Recent developments on design of composite columns in Hong Kong

While steel-concrete composite construction is widely adopted in many countries in the world since 1970's, its application in many Asian countries is significantly hindered by the lack of integrated recommendations and codes of practice on material supply, design and construction. Hence, it is often necessary to make reference to modern design codes in other countries, such as those in the United Kingdom, Australia and the United States. Currently, BS EN1994-1-1:2005 provides a comprehensive set of recommendations on the design and construction of composite structures, using steel sections of grades S235 to S460 and concrete of strength classes C20/25 to C50/60. More specifically, Clause 6.7 of the code presents the design methods of composite columns, providing new opportunities for architects and engineers to build columns of increased load carrying capacities using members of reduced cross-sections in high-rise buildings. This paper describes an overview on the design provisions of composite columns with concrete filled hollow sections, and illustrates some of the key advances in the code, in particular, the expanded use of non-linear interaction curves between compression and moment capacities of both stocky and slender columns. It aims to provide practical design guidance to facilitate practicing engineers in Hong Kong to design composite columns according to the latest design recommendations. The technical information is also considered to be highly relevant to engineers in other Asian countries and cities, such as Singapore, Malaysia, Macau and major cities in China.