• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.43-52
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• 2015

Constructions of buildings downtown are increasing as much as ever with a strong demand. Top-Down Method is suitable for its advantage in minimizing its disturbance to the neighborhood. Pre-founded when applied to CFT Column on-site welded is required for splicing. To complement the welded built-up square composite Column was developed. Top-down process will be pouring concrete in accordance with a step-by-step process. Thus, Pre-founded Column and cover concrete to determine the stress condition. Therefore, Concrete filled steel square tubular columns encased with precast concrete were studied. Five Centrally loaded Columns were tested to investigate the axial load carrying capacity. we analyzed the strength and behavior of CET Column by Loading conditions and concrete strength, thickness of cover concrete through structure experiments.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.69-74
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• 2007

Recently, to improve performance and strength of circular steel columns, application of concrete-filled steel tube(CFT) type are gradually increased. To accurately predict the plastic design of concrete-filled steel tube columns, a plasticity model is required which can be describe large deformation behavior of concretes and steels. In this study, elastic-plastic large deformation analysis is developed by using the plasticity model of structural steels, and accurate and validity of the developed program is verified by comparing between the experiment and the analysis for concrete-filled steel tube column. In concrete-filled steel tube columns, influence of initial deflection on ultimate strength behavior is investigated by using developed program.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.473-483
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• 2014

According to the Korean Building Code (KBC), the validity of the application of 800MPa grade steel(HSA800) to composite column should be verified by experimental or analytical method. Thus, stub column tests for encased and filled composite members with HSA800 steel were conducted, and axial strength and the validity of design compressive strength equations in KBC were evaluated. The test results show that the equation of the compressive strength of encased composite column member in KBC should be modified in order to use HSA800 steel without any reduction of specified minimum yield strength. For this purpose, it is suggested that the interval of hoop should be narrowed and the effective concrete area should be used. The equation of the compressive strength of filled composite column member in KBC is applicable to filled composite column with HSA800 steel without any modification.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.1-8
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• 2001

The purpose of this study is to examine the utility of concretefilled steel tubular column to H-beam connections with tubular stiffener. As a preliminary step. a tensile experiment was undertaken to scrutinize characteristics of the structural behavior that take place between beam flanges and column with tubular stiffener. A total of 4 types of experimental settings were developed as tabular stiffeners are made up 9, 18, and 27 mm of thickness and 50 and 80 mm of height respetively Along with the overall load subsequently the degree of displacement and strain were recorded. Based on the yield line theory results of this of this study were evaluated and further critically reviewed the applicability of the strength formula. This study found that collapse mechanism was emerged on the beam flange as reinforcing tabular stiffeners Complementary studies of this sort, including numerical analyses should be undertaken in order to develope specific design critera.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.387-395
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• 2000

The purpose of this research is to evaluate the capacity of strength and plastic deformation of those members, and provide experimental data on the seismic behavior of these members as a basis for developing guidelines for designing seismically resistant concrete-filled steel tubular columns. Eighteen cantilever-type specimens were tested under constant axial load and cyclically lateral load as models of bottom columns in high-rise building. The parameters studied in the test program included, are width-thickness ratio of steel tube, slenderness ratio (Lo/D) and axial force ratio. From the test results, the effects of parameters on the strength, the deformation capacity, energy absorption capacity are discussed. The specimen flexural capacity under combined axial and lateral loading was found to be almost accurately predicted by criteria AIJ and AISC-LRFD providing conservative results. Therefore KSSC for encased composite column can be applied to the concrete filled column if composite section and elastic modulus are modified according to AIJ and AISC-LRFD. Finally, the proposed flexural capacity considering confinement effects is a food agreement on the tests results.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.641-655
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• 1998

It researched several jointing-methods of frame consisting of a concrete-filled steel tubular column and H-shaped beam. These beam-to-column connections is parameters to following: columns of square shape pipe infilled with or without concrete, joints assembled two types of diaphragm, outside-type and through-type. And it is testing that cyclically lateral loadings used hydraulic ram. In testing. we'll be on purposed to estimate the hysteretic behavior, strength and stiffness, energy absorption capacity, deformation capacity and failure configuration of each specimen. It is concluded that the frame specimens with outside-type are more stable and exhibit more energy absorption capacity compared with the through-type, in column of filled with concrete.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.431-439
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• 2014

Concrete filled tubular columns are widely used because the mutual reaction between the concrete and the tube improves strength and ductility of the columns. In an attempt to secure efficient use of members, built-up square columns featuring large width-thickness ratio and the use of thin steel plates are suggested in this study. In order to evaluate the structural characteristics and seismic performance of the column-to-beam connections of the new shape columns, cyclic load test of T-shaped column-to-beam connections was conducted with variables of diaphragms and concrete-filling. Moment-rotational angle relationship, dissipated energy and failure behavior were compared to evaluate stress transfer mechanism of the new shape built-up square column-to-beam connections associated with the variables.

• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.399-410
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• 2015

Concrete filled steel tube(CFT) has outstanding deformation capacity and strength in comparison with reinforced concrete or steel tube. CFT drilled shaft, which is developed large shear force due to seismic load and soil liquefaction, is designed as large diameter. However, shear design equations of the current standards do not consider bond stress of CFT and it results in extremely conservative design. Currently, previous studies for improving shear equations scarcely exist and are impossible applied to large CFT drilled shafts since these studies focus on only small scale experimental research. In this study, eventually to propose improving shear equation of large diameter CFT, it is preliminary research to compare and investigate the previous studies and current standards.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.741-748
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• 1998

Experimental studies were carried out with test parameters: diaphragm yield type and beam yield type, the opening hole size of inner steel diaphragm, and the existence of slab in order to understand the behavior of beam-to-concrete filled steel tube column rigid connections under cyclic loading condition. Test results show that the connections have good rotational capacity when the beam yields first and the joints should be designed such that the beam yields prior to the inner diaphragms.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.205-213
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• 2008

The objective of this study is to evaluate the yield stress of SM570TMC CFT column subject to axial force. These columns were evaluated and compared by statistical tests, during which the displacements and axial loads of column specimens were measured. Test results showed that the yield stress of CFT columns under axial load could be predicted using the previously proposed the yield stress of steel columns.