, unidirectional composites wrapped around the brace axis, covering both sides of the brace-chord interface, are most effective for SCF reduction.

The findings of this study are crucial for adequate reinforcement of tubular joints using composites, offering a broader and universally applicable optimum orientation that transcends specific joint and load configuration.

Presents an overview and discusses the applications of fibre reinforced polymer (FRP) sheets and plates in the strengthening of concrete structures. An insight may be obtained from the discussions made to enhance the use of these techniques for productive use. In addition, selected case studies have been furnished where FRP materials have been used for repairing/retrofitting, emphasizing the application of different types of FRP materials in strengthening concrete structures. Concludes that the use of FRP material is rapidly gaining pace and replacing the traditional steel or metal based materials due to its enhanced properties and cost effectiveness.

Advanced fibre-reinforced polymer (FRP) composites have been increasingly used over the past two decades for strengthening, upgrading and restoring degraded civil engineering infrastructure. Substantial experimental investigations have been conducted in recent years to understand the compressive behaviour of FRP-confined concrete columns. A considerable number of confinement models to predict the compressive behaviour of FRP-strengthened concrete columns have been developed from the results of these experimental investigations. The purpose of this paper is to present a comprehensive review of experimental investigations and theoretical models of circular and non-circular concrete columns confined with FRP reinforcement.

The paper reviews previous experimental test results on circular and non-circular concrete columns confined with FRP reinforcement under concentric and eccentric loading conditions and highlights the behaviour and mechanics of FRP confinement in these columns. The paper also reviews existing confinement models for concrete columns confined with FRP composites in both circular and non-circular sections.

This paper demonstrates that the performance and effectiveness of FRP confinement in concrete columns have been extensively investigated and proven effective in enhancing the structural performance and ductility of strengthened columns. The strength and ductility enhancement depend on the number of FRP layers, concrete compressive strength, corner radius for non-circular columns and intensity of load eccentricity for eccentrically loaded columns. The impact of existing theoretical models and directions for future research are also presented.

Potential researchers will gain insight into existing experimental and theoretical studies and future research directions.

In this paper a model for the prediction of the failure strain of fiber reinforced polymer (FRP) sheets is proposed, based on a significant database consisting of results reported in the literature for concrete columns with circular cross-section confined with carbon, glass and aramid fiber reinforced polymers. This study aims to analyze the aforementioned model.

Significant experimental research on the confinement of columns externally wrapped with FRP has been carried out in the last decades. Several models of confined concrete have been proposed using different approaches for the prediction of the failure strain of FRP sheets. The majority of those proposals were developed to be simple, thus significant differences with experimental results can be found.

The results of a total of 572 specimens were considered. Statistical analysis was used to derive a regression model, which relates the outcome to a set of predictors of interest using linear assumptions.

The proposed model is shown to be more accurate than other proposals found in the literature.

Confidence in the use of Fiber Reinforced Polymer (FRP) for Reinforced Concrete (RC) members in multi-story buildings, parking garages, and industrial structures is poor due to lack of provisions and calculation models taking account of fire condition. In the past, to contribute to refining existing codes for the design of FRP-RC structures, authors tested six concrete slabs reinforced with Glass FRP (GFRP) bars characterized by different values of concrete cover and anchoring length in fire condition. Recently, further three fire tests were carried out on concrete slabs reinforced with GFRP bars bent at the ends. The anchoring of the FRP bars in the zone of slab not directly exposed to fire at the end of the members revealed essential to ensures slab resistance, once in the fire exposed zone of slab the glass transition temperature was attained and the resin softening reduced the adhesion at the FRP-concrete interface.