THE STUDY OF THE AXIAL COMPRESSIVE STRENGTH OF CONCRETE FILLED STEEL TUBE (CFST) BASED ON THE TWIN SHEAR UNIFIED STRENGTH THEORY

For strain-constrained concrete cylinders in CFST, formulae of compressive strength were presented based on the Twin Shear Unified Strength Theory. Axial compressive tests of CFST were conducted and curves of deformation versus limit load were obtained from the tests. Predictions from the derived formulae were compared with test results and satisfactory agreements were reached. It is concluded that the Twin Shear Unified Strength Theory is versatile in theoretical analyses of CFST.