FRP-strengthened RC beams. I: review of debonding strength models

Shear capacity of FRP-strengthened RC beams: FRP debonding

This is a review of cement-matrix composites containing short carbon fibers. These composites exhibit attractive tensile and flexural properties, low drying shrinkage, high specific heat, low thermal conductivity, high electrical conductivity, high corrosion resistance and weak thermoelectric behavior. Moreover, they facilitate the cathodic protection of steel reinforcement in concrete, and have the ability to sense their own strain, damage and temperature. Fiber surface treatment can improve numerous properties of the composites. Conventional carbon fibers of diameter 15 μm are more effective than 0.1 μm diameter carbon filaments as a reinforcement, but are much less effective for radio wave reflection (EMI shielding). Carbon fiber composites are superior to steel fiber composites for strain sensing, but are inferior to steel fiber composites in the thermoelectric behavior.

Cement reinforced with short carbon fibers: a multifunctional material

The electrical applications of carbons and their composites are reviewed, with emphasis on applications that are relevant to industrial needs. The applications include electrical conduction, electrical contacts, electrodes, electromagnetic interference shielding, resistance heating, thermoelectricity, sensing, electrical switching, electronic devices and thermal pastes. The carbons include graphite, coke, carbon fibers, carbon filaments, carbon black and flexible graphite.

Electrical applications of carbon materials

Extensive research has been carried out in recent years on the use of fibre-reinforced polymer (FRP) composites in the strengthening of reinforced concrete (RC) structures. This paper provides a concise review of existing research on the behaviour and strength of FRP-strengthened RC structures, with a strong focus on those studies which contribute directly to the development of strength models. Topics covered include flexural and shear strengthening of beams, flexural strengthening of slabs, and strengthening of columns subject to both static and seismic loads. For each of the topics covered, the methods of strengthening are first explained, followed by a description of the common failure modes. Available strength models are then summarised and discussed.

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Behaviour and strength of FRP-strengthened RC structures: a state-of-the-art review

This paper presents the results of an experimental study on flexural behaviour of reinforced concrete (RC) beams strengthened with carbon fibre (CF)-reinforced plastic sheets. The CF sheets were bonded on the soffit of the beam using epoxy resin adhesive. Six medium-sized RC beams were tested in bending to evaluate reinforcing effects of the CF sheets. A large-sized RC beam which was initially crack-damaged by pre-loading and subsequently repaired by injection of epoxy resin was also tested to simulate the performance in real structures. The results indicated that the flexural rigidity and strength of the RC beams are increased by reinforcing with the CF sheets. Beneficial reinforcing effects were also observed for the crack-damaged RC beam.

Flexural behaviour of reinforced concrete beams strengthened with carbon fibre sheets

This paper presents the results of a study on shear reinforcement of reinforced concrete (RC) beams strengthened with carbon fiber (CF) reinforced plastics sheets. The CF sheets are externally bonded on both sides of the beam using epoxy resin adhesive. Six RC beam specimens are tested under antisymmetric bending load. Some specimens are crack-damaged by pre-loading, or crack-damaged and afterwards repaired by injecting epoxy resin into the cracked parts. A simple analysis of shear transfer in the strengthened beam is performed by using the truss model to evaluate shear-reinforcing effects of the CF sheet. The result indicates that the ultimate shear strength of the strengthened beam is about 1.3 to 1.8 times higher than that of the virgin beam, and the shear-reinforcing effect of the sheet can be fairly well predicted by the analysis using the truss model and the bond test results of concrete members strengthened with the CF sheets.

A study on shear reinforcement of reinforced concrete beams externally bonded with carbon fiber sheets

It is well known that the tensile strength of concrete is affected by the size of the test specimen; this is called the size effect The tensile and flexural strengths of carbon fibre-reinforced cement composite (CFRC) also exhibit the size effect, ie they decrease with increasing specimen size In this study, flexural tests of CFRC beams of various sizes were performed to investigate the size effect on the tensile and flexural characteristics of CFRC Flexural analysis of CFRC beams considering the size effect was also conducted From the test results, it is clear that the size effect becomes larger as the fibre length increases Reasonable agreement between experimental and analytical results was obtained for the load-displacement relationship of CFRC beams

Study on the size effect of tensile characteristics of carbon fibre-reinforced cement composites

PURPOSE:To rationalize the machining and assembling work, improve the workability of fiber-reinforcement concrete and improve the quality of PC panel by uniting a reinforcement. CONSTITUTION:A mesh reinforcement 3 is arranged on a bed 1 in a circumferential formwork. A cage type reinforcement 4 is arranged in an X-directional rib part in the self-standing state. The cage type reinforcement 4 is formed as a unit reinforcement in which a lower end reinforcing bar 4a having two round steels arranged in parallel to each other and an upper end main reinforcement 4b having two round steels arranged in parallel to each other are integrally welded and assembled by a plurality of reinforcing bars 44c formed by bending round steels in U-shape. A ladder type reinforcement 5 is arranged in a Y-directional rib part. The ladder type reinforcement 5 is arranged in the state superposed on the cage type reinforcement 4 in grade separation form. The ladder type reinforcement 5 is formed as a unit reinforcement in which reinforcing bars 5b are orthogonally arranged on two parallel main reinforcements 5a at proper intervals, integrally welded and assembled thereto.

Unit reinforcement for pc panel with rib and its arrangement thereof

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Hiromichi Sakai

Papers

Flexural behaviour of reinforced concrete beams strengthened with carbon fibre sheets

A study on shear reinforcement of reinforced concrete beams externally bonded with carbon fiber sheets

Study on the size effect of tensile characteristics of carbon fibre-reinforced cement composites

Unit reinforcement for pc panel with rib and its arrangement thereof

Experimental study on mix proportion and mechanical characteristics of carbon fiber reinforced concrete including coarse aggregate