Mechanical Properties of High Strength Concrete Filled Steel Tubular Columns

This study investigated the mechanical properties of High Strength Concrete filled steel tubular short columns (HSCFSTSC) with length to diameter ratio (LID) of 3.5. The strength of concrete used to fill the steel tubular columns ranged from 54MPa to 116MPa. The test results showed that using a steel tube as confinement can significantly improve the ductility and compressive strength of core concrete. The magnitude of compressive strength increase of core concrete was directly proportional to the Confinement Index, Phi, and the extent of improvement of the ductility increases as the Phi increases. For thoroughly improving the ductility of core concrete, the Confinement Index Phi should be equal or larger than 0.48. The formula used to calculate the load bearing capacity of HSCFSTSC was given out.