Past research into the local buckling behaviour of fully profiled sandwich panels has been based on polyurethane foams and thicker lower grade steels. The Australian sandwich panels use polystyrene foam and thinner and high strength steels, which are bonded together using separate adhesives. Therefore a research project on Australian sandwich panels was undertaken using experimental and finite element analyses. The experimental study on 50 foam-supported steel plate elements and associated finite element analyses produced a large database for sandwich panels subject to local buckling effects, but revealed the inadequacy of conventional effective width formulae for panels with slender plates. It confirmed that these design rules could not be extended to slender plates in their present form. In this research, experimental and numerical results were used to improve the design rules. This paper presents the details of experimental and finite element analyses, their results and the improved design rules. KEYWORDSProfiled sandwich panels, slender plates, local buckling, buckling coefficient, effective width, finite element analysis.

Sandwich panels exhibit various types of failure modes depending on the steel face used. For the flat and lightly profiled sandwich panels, flexural wrinkling is an extremely important design criterion as the behaviour of these panels is governed mainly by flexural wrinkling. However, in the lightly profiled panels, when the depth or spacing of the ribs increases, flat plate buckling between the ribs occurs leading to the failure of the entire panel due to the interaction between local buckling and flexural wrinkling modes. Current design formulae for sandwich panels do not consider such interactive buckling effects. To obtain a safe design solution, this interactive buckling behaviour should be taken into account in the design of lightly profiled sandwich panels. Therefore a research project was undertaken to investigate the interactive buckling behaviour of lightly profiled panels with varying depths and spacings of the ribs using a series of experiments and finite element analyses. A new improved design formula was developed for the safe and economical design of lightly profiled panels that takes into account the interaction between local buckling and flexural wrinkling. This paper presents the details of this investigation, the results and the new design formula.

The use of sandwich panels in Australia has increased significantly in recent years due to their widespread structural applications in building systems. Structural sandwich panels generally used in Australia comprise of polystyrene foam core and thinner and high strength steel faces. The fully profiled sandwich panels, when subjected to axial compression and/or bending effects, are susceptible to local buckling failures. A research project was undertaken using a detailed experimental study on 50 foam-supported steel plate elements to investigate the local buckling and postbuckling behaviour of sandwich panels and to examine the adequacy of currently used effective width approach for design. Experimental results have revealed that current method is adequate for the steel plate elements with low b/t ratios.However, it appears to be inadequate for the plate elements with higher b/t ratios (slender plates). This paper presents the details of the experimental studies on polystyrene foam supported steel plates, the results, and the evaluation of current design rules for profiled sandwich panels subject to local buckling effects.

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