• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.113-120
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• 2007

A new material was tested and its applicability was investigated so as to give the capability of self-diagnosis of fracture in composite mortar. In the research for giving self-diagnosis capability, conductive mortar intermixed with cokes and carbon fiber powder(milled carbon fiber) was developed and its using for self-diagnosis material was proposed. Then after examining change in the value of electric resistance and AE characteristics before and after the occurrence of cracks at each weight-stage, the relationships of each factors were analyzed. As the results, it can be recognized that a new composite material with cokes and carbon fiber powder(milled carbon fiber) can be applied for self-diagnosis of fracture in mortar specimen.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.133-135
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• 2006

We propose and fabricate a novel fiber optic sensor for the detection of abnormal structural signals from various constructions. It's advantages are highly sensitive. small in dimension and electro-magnetic immune. Since this sensor was simply constructed with a single-mode fiber at infra-red wavelength and a laser-diode with the wavelength of 625 nm, the modes in the end of the optical fiber were not show as Gaussian distributed. So, we used the change of the mode distribution to get the sensor output by the external abnormal effect of structures. We investigated the resonance by performing the bending test of an aluminum beam attached with the fiber sensor. In the test, we could obtained a feasible signal to sense the abnormal condition of structures.

• Computational Structural Engineering
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• v.23 no.5
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• pp.42-50
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• 2010

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.587-596
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• 2009

The fiber bridging model is the crucial factor to predict or analyze the tensile behavior of fiber reinforced cementitious composites. This paper presents the fiber bridging constitutive law considering the distribution of fiber inclined angle and the number of fibers in engineered cementitious composites. The distribution of fiber inclined angle and the number of fibers are measured and analyzed by the image processing technique. The fiber distribution are considerably different from those obtained by assuming two- or three-dimensional random distributions for the fiber inclined angle. The simulation of the uniaxial tension behavior was performed considering the distribution of fiber inclined angle and number of fibers measured by the sectional image analysis. The simulation results exhibit multiple cracking and strain hardening behavior that correspond well with test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.102-108
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• 2010

The main objective of this study was to evaluate the effect of recycled PET (RPET) fiber made from waste PET bottles to examine application on concrete member. To evaluate the reinforcement effect of RPET fiber in concrete member, experimental tests were performed, such as mechanical property tests (compressive strength, modulus of elasticity and splitting tensile strength) and drying shrinkage test. In mechanical property tests, compressive strength and modulus of elasticity in concrete mixed with RPET fiber gradually decreased, but splitting tensile strength gradually increased as volume fraction of fiber increased. In drying shrinkage test, free drying shrinkage increased. In restrained case, in contrast, crack occurrence was delayed because of tensile resistance increase by RPET fiber. The comparison of RPET and PP fiber added concrete specimen's properties showed that two materials had similar properties. In conclusion, RPET fiber is an alternative material of PP fiber, even finer for its excellence in eco-friendliness due to the recycling of waste PET bottles and its possible contribution to the pollution declination.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.237-248
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• 2011

Tensile softening characteristics play an important role in the structural behavior of steel fiber-reinforced ultra high performance concrete. Tension softening modeling and numerical analysis method are necessary for the prediction of structural performance of steel fiber-reinforced concrete. The numerical method to predict the flexural behavior is proposed in this study. Tension softening modeling is carried out by using crack equation based on fictitious crack and inverse analysis in which load-crack opening displacement relationship is considered. Thereafter material modeling is performed considering tension softening. The comparison of moment-curvature curves of the numerical analysis results with the test results indicates a reasonable agreement. Therefore, the present numerical results prove that good prediction of flexural behavior of steel fiber-reinforced ultra high performance concrete beams can be achieved by employing the proposed method.

• Structural Engineering and Mechanics
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• v.81 no.3
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• pp.281-292
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• 2022

This study aimed to analyze the dynamic punching shear performance of slab-column joints under cyclic loads with the use of double-hooked end (5D) steel fibers. Structural systems such as slab-column joints are widely found in infrastructures. The susceptibility to collapse of such structures when submitted to seismic loads is highly dependent on the structural performance of the slab-column connections. For this reason, the punching capacity of reinforced concrete (RC) structures has been the subject of a great number of studies. Steel fibers are used to achieve a certain degree of ductility under seismic loads. In this context, 5D steel hooked fibers provide high levels of fiber anchoring, tensile strength and ductility. However, only limited research has been carried out on the performance under cyclic loads of concrete structural members containing steel fibers. This study covers this gap with experimental testing of five different full-scale subassemblies of RC slab-column joints: one without punching reinforcement, one with conventional punching reinforcement and three with 5D steel fibers. The subassemblies were tested under cyclic loading, which consisted of applying increasing lateral displacement cycles, such as in seismic situations, with a constant axial load on the column. This set of cycles was repeated for increasing axial loads on the column until failure. The results showed that 5D steel fiber subassemblies: i) had a greater capacity to dissipate energy, ii) improved punching shear strength and stiffness degradation under cyclic loads; and iii) increased cyclic loading capacity.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2000.10a
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• pp.59.1-59
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• 2000

No Abstract.See Full-text

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.635-638
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• 2007

In this paper, we described the fundamental concepts of proposed structural health monitoring system for Uldolmok Tidal Current Power Plant focusing on the use of smart sensors including fiber bragg grating sensors and macro fiber composite sensors. The structural health monitoring system can play an important role to maintain the structural safety for offshore structures like as bridges and high-rise buildings. In the case of tidal current power plant, the monitoring system is much more important since the structures are usually constructed at the site with severer environmental loadings such as high current speed.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.7-15
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• 2005

Currently, the structural material, namely glass fiber reinforced polymer (GFRP) is focused on innovative structure due to lightness, excellent workability and noncorrosive characteristics, etc. However, the lack of GFRP connection technology produces only an imitation of steel and wood structures. This uses univentive design principles as well as unsuitable material applications, causes tons of surplus of materials to be wasted, and results in uneconomical structures, because the characteristics between steel and GFRP are completely different. Thus, this research develops the new, innovative GFRP connection system with considerations of the characteristics of GFRP and adopts it to a mobile und modular membrane pavilion.