Bonded Carbon Fiber-reinforced Polymer Plates Research Articles

Experimental Investigation of Lap Splices in Externally Bonded Carbon Fiber-Reinforced Plastic Plates

This paper identifies a primary mode of failure of lap splices in externally bonded carbon fiber-reinforced polymer (CFRP) tension reinforcement. Results of small-scale tension tests are compared to large-scale beam tests. The small-scale tension tests show promise as a means of identifying a combination of adhesive and splice plate material that will optimize splice performance.

Prediction of premature separation of bonded CFRP plates from strengthened steel beams using a fracture criterion

This paper presents a method for predicting premature separation of carbon fiber reinforced plastic (CFRP) plates from strengthened steel beams. The fracture criterion based on material-induced singularity is formulated in terms of a singular intensity factor. Static test on double strap joints was selected to provide the critical stress intensity factor in the criterion because good degree of accuracy and consistency of experimental data can be expected compared with the unsymmetrically loaded single lap joints. The debond/separation loads of steel beams with different CFRP lengths were measured and compared with those predicted from the criterion. Good agreement between the test results and the prediction was found.

Flexural Strengthening of Four 76-Year-Old T-Beams with Various Fiber-Reinforced Polymer Systems: Testing and Analysis

This study was conducted to examine the performance of four 76-year-old, deteriorated RC beams retrofitted with external carbon fiber-reinforced polymer (CFRP) post-tensioning rods, bonded CFRP plates, bonded CFRP fabrics, and bonded CFRP plates with mechanical anchors, respectively. The various FRP systems studied produced different failure modes and strength gains. In spite of the extensive deterioration and age of the beams, the retrofitted beams could develop and exceed the expected capacity computed based on available design guideliness. For cases where guidelines were unavailable, simple, yet effective, methods were developed to establish the capacity of the retrofitted beams.

Strength and Ductility of RC Beams Repaired with Bonded CFRP Laminates

The objective of this study is to investigate the strength and ductility aspects of reinforced concrete (RC) beams strengthened with an externally bonded carbon fiber reinforced polymer (CFRP) laminate and to examine how such retrofitting affects strength, deflection, curvature, and energy, as exemplified by the area under the load-deflection curve of the strengthened composite beam. Three series of tests on eleven RC beams were carried out and their ultimate load capacities and ductilities evaluated. The variables in the experimental program were longitudinal steel ratio, volume of internal stirrups, and the location and configuration of external anchorages. The results show that both deflection and energy absorption are drastically reduced when beams are strengthened with bonded CFRP plates without external anchorages. Suitably designed and positioned external anchorages allow much of this lost ductility to be regained; however, even then the ductility of the strengthened beam cannot be restored to its original level. It is shown that definitions of ductility based on deflection and energy are able to give a good and rational representation of the physical aspects of ductility of RC beams strengthened with bonded CFRP laminates with or without external anchorages. The results show that the effects on ductility arising from strengthening existing RC beams with CFRP laminates cannot be ignored, even if it is not clear at this stage how to apply the concept of ductility indices and ductility ratios developed in this paper in design practice.

Fatigue Performance of Concrete Beams Strengthened with CFRP Plates

Recent increases in bridge design loading requirements have highlighted the need for fast, efficient, and durable strengthening methods. External steel plate bonding provides a satisfactory solution, but carbon fiber reinforced plastic (CFRP) offers the added advantages of resistance to corrosion, low weight, and high mechanical strength. This paper examines the fatigue performance of CFRP-strengthened concrete beams as part of a project investigating the use of CFRP as an alternative to steel. Five reinforced concrete beams were tested in fatigue; two control beams and three strengthened with externally bonded CFRP plates. Three loading options were used: (1) apply the same loads to both plated and unplated beams, (2) apply loads to give the same stress range in the rebar in both beams, and (3) apply the same percentage of the ultimate load capacity to each beam. Fatigue fracture of the internal reinforcement steel would appear to be the dominant factor governing failure, and it would appear reasonable to expect the same fatigue life for plated and unplated beams with comparable values of stress range in the steel bar.

Fatigue Performance of Concrete Beams Strengthened with CFRP Plates

Recent increases in bridge design loading requirements have highlighted the need for fast, efficient, and durable strengthening methods. External steel plate bonding provides a satisfactory solution, but carbon fiber reinforced plastic (CFRP) offers the added advantages of resistance to corrosion, low weight, and high mechanical strength. This paper examines the fatigue performance of CFRP-strengthened concrete beams as part of a project investigating the use of CFRP as an alternative to steel. Five reinforced concrete beams were tested in fatigue: two control beams and three strengthened with externally bonded CFRP plates. Three loading options were used: (1) apply the same loads to both plated and unplated beams, (2) apply loads to give the same stress range in the rebar in both beams, and (3) apply the same percentage of the ultimate load capacity to each beam. Fatigue fracture of the internal reinforcement steel would appear to be the dominant factor governing failure, and it would appear reasonable to expect the same fatigue life for plated and unplated beams with comparable values of stress range in the steel bar.

Structural Behavior of Composite RC Beams with Externally Bonded CFRP

The overall objective of this paper is to establish the structural behavior of reinforced concrete (RC) beams strengthened with externally bonded carbon-fiber-reinforced plastic (CFRP) sheets. Four beams, three with bonded CFRP plates on the tension face, and two of which were provided with carefully designed external anchorages at the ends of the plates and along the span, were tested under four-point bending over a span of 4.8 m. The tests were carried out under displacement control. The beams were extensively instrumented to monitor strains, deflection, and curvature over the entire spectrum of loading to total failure, and to determine the structural response to load of the composite beams. The results show that bonding a CFRP plate on the tension face of a RC beam, without consideration of the end-anchorage stresses and the bond slip between the plate and the concrete substrate, can lead to significant degradation in the structural response of the plated beam. Carefully designed external anchorages, ...