• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.605-610
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• 1997

An experimental investigation was conducted to examine the feasibility of Carbon Fiber Sheet(CFS), a kind of high strength fiber, for a repair and reinforcement method of concrete structures. The experimental program included tests of flexural beams different in wrapping method and amount of CFS. The beams were subjected to monotonic loading. Although the flexural strength for concrete members increases with wrapping methods of CFS., the reduction factor due to the distribution, amount bond of CFS should be completely examined. This study approached the effectiveness and application of CFS, along with reinforcement effects of CFS on reinforced concrete beams through tests. Test results indicated that the increase in the number of CFS layer caused the increase in strength of beams in strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1073-1078
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• 2000

This study is to investigate the effect of construction element such as the number of CFS ply, curing temperature, splice length and curing periods on the mechanical properties of Carbon Fiber Sheet (CFS). Through the tensile tests of CFS specimens, it can be said that the reduction factor stemmed from the number of CFS ply must be considered in the calculation of the design tensile strength of CFS. Also, the minimum splice length of CFS and curing period in $20^{\circ}C$ to satisfy the standard tension strength of CFS are over 5cm and after 3days, respectively. The measuring error of epoxy resin have no effect to tension strength of CFS until $\pm$20% error.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.201-208
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• 1998

To observe the confinement effects of Carbon Fiber Sheet(CFS) on the high-strength R/C short columns, Fifteen specimens with CFS were manufactured and tested under uni-axial compressive load. Major variables of this study are amount, spacing, type of CFS and amount of transverse steel. Increasing the amount of transverse steel and CFS, compressive strength and axial rigidity is improved. R/C columns with transverse steel and CFS exhibited less axial stress than columns with only CFS. From the test results, it is shown that the area confined with transverse steel and CFS is considerably important to evaluate axial stress of R/C short columns.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.203-211
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• 1999

This study is to examine the feasibility of carbon fiber sheet(CFS), a kind of fiber reinforced plastic(FRP), for a repair and reinforcement of R/C beams. The flexural strength of R/C beams, that were preloaded and then the cracks were repaired, maintains that of the uncracked R/C beams. The flexural strength of R/C beams increases with the reinforcement of CFS. In order to practically apply the repair and reinforcement method, further research is needed for the distribution, amount, and bond of CFS. In this study, an experiment was conducted for R/C beams reinforced with CFS, for various wrapping method and amounts of CFS. Experimental results showed the wrapping method increasing the bond area and amount of CFS layer caused the increase in the strength of the beams. It is found that the strength of CFS should be used as 70% of the maximum strength in retrofitting reinforced concrete beams in evaluating flexural capacity on the basis of ultimate strength design method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.125-133
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• 2007

External confinement by CFS (Carbon Fiber Sheet) is a very effective retrofit method for the reinforced concrete columns subject to either static or seismic loads. For the reliable and cost-effective design of CFS, an accurate stress-strain curve is required for CFS-confined concrete. In this paper, uniaxial compression test on short RC column with circular section was performed. To evaluate the effect of confinement on the stress-strain relationship of CFS-confined concrete, CFS area ratio, spiral area ratio, and concrete compressive strength are considered as the test variables. Experiment results indicate that CFS jacketing significantly enhances strength and ductility of concrete. In addition, the CFS-jacketed specimens with the spiral steel show the lower load increasement ratio than those without the spiral steel.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.621-626
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• 1998

In this study, the analytic model of concrete column strengthened with CFS(carbon fiber sheets) for obtaining P-M interaction is presented. Firstly, an algorithm to evaluate accurate behavior of CFS is presented using laminate theory. Stress-strain model of CFS is presented based on the results of this algorithm. Secondly, an algorithm to evaluate stress-strain relationship of concrete column confined with CFS is presented. In order to evaluate the reliability of these algorithms, the results of analysis are compared with experimental data. Lastly, section analysis is performed by using constitutive equations of materials. As a result, P-M interaction curve of the column strengthened is obtained and the strengthening effects of CFs are analyzed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.573-578
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• 1998

Recently, the Carbon Fiber Sheet(CFS) is widely used to strengthen the RC beams. But the behaviour of the RC beams which is strengthened with the CFS is not clearly defined yet. So, in this study we experimented with simply supported RC beams strengthened with the CFS, under monotonic loads. We included three parameters in this experiment which are the number of the sheets, the length of the sheets, and the existence of the anchor bolts. We investigated the strength effect of the RC beams by adhesion of the CFS, and the strengthening effect of CFS as to the respective parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.727-732
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• 2001

External Confinement of concrete in CFS enhances strength and ductility of concrete columns. This paper presents the test results on the study of reinforced concrete columns strengthened with carbon fiber sheets. The purpose of this research is to evaluate the CFS confinement characteristics of square reinforced concrete columns and the CFS efficiency. The tests were performed with different lateral reinforcement ratios, CFS reinforcement ratios and concrete strength. Test results were characterized according to maximum loads and lateral strain of CFS.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.697-702
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• 1997

This study presents test results of RC beams strengthened by carbon fiber sheet (CFS) or carbon fiber reinforced plastics (CFRP) for increasing shear resistance. Fifteen specimens were tested, and the test was performed with different parameters including the type of strengthening materials (CFS, CFRP), shear-strengthening methods (wing type, jacket type, strip type), strip-spacing, strengthening direction of FRP. The results show that shear-damaged RC beams strengthened by either CFS or CFRP have more improved the shear capacity.

• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.51-59
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• 2013

The use of light-gauge steel framing in low-rise commercial and industrial building construction has experienced a significant increase in recent years. In such construction, the wall framing is an assembly of cold-formed steel (CFS) studs held between top and bottom CFS tracks. Current construction methods utilize heavy hot-rolled steel sections, such as steel angles or hollow structural section tubes, to transfer the load from the end seats of the floor joist and/or from the load-bearing wall studs of the stories above to the supporting load-bearing wall below. The use of hot rolled steel elements results in significant increase in construction cost and time. Such heavy steel elements would be unnecessary if the concrete slab thickening on top of the CFS wall can be made to act compositely with the CFS track. Composite action can be achieved by attaching stand-off screws to the track and encapsulating the screw shank in the deck concrete. A series of experimental studies were performed on full-scale test specimens representing concrete/CFS flexural elements under gravity loads. The studies were designed to investigate the structural performance of concrete/CFS simple beams and concrete/CFS continuous headers. The results indicate that concrete/CFS composite flexural elements are feasible and their structural behavior can be modeled with reasonable accuracy.