A Study on the Fire-resistance of High-Strength Concrete filled Square Steel Tube Columns under Constant Axial Loads
Su-HeePark[1] Kyung-SooChung[2] Sung-Mo Choi[3],*
1,3Department of Architectural Engineering, University of Seoul 130-743, Seoul, Korea
2Senior Researcher, Architectural Engineering Research Team, Research Institute of Industrial Science and Technology, 79-5 Yongcheon, Dongtan, Hwasung, Kyongki-do 445-810, Korea
ABSTRACT :Recently through the domestic mass communications, it was embossed that existing high buildings are weak as fire resistive constructions due to the spalling of high strength concrete (HSC) by the high fever happened at fire.Partial damages and reinforcement exposure by the spalling of high strength concrete (HSC) become critical factors which rapidly deteriorate stability and intensity of members. As an alternative of these problems, this paper considers the fire resistance and structural behaviors of high-strength concrete filled square steel tube (square CFT) columns through the experimental study. To evaluate the fire resistance of high-strength concrete filled square steel tube (square CFT) columns without fire protection under constant axial loads, three specimens for concrete filled square steel tube columns were manufactured. During the test, the column was exposed to heating controlled in such a way that the average temperature in the furnace followed ISO 834 standard fire curve. The sectional dimension of the square CFT columns was 300mm and the wall thickness was 9mm. The specimens were 3,000mm and 3,500mm long. The axial load ratio(N/Nc) of all specimens was kept equally by 0.32. For evaluation the fire resistance of CFT columns subjected to central compressive load, the significant parameters were determined, such as concrete strength and reinforcement. The concrete strength was 40MPa (Normal Strength Concrete) and 75MPa (High Strength Concrete), respectively.Also, one specimen consists of reinforced high-strength concrete with 2% steel reinforcement and a cover of 50mm. This paper analyzed the effects that HSC filling and reinforcement cause in the fire resistance of CFT columns and the structural behavior under fire.Through this analysis, this paper presents a feasible plan that can improve the fire-resistance of CFT columns that fill up high-strength concrete.
Keywords : Fire Resistance, Concrete-filled Square Steel Tube Column, High-Strength Concrete, Constant Axial Load, Reinforcement, High Temperature
[1]Graduate Student (Ph.D. candidate)
[2]Research Associate
[3]Professor,Corresponding Author, E-mail: