Analysing the Confinement Effect in Hollow Core Steel-Concrete Composite Columns under Axial Compression.

Spun concrete technology allows manufacturing the reinforced concrete poles, piles, and columns with a circular hollow core. This concreting method ensures higher concrete density and strength than the traditional vibration technique and self-compacting concrete. This technology defines an attractive alternative for producing steel-concrete composite elements, allowing efficient utilisation of the materials due to the confinement effect. This study experimentally investigates the material behaviour of the composite columns subjected to axial compression. The experimental results support the above inference-the test outcomes demonstrate the 1.2-2.1 times increase of the compressive strength of the centrifugal concrete regarding the vibrated counterpart; the experimental resistance of the composite columns 1.25 times exceeds the theoretical load-bearing capacity. The proposed mechanical-geometrical parameter can help to quantify the composite efficiency. The parametric analysis employs the finite element model verified using the test results. It demonstrates a negligible bond model effect on the deformation prediction outcomes, indirectly indicating the steel shell confinement effect and confirming the literature results.