scholarly journals Behaviour of Eccentric Concrete Columns Reinforced with Carbon Fibre-Reinforced Polymer Bars

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zrar Sedeeq Othman ◽  
Ahmed Heidayet Mohammad
Keyword(s):  
Carbon Fibre ◽  
Concrete Columns ◽  
Theoretical Models ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Conventional Steel ◽  
Reinforced Polymer ◽  
Steel Bars ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

The use of steel bars as reinforcement is not preferred in some concrete structures because steel causes corrosion or electric magnetic field problems. One of the best alternatives to steel bars is carbon fibre-reinforced polymer (CFRP) bars. The experimental program consisted of 18 reinforced rectangular concrete columns under different eccentric loadings. Out of the 18 columns, 15 were reinforced with CFRP longitudinal rebars and ties and 3 were reinforced with conventional steel rebars and ties as reference columns. The following parameters were included in this study: the replacement of steel with CFRP bars, eccentricity of load, longitudinal reinforcement ratios, and tie spacing. Test results in terms of load-strain, load-mid height deflection curves, and crack patterns showed that the column reinforced with CFRP bars behaved similarly to the concrete column reinforced with conventional steel bars with a slight difference in axial and flexural capacity. The increment in CFRP longitudinal reinforcement ratios from 1.4% to 2.0% and 3.6% reasonably increased the maximum carrying capacity for different eccentricities used herein. The axial ratios of experimental to theoretical results (PExp./PTheor.) were determined for specimens in the present work and those from previous studies to assess the efficiency of the theoretical models.

scholarly journals Behaviour of carbon fibre–reinforced polymer-confined hollow circular concrete columns with inner polyvinyl chloride tube

2018 ◽  
Vol 21 (8) ◽  
pp. 1120-1133
Author(s):  
Hussam A Goaiz ◽  
Tao Yu ◽  
Muhammad NS Hadi
Keyword(s):  
Polyvinyl Chloride ◽  
Concrete Columns ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Test Results ◽  
Reinforced Polymer ◽  
Inner Surface ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Strength And Ductility

Existing studies have shown that the use of an inner tube can significantly enhance the effectiveness of confinement in fibre-reinforced polymer-confined hollow columns. The inner tube used in the existing studies, however, generally had a large stiffness and also served as longitudinal reinforcement. The use of a stiff inner tube is inefficient in resisting bending for hollow columns with a relatively small void and may be unnecessary for constraining the inner surface of concrete. Against this background, this article presents the first experimental study on fibre-reinforced polymer-confined hollow columns with an inner polyvinyl chloride tube. The experimental program included a total of 18 specimens which were tested under axial compression. The test variables included the section configuration (i.e. solid specimens, hollow specimens and hollow specimens with a polyvinyl chloride tube) and the thickness of fibre-reinforced polymer. The test results showed that due to the beneficial effect of the polyvinyl chloride tube which provided constraints/confinement from inside, fibre-reinforced polymer-confined hollow columns with an inner polyvinyl chloride tube generally possessed good strength and ductility compared to their counterparts without a polyvinyl chloride tube.

Fatigue behaviour of cracked steel beams retrofitted with carbon fibre–reinforced polymer laminates

2017 ◽  
Vol 21 (8) ◽  
pp. 1148-1161 ◽  
Author(s):  
Qian-Qian Yu ◽  
Yu-Fei Wu
Keyword(s):  
Carbon Fibre ◽  
Fatigue Behaviour ◽  
Interfacial Debonding ◽  
Experimental Program ◽  
Steel Beams ◽  
Special Focus ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Polymer Laminates

In recent years, externally bonded carbon fibre–reinforced polymer has been considered an innovative way to strengthen steel structures attributed to its high strength-to-weight ratio, excellent corrosion resistance and fatigue performance. This article presents an experimental and numerical study on the fatigue behaviour of defected steel beams strengthened with carbon fibre–reinforced polymer laminates, with a special focus on the effect of interfacial debonding. Analytical modelling and numerical simulation confirmed that the interfacial debonding had a pronounced effect on carbon fibre–reinforced polymer strain and stress intensity factor at the crack front. After introducing interfacial debonding from experimental findings into the numerical analysis, the fatigue life and crack propagation versus cycle numbers of the specimens compared well with the test results. Based on the current experimental program, specimens with Sikadur 30 were more prone to debonding failure; therefore, Araldite 420 is suggested for strengthening schemes.

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.

Accelerated corrosion and repair of reinforced concrete columns using carbon fibre reinforced polymer sheets

2000 ◽  
Vol 27 (5) ◽  
pp. 941-948 ◽  
Author(s):  
C Lee ◽  
J F Bonacci ◽  
M DA Thomas ◽  
M Maalej ◽  
S Khajehpour ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Columns ◽  
Corrosion Monitoring ◽  
Reinforced Concrete Columns ◽  
Accelerated Corrosion ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

An experimental study on the simulation of corrosion in large-scale reinforced concrete columns and their repair using carbon fibre reinforced polymer (CFRP) sheets is presented. Seven columns were subjected to an accelerated corrosion regime, wrapped using CFRP sheets, then tested to structural failure and (or) subjected to further post-repair accelerated corrosion, monitoring, and testing. Accelerated corrosion was achieved by adding sodium chloride to the mixing water, applying a current to the reinforcement cage, and subjecting the specimens to cyclic wetting and drying. Results showed that the CFRP repair greatly improved the strength of the repaired member and retarded the rate of post-repair corrosion. Moreover, subjecting the repaired column to extensive, post-repair corrosion resulted in no loss of strength or stiffness and only a slight reduction in the ductility of the repaired member.Key words: accelerated corrosion, carbon fibre reinforced polymer, composites, corrosion damage, corrosion rate, external confinement, reinforced concrete columns.

scholarly journals Effect of Carbon Fibre Reinforced Polymer Strengthening on Axial Capacity and Ductility of Non-slender Square Concrete Columns

2020 ◽  
Author(s):  
Muthomi Munyua ◽  
Siphila Mumenya ◽  
John Mwero
Keyword(s):  
Carbon Fibre ◽  
Research Programme ◽  
Concrete Columns ◽  
Steel Reinforcement ◽  
Axial Capacity ◽  
Reinforced Polymer ◽  
Number Of Layers ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Cfrp Confinement

This research investigated the effect of Carbon Fibre Reinforced Polymer (CFRP) strengthening on the axial capacity and ductility of non-slender square concrete columns. There was a problem of buildings collapsing in Kenya. Retrofitting of the buildings vulnerable to collapse was of great importance to ensure the safety of the occupants and to address the housing deficit in the country. An experimental research programme was conducted on 90 non-slender square concrete columns to find out the gain in axial capacity and ductility of the columns strengthened by CFRP. The specimens (150mm x 150mm x 350mm) were made of plain and reinforced concrete. Three different concrete grades: C8/10, C12/15 and C16/20 were used. The specimen had varying configurations of CFRP wrap: partial and full confinement in one and two layers. Four parameters were investigated in this study: concrete grade, steel reinforcement, degree of confinement and the number of layers of CFRP wrap. The specimens were subjected to uniaxial compression up to failure, and the stress-strain curves were plotted. This study found that weaker concrete grades experienced the highest effect due to CFRP strengthening. Presence of reinforcement had a significant effect on the axial capacity and ductility of columns without CFRP strengthening. On the contrary, the presence of steel reinforcement reduced the effectiveness of CFRP strengthening. Partial CFRP confinement offered better material efficiency as compared to full CFRP confinement, and the number of layers had a direct relationship with the increase in strength and ductility.

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.

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