Flexural behaviour of high-strength rectangular concrete-filled steel hollow sections

Abstract This paper presents a study of the flexural behaviour of 12 1600-mm-long high-strength rectangular concrete-filled steel hollow section (CFSHS) specimens tested to failure under pure bending. Three different sizes of steel hollow sections (150×150, 200×150 and 250×150 mm) were in-filled with high-strength concrete. ( f c ' = 56.3∼90.9 MPa). The yield stresses of the steel hollow sections were 438, 495 and 409 MPa, respectively. A good ductility performance of the specimens was observed in all tests. Local buckling was specifically noted on the compression face of the specimens. A comparison of the experimental moment capacities with the values calculated from the formulae in the codes showed that EC4, ACI and AISC considerably underestimated the flexural strengths of the specimens by 11, 15 and 18%, respectively. However, it should be noted that the formulae in the codes were derived based on normal strength steel hollow section and concrete. More studies are needed to be carried out to better understand the behaviour of rectangular CFSHS columns with high-strength materials.