scholarly journals EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF THE EFFECT OF FIBRE REINFORCED POLYMER ON THE SHEAR STRENGTH OF REINFORCED CONCRETE BEAMS

2020 ◽  
Vol 4 (3) ◽  
pp. 60-71
Author(s):  
Nurudeen Yusuf ◽  
J. M. KAURA ◽  
A. Ocholi ◽  
M. Abbas ◽  
A. Mohammed
Keyword(s):  
Shear Strength ◽  
Carbon Fibre ◽  
Experimental Results ◽  
Rc Beams ◽  
Cfrp Laminate ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Analytical Results ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper presents the experimental and analytical results of the contribution of carbon fibre reinforced polymer (CFRP) laminates to the shear strength of RC beams. To assess the efficiency of the carbon fibre reinforced polymer (CFRP)  laminates on the strengthened specimens, twelve identical beams of cross-sectional dimensions 150x150x750mm were cast, out of which three are un-strengthened and nine were strengthened with U-wrap strips at 100 mm away from each support at varying CFRP laminates layers of  single, double and triple amounts. The prepared specimens were subjected to a three-point bending test. The results obtained revealed that the CFRP laminate increased the shear strength of the strengthened specimens over the control (un-strengthened) by 35.06%, 54.40% and 69.30% for single, double and triple layers of CFRP laminate respectively. The experimental results was also compared with the analytical results obtained based on the equation proposed by Khalifa et al., 1998. The analytical results obtained from the equation closely agreed with the experimental results. Therefore, it implies that the CFRP has the potentials of strengthening shear defiant RC beams.

Experimental and numerical study on the effect of repairing reinforced concrete cracked beams strengthened with carbon fibre reinforced polymer laminates

2014 ◽  
Vol 41 (3) ◽  
pp. 222-231 ◽  
Author(s):  
P. Duarte ◽  
J.R. Correia ◽  
J.G. Ferreira ◽  
F. Nunes ◽  
M.R.T. Arruda
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Fracture Energy ◽  
Numerical Study ◽  
Structural Response ◽  
Rc Beams ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper presents experimental and numerical investigations on the effect of repairing cracks in reinforced concrete (RC) beams prior to strengthening them with carbon fibre reinforced polymer (CFRP) laminates. The experimental campaign comprised flexural tests on three types of full-scale RC beams with T-shaped cross-section: (i) two reference un-strengthened beams, (ii) two CFRP-strengthened beams previously loaded and cracked, and (iii) two CFRP-strengthened beams, previously loaded, cracked and repaired with epoxy resin. The repair and strengthening techniques consisted of respectively injecting the cracks with epoxy resin and applying CFRP laminates according to the externally bonding reinforcement technique. In the numerical study, the structural response of all beams tested was simulated using the finite element software Atena, which features a smeared cracked model constitutive relationship for concrete. A parametric study was carried out in which the influence of material parameters, namely the fracture energy, on the beams structural response was assessed. Experimental results showed that repairing cracks by means of epoxy injection before strengthening them with CFRP laminates provided a considerable increase of stiffness, but only a slight increase of ultimate strength, as failure was triggered by the debonding of the strengthening system at the anchorage zones. In the numerical study a very good agreement with experimental data was obtained. For the repaired and strengthened beams, such agreement was obtained by increasing concrete’s fracture energy when compared to that of the reference beams.

Behaviour of reinforced concrete beams strengthened with carbon fibre reinforced polymer laminates subjected to corrosion damage

2000 ◽  
Vol 27 (5) ◽  
pp. 1005-1010 ◽  
Author(s):  
Khaled A Soudki ◽  
Ted G Sherwood
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Beams ◽  
Corrosion Damage ◽  
Corrosion Process ◽  
Reinforced Concrete Beams ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

The viability of carbon fibre reinforced polymer (CFRP) laminates for the strengthening of corrosion damaged reinforced concrete bridge girders is addressed in this paper. Ten reinforced concrete beams (100 × 150 × 1200 mm) with variable chloride levels (0-3%) were constructed. Six beams were strengthened by externally epoxy bonding CFRP laminates to the concrete surface. The tensile reinforcements of three unstrengthened and four strengthened specimens were subjected to accelerated corrosion by means of impressed current to 5, 10, and 15% mass loss. Strain gauges were placed on the CFRP laminates to monitor and quantify tensile strains induced by the corrosion process. Following the corrosion phase, the specimens were tested in flexure in a four-point bending regime. Test results revealed that CFRP laminates successfully confined the corrosion cracking, and the total expansion of the laminate exhibited an exponential increase throughout the corrosion process. All the strengthened beams exhibited increased stiffness over the unstrengthened specimens and marked increases in the yield and ultimate strength. The CFRP strengthening scheme was able to restore the capacity of corrosion damaged concrete beams up to 15% mass loss.Key words: CFRP laminates, corrosion, confinement, expansion, load tests, strengthening, bond strength, reinforced concrete.

Impact resonance method for fatigue damage detection in reinforced concrete beams with carbon fibre reinforced polymer

2005 ◽  
Vol 32 (6) ◽  
pp. 1093-1102 ◽  
Author(s):  
Catalin Gheorghiu ◽  
Jamal Eddine Rhazi ◽  
Pierre Labossière
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Fatigue Damage ◽  
Concrete Beams ◽  
Resonance Method ◽  
Rc Beams ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Impact Resonance

This paper reports on the potential of using the impact resonance method (IRM) for detecting fatigue damage in strengthened reinforced concrete (RC) beams. In this experimental program, 1.2 m long RC beams strengthened with a carbon fibre reinforced polymer (CFRP) plate have been employed. The specimens were subjected to fatigue loading under four-point bending for up to 2 × 106 cycles at 3 Hz. The load amplitude was varying from 15% to 75% of the cycles yielding load of the beam. Throughout fatigue testing, the cycling was stopped for IRM measurements to be taken. The obtained data provided information about changes in modal properties, such as, fundamental frequencies and damping ratios. Moreover, the results have shown that the IRM technique was successfully employed in laboratory for detecting fatigue damage in concrete beams strengthened with CFRP laminates.Key words: impact resonance method, modal properties, RC beam, FRP-strengthening, fatigue test, cracking.

Shear behavior of reinforced concrete beams strengthened in flexure with bonded carbon fibre reinforced polymers laminates

2005 ◽  
Vol 32 (5) ◽  
pp. 812-824 ◽  
Author(s):  
Francesco Bencardino ◽  
Vincenzo Colotti ◽  
Giuseppe Spadea ◽  
Ramnath Narayan Swamy
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Shear Behavior ◽  
Structural Performance ◽  
Rc Beams ◽  
Shear Reinforcement ◽  
Brittle Behavior ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

The aim of this paper is to clarify the structural performance of reinforced concrete (RC) beams with weak or without any internal shear reinforcement and externally strengthened in flexure with carbon fibre reinforced polymer (CFRP) laminates, when subjected to a shear-dominant-loading regime. Seven RC beams were specifically designed, without and with an external anchorage system, which was carefully detailed to enhance the benefits of the strengthening laminate and counteract the destructive effects of shear forces. All the beams were identical in terms of their geometry, longitudinal internal reinforcement, and concrete strength but varied, to highlight the role of shear behavior, in terms of their internal and external shear reinforcement as well as in their loading test regime. The beams were tested under four-point bending and extensively instrumented to monitor strains, deflection, cracking, load carrying capacity, and failure modes. The structural response of the tested beams has, then, been critically analyzed in terms of deformability, strength, and failure processes that occur under a shear-dominant loading regime. It is shown that with a carefully designed anchorage system, a brittle behavior without yielding of tension steel reinforcement of a flexural strengthened beam can be transformed to a less brittle behavior with yielding of tension steel reinforcement and a well-defined enhancement of structural performance in terms of both deformation and strength. The results presented in this paper should enable engineers to counteract shear failure of externally strengthened beams with little or even no internal shear reinforcement.Key words: carbon fibre reinforced polymer, shear behavior, external flexural strengthening, structural performance.

Impact resonance method for damage detection in carbon-fibre-reinforced polymer–strengthened reinforced concrete beams subjected to fatigue and thermal cycling

2008 ◽  
Vol 35 (11) ◽  
pp. 1251-1260 ◽  
Author(s):  
C. Ward ◽  
N. Rattanawangcharoen ◽  
C. Gheorghiu
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Resonance Method ◽  
Experimental Program ◽  
Rc Beams ◽  
Structural Health ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Impact Resonance

Much of North America’s civil infrastructure is rapidly aging and, in some cases, exceeding its design life and load. To combat this, the exploration of simple and effective methods for rehabilitation and structural health monitoring has been receiving much attention in industry and academia. This paper reports on the use of the impact resonance method (IRM) for evaluating the structural health of thermal-cycled reinforced concrete (RC) beams with and without externally strengthened carbon-fibre-reinforced polymer (CFRP) pultruded plates. In the experimental program, 1.2 m long specimens were subjected to 55 thermal cycles ranging from +23 to −18 °C. Fatigue loading consisting of up to two million cycles at high and low stress levels was performed. At pre-determined load cycle intervals, the loading was stopped and the IRM was performed on the specimens. Parameters including the appearance of the fast Fourier transform (FFT) spectrum of the specimens’ vibration, modal fundamental frequencies, and dynamic properties were used to assess damage in the specimen. Conclusions were made regarding the use of the IRM in monitoring the health of strengthened and unstrengthened RC beams subjected to thermal and fatigue cycles.

scholarly journals Experimental Studies on Cohesion of Carbon Fibre Reinforced Polymer for Reinforcement of Bridge Deck Slabs

2016 ◽  
Vol 10 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Tian Shuai ◽  
Yu Tianlai ◽  
Zhao Yunpeng ◽  
Guo Weimin ◽  
Li Haisheng
Keyword(s):  
Shear Strength ◽  
Carbon Fibre ◽  
Bridge Deck ◽  
Experimental Studies ◽  
Construction Technique ◽  
Reinforced Polymer ◽  
Deck Slabs ◽  
Carbon Fibre Reinforced Polymer ◽  
Bridge Deck Slabs ◽  
Fibre Reinforced Polymer

Bridge deck slabs reinforced by carbon fibre reinforced polymer (CFRP) are subjected to a number of problems related to cohesion, such as slippage, disengaging, and debonding. In order to address such problems, we conducted indoor shear, stretching, and debonding tests, analysed the change rule of cohesion in these three different environments, and determined the optimum construction technique for improving the cohesion of CFRP. We found that to obtain acceptable shear strength, manufactured sand should be spread on the surface of the impregnating resin adhesive. Soaking, freeze thawing, and wheel grinding processes affected the tensile strength of the interface, which was related linearly to the shear strength of the interface. Following wheel grinding on an asphalt surface at high temperatures, the test value for the bearing-debonding capacity on a test slab was unchanged, and the effectiveness of the CFRP was still apparent. The influence of high-temperature wheel grinding can be ignored. This study can serve as a reference for the design of reinforced bridge deck slabs.

scholarly journals Durability of Epoxy Adhesives and Carbon Fibre Reinforced Polymer Laminates Used in Strengthening Systems: Accelerated Ageing versus Natural Ageing

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1533
Author(s):  
Ricardo Cruz ◽  
Luís Correia ◽  
Aloys Dushimimana ◽  
Susana Cabral-Fonseca ◽  
José Sena-Cruz
Keyword(s):  
Carbon Fibre ◽  
Outdoor Environment ◽  
Experimental Program ◽  
Accelerated Ageing ◽  
Natural Ageing ◽  
Cfrp Laminates ◽  
Epoxy Adhesives ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This work addresses the durability of structural epoxy adhesives and carbon fibre reinforced polymer (CFRP) laminates typically used in strengthening of existing reinforced concrete structures exposed to natural ageing. The experimental program included four natural (real) outdoor environments inducing ageing mainly caused by carbonation, freeze-thaw attack, elevated temperatures, and airborne chlorides from seawater. Moreover, a control (reference) environment (20 °C of temperature and 55% of relative humidity) and an environment involving water immersion of the materials under controlled temperature (20 °C of temperature) were also included in this investigation. The characterization involved the assessment of the physical, chemical and mechanical properties along a study period of up to two years. Furthermore, comparisons between the natural ageing tests developed in the scope of the present work and accelerated ageing tests existing in the literature were performed. Regarding to the epoxy adhesives, an increase in the glass transition temperature with the time was observed, while the tensile properties decreased, regardless of the outdoor environment. The CFRP laminates were marginally affected by the studied environments. Despite the remarkable dispersion of the results observed in the accelerated ageing tests for the period investigated, this testing protocol yielded higher mechanical degradation than under natural ageing.

Experimental study of the strength and deformations of carbon fibre reinforced polymer (CFRP) retrofitted reinforced concrete slabs under blast loadThis article is one of a selection of papers published in the Special Issue on Blast Engineering.

2009 ◽  
Vol 36 (8) ◽  
pp. 1366-1377 ◽  
Author(s):  
A. Ghani Razaqpur ◽  
Ettore Contestabile ◽  
Ahmed Tolba
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Slabs ◽  
Cfrp Laminates ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Blast Response ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Complete Failure

The blast response and ultimate resistance of reinforced concrete slabs externally strengthened with carbon fibre reinforced polymer (CFRP) laminates were investigated. Five square slab specimens, 1 m on a side, were retrofitted with 500 mm wide CFRP laminates bonded to their top and bottom surfaces. Another four nominally identical unretrofitted slabs were used as control specimens. Four of the retrofitted and the four control slabs were first subjected to the detonation of either 22.4 or 33.4 kg of explosive at a stand-off distance of 3.0 m. For reference, the fifth retrofitted slab was only statically tested to failure. Blast pressures and impulses and slab deformations were measured. After exposure to the blast, the slabs that were not completely damaged were statically tested to failure. Overall the retrofitted slabs performed better than the control slabs, but one retrofitted slab completely failed under the blast load while none of the control slabs experienced complete failure under similar load.

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