Sectional Buckling of Built-up Cold-Formed Steel Columns
Access status:
Open Access
Type
ThesisThesis type
Doctor of PhilosophyAuthor/s
Abbasi, MandanaAbstract
Cold-formed steel (CFS) sections are characterised by their high strength-to-weight ratio resulting in extensive applications that range from sheeted wall systems to low-rise frames. The manufacturing process of CFS and the introduction of built-up sections permit the optimisation ...
See moreCold-formed steel (CFS) sections are characterised by their high strength-to-weight ratio resulting in extensive applications that range from sheeted wall systems to low-rise frames. The manufacturing process of CFS and the introduction of built-up sections permit the optimisation of their geometry for enhanced capacity, which can further extend CFS applications. However, the presence of discrete fasteners can influence the behaviour of built up members, including their buckling modes and associated capacities. This research investigates the sectional buckling of built-up CFS columns through a series of experimental tests and detailed finite element (FE) analyses. A comprehensive nonlinear FE model was developed by appropriately accounting for material and geometric nonlinearities, imperfections, restraint conditions, and constraints due to discrete fasteners and contact between component elements. The numerical model was shown to yield predictions in excellent agreement with experimental observations and utilised to perform extensive parametric studies on the influence of cross-section geometry and fastener spacing. A novel application of the Compound Strip Method to the elastic stability analysis of built-up members with discrete fasteners was also established to serve as a simple yet accurate analytical tool for practical design purposes. The reliability of the effective width method and the Direct Strength Method (DSM) for the design of built-up columns was assessed in the context of the Australian and North American provisions. The current DSM equations for local and distortional buckling capacities were rationally modified for conformal reliability in terms of the relative number of restrained components undergoing the sectional buckling mode of interest and the fastener spacing ratio normalised to the associated critical buckling half-wavelength. The proposed adjustments provided consistent predictions for different cross-section and fastener configurations.
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See moreCold-formed steel (CFS) sections are characterised by their high strength-to-weight ratio resulting in extensive applications that range from sheeted wall systems to low-rise frames. The manufacturing process of CFS and the introduction of built-up sections permit the optimisation of their geometry for enhanced capacity, which can further extend CFS applications. However, the presence of discrete fasteners can influence the behaviour of built up members, including their buckling modes and associated capacities. This research investigates the sectional buckling of built-up CFS columns through a series of experimental tests and detailed finite element (FE) analyses. A comprehensive nonlinear FE model was developed by appropriately accounting for material and geometric nonlinearities, imperfections, restraint conditions, and constraints due to discrete fasteners and contact between component elements. The numerical model was shown to yield predictions in excellent agreement with experimental observations and utilised to perform extensive parametric studies on the influence of cross-section geometry and fastener spacing. A novel application of the Compound Strip Method to the elastic stability analysis of built-up members with discrete fasteners was also established to serve as a simple yet accurate analytical tool for practical design purposes. The reliability of the effective width method and the Direct Strength Method (DSM) for the design of built-up columns was assessed in the context of the Australian and North American provisions. The current DSM equations for local and distortional buckling capacities were rationally modified for conformal reliability in terms of the relative number of restrained components undergoing the sectional buckling mode of interest and the fastener spacing ratio normalised to the associated critical buckling half-wavelength. The proposed adjustments provided consistent predictions for different cross-section and fastener configurations.
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Date
2022Rights statement
The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.Faculty/School
Faculty of Engineering, School of Civil EngineeringAwarding institution
The University of SydneyShare