Experimental behaviour of square CFST under local bearing forces

An experimental investigation of square concrete-filled thin-walled steel tube under local bearing forces is described, and the loads are applied by a steel bearing member (BM). A total of 20 specimens, including 12 concrete-filled steel tubular (CFST) members, 4 reference hollow structural section (HSS) members and 4 reference plain concrete (PC) members, were tested. The parameters considered in the tests included (1) type of BM: solid and hollow; (2) width ratio between BM and compression member: from 0.36 to 0.73; (3) wall thickness of the steel tube of the compression member: 2.6 mm and 3.7 mm, and (4) angle between BM and the compression member: 45° and 90°. It is found that, while being subjected to local bearing forces, square CFST has a higher bearing capacity and a better deformation-resistant ability, and the performance of a CFST member is better than that of the superposition of HSS and PC members. The calculated bearing capacities of square CFST under local bearing forces using the simplified design method in CIDECT design guide [9] and Feng and Young [12] are evaluated by comparison with the experimental results.