Statistical calibration of safety factors for flexural stiffness of composite columns

Dr Stephen Hicks has been working with Dr Farhad Aslani, Ryan Lloyd and Prof. Uy of the Centre for Infrastructure Engineering and Safety at the University of New South Wales, together with Dr Won-Hee Kang of Western Sydney University, on design rules for the flexural stiffness of composite columns for the forthcoming standard AS/NZS 2327.

The basis for these rules has recently been published as a peer-reviewed paper in the international journal Steel and Composite Structures, which is summarised as Statistical Calibration of Safety Factors for Flexural Stiffness of Composite Columns Farhad Aslani, Ryan Lloyd, Brian Uy, Won-Hee Kang, and Stephen Hicks (pages 127-145. DOI: 10.12989/scs.2016.20.1.127).

Composite column design is strongly influenced by the computation of the critical buckling load, which is very sensitive to the effective flexural stiffness (EI) of the column. Because of this, the behaviour of a composite column under lateral loading and its response to deflection is largely determined by the EI of the member.

Thus, prediction models used for composite member design should accurately mirror this behaviour. However, EI varies due to several design parameters, and the implementation of high-strength materials, which are not considered by the current composite design codes of practice.

The reliability of the design methods from six codes of practice (i.e., AS 5100, AS/NZS 2327, Eurocode 4, AISC 2010, ACI 318, and AIJ) for composite columns is studied in this paper.

Also, the reliability of these codes of practice against a serviceability limit state criterion are estimated based on the combined use of the test-based statistical procedure proposed by Johnson and Huang (1997) and Monte Carlo simulations. The composite columns database includes 100 tests of circular concrete-filled tubes, rectangular concrete-filled tubes, and concrete-encased steel composite columns.

A summary of the reliability analysis procedure and the evaluated reliability indices are provided. The reasons for the reliability analysis results are discussed to provide useful insight and supporting information for a possible revision of available codes of practice.

A copy of the above paper is available to members from the HERA Library.