Design of Concrete Filled Tubular Beam-columns with High Strength Steel and Concrete J.Y. Richard Liew ⁎, Mingxiang Xiong, Dexin Xiong Department of Civil & Environmental Engineering, National University of Singapore, Singapore abstract article info Article history: Received 21 February 2016 Received in revised form 15 May 2016 Accepted 16 May 2016 Available online xxxx Concrete ﬁlled steel tubular column comprising a hollow steel tube inﬁlled with concrete has been used widely in high rise buildings. Although modern design codes provide guides on concrete ﬁlled steel tubular members, they do not cover their applications involving high strength concrete and high tensile steel. Set against this background, new tests have been conducted to supplement the dearth of research on concrete ﬁlled steel tubular members with ultra-high strength concrete (f ck up to 190 N/mm 2 ) and high tensile steel (f y up to 780 N/mm 2 ). In this paper, a design guide has been proposed for concrete ﬁlled steel tubular members based on an extension of Eurocode 4 method for concrete compressive strength up to 190 N/mm 2 and high tensile steel with yield strength up to 550 N/mm 2 . More than 2030 test data collected from the literature on concrete ﬁlled steel tubes with nor- mal and high strength materials have been analysed to formulate this design guide. This paper provides insights to this design guide sharing some of the expertise and knowledge involving the applications of high strength con- crete ﬁlled tubular members in high rise buildings. © 2016 The Institution of Structural Engineers. Published by Elsevier Ltd. All rights reserved. Keywords: Concrete ﬁlled columns Eurocode steel design High strength concrete High rise buildings High tensile steel Steel–concrete composite 1. Introduction High strength construction materials are now attractive owing to their economic and architectural advantages. The higher the material strength, the smaller is the required member size. Floor space can be saved and cost can be signiﬁcantly reduced in high-rise construction. However, material brittleness could be one of the problems for high strength concrete and local buckling may be a problem for structural members with high tensile steel. To overcome these problems, one solution is to use composite structural members, especially concrete ﬁlled steel tubes as columns, where the ductility and strength of the concrete core can be enhanced by the conﬁnement effect from the steel tubes while the local buckling of the steel tube can be delayed or even prevented by the concrete core. Concrete ﬁlled steel tubular (CFST) column, comprising a hollow steel tube inﬁlled with concrete with or without additional reinforce- ments or steel section, has been widely used in high rise building construction. The main advantage of CFST column is that the local buck- ling of the outer steel tube is delayed or even prevented by the concrete core while the inner concrete core is conﬁned by the steel tube provid- ing enhancement in strength and ductility under high compressive load. The steel tube can serve as permanent formwork for concrete casting and thus it eliminates the need of additional work and leads to fast track construction [1,2]. The CFST columns have various composite cross-sections as shown in Fig. 1. Circular, square and rectangular sections are commonly adopted while polygonal or elliptical sections also may be used for architectural and functional requirements. Con- ventionally, only plain concrete is ﬁlled into the hollow steel sections. Nowadays, the concrete core may be reinforced by ﬁbres or steel bars to enhance ductility and ﬁre resistance of the column. For convenience, the reinforcements can be replaced by an internal steel tube which can provide higher conﬁnement to the concrete core. Other steel sections, such as solid steel section or H-section, can be inserted into the concrete core to further enhance the compression resistance and thus reduce the column size. For columns subjected to high ﬂexural loading, concrete ﬁlled double-tube sections can be used to increase the ﬂexural stiffness with less material used. High strength materials may reduce the use of construction mate- rials, thus reducing the use of water, energy and manpower in handling such materials. High strength materials are mostly used for structural components subjected to compression such as columns in high-rise buildings. Fig. 2(a) shows the Petronas Tower in Kuala Lumpur, Malaysia, which is a 88-storey building utilising Grade 80 high strength concrete for columns with outer diameter up to 2.4 m. The Sail at the Marina Bay Singapore shown in Fig. 2(b) is a 70-storey residential build- ing with a height of 245 m, also utilising Grade 80 high strength concrete with column size about 2.0 m diameter. The Hong Kong Inter- national Commerce Centre with 110 storeys and 480 m height was constructed using Grade 90 concrete. WFC Shanghai, as shown in Fig. 2(c), utilised Grade 450 steel plate of thickness up to 100 mm for the composite columns. Part of the structure of the Tokyo Sky Tree (Fig. 2(d)) in Japan was constructed using Grade 700 steel tubes. Structures xxx (2016) xxx–xxx ⁎ Corresponding author. E-mail address: ceeljy@nus.edu.sg (J.Y.R. Liew). ISTRUC-00110; No of Pages 14 http://dx.doi.org/10.1016/j.istruc.2016.05.005 2352-0124/© 2016 The Institution of Structural Engineers. Published by Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Structures journal homepage: www.elsevier.com/locate/structures Please cite this article as: Liew JYR, et al, Design of Concrete Filled Tubular Beam-columns with High Strength Steel and Concrete, Structures (2016), http://dx.doi.org/10.1016/j.istruc.2016.05.005