Journal articles on the topic 'CFRP-reinforced steel structures'
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1
WU, CHAO, XIAO LING ZHAO, RIADH AL-MAHAIDI, and WEN HUI DUAN. "MODE I STRESS INTENSITY FACTOR OF CENTER-CRACKED TENSILE STEEL PLATES WITH CFRP REINFORCEMENT." International Journal of Structural Stability and Dynamics 13, no. 01 (February 2013): 1350005. http://dx.doi.org/10.1142/s0219455413500053.
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Advanced carbon fiber reinforced polymer (CFRP) demonstrates promise for the fatigue strengthening of steel structures. By decreasing the stress field at the crack tip, the stress intensity factors (SIFs) can be effectively reduced by CFRP reinforcement. In this paper, the mode I SIF of CFRP-reinforced center-cracked tensile (CCT) steel plate is proposed based on a series of fatigue tests. The selected fatigue tests include experiments conducted by the authors as well as fatigue tests reported in the literature, covering different CFRP systems (low/high modulus, CFRP sheeting/plate) with various CFRP strengthening dimensions. The classical mode I SIF of CCT steel plate without CFRP strengthening is selected as the basis of the proposed solution. Then two reduction factors, similar to the correction factors given in the Japanese Society of Steel Construction (JSSC) standard, are introduced to study the effects of the mechanical properties of CFRP composites and the geometries of the CFRP reinforcement, respectively. Modified SIFs for both single-side CFRP-reinforced and double-side CFRP-reinforced CCT steel plates are proposed. It is found that the experimental SIFs of CFRP-reinforced CCT steel plates can be reasonably captured by the proposed mode I SIF formula. Finally, parametric studies for investigating the sensitivity of SIF to various mechanical and geometric factors are presented.
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M.A. Gharib, W.H. Khushefati, M.A. Khedr, and E.Y. Sayed-Ahmed. "Performance of steel beams strengthened with prestressed CFRP laminate." Electronic Journal of Structural Engineering 15 (June 1, 2015): 60–69. http://dx.doi.org/10.56748/ejse.15203.
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Prestressed Carbon Fibre Reinforced Polymer (CFRP) system is generally used for strengthening reinforced concrete beams where CFRP laminate can improve both the strength and serviceability behaviour of reinforced concrete beams via increasing the overall member stiffness. However, the applicability of this technique to strengthening steel structures is still lagging behind its application to concrete structures. In this study, the flexural behaviour of steel I-beams strengthened with prestressed CFRP laminate using a mechanical anchorage system is experimentally investigated. A total of nine steel beams subjected to flexural loading are tested in various conditions to evaluate the effectiveness of the proposed strengthening system. The experimental investigation confirmed that CFRP prestressing increases the ultimate load of the strengthened steel beams and moderately delays the premature debonding failure of the CFRP laminate. Even with low level of CFRP prestressing, significant enhancement in the ultimate load of the strengthened beam was recorded. Beams strengthened using non-prestressed CFRP laminate mainly failed due to premature debonding of the laminate with a slight increase in the failure load. Mechanical end anchorages maintain the CFRP laminate prestress after releasing the jacking force without encountering any debonding of the CFRP laminate till final failure of the strengthened steel beam. The results of the experimental programme and its outcomes are presented and discussed.
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Wang, Lei, Jiwang Zhang, Changshi Huang, and Feng Fu. "Comparative Study of Steel-FRP, FRP and Steel-Reinforced Coral Concrete Beams in Their Flexural Performance." Materials 13, no. 9 (May 1, 2020): 2097. http://dx.doi.org/10.3390/ma13092097.
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In this study, a comparative study of carbon fiber reinforced polymer (CFRP) bar and steel–carbon fiber composite bar (SCFCB) reinforced coral concrete beams was made through a series of experimental tests and theoretical analyses. The flexural capacity, crack development and failure modes of CFRP and SCFCB-reinforced coral concrete were investigated in detail. They were also compared to ordinary steel-reinforced coral concrete beams. The results show that under the same conditions of reinforcement ratios, the SCFCB-reinforced beams exhibit better performance than CFRP-reinforced beams, and stiffness is slightly lower than that of steel-reinforced beams. Under the same load conditions, the crack width of SCFCB beams was between that of steel-reinforced beams and CFRP bar-reinforced beams. Before the steel core yields, the crack growth rate of SCFCB beam is similar to the steel-reinforced beams. SCFCB has a higher strength utilization rate—about 70–85% of its ultimate strength. Current design guidance was also examined based on the test results. It was found that the existing design specifications for FRP-reinforced normal concrete is not suitable for SCFCB-reinforced coral concrete structures.
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Wang, Xiao Chu, and Hong Bin Nie. "Research of the CFRP Strengthened Reinforced Concrete Structures." Applied Mechanics and Materials 193-194 (August 2012): 579–83. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.579.
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This paper analyzes mainly that the CFRP reinforced concrete research and FRP cloth reinforced characteristics and advantages, and from the material aspects illustrate the CFRP cloth’s faults. For different components, materials, and the nonlinear programming and analysis, through the integral, combination, discrete type three calculation model of material and materials between, namely, concrete, steel, concrete and reinforced, GFRP cloth, concrete and CFRP cloth the constitutive relation analysis, this paper expounds the present research, points out the existing limitations of the present study and later the research direction. Finally, the paper draw the conclusion that the column and beam mechanical strength, toughness, and crack resistance, impact resistant properties and durability of these aspects to illustrate the superiority of the CFRP reinforced concrete. That fiber reinforced polymer (FRP) strengthening, repairing concrete has broad prospects for development.
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Othman, Zrar Sedeeq, and Ahmed Heidayet Mohammad. "Behaviour of Eccentric Concrete Columns Reinforced with Carbon Fibre-Reinforced Polymer Bars." Advances in Civil Engineering 2019 (July 22, 2019): 1–13. http://dx.doi.org/10.1155/2019/1769212.
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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.
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Satria Yoresta, Fengky, Ryotaro Maruta, Genki Mieda, and Yukihiro Matsumoto. "Strengthening of steel member using unbonded CFRP laminates." E3S Web of Conferences 156 (2020): 05025. http://dx.doi.org/10.1051/e3sconf/202015605025.
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Excellent mechanical and physical properties make carbon fiber reinforced polymer (CFRP) the best options for repair, retrofit, and rehabilitation of civil engineering structures. A great success on application of this material in reinforced concrete (RC) structures has attracted much attention from many researchers to develop it in combination with steel. The number of studies on the use of CFRP composites for strengthening steel structures has still been limited and needs to be more explored. To date, the research in this field has mainly focused on CFRP strengthening with adhesively-bonded technique. This paper reports an experimental study to investigate the performance of slender axial compression steel members partially strengthened with unbonded CFRP composites. The requirements for stiffener to prevent buckling occurred in stiffening region are derived from structural equilibrium conditions. Vacuum-assisted Resin Transfer Molding (VaRTM) method is adopted to form CFRP laminates in the strengthened specimens. Totally eight small scale specimens are tested, and it is clear from the test that improvement in load-carrying capacity can be achieved by using CFRP.
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Piątek, Bartosz, Tomasz Siwowski, Jerzy Michałowski, and Stanisław Błażewicz. "Development of Bonded/Riveted Steel Anchorages of Prestressed CFRP Strips for Concrete Strengthening." Materials 13, no. 10 (May 12, 2020): 2217. http://dx.doi.org/10.3390/ma13102217.
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CFRP (carbon fiber reinforced polymer) strips are currently often used to strengthen reinforced concrete structures in flexure. In order to ensure effective strengthening, proper connection between FRP material and concrete structure is needed. CFRP strips can be applied passively (only by bonding to the concrete surface) or actively (by prestressing before bonding). In the case of passive strengthening, CFRP strips connecting by bonding to the surface along the strengthened element are usually sufficient. However, active (prestressing) CFRP strips should be additionally anchored at their ends. Anchoring of unidirectional CFRP strips to the reinforced concrete is difficult because of their weak properties in transverse directions. The paper presents a development of mechanical steel anchorages used in an active CFRP flexural strengthening system for reinforced concrete structures. The anchorages were made of steel plates connected to CFRP strips with steel rivets and epoxy adhesive. They were developed within series of tests on specimens from small-scale to full-scale tested in an axial tensile scheme. The paper describes successive modifications of the anchorages as well as the results of full-scale tests. The final version of the anchorage developed during the research had a tensile failure force of 185 kN, which is sufficient value for CFRP strengthening purposes.
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Keykha, Amir Hamzah. "A Numerical Investigation on the Structural Behavior of Deficient Steel Frames Strengthened using CFRP Composite." Civil Engineering Dimension 20, no. 1 (April 7, 2018): 1. http://dx.doi.org/10.9744/ced.20.1.1-7.
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Carbon fiber reinforced polymers (CFRP) is one of the materials that is used to strengthen steel structures. Most studies on CFRP strengthening steel on structures have been done on beams and steel columns. No independent study has studied the effect of CFRP strengthening on the structural behavior of steel frames having initial deficiency.The deficiency in steel structures may be created due to the errors caused by construction and others.This study aims to carry out a numerical study on the efficiency of CFRP sheet on strengthening square hollow section (SHS) steel frames having initial deficiency. Seven specimens, five of which were strengthened using CFRP sheets, were analyzed. ANSYS software was used to analyze the SHS steel frames. The results showed that the coverage length, the width, and the number of CFRP layers have a significant effect on increasing and recovering the ultimate load capacity of the SHS steel frames having initial deficiency.
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Dong, Chen Song. "Experimental Study on Strengthening of Steel Structures with Fiber Reinforced Plastic." Advanced Materials Research 275 (July 2011): 239–42. http://dx.doi.org/10.4028/www.scientific.net/amr.275.239.
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An experimental study on the strengthening of steel structures with FRP (Fiber Reinforced Plastic) is presented in this paper. Test coupons were prepared by applying FRP patches on both sides of steel coupons. Standard tensile tests were conducted to the test coupons. Two types of CFRP (Carbon Fiber Reinforced Plastic) and one type of GFRP (Glass Fiber Reinforced Plastic) were studied. The load and strain data were recorded, and the stiffness and strength were derived. The results show that CFRP provides better strengthening than GFRP, but there is no significant difference between PAN graphite/epoxy and pitch graphite/epoxy laminates.
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Sun, Yanan, Pengfei Li, and Guojin Qin. "Study on Calculation of Bearing Capacity of Axially Loaded CFRP-Strengthened Cold-Formed Thin-Walled Lipped Channel Steel Columns." Advances in Civil Engineering 2020 (October 19, 2020): 1–16. http://dx.doi.org/10.1155/2020/9682929.
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With the development of carbon fiber reinforced composites and the continuous improvement of the properties of bonding agents, scholars recommended using carbon fiber reinforced plastics (CFRP) to enhance cold-formed thin-walled C-shaped steel structures. It can provide a fast and effective way to strengthen and repair damaged steel structures. However, discussion on the bearing capacity calculation of cold-formed thin-walled C-section steel column strengthened by CFRP was limited. Also, the relevant influencing factors (the number of CFRP reinforcement layers), the orientation of CFRP (horizontal, vertical), and the location of CFRP reinforcement (web + flanges + lips, web + flanges, web, and flanges) were overlooked in calculating the bearing capacity of cold-formed thin-walled C-section steel column strengthened by CFRP. Then, the calculation result of the load capacity will be inaccurate. This work, therefore, studied the effects of CFRP reinforcement layers, CFRP direction, and CFRP reinforcement position on the ultimate load of CFRP-strengthened cold-formed thin-walled C-section steel column. A three-dimensional (3D) finite element model of cold-formed thin-walled steel strengthened by CFRP was established to discuss the bearing capacity under axial compression. Furthermore, a method for calculating the bearing capacity of the CFRP-strengthened cold-formed thin-walled C-section steel column was proposed based on the direct strength methods (DSM). The results indicate that not only the slenderness ratio, section size, and length of members but also the number of CFRP reinforcement layers and orientation of CFRP have an impact on the calculation of bearing capacity. The equation modified in this work has excellent accuracy and adaptability. Predicting the bearing capacity of reinforced members is necessary to give full play to the performance of CFRP accurately. Thus, the methods proposed can provide a reference value for practical engineering.
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Benmokrane, Brahim, Burong Zhang, Kader Laoubi, Brahim Tighiouart, and Isabelle Lord. "Mechanical and bond properties of new generation of carbon fibre reinforced polymer reinforcing bars for concrete structures." Canadian Journal of Civil Engineering 29, no. 2 (April 1, 2002): 338–43. http://dx.doi.org/10.1139/l02-013.
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This paper presents laboratory test results on the mechanical properties and bond strength of new generation of carbon fibre reinforced polymer (CFRP) reinforcing bars used as nonprestressed reinforcement for concrete structures. Two types of CFRP reinforcing bars, namely, 9-mm-diameter CFRP ribbed bars and 9.5-mm-diameter CFRP sand-coated bars, were investigated. Tensile tests and pullout bond tests were conducted to evaluate the tensile properties and bond strength of the CFRP bars in comparison with that of the steel bar. Experimental results showed that the tensile stress-strain curves of the CFRP bars were linear up to failure. The ultimate tensile strength of the two types of CFRP bars was at least 1500 MPa, three times that of steel bars. The modulus of elasticity of two types of the CFRP bars was 128145 GPa, about 6575% that of steel. Furthermore, both types of the CFRP bars exhibited almost the same bond strength to concrete similar to steel bars. The minimum bond development length for the two types of CFRP bars seemed to be equal to about 20db for the sand-coated bars and 30db for the ribbed bars.Key words: fibre reinforced polymer (FRP), carbon FRP (CFRP), bar, mechanical properties, tensile strength, embedded length, pullout, bond strength, concrete structures.
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Salleh, Norhafizah, Abdul Rahman Mohd Sam, Jamaludin Mohd Yatim, and Mohd Firdaus bin Osman. "Flexural Behaviour of Reinforced Concrete Beam with Glass Fiber Reinforced Polymer (GFRP) Bar Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Plate." Advanced Materials Research 1051 (October 2014): 748–51. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.748.
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The use of glass-fiber-reinforced polymer (GFRP) bar to replace steel reinforcement in concrete structures is a relatively a new technique. The GFRP bars possess mechanical properties different from steel bars, including high tensile strength combined with low elastic modulus and linear stress–strain relationship up to failure. Therefore, design procedures and process should account for these properties. This paper presents the experimental work on the flexural behavior of concrete beam reinforced with GFRP bars and strengthen with CFRP plate. A total of ten reinforced concrete beams reinforced with either steel and GFRP bars were cast and tested under four point loads. Eight concrete beams (200x250x2800mm) were reinforced with 13mm diameter GFRP bars together with strengthening using CFRP plate and two control beams reinforced with 12mm diameter steel bars were tested. The experimental results show that although the stiffness of the beams reduced but the ultimate load of the GFRP reinforced concrete beam is bigger than steel reinforced beam. It was also found that strengthening using CFRP plate will further enhanced the flexural performance of the beams with GFRP bars.
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Zhang, Guoxue, Yingfeng Wang, Shixiang Xu, Juan Lu, and Yangyang Zhou. "Experimental on Impact Mechanical Behavior of the Carbon Fibre Reinforced Plastic-Reinforced Stainless Steel Reinforced Concrete Piers." Science of Advanced Materials 12, no. 5 (May 1, 2020): 769–77. http://dx.doi.org/10.1166/sam.2020.3734.
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To study the impact resistance of the stainless steel reinforced concrete after reinforced with CFRP (Carbon Fibre Reinforced Plastic), the multifunction ultra-high heavy drop hammer test system was adopted to conduct multiple horizontal impact test research on three stainless steel reinforced concrete piers before and after they are reinforced. The test results showed that with equal impact energy, the maximum impact force of the stainless steel reinforced concrete piers was larger than that of the stainless steel reinforced concrete piers that were reinforced with CFRP, while after the concrete piers were reinforced, the peak displacement of the piers was obviously smaller than that before they were reinforced and the residual deformation also became smaller, which improved the flexural rigidity of the section. And the local anti-damage capacity can be improved so as to lengthen the life of structures by reinforcing the stainless steel reinforced concrete pier with carbon fiber.
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Yang, Yi, Zuodong Wu, Qianziyang Zhou, Jiahao Bai, and Xinyan Guo. "An Experimental Study on Shear Performance of Adhesive Interface between Steel Plates and CFRP." Stavební obzor - Civil Engineering Journal 31, no. 4 (December 31, 2022): 561–70. http://dx.doi.org/10.14311/cej.2022.04.0042.
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CFRP (Carbon Fiber Reinforced Polymer) are widely used in steel structural reinforcement. For steel structures strengthened with CFRP, except the cases the structures have defects before strengthening, the adhesive interface is the weakest part and CFRP debonding is the most common failure mode. In order to investigate the failure mechanism of CFRP strengthened steel structures, this paper presents an experimental study on shear performance of adhesive interface between steel plate and CFRP by twin shear model. Six steel plates strengthened with CFRP are divided into two groups, one has no damage, another has a gap at the mid. The specimens are tested under tensile loadings. The study results show that, the plates with a gap failed for CFRPs debonding, the cracking loading and breaking loading are 14.85kN, and 17.88kN respectively; the strain-loading curves had long linear stages, two strains decrease and other strains of another side increased rapidly at the cracking loading, then they both rose until the plates failed.
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Tarigan, Johannes, Andrew Pakpahan, Medis Surbakti, and Nursyamsi Nursyamsi. "Analysis and experimental usage of CFRP wrap type on flexural strength of concrete beam." MATEC Web of Conferences 258 (2019): 03001. http://dx.doi.org/10.1051/matecconf/201925803001.
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Today, reinforced concrete structures are commonly used in buildings because the price cheaper than steel structures. However, many concrete structures are damaged. There are several ways to overcome this problem, and one of them is by strengthening the structure using Fiber Reinforced Polymer (FRP). This study discussed the flexural strength of reinforced concrete beams using Fiber Reinforced Polymer (FRP). In this case, the researchers used Carbon Fiber Reinforced Polymer (CFRP) Wrap Type as the external reinforcement. The beam’s dimension was 15 x 25 cm with a length of 320 cm. Based on the analysis results, the beam using CFRP Wrap type can increase the load 3.12 % times. Furthermore, the experimental results show that the beam with the CFRP type Wrap increases the load by 2.5 times. In conclusion, beams strengthened with CFRP Wrap type can inhibit initial cracks and hold the tensile and flexural strength greater than un-strengthened beams.
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Li, Shan, Hui Tao Ren, Yi Yan Lu, and Mu Huan Shi. "Environmental Degradation of Carbon Fiber Reinforced Polymer (CFRP) and Steel Bond Subjected to Hygrothermal Aging and Loading." Materials Science Forum 675-677 (February 2011): 559–62. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.559.
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Carbon fiber-reinforced polymer (CFRP) material is increasingly being used for the repair of steel structures, mainly because of their superior mechanical properties. However, there is insufficient information on the environmental durability of CFRP-steel bond, especially in hygrothermal aging combined with sustained load. In this paper, 500 mm long І steel beam specimens reinforced with externally bonded wet-laid CFRP sheets are investigated. The specimens are subjected to a sustained four point flexural load of about 30% of initial ultimate load, placed into hygrothermal condition. The ultimate bear capacity and the failure characteristics of the CFRP and steel interface are studied after hydrothermal age and loading. The test results show that the coupled action of sustained load and hygrothermal aging reduces the bond strength of CFRP-steel, even for relatively short conditioning periods, and appears to significantly affect the failure characteristics of specimens.
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Li, Shan, Tao Zhu, Yiyan Lu, and Xiaojin Li. "Effect of Temperature Variation on Bond Characteristics between CFRP and Steel Plate." International Journal of Polymer Science 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/5674572.
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In recent years, application of carbon fiber reinforced polymer (CFRP) composite materials in the strengthening of existing reinforced concrete structures has gained widespread attention, but the retrofitting of metallic buildings and bridges with CFRP is still in its early stages. In real life, these structures are possibly subjected to dry and hot climate. Therefore, it is necessary to understand the bond behavior between CFRP and steel at different temperatures. To examine the bond between CFRP and steel under hot climate, a total of twenty-one double strap joints divided into 7 groups were tested to failure at constant temperatures from 27°C to 120°C in this paper. The results showed that the joint failure mode changed from debonding along between steel and adhesive interface failure to debonding along between CFRP and adhesive interface failure as the temperature increased beyond the glass transition temperature (Tg) of the adhesive. The load carrying capacity decreased significantly at temperatures approaching or exceedingTg. The interfacial fracture energy showed a similar degradation trend. Analytical models of the ultimate bearing capacity, interfacial fracture energy, and bond-slip relationship of CFRP-steel interface at elevated temperatures were presented.
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Tafsirojjaman, T., Sabrina Fawzia, and David Thambiratnam. "Numerical Investigation on the CFRP Strengthened Steel Frame under Earthquake." Materials Science Forum 995 (June 2020): 123–29. http://dx.doi.org/10.4028/www.scientific.net/msf.995.123.
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Steel structures are commonly used in seismic regions of the world because of its strength and ductility. However, these structures are still prone to damage during an earthquake. With this risk of seismic damage, the strengthening of steel structures is a major concern in order to resist the dynamic loads resulted from earthquakes. This report investigates the potential for the use of Carbon Fibre Reinforced Polymer (CFRP) to strengthen the rigid steel frame under a real earthquake load. This research will be undertaken using Strand7, a finite element (FE) analysis software. To validate the accuracy of this research, the finite analysis results have been compared to the available experimental study by the Authors. First, both FE models of a five-story bare steel frame and CFRP strengthened steel frame has been developed. Then the predicted numerical results of bare steel frame and CFRP strengthened steel frame under earthquake excitation are compared. The results indicated an increase in the seismic performance of the steel structure due to the strengthened with CFRP. The CFRP strengthened steel frame showed 15% less tip deflection compared to bare steel frame. Further analysis on the strengthening capabilities of higher thickness CFRP was performed to assess the effect of the thickness of CFRP and the higher thickness CFRP showed better seismic performance compare to normal thickness CFRP by reducing 34.38% of tip deflection.
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Liu, Zhi Ping, Xuan Li, Ming Chang Li, Xing Le Liu, and Liang Ke. "Research of Detecting Methods of Welding Cracks in CFRP-Steel Structures Based on Eddy Current Pulsed Thermography." Materials Science Forum 860 (July 2016): 53–56. http://dx.doi.org/10.4028/www.scientific.net/msf.860.53.
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CFRP (Carbon Fiber Reinforced Plastics) reinforcement has a significant effect and advantages of steel structure, has extensive application prospects in the field of engineering structure. However, both of the detection methods and effects evaluation are still in blank, which has restricted the application of CFRP reinforcing steel structures. This paper is based on Eddy Current Pulsed Thermography (ECPT) and focused on the detection of fatigue damage in steel structure strengthened with CFRP sheet. The main research following several parts: first, the mechanism of eddy current thermal excitation on multilayer anisotropic medium was analyzed. Second, the direction and length of steel crack can be found out in any streel crack image. Finally, the feasibility of numerical models and recognition algorithm are verified through experiments. The paper provided an effective method in damaged structures strengthened with CFRP based on ECPT, as well as establishing the theory and technique for developing ECPT instruments for CFRP sheet-strengthened steel structures.
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Van Nguyen, Chinh, Paul Lambert, Pal Mangat, Fin O’Flaherty, and Graeme Jones. "The Performance of Carbon Fibre Composites as ICCP Anodes for Reinforced Concrete Structures." ISRN Corrosion 2012 (December 20, 2012): 1–9. http://dx.doi.org/10.5402/2012/814923.
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Cathodic protection has been proven to be one of the most widely applicable and cost-effective solutions for tackling steel corrosion in reinforced concrete. In this study, the possible use of carbon fibre composites, which are primarily used to strengthen concrete members, has been investigated as impressed current cathodic protection anodes. Carbon fibre anodes have been assessed in both concrete and calcium hydroxide solution. Two bonding mediums incorporating epoxy and geopolymer have also been investigated. The results demonstrate that epoxy resin can be used for bonding carbon fibre fabric anodes to reinforced concrete structures while geopolymer is more effective for bonding carbon fibre reinforced polymer (CFRP) rod into preformed grooves in the concrete surface. The dissolution of carbon fibre anode appears to stablise after a period of time, dependent upon the size and shape of the anode and applied voltage and current. Based on the present results, a maximum current density of 128 mA/m2 of reinforcing steel area is recommended for the operation of CFRP fabric anode and 64 mA/m2 of reinforcing steel area for that of CFRP rod anode.
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Li, Bin, Hua Luo, and Xianqiao Wang. "Failure Analysis of Locally Damaged Slender Steel Bars Strengthened with CFRP Composites: Experiments, Theory, and Computational Simulations." Advances in Civil Engineering 2020 (October 20, 2020): 1–14. http://dx.doi.org/10.1155/2020/8831701.
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Carbon fiber-reinforced polymer/plastic (CFRP) composites bear attractive performance in resistance to tension, fatigue, and corrosion and, thus, have been recognized as a promising candidate for repairing and strengthening steel structures in engineering. Here, we combine experiments, theory, and numerical simulations to elucidate how the location and degree of local damages, as well as the reinforcement mode, affect the stability of slender steel bars repaired by CFRP. The deformation, failure mode, and the critical buckling load of the reinforced steel flat bars subjected to axial compressive forces are experimentally evaluated. We show that all tested specimens exhibit buckling failure, before which the damaged steel bars have entered an elastic-plastic stage. Our theoretical analysis provides an upper bound for the critical force, which is sensitive not only to the damage degree but also to the damage location. Damage locating at the middle regime of the specimens will remarkably reduce stability of the steel bars, but an optimized combination of wrapping method and number of CFRP layers can restore and even enhance the stability of the damaged structures beyond the undamaged counterparts. Finite element simulations are implemented in the same scenario as experiments, showing good agreement with our measurements. Our findings suggest that, to improve the stability of the damaged steel bars reinforced by CFRP, the load carrying capacity of the the bars, the number of CFRP layers, and the construction convenience should be taken into account.
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Pakpahan, Andrew Agaton. "Analysis And Experimental Use Of CFRP Wrap Type On Flexible Reinforcement Of Concrete Beam." Jurnal Mekintek : Jurnal Mekanikal, Energi, Industri, Dan Teknologi 13, no. 1 (April 8, 2022): 12–18. http://dx.doi.org/10.35335/mekintek.v13i1.33.
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Now, reinforced concrete structures are more commonly used in buildings because they are cheaper than steel structures. However, many concrete structures are damaged due to planning errors and changes in building functions, so there are several ways to overcome this problem, by providing Fiber Reinforced Polymer (FRP) reinforcement. In this study, researchers discussed the comparison of the flexural strength of reinforced concrete beams using Fiber Reinforced Polymer (FRP). In this case, the researcher uses a Wrap-Type Carbon Fiber Reinforced Polymer (CFRP) as external reinforcement. The beam dimensions are 15 x 25 cm with a length of 320 cm. Based on the results of the analysis, the strength of the beam with CFRP is 1.877 times its initial strength. Based on the test results, the strength of the CFRP beam is 1.5 times its initial strength. Based on the results of this test.
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Lozano, Christine M., and Guillermo A. Riveros. "Effects of Adhesive Bond-Slip Behavior on the Capacity of Innovative FRP Retrofits for Fatigue and Fracture Repair of Hydraulic Steel Structures." Materials 12, no. 9 (May 8, 2019): 1495. http://dx.doi.org/10.3390/ma12091495.
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Over eighty percent of the navigation steel structures (NSS) in the United States have highly deteriorated design boundary conditions, resulting in overloads that cause fatigue cracking. The NSSs’ highly corrosive environment and deterioration of the protective system accelerate the fatigue cracking and cause standard crack repair methods to become ineffective. Numerous studies have assessed and demonstrated the use of carbon fiber reinforced polymers (CFRP) to rehabilitate aging and deteriorated reinforced concrete infrastructure in the aerospace industry. Due to the increase of fatigue and fracture failures of NSS and the shortage of research on CFRP retrofits for submerged steel structures, it is imperative to conduct research on the effects of CFRP repairs on NSS, specifically on the adhesive’s chemical bonding to the steel substrate. This was accomplished by developing a new analytical algorithm for CFRP bond-slip behavior, which is based on Volkersen’s contact shear single lap joint (SLJ) connection. The algorithm was validated by experimental results of fatigue center-cracked large steel plates repaired with CFRP patches. The state of stresses at the crack tip are largely influenced by a combination of the crack tip plasticity radius and overall bond surface area.
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Guo, Xin-Yan, Yi-Lin Wang, Pei-Yan Huang, Xiao-Hong Zheng, and Yi Yang. "Fatigue Life Prediction of Reinforced Concrete Beams Strengthened with CFRP: Study Based on an Accumulative Damage Model." Polymers 11, no. 1 (January 13, 2019): 130. http://dx.doi.org/10.3390/polym11010130.
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With the prestressed carbon fiber reinforced polymer (CFRP) strengthening technique widely used in reinforced concrete (RC) structures, it is more and more important to study the fatigue performance of RC structures. Since the fracture of a tensile steel bar at the main cracked section is the leading reason for the failure of RC beams reinforced by prestressed CFRP, a fatigue life prediction model of RC beams reinforced by prestressed CFRP was developed based on an accumulative damage model. Moreover, gradual degradation of the performance of the concrete was considered in the fatigue life prediction model. An experimental study was also conducted to research the fatigue behavior of RC beams reinforced by prestressed or non-prestressed carbon fiber laminate (CFL). During the tests, fatigue crack patterns were captured using a digital image correlation (DIC) technique, and the fatigue lives of a total of 30 beams were recorded. The results showed that the predicted main crack propagation curves and the fatigue lives were close to the experimental data. This study also exhibited that the prestressed CFRP could reduce the stress of main steel bars in RC beams and effectively improve the fatigue performance of the RC beams.
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Wang, Hua-Ping, Yi-Bin Wu, Cong Chen, Hu-Yuan Zhang, Hao Jiang, Xue-Mei Zhang, and Xiang-Yang Xu. "Dynamic Response of CFRP Reinforced Steel Beams Subjected to Impact Action Based on FBG Sensing Technology." Sensors 22, no. 17 (August 24, 2022): 6377. http://dx.doi.org/10.3390/s22176377.
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The in-situ health condition of carbon fiber reinforced polymer (CFRP) reinforced structures has become an important topic, which can reflect the structural performance of the retrofitted structures and judge the design theory. An optical fiber-based structural health monitoring technique is thus suggested. To check the effectiveness of the proposed method, experimental testing on smart CFRP reinforced steel beams under impact action has been performed, and the dynamic response of the structure has been measured by the packaged FBG sensors attached to the surface of the beam and the FBG sensors inserted in the CFRP plates. Time and frequency domain analysis has been conducted to check the structural feature of the structures and the performance of the installed sensors. Results indicate that the packaged Fiber Bragg Grating (FBG) sensors show better sensing performance than the bare FBG sensors in perceiving the impact response of the beam. The sensors embedded in the CFRP plate show good measurement accuracy in sensing the external excitation and can replace the surface-attached FBG sensors. The dynamic performance of the reinforced structures subjected to the impact action can be straightforwardly read from the signals of FBG sensors. The larger impact energies bring about stronger impact signals.
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Zhang, Long, Shuangyin Cao, and Xin Tao. "Experimental Study on Interfacial Bond Behavior between CFRP Sheets and Steel Plates under Fatigue Loading." Materials 12, no. 3 (January 25, 2019): 377. http://dx.doi.org/10.3390/ma12030377.
Full textAbstract:
Using carbon fiber reinforced polymer (CFRP) composites for enhancing the fatigue behavior of the steel structures will be an important application. As the most critical part, the fatigue behavior of the CFRP-to-steel bonded interface directly determines the strengthening effect of steel structures reinforced by CFRP. In this paper, a series of CFRP-to-steel double-shear specimens are performed in order to study the interfacial bond behavior between CFRP and steel under fatigue loading. Two parameters are considered: the upper bound value and the lower bound value of the fatigue loading. An analysis of test results indicates that the crack development rate increases with the increment of the stress ratio or stress level and the crack development process includes two phases: crack stable development phase and debonding failure phase. A calculation model is put forward to describe the relationship between the crack development rate and the stress level. Besides, it can be obtained from the test results that the fatigue lives of the specimens decrease with the increment of the stress level. The empirical formula of S-N curve based on the form of single logarithm formula is proposed and the fatigue limit under the experimental conditions in this paper is determined to be 0.343 by computational analysis.
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Belarbi, A., M. Reda, P. Poudel, H. Tahsiri, M. Dawood, and B. Gencturk. "Prestressing Concrete with CFRP Composites for Sustainability and Corrosion-Free Applications." MATEC Web of Conferences 149 (2018): 01010. http://dx.doi.org/10.1051/matecconf/201814901010.
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Advancement in material science has enabled the engineers to enhance the strength and long-term behavior of concrete structures. The conventional approach is to use steel for prestressed bridge girders. Despite having good ductility and strength, beams prestressed with steel are susceptible to corrosion when subjected to environmental exposure. The corrosion of the prestressing steel reduces load carrying capacity of the prestressed member and result in catastrophic failures. In the last decades, more durable composite materials such as Aramid Fiber Reinforced Polymer (AFRP), Glass Fiber Reinforced Polymer (GFRP) and Carbon Fiber Reinforced Polymer (CFRP) have been implemented in concrete structures as a solution to this problem. Among these materials, CFRP stands out as a primary prestressing reinforcement, which has the potential to replace steel and provide corrosion free prestressed bridge girders. Despite its promise, prestressing CFRP has not frequently been used for bridge construction worldwide. The major contributing factor to the lack of advancement of this promising technology in the United States (U.S.) is the lack of comprehensive design specifications. Apart from a limited number of guides, manuals, and commentaries, there is currently no standard or comprehensive design guideline available to bridge engineers in the U.S. for the design of concrete structures prestressed with CFRP systems. The main goal is to develop design guidelines in AASHTO-LRFD format for concrete bridge girders with prestressing CFRP materials. The guidelines are intended to address the limitation in current AASHTO-LRFD Bridge Design Specifications which is applicable for prestressed bridge girders with steel strands. To accomplish this goal, some of the critical parameters that affect the design and long-term behavior of prestressed concrete bridge girders with prestressing CFRP systems are identified and included in the research work. This paper presents preliminary results of an experimental study that is part of a National Highway Co-operative Highway Research Program (NCHRP) project.
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Ye, Lingpeng, Baisheng Wang, and Pujian Shao. "Experimental and Numerical Analysis of a Reinforced Wood Lap Joint." Materials 13, no. 18 (September 16, 2020): 4117. http://dx.doi.org/10.3390/ma13184117.
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During the restoration of ancient wood structures, the original material of the structures should be kept as much as possible, so a spliced method by using lap joints is commonly used to repair ancient wood structures. This study studies the mechanical behavior of a lap joint which was reinforced with fiber composite materials or steels. An experimental and numerical analysis were performed to study the strength, stiffness and failure modes of the lap joints. The test results showed that the strengthening effect of sticking carbon fiber-reinforced polymer (CFRP) sheets is better than that of sticking CFRP bars or steel bars due to the better bonding conditions; therefore, the lap joint reinforced with CFRP sheets was further analyzed using a numerical approach. The strength and stiffness were enhanced by increasing the reinforcement ratio of CFRP sheets. The use of a 0.34% reinforcement ratio made the bearing capacity of the lap joint reach that of the intact beam. The numerical model agreed well with the experiments in terms of stiffness. By analyzing the numerical analysis results, the structural behavior of the lap joint was revealed. A numerical model can be used to predict the stiffness and behavior of spliced beams with lap joints of different sizes.
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Suriyati, Ridwan, Zulfikar Djauhari, and Iskandar Romey Sitompul. "Seismic performance of building reinforced with CFRP bars." MATEC Web of Conferences 276 (2019): 01021. http://dx.doi.org/10.1051/matecconf/201927601021.
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Over the past two decades, laboratory tests have suggested that fibre reinforced polymer (FRP) bars can replace steel bars as internal reinforcement in concrete structures, especially those are subjected to aggressive environments. FRP bars has potential for replacing steel bars as these material are corrosion-resistant and have high tensile strength, make it suitable for use as structural reinforcement. Unfortunately, the application of FRP for reinforcing structures in Indonesia is dubious. This paper aims to study the behaviour of reinforced concrete (RC) building reinforced with Carbon FRP (CFRP) and steel bars. The observed building was designed for Pekanbaru, according to SNI 2847:2013 for design of structural RC with steel bars reinforcement and the ACI 440.1R-15 for design and construction of structural RC with FRP bars. Two reinforcedconcrete moment resisting frames, extracted from 6 storey heights building with rectangular floor plan, were designed for the city of Pekanbaru. The building had the typical storey height of 3.6 m except for the first floor where the column length was 4.0 m. Two frames were investigated, including the frame without (Frame A) and with shear wall (Frame B). Pushover analysis was conducted to establish the design force and the design deformation demands. The results show that the amount of bar areas needed for reinforcing the building with CFRP bars was significantly reduced. Moreover, the maximum forced demand attained for the building reinforced with CFRP bars were enhanced by about 1.9 times compared to that of reinforced with steel bars.
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Li, Yi Heng, and Zhen Guo Li. "Hysteretic Behavior of Steel Members Strengthened with CFRP under Cyclic Lateral Loading in Different Temperature." Advanced Materials Research 567 (September 2012): 170–73. http://dx.doi.org/10.4028/www.scientific.net/amr.567.170.
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With the development of strengthening and repairing technology, carbon fiber-reinforced polymer (CFRP) has been widely applied in concrete and masonry structures for high efficiency. However, there is limited information about how they can be used to strengthen steel members. This paper presents the strengthening effect of CFRP on steel column under cyclic lateral loading in thermal environment. The results indicate that application of CFRP in steel column under cyclic lateral loading in thermal environment has substantial benefits. In particular, the CFRP wraps can improve the ultimate cyclic lateral load and ductility of steel column prominently in thermal environment which can meet the higher requirements of stiffness.
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Zhou, Yingwu, Lili Sui, Feng Xing, Xiaoxu Huang, Yaowei Zheng, and Debo Zhao. "Bond Performance of Carbon Fiber-Reinforced Polymer Bar with Dual Functions of Reinforcement and Cathodic Protection for Reinforced Concrete Structures." Advances in Polymer Technology 2020 (January 25, 2020): 1–13. http://dx.doi.org/10.1155/2020/2097369.
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The dual function of a carbon fiber-reinforced polymer (CFRP) bar working as reinforcement and impressed current cathodic protection (ICCP) anode for reinforced concrete structures has been proposed and researched in this paper. The ICCP tests with different current densities and polarization durations were first conducted for the concrete with high chloride content. After the ICCP application, pull out tests were then performed to investigate the bond behaviors of CFRP bars. Experimental results have shown the effectiveness of the new-type ICCP system with the CFRP bar as the anode on corrosion protection. The ICCP system provided electrons to the steel bar continuously and brought the potential of the steel bar down to the immunity region. Under the anodic polarization with a large current density of 100 mA/m2, the CFRP bar-concrete interface presented acidification and the chemical adhesion on the interface was decreased significantly. However, for cases in the experiment, the ICCP application had an insignificant influence on the ultimate bond strength.
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Liu, Zhi Ping, Zong Chen Li, Ming Chang Li, Kai Chen, and Chao Chao He. "Study of Box Girder Steel Structure Locally Reinforced by CFRP." Materials Science Forum 860 (July 2016): 57–60. http://dx.doi.org/10.4028/www.scientific.net/msf.860.57.
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On the basis of using CFRP (Carbon Fiber Reinforced Polymer) to reinforce steel materials and structures, this paper focused on the reinforcement method of box girder steel structure. Firstly, FEM models were set up to discuss the reinforce method, stress distribution between overall strengthening of flange and locally strengthening. Secondly, typical crack model was raised on the basis of mechanics characteristic, reinforcement effects under different methods was analyzed. The results showed that locally strengthening method to reinforce the certain fatigue areas could improve stress concentration phenomenon and SIF effectively. This paper offered a significant basement for reinforcing box girder steel structures and repairing fatigue cracks using CFRP.
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Liu, Yuwen, Wei Chen, Chun Liu, and Na Li. "Bond Performance of CFRP/Steel Double Strap Joint at Elevated Temperatures." Sustainability 14, no. 23 (November 22, 2022): 15537. http://dx.doi.org/10.3390/su142315537.
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Carbon fiber-reinforced polymer (CFRP) has been used widely in the strengthening of steel structures. Steel/CFRP systems being subjected to elevated temperatures is realistic in summer climate events in many countries, which leads to the degradation of the bond performance between CFRP and steel. Therefore, it is critical to study the bond behavior of the CFRP/steel system under elevated temperature. This paper investigates the mechanical performance of CFRP/steel adhesively bonded double strap joints under different temperatures. Thirty CFRP/steel double strap joints were tested to failure under temperatures between 10 °C and 90 °C. It was found that the joint failure mode changed from adherend failure to debonding failure as the temperature was approaching glass transition temperatures. In addition, the ultimate load and joint stiffness decreased significantly under temperatures near to and higher than glass transition temperatures. Based on the experimental results, a model is proposed to predict the bond stress of the CFRP/steel under different temperatures.
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Zhou, Yingwu, Yaowei Zheng, Lili Sui, Biao Hu, and Xiaoxu Huang. "Study on the Flexural Performance of Hybrid-Reinforced Concrete Beams with a New Cathodic Protection System Subjected to Corrosion." Materials 13, no. 1 (January 5, 2020): 234. http://dx.doi.org/10.3390/ma13010234.
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Steel corrosion is considered as the main factor for the insufficient durability of concrete structures, especially in the marine environment. In this paper, to further inhibit steel corrosion in a high chloride environment and take advantage of the dual-functional carbon fiber reinforced polymer (CFRP), the impressed current cathodic protection (ICCP) technique was applied to the hybrid-reinforced concrete beam with internally embedded CFRP bars and steel fiber reinforced polymer composite bar (SFCB) as the anode material while the steel bar was compelled to the cathode. The effect of the new ICCP system on the flexural performance of the hybrid-reinforced concrete beam subjected to corrosion was verified experimentally. First, the electricity-accelerated precorrosion test was performed for the steel bar in the hybrid-reinforced beams with a target corrosion ratio of 5%. Then, the dry–wet cycles corrosion was conducted and the ICCP system was activated simultaneously for the hybrid-reinforced concrete beam for 180 days. Finally, the three-point bending experiment was carried out for the hybrid-reinforced concrete beams. The steel bars were taken out from the concrete to quantitatively measure the corrosion ratio after flexural tests. Results showed that the further corrosion of steel bars could be inhibited effectively by the ICCP treatment with the CFRP bar and the SFCB as the anode. Additionally, the ICCP system showed an obvious effect on the flexural behavior of the hybrid-reinforced concrete beams: The crack load and ultimate load, as well as the stiffness, were enhanced notably compared with the beam without ICCP treatment. Compared with the SFCB anode, the ICCP system with the CFRP bar as the anode material was more effective for the hybrid-reinforced concrete beam to prevent the steel corrosion.
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Wang, Bo, Hui Peng, and Jian Ren Zhang. "Behavior of Pre-Cracked Reinforced Concrete Beam Strengthened with Prestressed CFRP Plate." Applied Mechanics and Materials 351-352 (August 2013): 1397–403. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1397.
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The technique of strengthening structures with prestressing CFRP can improve the load-carrying behavior of reinforced concrete structures and has gained more and more attention recent years. However the research about behavior of the pre-cracked structures after retrofit is rather limited. In this paper two RC beams with large dimension were constructed. One beam was strengthened by non-prestressed CFRP plate serving as reference beam. And the other beam had been loaded to its yielding load before it was strengthened with a prestressed CFRP plate. The monotonic tests were conducted to investigate the effect of strengthening with prestressed CFRP on the behavior of the pre-damaged beam. Based on the experiment results, the comparison of behavior between the beam with non-prestressed CFRP plate and the pre-cracked beam with prestressed CFRP was conducted. The experiment results indicated that although having been loaded to its steel yielding before being strengthened, the specimen with prestressed CFRP plate had a load-carrying capacity no less than the intact beam with non-prestressed CFRP plate. Despite the serious damages of section, the stiffness of the pre-cracked specimen was almost equal to that of the reference specimen, which indicates that the technique of strengthening structures with prestressed CFRP plates can be effective in the retrofit of the seriously cracked reinforced concrete structures.
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Shill, Sukanta Kumer, Estela O. Garcez, Riyadh Al-Ameri, and Mahbube Subhani. "Performance of Two-Way Concrete Slabs Reinforced with Basalt and Carbon FRP Rebars." Journal of Composites Science 6, no. 3 (March 1, 2022): 74. http://dx.doi.org/10.3390/jcs6030074.
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Fibre-reinforced polymer (FRP) rebars are being increasingly used to reinforce concrete structures that require long-term resistance to a corrosive environment. This study presents structural performance of large scale two-way concrete slabs reinforced with FRP rebars, and their performances were compared against conventional steel reinforced concrete. Both carbon FRP (CFRP) and basalt FRP (BFRP) were considered as steel replacement. Experimental results showed that the CFRP- and BFRP-RC slabs had approximately 7% and 4% higher cracking moment capacities than the steel-RC slab, respectively. The BFRP-RC slabs experienced a gradual decrease in the load capacity beyond the peak load, whereas the CFRP-RC slabs underwent a sharp decrease in load capacity, similar to the steel-RC slab. The BFRP-RC slabs demonstrated 1.72 times higher ductility than CFRP-RC slabs. The steel-RC slab was found to be safe against punching shear but failed due to flexural bending moment. The FRP-RC slabs were adequately safe against bending moment but failed due to punching shear. At failure load, the steel rebars were found to be yielded; however, the FRP rebars were not ruptured. FRP-RC slabs experienced a higher number of cracks and higher deflection compared to the steel-RC slab. However, FRP-RC slabs exhibited elastic recovery while unloading. Elastic recovery was not observed in the steel-RC slab. Additionally, the analytical load carrying capacity was validated against experimental values to investigate the efficacy of the current available standards (ACI 318-14 and ACI 440.1R-15) to predict the capacity of a two-way slab reinforced with CFRP or BFRP. The experimental load capacity of the CFRP-RC slabs was found to be approximately 1.20 times higher than the theoretical ultimate load capacity. However, the experimental load capacity of the BFRP-RC slabs was 6% lower than their theoretical ultimate load capacity.
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Gao, Tian-Bao, Peng-Xiang Ma, Guo-Min Zhao, Zhu-Hui Zhang, and Xiao-Yao Yao. "Bonding Performance of CFRP-Steel Interface after Continuous High Temperature." Advances in Materials Science and Engineering 2022 (May 28, 2022): 1–10. http://dx.doi.org/10.1155/2022/3754626.
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The bonded shear performance of CFRP-reinforced steel structures following continuous high-temperature natural cooling was investigated experimentally, and 30 CFRP-steel specimens were subjected to single-shear tensile testing. In analyzing the shear stress-displacement relationship in each working condition, the equation for the coupling effect of the heating temperature and duration on the ultimate shear stress was proposed. The results show that the ultimate shear stress at the CFRP-steel interface tends to decrease with the increase of heating temperature, and the ultimate shear stress at the heating temperature of 300°C is 32.37% of that at 25°C. The high-temperature duration has an obvious influence on the bonding performance of the CFRP-steel interface, and the CFRP-steel specimens fail when the heating temperature is 300°C and lasts for 120 min.
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Kim, Jusung, Sumi Jeong, Hojin Kim, Youngjin Kim, and Sungyu Park. "Bond Strength Properties of GFRP and CFRP according to Concrete Strength." Applied Sciences 12, no. 20 (October 20, 2022): 10611. http://dx.doi.org/10.3390/app122010611.
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Reinforced concrete is the most commonly used material in the construction industry. However, one disadvantage of reinforced concrete is that environmental factors cause materials to penetrate the concrete and cause steel bar corrosion. Rebar corrosion increases its volume significantly by approximately 3–6 times, which lowers concrete–rebar adhesion. This severely affects the serviceability and durability of concrete structures. The economic and social impacts of such deterioration are extremely large. To reduce corrosion, glass fiber-reinforced plastics (GFRP) and carbon fiber-reinforced plastics (CFRP) can be applied to concrete. The rebar–concrete bond strength is an important factor to be considered while applying GFRP and CFRP. Thus, we experimentally investigated the adhesion strength of GFRP and CFRP in relation to the strength of concrete and water–cement ratio according to ASTM C 234 to correlate the data for the development of GFRP and CFRP as substitutes for deformed reinforcing bars. The results showed that a lower water–cement ratio yielded higher compressive strength and bond strength; the bond strength of GFRP was approximately 23% lower than that of CFRP. The coating of the rebar surface required for GFRP and CFRP application in reinforced concrete structures ought to be investigated in the future.
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Sternsdorff, Florian, Yvonne Ciupack, and Hartmut Pasternak. "EXPERIMENTAL INVESTIGATIONS ON INNOVATIVE CRACK REPAIR METHODS AND REINFORCING STEEL STRUCTURES WITH ADHESIVLY BONDED CFRP – LAMELLAS." Engineering Structures and Technologies 13, no. 1 (July 8, 2022): 1–6. http://dx.doi.org/10.3846/est.2021.15036.
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The paper describes some of the experiments carried out at the Chair of Steel and Timber Construction to reinforce steel with adhesively bonded CFRP lamellas. The first topic deals with the repair of cracks in steel structures exposed to fatigue. The aim was to extend the remaining service life of these components by means of adhesively bonded CFRP lamellas and then to compare the results obtained with established methods for repairing cracks. In order to improve the informative value of the investigations, several test parameters such as adhesive candidates, temperature, creep effects, degrees of prestressing, load levels and the position of the reinforcement measures were varied. The second set of topics examined the extent to which a typical steel beam-to-column connection can be reinforced with the help of adhesively bonded CFRP lamellas.
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Kim, Tae-Kyun, Jong-Sup Park, Sang-Hyun Kim, and Woo-Tai Jung. "Structural Behavior Evaluation of Reinforced Concrete Using the Fiber-Reinforced Polymer Strengthening Method." Polymers 13, no. 5 (March 4, 2021): 780. http://dx.doi.org/10.3390/polym13050780.
Full textAbstract:
Reinforced concrete (RC) structures age with time, which results in performance degradation and cracks. These performance degradations do not recover easily, but a performance higher than the existing structures can be expected through reinforcement. There are various reinforcement methods for RC structures. This study selected four reinforcement methods: near-surface mounting (NSM), external prestressing (EP), external bonding (EB), and section enlargement (SE). In the past, steel bars were often used as reinforcements. However, this study uses fiber-reinforced polymer (FRP), which is an alternative to steel bars owing to its high tensile strength, and its non-corrosive and lightweight properties. It is a basic strengthening material, along with a carbon-fiber-reinforced polymer (CFRP) and glass-fiber-reinforced polymer (GFRP) in bar and sheet forms. Various strengthening materials such as a CFRP, GFRP, and prestressing (PS) strand are applied to the NSM, EP, EB, and SE methods, followed by flexural experiments. In addition, changes in the ductility of the RC structures were examined. The concrete EP and near-surface mounting prestressing (NSM(P)) methods have a stiffness that is almost double the non-strengthened specimen. However, because the EP and EB methods are brittle, the NSM(P) method with ductile behavior is considered the most effective.
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Aoki, Yoshio, Goichi Ben, and Yuka Iizuka. "Development and Impact Behaviors of AL Door Guarder Beam Reinforced with CFRP for Side Collision of Automobiles." Key Engineering Materials 334-335 (March 2007): 197–200. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.197.
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Carbon fiber reinforced plastic (CFRP) laminates are used in the wide field, because they have excellent properties of a specific strength and of a specific stiffness. The CFRP has a possibility of weight reduction automotive structures which can contribute to improve mileage and then to reduce Carbon dioxide. On the other hand, the safety of collision should be also made clear in the case of employing the CFRP to automotive structures. In this paper, the Al guarder beam reinforced with the CFRP is examined by an experiment and by a numerical analysis for replacing it to the conventional steel door guarder beam equipped in the automotive door. The experimental relations of impact load to displacement for the Al guarder beams with the different thickness of CFRP showed the good agreement with those of numerical results. From the comparison of these results, the numerical method developed here is quite useful for estimating the impact behaviors of Al guarder beam with CFRP layer.
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Bakar, Mohd Basri Che, Raizal Saifulnaz Muhammad Rashid, Mugahed Amran, Mohd Saleh Jaafar, Nikolai Ivanovicn Vatin, and Roman Fediuk. "Flexural Strength of Concrete Beam Reinforced with CFRP Bars: A Review." Materials 15, no. 3 (February 1, 2022): 1144. http://dx.doi.org/10.3390/ma15031144.
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Conventional reinforced concrete (RC) structures are commonly associated with the corrosion of steel reinforcement. The application of carbon fiber reinforced polymer (CFRP) bars as flexural reinforcement has become a new promising option. This paper presents a state-of-the art flexural strength on concrete beams reinforced with CFRP bars. Concrete compressive and CFRP bar tensile strain, reinforcement ratio, types of surface treatment on CFRP bar and concrete compressive strength were identified as aspects of behavior. Significant findings in the literature had manifested all aspects of behavior that were affecting the flexural strength, deflections and crack characteristics of CFRP RC beams. In addition, the experimental result on 98 specimens of CFRP RC beams from the literature show that ACI 440.1R-15 and CSA S806-12 standards underestimate the ultimate flexural moment capacity of CFRP RC beams. On the other hand, Kara and Ashour predictions are more accurate with the experimental values. Moreover, hotspot research topics were also highlighted for further considerations in future studies.
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Jiang, Jian, Jinwei Jiang, Xiaowei Deng, and Zifeng Deng. "Detecting Debonding between Steel Beam and Reinforcing CFRP Plate Using Active Sensing with Removable PZT-Based Transducers." Sensors 20, no. 1 (December 19, 2019): 41. http://dx.doi.org/10.3390/s20010041.
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Carbon fiber reinforced polymer (CFRP) plates are widely used to retrofit or reinforce steel structures, and the debonding damage between the steel structure and the CFRP plate is a typical failure in strengthening steel structures. This paper proposes a new approach to detecting debonding between a steel beam and a reinforcing CFRP plate by using removable lead zirconate titanate (PZT)-based transducers and active sensing. The removable PZT-based transducers are used to implement the active sensing approach, in which one transducer, as an actuator, is used to generate stress wave, and another transducer, as a sensor, is used to detect the stress wave that propagates across the bonding between the steel beam and the reinforcing CFRP plate. The bonding condition significantly influences the received sensor signal, and a wavelet-packet-based energy index (WPEI) is used to quantify the energy of the received signal to evaluate the severity of debonding between the steel beam and the reinforcing CFRP plate. To validate the proposed approach, experimental studies were performed, and two removable PZT-based transducers were designed and fabricated to detect the debonding between a steel beam and the reinforcing CRFP plate. The experimental results demonstrate the feasibility of the proposed method in detecting the debonding between a steel beam and the reinforcing CFRP plate using removable PZT-based transducers.
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Yoresta, Fengky Satria, Phan Viet Nhut, Daiki Nakamoto, and Yukihiro Matsumoto. "Experimental Investigation on the Buckling Capacity of Angle Steel Strengthened at Both Legs Using VaRTM-Processed Unbonded CFRP Laminates." Polymers 13, no. 13 (July 5, 2021): 2216. http://dx.doi.org/10.3390/polym13132216.
Full textAbstract:
Strengthening steel structures by using carbon fiber reinforced polymer (CFRP) laminates showed a growth trend in the last several years. A similar strengthening technique, known as adhesive bonding, has also been adopted. This paper presented a promising alternative for strengthening steel members against buckling by using vacuum-assisted resin transfer molding (VaRTM)-processed unbonded CFRP laminates. A total of thirteen slender angle steel members (L65x6), including two control specimens, were prepared and experimentally tested. The specimens were strengthened only at both legs and were allowed to buckle on their weak axes. The test showed that the unbonded CFRP strengthening successfully increased the buckling capacity of the angle steel. The strengthening effect ranged from 7.12% to 69.13%, depending on various parameters (i.e., number of CFRP layers, CFRP length, and angle steel’s slenderness ratio). Flexural stiffness of the CFRP governed the failure modes in terms of location of plastic hinge and direction of buckling curvature.
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VIEIRA, M. M., A. R. S. SANTOS, A. M. MONT'ALVERNE, L. M. BEZERRA, L. C. S. MONTENEGRO, and A. E. B. CABRAL. "Experimental analysis of reinforced concrete beams strengthened in bending with carbon fiber reinforced polymer." Revista IBRACON de Estruturas e Materiais 9, no. 1 (February 2016): 123–52. http://dx.doi.org/10.1590/s1983-41952016000100008.
Full textAbstract:
The use of carbon fiber reinforced polymer (CFRP) has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference) and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.
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Narmashiri, Kambiz, Mohd Zamin Jumaat, and Nor Hafizah Ramli Sulong. "Failure Modes of CFRP Flexural Strengthened Steel I-Beams." Key Engineering Materials 471-472 (February 2011): 590–95. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.590.
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This paper presents the experimental and numerical studies on the flexural strengthened steel I-beams by using Carbon Fiber Reinforced Polymer (CFRP) strips. Nowadays, strengthening existing steel structures by using CFRP has been widely interested. One of the common usages of CFRP to strengthen steel beams is the flexural upgrading. In this case, CFRP strips are pasted on the tensile flange to improve flexural behaviors. The problems that are frequently reported for CFRP strengthened steel beams are the debonding, delaminating (peeling), and splitting. Identification these failure modes are essential to provide an appropriate level of safety for strengthened steel beams. To investigate the CFRP failure modes, four strengthened steel I-beams were chosen. The CFRP plates with different thicknesses in single and double (splice) layers were used. Both experimental test (four-points bending test) and numerical simulation (full 3D simulation with ANSYS) were employed. The incremental loading was applied until failure while deformations in the critical regions were recorded. The results reveal that for the CFRP flexural strengthened steel beams the following failure modes occurred: (a) debonding at the CFRP plate tips, (b) debonding below point loads, (c) delaminating at the ends of CFRP plate, and (d) splitting below point loads. The sequence of failure modes depended on the specifications of CFRP plate. Some recommendations are provided to overcome/retard these failures.
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Li, Anbang, Hao Wang, Han Li, Deliang Kong, and Shanhua Xu. "Estimation of Bond Strength and Effective Bond Length for the Double Strap Joint between Carbon Fiber Reinforced Polymer (CFRP) Plate and Corroded Steel Plate." Polymers 14, no. 15 (July 29, 2022): 3069. http://dx.doi.org/10.3390/polym14153069.
Full textAbstract:
In this paper, we examine the development of the estimation models of bond strength and effective bond length for a double strap joint between carbon fiber reinforced polymer (CFRP) plate and corroded steel plate. The experimental study on the bond behavior between CFRP plate and corroded steel plate is summarized first and the analytical interfacial bond–slip model for CFRP plate externally bonded to corroded steel plate is proposed. Based on the theoretical stress analysis for the CFRP plate–corroded steel plate double-lap joint, the piecewise expressions of the interfacial shear stress and the normal peel stress of the interface between CFRP plate and corroded steel plate were established. The estimation models of the bond strength and the effective bond length for the double strap joint between the CFRP plate and the corroded steel plate were consequently developed on the basis of interfacial stress distribution equations and the stress boundary conditions. The comparison between the predicted and experimental results indicated that the proposed models could be adopted to predict the bond strength and effective bond length for the CFRP plates externally bonded to corroded steel substrates with reasonable accuracy. The proposed estimation models are expected to provide meaningful references and essential data for the reliable application of CFRP strengthening system to the performance improvement of corroded steel structures.
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Zeng, Xian Tao, and Zhen Hua Ren. "Quasi-Plane-Hypothesis of Strain Coordination for RC Beam Strengthened with Near-Surface Mounted Carbon Fiber Reinforced Plastic Bar or Helical Rib Bar." Advanced Materials Research 243-249 (May 2011): 541–45. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.541.
Full textAbstract:
Rehabilitation of existing structures with fiber reinforced plastics (FRP) has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high stiffness-to-weight ratio. This paper presents strain coordination results of (two groups)6 reinforced concrete beams strengthened with different methods including near-surface mounted CFRP bar and helical rib rebar in order to investigate the strain coordination of CFRP bar or HR bar and steel rebar of RC beam. Because there is relative slipping between RC beam and bar, the strain of CFRP or HR bar and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height (h0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis, the strain of CFRP or HR and steel rebar satisfies the equation:εCH=βεsteel , the value of β is equal to 1.0～1.2 according to the test results.
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Gong, Yongzhi, Yingjie Shan, Yuyuan Wu, Liping Wang, Xiaojie Liu, and Faxing Ding. "Bond Properties of Carbon Fiber Reinforced Polymer and Corrosion-Cracked Reinforced Concrete Interface: Experimental Test and Nonlinear Degenerate Interface Law." Materials 14, no. 18 (September 15, 2021): 5333. http://dx.doi.org/10.3390/ma14185333.
Full textAbstract:
Existing experimental research on bond properties of the interface between Carbon Fiber Reinforced Polymer (CFRP) and damaged concrete is limited, although CFRP strengthening technology has been widely used for corroded reinforced concrete structures. This work investigated the bond behavior of CFRP to the corrosion-cracked concrete interface, in which three factors were considered for experimentation, including corrosion degree, concrete strength and concrete cover thickness. The tests were conducted by developing a self-balancing double shear lap test device. In addition, a corrosion scene was provided simultaneously to simulate the external corrosion environment. The results showed that three peeling modes of CFRP sheets were observed with respect to corrosion degrees of the steel bars. The effects of the three factors on the stripping bearing capacity and effective bond length of CFRP sheets were discussed by systematic parametric analysis. Finally, a nonlinear degenerate law of CFRP-to-concrete interface considering the corrosion degree was improved and verified in this study.
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Lu, Shao Wei, and Huai Qin Xie. "Real-Time Monitoring and Simulating the Load Effects of Smart” CFRP- Strengthened RC Beams." Key Engineering Materials 324-325 (November 2006): 129–32. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.129.
Full textAbstract:
FBG sensors have excellent compatibility with CFRP sheets. It can be embedded into CFRP sheets to fabricate the “smart” CFRP. This paper conducted 4 pieces of CFRP-strengthened RC beams, and embedded FBG sensors and strain gauges on the steel, concrete and CFRP of RC beams. The simulation program of flexural load effects of RC beams is compiled based on the theory of reinforced concrete and ANSYS. The experimental results show that during the load bearing process: the compatibility is perfect between FBG sensor and CFRP; the linear relationship of FBG sensor and strain gauge is uniform; the numerical simulation results and the measuring results of strains of tensile steel and compressive concrete, the load agree well. So utilizing the smart CFRP strengthened RC structures can realize the dual function of advanced rehabilitation and real-time health monitor and evaluation.