• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.34-34
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• 2010

This paper describes effect of the bending deformation of high voltage composite bushing with winding tension. The composite bushing can be formed, by adding silicone rubber sheds to a tube of composite materials. The FRP tube is internal insulating part of a composite bushing and is designed to ensure the mechanical characteristics. Generally the properties of FRP tube can be influenced by the winding angle, wall thickness and winding tension. As winding tension is increased glass contents was increased in the range of 70.4~76.6%. In the bending test, winding tension is increased residual deflection was decreased in the range of 14.0~12.2 mm.

• Steel and Composite Structures
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• v.13 no.3
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• pp.277-293
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• 2012

The interaction between steel tube and concrete core is the key design considerations for concrete-filled steel tube columns. In a concrete-filled steel tube (CFST) column, the steel tube provides confinement to the concrete core which permits the composite action among the steel tube and the concrete. Due to construction faults and plastic shrinkage of concrete, the debonding separation at the steel-concrete interface weakens the confinement effect, and hence affects the behaviour and bearing capacity of the composite member. This study investigates the axial loading behavior of the concrete filled circular steel tube columns with debonding separation. A three-dimensional nonlinear finite element model of CFST composite columns with introduced debonding gap was developed. The results from the finite element analysis captured successfully the experimental behaviours. The calibrated finite element models were then utilized to assess the influence of concrete strength, steel yield stress and the steel-concrete ratio on the debonding behaviour. The findings indicate a likely significant drop in the load carrying capacity with the increase of the size of the debonding gap. A design formula is proposed to reduce the load carrying capacity with the presence of debonding separation.

• Steel and Composite Structures
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• v.43 no.2
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• pp.257-270
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• 2022

Recycled aggregate concrete (RAC) is rarely used in load-carrying structural members. To widen its structural application, the compressive behavior of a promising type of composite column, steel-fiber reinforced polymer (FRP) double-tube confined RAC column, has been experimentally and analytically investigated in this study. The objectives are the different performance of such columns from their counterparts using natural aggregate concrete (NAC) and the different mechanisms of the double-tube and single-tube confined concrete. The single-tube confined concrete refers to that in concrete-filled steel tubular (CFST) columns and concrete-filled FRP tubular (CFFT) columns. The test results showed that the use of recycled coarse aggregates (RCA) affected the axial load-strain response in terms of deformation capacity but such effect could be eliminated with the increasing confinement. The composite effect can be triggered by the double confinement of the steel and carbon FRP (CFRP) tubes but not by the steel and polyethylene terephthalate (PET) FRP tubes. The proposed analysis-oriented stress-strain model is capable to capture the load-deformation history of such steel-FRP double-tube confined concrete columns under axial compression.

• Steel and Composite Structures
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• v.12 no.3
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• pp.261-273
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• 2012

This study proposes and examines a circular composite bridge pier for seismic resistance. The axial and flexural strengths of the proposed bridge pier are provided by the longitudinal reinforcing bars and the concrete, while the transverse reinforcements used in the conventional reinforced concrete pier are replaced by the steel tube. The shear strength of this composite pier relies on the steel tube and the concrete. This system is similar to the steel jacketing method which strengthens the existing reinforced concrete bridge piers. However, no transverse shear reinforcing bar is used in the proposed composite bridge pier. A series of experimental studies is conducted to investigate the seismic resistant characteristics of the proposed circular composite pier. The effects of the longitudinal reinforcing bars, the shear span-to-diameter ratio, and the thickness of the steel tube on the performance of strength, ductility, and energy dissipation of the proposed pier are discussed. The experimental results show that the strength of the proposed circular composite bridge pier can be predicted accurately by the similar method used in the reinforced concrete piers with minor modification. From these experimental studies, it is found that the proposed circular composite bridge pier not only simplifies the construction work greatly but also provides excellent ductility and energy dissipation capacity under seismic lateral force.

• Steel and Composite Structures
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• v.12 no.2
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• pp.167-181
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• 2012

Ultra high performance cementitious composite material is applied to the design of multifunctional permanent form for bridge pier in this paper. The basic properties and calculating constitutive model of ultra high performance cementitious composite are introduced briefly. According to momental theory of thin-walled shell, the analytical solutions of structural behavior parameters including circumferential stress, longitudinal stress and shear stress are derived for UHPCC thin-walled circular tube. Based on relevant code of construction loads (MHURD of PPC 2008), the calculating parameter expression of construction loads for UHPCC thin-walled circular tube is presented. With geometrical dimensions of typical pier, the structural behavior parameters of UHPCC tube under construction loads are calculated. The effects of geometrical parameters of UHPCC tube on structural behavior are analyzed and the design advices for UHPCC tube are proposed. This paper shall provide a scientific reference for UHPCC permanent form design and UHPCC hybrid structure application.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.1-7
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• 2003

The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both the experimental and analytical investigations of axial behavior of large-scale square concrete columns confined by carbon composite tube are presented. The specimens are filament-wound carbon composite with 90$^{\circ}$+30$^{\circ}$, 90$^{\circ}$+45$^{\circ}$ winding angle respect to longitudinal axis of tube. The instrumented large-scale concrete-filled composite tubes(CFCT) are subjected to monotonic axial loads exerted by 10,000kN UTM. The influence of winding angle, thickness of tube on stress-strain relationships of the confined columns is identified and discussed. Proposed equations to predict both the strength and ductility of confined columns by carbon composite tube demonstrate good correlation with test data obtained from large-scale specimens.

• Advances in concrete construction
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• v.8 no.4
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• pp.335-349
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• 2019

To investigate the axial compressive performance of the recycled aggregate concrete (RAC) filled glass fiber reinforced polymer (GFRP) tube and profile steel composite columns, static loading tests were carried out on 18 specimens under axial loads in this study, including 7 RAC filled GFRP tube columns and 11 RAC filled GFRP tube-profile steel composite columns. The design parameters include recycled coarse aggregate (RCA) replacement percentage, profile steel ratio, slenderness ratio and RAC strength. The failure process, failure modes, axial stress-strain curves, strain development and axial bearing capacity of all specimens were mainly analyzed in detail. The experimental results show that the GFRP tube had strong restraint ability to RAC material and the profile steel could improve the axial compressive performance of the columns. The failure modes of the columns can be summarized as follow: the profile steel in the composite columns yielded first, then the internal RAC material was crushed, and finally the fiberglass of the external GFRP tube was seriously torn, resulting in the final failure of columns. The axial bearing capacity of the columns decreased with the increase of RCA replacement percentage and the maximum decreasing amplitude was 11.10%. In addition, the slenderness ratio had an adverse effect on the axial bearing capacity of the columns. However, the strength of the RAC material could effectively improve the axial bearing capacity of the columns, but their deformability decreased. In addition, the increasing profile steel ratio contributed to the axial compressive capacity of the composite columns. Based on the above analysis, a formula for calculating the bearing capacity of composite columns under axial compression load is proposed, and the adverse effects of slenderness ratio and RCA replacement percentage are considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.493-494
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• 2008

During the last years hollow core insulators started their success story in the field of high voltage engineering for electrical apparatus, substituting porcelain insulators. The termination, also named top and bottom fittings are used for the connection to the rest of the electrical apparatus. The top and bottom flange are attached to the composite to transmit mechanical load and also ensure the gas tightness. They are bonded by epoxy glue with a glass transition temperature of about $130^{\circ}C$-$150^{\circ}C$ the glass reinforced epoxy tube of filament winding. This paper describes the results of a study on the bonded joints of fiber reinforced epoxy tube and cast aluminum. This suggests that surface roughness and glue types play an important role in evaluating of gas sealing capability on the flange and fiber reinforced epoxy tube in the composite hollow bushing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.390-391
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• 2009

Recently, composite hollow bushings have been increasingly employed mainly from the various characteristics. Composite bushings are superior to porcelain bushings in several respects, including lighter weight, better anti-pollution and anti-explosion properties, and easer manufacturing. This paper deals with the optimal thermal fitting for improved tightness characteristics of composite bushing. Two types of composite bushings were fabricated. For optimal fitting process, it is necessary using adhesive and designed internal structure of flange and FRP tube. In this study, for improved tightness characteristics of composite bushing has prominence and interface tolerance of flange and FRP tube. From FE-SEM analysis the adhesive layers were different with interface tolerance, sample 1 and 2 which have respective about $120{\mu}m$ and $50{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.378-379
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• 2008

Recently, composite hollow bushings have been increasingly employed mainly from the various characteristics. Composite bushings are superior to porcelain bushings in several respects, including lighter weight, better anti-pollution and anti-explosion properties, and easer manufacturing. Filament wound GRP tubes which have various winding angle were manufactured by using a filament winding machine. This paper will show some design issues and winding condition for composite bushing. And, results show that the winding condition of composite GRP tubes can be used to improved their bending strength and pressure, For bending and pressure tested, tubes with the hybrid winding pattern show higher strength than those of unit winding pattern. Also, the influence of absorption was evaluated through such as measurement of the dye penetration test and water diffusion test, also aspects of surface state using scanning electron microscopy.