• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.129-139
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• 2016

Cast-in-place concrete-filled hollow PC (HPC) columns are used to reduce lifting load of heavy-weight PC columns and to improve the structural integrity of joints. In the present study, a new type of HPC column was proposed to improve the productivity and structural integrity of the concrete. To form the hollow PC columns, a permanent inner form was prefabricated using structural deck plates and penetrated lateral bars. Half-scale specimens of four HPC columns were tested under combined axial compression and lateral cyclic loading to evaluate the seismic resistance. In the design of test specimens, various parameters such as the spacing of lateral re-bars, the use of steel fiber, and the thickness of PC cover were considered. The test results showed that the proposed HPC columns generally exhibited satisfactory load-carrying capacity and deformation capacity without brittle failure of PC. If closely spaced hoops or fiber reinforcements are used for PC, the deformation capacity can be improved further by restraining PC spalling.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.711-722
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• 2008

Existing tube for concrete filled tubular structure is made through welding of four plates irrespective of tube thickness, so production performance is poor and special welding technique is needed to weld the internal diaphragm and through the diaphragm. Therefore, through manufacturing by cold forming development of beam to column connections that is no welding in position of stress concentration is needed. In this study the proposal of beam to column connections details and to making tube specimens by method of bending steel plates, we want to know the compositeeffect between internal anchor and concrete by processing on stress distribution and internal force evaluation of concrete filled tube beam to column connections with a variable of flange welding existence between column and beam, welding quantity between column and diaphragm, existence of concrete in tube, column with diaphragm and general column.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.89-98
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• 2007

The purpose of this study is to experimentally evaluate the structural behavior of built-up type column consisted of angles and y-shape steel sheet forms for filling concrete. This column for minimizing form working and reinforcement placing is able to improve capacity of construction and reduce the term of works. Thirteen 1/3 scaled columns were fabricated. The main variables are 1) effect of angles and y-shape steel sheets of fabricated columns, 2) slenderness of column, 3) eccentricity of column. The results show that the experimental capacity of built-up type column is similar to theoretical one by reinforcement concrete design code. The maximum loads increase according to the rate of angle to cross section of column.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.1-8
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• 2003

In locations where the cost of concrete is relatively high or in situations where the weight of concrete members has to be kept to a minimum, it may be more economical to use hollow reinforced concrete vertic al members. Hollow reinforced concrete colun-ms with a low axial load, a moderate longitudinal steel percentage and a reasonably thick wall were found to perform in a ductile manner at the flexural strength, similar to solid columns. Hollow reinforced concrete columns with a high axial load, a high longitudinal steel percentage, and a thin wall were found, however, to behave in a brittle manner at the flexural strength, since the neutral axis is forced to occur away from the inside face of the tube towards the section centroid and, as a result, crushing of concrete occurs near the unconfined inside face of the section. If, however, a steel tube is placed near the inside face of a circular hollow column, the column can be expected not to fail in a brittle manner through the disintegration of the concrete in the compression zone. A design recommendation and example through the moment-curvature analysis program for curvature ductility are herein presented. A theoretical moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted, providing that the stress-strain relation for the concrete and steel are known. In this paper, a unified stress-stain model for confined concrete by Mander is developed foi members with circular sections.

• Magazine of the Korea Concrete Institute
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• v.24 no.5
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• pp.41-45
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• 2012

• Explosives and Blasting
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• v.25 no.2
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• pp.1-10
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• 2007

In this paper, the 1/5 scale models of the reinforced concrete colunms were designed and fabricated. The influence of the number of blasting holes on the exposed length of steel bars and vertical load was investigated. The relation between the length of steel bar and the number of blasting holes was examined by performing the blast tests considering the vertical load on the scaled reinforced concrete columns. Weight of scaled column models by blasting and that of exposed was compared with the number of blasting holes. Finally, based on the exposed length of steel bars and vertical load, the number of blasting holes were calculated. Results shows that the number of blasting holes calculated in this study are suitable for scaled structure models test by blasting demolition.

• Journal of Korean Society of Steel Construction
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• v.19 no.3
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• pp.335-344
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• 2007

The steel-concrete composite column (i.e., the SC composite column) supports large-gravity loads and simplifies the installation and removal of the work in pouring the concrete. The column takes advantage of the in-plant prefabrication of steel, the speed of erection of a steel structure, and the fire resistance of steel. This paper presents the results of a parametric study using heat transfer analysis and a P-M interaction curve, and compares these results with the experimental results to check the accuracy of the proposed parametric studies. The parametric studies, such as the study of the concrete ratio of an area and the fire protection thickness, provide information on the fire resistance of SC composite columns.

• Journal of Korean Association for Spatial Structures
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• v.7 no.2 s.24
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• pp.83-90
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• 2007

Buildings become high and large. CFT(Concrete Filled steel Tube) columns have been developed to manage effectively that loads which columns support and cross sections of columns are increased. Because CFT column is the composite structure made of two different materials, many researches have been performed to look into mechanical behaviors. This study is an analytic study about bond stress on interface between concrete core and steel tube in circular and rectangular CFT columns. ABAQUS/Standard Version 5.8 is used to analyze bond stress by bond form and position of shear-connector, and improved analystic method about mechanical characters on interface is suggested.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.369-376
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• 2003

One of the most complex reinforcement location in the precast building frame is the beam-column joint in a prefabricated construction. It is generally resulted from the vortical bars of column, anchorage bars of beam, and bars of hoop. Particularly the hooked anchorage bars of beam are confronted with hoop and main column bars. The headed reinforcement is considered to place them easily and to reduce the anchorage length in a precast construction. Reversed cyclic loading tests are performed on four beam-column specimens to evaluate the strength and behavior of beam to column and column to column connections. The result of test shows that the headed reinforcement has a similar performance than that of hooked reinforcement in a precast specimen with strong column and weak beam joints. The splice column joints which are used frequently in the domestic fields also show reliable behaviors in those tests with strong column and weak beam joints.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.4
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• pp.1-10
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• 2004

The purpose of this study is to investigate the flexural behavior of square concrete filled carbon tube (CFCT) columns subjected to constant axial load with the cyclic lateral load. Two parameters, wnding angle and thickness of tube, were chosen to evaluate the flexural capacity and behavior of rectangular CFCT columns. Selected two parameters were considered simultaneously in order to evaluate the flexural behavior of a rectangular CFCT columns more precisely. Flexural strength, deformation capacity, ductility and energy dissipation capacity of rectangular CFCT columns were evaluated by calculating the area of load-displacement envelope curves and load-dispalcement hysteresis curves obtained from experiment. Also, the ductile capacity obtained from experiment was compared to that of reinforced masonry wall for the comparison of existing structural element.