Interaction Diagram of Rubberised Concrete Filled Circular Hollow Sections

Concrete filled steel tube (CFST) is increasingly used in engineering construction as columns and beams. CFST is known to absorb large amounts of energy as a result of the composite effect. Internationally, there are increasing amounts of waste rubber. In this study recycled rubber is used as aggregate supplement in concrete. Rubberised concrete is known to be more ductile than conventional concrete however has a lower compressive strength. This study investigated the performance of thirty rubberised concrete-filled single-skin steel tubes under combined loading conditions and compared the results against six steel hollow tubular members. Three rubber replacement ratios, 0%, 15% and 30%, three load eccentricities and four tube sections with section slenderness (b/t, width/thickness) of 18 to 36 were examined. The results have shown that the composite section had greatly improved load carrying capacity. The ductile rubberised concrete was more effective in delaying the premature buckling failure of the steel tube compared to the normal concrete. The interaction diagrams were constructed from the experiments and theoretical calculations. It was found that the behaviours of the rubberised concrete filled steel tubes could be accurately predicted using existing design guidelines. This study demonstrated the potential of using rubberised concrete as a cost-effective solution to safe roadside barriers and structural members in buildings located in seismic active zones.