• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.101-111
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• 1998

This study presents test results of RC beams strengthened by carbon fiber sheet(CFS), carbon fiber reinforced plastics(CFRP) or glass fiber reinforced plastics(GFRP) for increasing shear resistance. Nineteen specimens were tested, and the test was performed with different parameters including the type of strengthening materials(CFS, GFRP, CFRP), shear-strengthening methods(wing type, jacket type, strip type), strip-spacing, strengthening direction of FRP. The test results show that shear-damaged RC beams strengthened by FRP(CFS, GFRP, CFRP) have more improved the shear capacity. The mathematical model based on plastic theory was also developed to predict shear strength of shear-damaged RC beams strengthened by FRP. The predictions using the mathematical model. are agreed with the observations from the observed shear strengths for 19 test beams.

• Tribology and Lubricants
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• v.12 no.1
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• pp.6-14
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• 1996

Experimental investigation on the tribological behavior of fiber-reinforced plastics(FRP) has been studied. It is shown that the frictional behavior of carbon FRP depends on the fiber-orientation while glass FRP does not. The friction coefficient values for carbon FRP were about 0.8, 0.3, and 0.2 for normal, 45$^{\circ}$ and 0$^{\circ}$ sliding directions respectively. Also, the applied load was found to affect the friction coefficient. In the case of this work, 50 gf resulted in the highest value while 200 gf resulted in the lowest value. The friction coefficients for higher loads fell in between the two extreme values.

• Wind and Structures
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• v.3 no.2
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• pp.83-96
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• 2000

Due to their high corrosion and chemical resistance, fiber reinforced plastics (FRP) are becoming widely used as the main structural material for industrial chimneys. However, no national code currently exists for the design of such type of chimneys. The purpose of this study is to investigate analytically the response of FRP chimneys to wind loads. The classical lamination theory is used to substitute the angle-ply laminate of a FRP chimney with an equivalent orthotropic material that provides the same stiffness. Dynamic wind loads are applied to the equivalent chimney to evaluate its response to both along and across wind loads. A parametric study is then conducted to identify the material and geometric parameters affecting the response of FRP chimneys to wind loads. Unlike the across-wind response, the along-wind tip deflection is found to be highly dependent on the angle of orientation of the fibers. In general, the analysis shows that FRP chimneys are very vulnerable to across-wind oscillations resulting from the vortex shedding phenomenon.

• Steel and Composite Structures
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• v.2 no.1
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• pp.1-20
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• 2002

Fiber-Reinforced Plastics (FRP) have received significant attention for use in civil infrastructure due to their unique properties, such as the high strength-to-weight ratio and stiffness-to-weight ratio, corrosion and fatigue resistance, and tailorability. It is well known that FRP wraps increase the load-carrying capacity and the ductility of reinforced concrete columns. A number of researchers have explored their use for seismic components. The application of concern in the present research is on the use of FRP for corrosion protection of reinforced concrete columns, which is very important in cold-weather and coastal regions. More specifically, this work is intended to give practicing engineers with a more practical procedure for estimating the strength of a deficient column rehabilitated using FRP wrapped columns than those currently available. To achieve this goal, a stress-strain model for FRP wrapped concrete is proposed, which is subsequently used in the development of the moment-curvature relations for FRP wrapped reinforced concrete column sections. A comparison of the proposed stress-strain model to the test results shows good agreement. It has also been found that based on the moment-curvature relations, the balanced moment is no longer a critical moment in the interaction diagram. Besides, the enhancement in the loading capacity in terms of the interaction diagram due to the confinement provided by FRP wraps is also confirmed in this work.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.46-51
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• 2014

Increasing of waste FRP (fiber reinforced plastics) has caused environmental problems. Recently, the technology of making fibers from waste FRP, which can be used to reinforce the concrete, was developed and the reinforced concretes were tested to study the structural performance. The purpose of this study is to investigate the effect of the powder, obtained together with F-fiber from the waste FRP, on the compressive strength and the fire resistance performance as in the high strength concrete. Strength tests show that the use of recycled FRP powder does not reduce the compressive strength of high strength concrete if the volume fraction of FRP powder is less than 0.7%. Electric furnace test results also show that the use of recycled FRP powder may increase the fire resistance performance of high strength concrete significantly.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.163-168
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• 1990

This study shows both through experiment and based on theory the reinforcement effectiveness when using FRP(Fiber Reinforced Plastics) as a means of reinforcing the concrete of the deteriorated concrete. Non-deteriorated concrete and deteriorated concrete which is deteriorated by freezing and thawing are made three type specimens (non-reinforced) concrete beam, one layer FRP reinforced concrete beam, two layer FRP reinforced concrete beam) for this purpose. Bending strength and cracking load ratio is measured by bending test.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.219-226
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• 2020

Nondestructive testing is one of the most commonly used quality inspection methods for evaluating ship structures. However, accurate evaluation is dif icult because various composite materials, such as reinforcements, resin, and fiber-reinforced plastics (FRPs), are used in hulls, and manufacturing quality differences are likely to exist owing to the fabrication environment and the skill level of workers. This possibility is especially true for FRP ships because they are significantly thicker than other structures, such as automobiles and aircraft, and are mainly manufactured using the hand lay-up method. Because the density of a material is a critical condition for ultrasonic inspection, in this study, a hull plate was selected from a vessel manufactured using e-glass fiber, which is widely used in the manufacture of FRP vessels with the weight fraction of the glass content generally considered. The most suitable ultrasonic testing conditions for the glass FRP hull plate were investigated using a pulse-echo ultrasonic gauge. A-scans were performed with three probes (1.00, 2.25, and 5.00 MHz), and the results were compared with those of the hull plate thickness measured using a Vernier caliper. It was found that when the probe frequency was higher, the eco-pulse velocity of the receiver had to be lowered to obtain accurate measurement results, whereas fewer errors occurred at a relatively low probe frequency.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.547-552
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• 2009

When fiber reinforced plastics (FRP) products are manufactured, dust and odor materials are inevitably generated in a workplace. To improve the bad condition of the workshop, we developed the Hybrid Bag Filter attached activated carbon fiber (ACF) and installed the system at two companies producing FRP goods. In order to raise the efficiency of dust collection, we set the ducts both on the ceiling and at the bottom of the wall and according to the circumstances of the workshop's space, moving dust collector also adopted as a different type of flexible duct. Pulse Jet Type Bag Filter is also equipped to operate the system more effectively, for the improved fine environment because of high dust removal efficiency. Finally, we investigated the removal tendency of the dust and odor when operating the System of Hybrid Bag Filter.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.252-258
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• 2012

A study of terahertz waves was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The terahertz systems were consisted of time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both non-conducting polymeric composites and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. The CFRP (Carbon fiber reinforced plastics) laminates were utilized for confirming the experimentation in the terahertz NDE. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field direction of the terahertz waves and the intervening fiber directions. A refractive index (n) was defined as one of mechanical properties; so a method was obtained in order solve the "n" in the material with non-conductivity. The usefulness and limitations of terahertz radiation are investigated for the NDE of FRP composites.

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.117-117
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• 1996