Experimental investigation of lightweight aggregate concrete-filled cold-formed built-up box section (CFBBS) stub columns under axial compression

This paper presents an experimental investigation of cold-formed built-up box section (CFBBS) stub columns infilled with lightweight aggregate concrete under concentric loading. The programme included a series twenty-four concrete-filled sections comprising by two nested thin-walled C-sections using breakstem rivets at flange and eight reference hollow for comparison purposes. These four different cross-section sizes were three compression strengths, i.e., 20, 30 40 MPa. failure modes, ultimate compressive load load-end shortening relationship the test specimens compared discussed. A set performance indices was calculated from results to evaluate structural several aspects. In addition, confinement effect investigated extensively based on strain development. Finally, are used applicability design equations specified in existing codified provisions, including Eurocode (EC4), Australia/New Zealand Standard (AS/NZS 2327) America Specification (AISC 360-16). It found that EC4 consideration effective area outer CFBBS provided most accurate less scattered predictions. Predictions AS/NZS 2327 generally be slightly unsafe while those AISC 360-16 conservative.