• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.21-28
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• 2002

Ductile behavior and strength of concrete-filled steel(CFS) piers was supported by many quasi-static cyclic loading tests. This test method, however, only estimates the member′s deformation capacity under escalating and repetitive displacement and ignores dynamic and random aspects of an earthquake load. Therefore, to understand complete seismic behavior of the structure against an earthquake, dynamic tests such as shaking table test and pseudo-dynamic tests are required as well as quasi-static tests. In this paper, following "Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loadint Test", the seismic behavior of CFS and steel piers designed for I-Soo overpass in Seoul in investigated by the pseudo-dynamic test. In addition, the residual strength of both piers after an earthquake is estimated by the quasi-static test. The results show that both piers have satisfactory ductility and strength against well-known EI Centro earthquake although the CFS pier has better strength and energy dissipation than the steel pier.

• Computers and Concrete
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• v.9 no.4
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• pp.245-255
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• 2012

The damping effect of a Concrete-filled Rectangular Steel Tube (CRST) frame structure is studied in this paper. Viscous dampers are employed to insure the function of the building especially subjected to earthquakes, for some of the main vertical elements of the building are not continuous. The shaking table test of a 1:15 scale model was conducted under different earthquake excitations to recognize the seismic behavior of this building. And the vibration damping effect was also investigated by the shaking table test and the simulation analysis. The nonlinear time-history analysis of the shaking table test model was carried out by the finite element analysis program CANNY. The simulation model was constructed in accordance with the tested one and was analyzed under the same loading condition and the simulation effect was then validated by the tested results. Further more, the simulation analysis of the prototype structure was carried out by the same procedure. Both the simulated and tested results indicate that there are no obvious weak stories on the damping equipped structure, and the dampers can provide the probability of an irregular CRST frame structure to meet the requirements of the design code on energy dissipation and deformation limitation.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.711-723
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• 2012

Structural tests were performed to investigate the structural performance of concrete-filled steel tube column using different strength steels in their flange and web with high-strength steel HSA800 and mild steel SM490, respectively. The test parameters included the strength of column flange and infill concrete, and effect of concrete infill. Connection between different grade steels were welded using the electrode appropriate for mild steel and verified its performance. To evaluate the behavior of test specimens, eccentric loading tests were performed and the results were compared with the prediction by current design codes. Axial load and moment carrying capacity of test specimens increased with the yield strength of compression flange and weld fracture occurred after the specimen shows full strength. The prediction result for axial load-bending moment relationship and effective flexural stiffness gave good agreement with the test result.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.209-213
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• 2008

Recently, it increases in use of CFT(Concrete filled steel tube, below CFT) because material and method are required to be diversification and High-Performance according to increase the super-high structure. But, CFT column lose bearing capacity under fire because steel tube is exposed to outside. As a result, structure is collapsed and then it cause much damage. In case of the Europe, Japan and America, they have studied the fire-resistance performance of CFT under fire for a long time. However, it would have hardly studied it in domestic because it is much difficulty about experiment machine and cost. So it is needed base on fire-resist performance of CFT under fire. Therefore, this study dynamic specificity of stub column which made tester of stub column based on facts of strength and mixing fiber evaluated used heating and load testing machine. As a result, it is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with experiment according to the design high strength concrete.

• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.3-11
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• 2000

There is a possibility of poor-state concrete filling condition due to segregation and interlocking of aggregate and paste when a high performance concrete is used at reinforced concrete structure without compaction. This study was conducted to evaluate the flexural behavior of high performance concrete beams with design parameters such as c, t and different concrete filling conditions. Different concrete filling conditions were intentionally made such that the first type specimen was soundly cast to obtain the perfect concrete filling condition. Second type was cast in such a way that up to the longitudinal tensile reinforcement from the top, good concrete was filled while poor concrete was poured for the bottom part to simulate the poor strength, workability and unsatisfactory compaction. Third type was cast in such a was that up to the neutral axis of the beam section from the top, good concrete was filled while so did for the bottom part as the second type. The test results were analyzed in terms of load-displacement response, failure pattern, crack width and crack spacing. The test results indicate that have no effect of concrete filling conditions on the yielding strength of structures. But, have a grate influence on the stiffness and ductility of structures.

• Steel and Composite Structures
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• v.51 no.6
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• pp.619-645
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• 2024

In the construction industry, composite structures have revolutionized traditional design principles, opening innovative possibilities. The Concrete Encased - Concrete Filled Steel Tubular (CE-CFST) column stands out as a distinctive composite structure, offering structural stability and resilience for various engineering applications. Comprising Reinforced Concrete (RC) and Concrete Filled Steel Tubular (CFST) components, CE-CFST columns are valued for their inherent properties, including ductility and rigidity, CE-CFST is commonly used in the construction of bridges, high-rise buildings, and more. This article aims to provide a concise overview of the evolutionary development of CE-CFST columns and their performance in structural applications. Through a comprehensive review, the study delves into the behaviour of CE-CFST columns under different scenarios. It examines the influences of key parameters such as size, infills, cross section, failure causes, and design codes on the performance of CE-CFST columns, highlighting their enhanced functionality and future potential. Moreover, the review meticulously examines previous applications of CE-CFST columns, offering insights into their practical implementation.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.481-487
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• 2002

Currently, the load transfer's mechanism from a beam to a column has yet to ve clarified in a concrete filled steel tubular (CFT) structure with a connection type of an exterior diaphragm. The loads for each floor are transferred to the concrete core from a steel beam through ha contacted face between an in-filled concrete and the interior surface of a steel tube. Thus, a Push-Out test was performed to investigate the load transfer mechanism. A total of 30 samples were tested to confirm the bond stress and/or axial load distribution between a steel tube and in-filled concrete for CFT column. The main parameters considered for this study included concrete type, steel tube-shape/length, and the effect of a weld joint wit ha backing strip for a column splice. Test results were summarized to confirm load transfer behavior between a concrete and steel tube for each experimental parameter, using the analytical approach to verify experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.458-461
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• 2004

The column for Steel Framed Reinforced Concrete Structure (SFRCS) and the column for Reinforced Concrete Structure (RCS) could be the most common building structure. The increasing of the need for massive space hasaffected the size of building components for supporting the massive structure. However, the changing of components size makes inefficient space of building. Hence. to meet the need for acquiring efficient space comparing the budget and cost the new structure method, Concrete Filled Tube Steel (CFT), was developed. CFT is the structure for which steel tube instead of other materials such as wood for holding concrete is used. The most benefit of this one is to help in reducing the size of the building components and local buckling because of tube steel holding concrete. For this reason, this research will examine the probability of applying CFT on construction sites by using the concrete $(800kg/cm^2)$ especially for CFT through the data from the real size mock-up.

• Structural Engineering and Mechanics
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• v.19 no.6
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• pp.653-677
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• 2005

Concrete filled steel tubular columns (CFT) are widely used in civil engineering works, especially in large scale of works because of high strength, deformation, toughness and so on. On the other hand, as a kind of strengthening measure for seriously damaged reinforced concrete piers of viaduct in Hansin-Awaji earthquake of Japan in 1995, reinforced concrete piers were wrapped with steel plate. Then, a new kind of structure appeared, that is, reinforced concrete filled steel tubular column (RCFT). In this paper, compression test and bending-shearing test on RCFT are carried out. The main parameters of experiments are (1) strength of concrete, (2) steel tube with or without rib, (3) width-thickness ratio and (4) arrangement of reinforcing bars. According to the experimental results, the effect of parameters on mechanical characteristics of RCFT is analyzed clearly. At the same time, strength evaluation formula for RCFT column is proposed and tested by experimental results and existed recommendations (AIJ 1997). The strength calculated by the proposal formula is in good agreement with test result. As a result, the proposed evaluation formula can evaluate the strength of RCFT column properly.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.101-107
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• 2017

Over-break, which is excavated larger than planned line at tunnel excavation, is inevitable due to the nature of blasting. But regarding the bottom of the foundation, most of the domestic ordering organizations pay only 10 cm thick filled concrete when pouring concrete due to over-break. In accordance, the construction cost will increase greatly if all the depths of the designed over-break are filled only with concrete. When tunnel excavation occurs, concrete filling of 18 MPa(T = 100 mm) and 150 mm~237 mm auxiliary concrete layer and 240 mm concrete track(TCL) are applied to the upper part. The concrete is installed in an excessive amount of about 600 mm between the lower part of the rail and the tunnel rock bed. Therefore, in this study, it is necessary to analyze the concrete crack structure according to the depth of the existing tunnel and the modified tunnel section, and to evaluate the adequacy of the required thickness of the tunnel floor concrete for securing the crack stability of the concrete.