ABSTRACT
This paper presents an experimental study of concrete-filled high strength steel tubular members subjected to bending. Three cold-formed high strength steel square hollow sections, with nominal yield strength (0.2% proof stress) of 900 MPa, were filled with different strengths of concrete. The nominal concrete cylinder strengths of 40, 70 and 110 MPa were investigated. A total of thirteen four-point bending tests were carried out on both concrete-filled and hollow beam specimens. The moment capacities of the composite beams are generally 13–45% larger than those without concrete infilled. The ductility of composite beams is significantly improved. It should be noted that the very high strength steel material of 900 MPa is not covered in the current design provision. The current design equations were derived based on normal steel and concrete grades. The suitability of the current design rules is assessed for concrete-filled high strength steel hollow section members subjected to bending.
