Techno Press
Techno Press

Steel and Composite Structures   Volume 27, Number 4, May25 2018, pages 509-523
Residual bond behavior of high strength concrete-filled square steel tube after elevated temperatures
Zongping Chen, Xiang Liu and Wenxiang Zhou

Abstract     [Full Text]
    This paper presents experimental results on the residual bond-slip behavior of high strength concrete-filled square steel tube (HSCFST) after elevated temperatures. Three parameters were considered in this test: (a) temperature (i.e., 20°C, 200°C, 400°C, 600°C, 800°C); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 HSCFST specimens were designed for push-out test after elevated temperatures. The load-slip curves at the loading end and free end were obtained, in addition, the distribution of steel tube strain and the bond stress along the anchorage length were analyzed. Test results show that the shape of load-slip curves at loading ends and free ends are similar. With the temperature constantly increasing, the bond strength of HSCFST increases first and then decreases; furthermore, the bond strength of HSCFCT proportionally increases with the anchoring length growing. Additionally, the higher the temperature is, the smaller and lower the bond damage develops. The energy dissipation capacity enhances with the concrete strength rasing, while, decreases with the temperature growing. What is more, the strain and stress of steel tubes are exponentially distributed, and decrease from the free end to loading end. According to experimental findings, constitutive formula of the bond slip of HSCFST experienced elevated temperatures is proposed, which fills well with test data.
Key Words
    square steel tube; high strength concrete; elevated temperatures test; static test; residual bond strength
(1) Zongping Chen, Xiang Liu, Wenxiang Zhou:
College of Civil Engineering and Architecture, Guangxi University, 100# east daxue road, Nanning, 530004, China;
(2) Zongping Chen:
Key Laboratory of Disaster Prevention and Structure Safety of Chinese Ministry of Education, Guangxi University, 100# east daxue road, Nanning,530004, China.

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