Experimental behaviour of cold-formed steel welded tube filled with concrete made of crushed crystallized slag subjected to eccentric load

This paper presents results of tests conducted on thin welded rectangular steel stubs filled with concrete that gravel was substituted by 10 mm crushed crystallized slag stone. The studied section was made of two cold steel plates with U shape and welded with electric arc to form a steel box section. The cross-section dimensions were: 100×70×2 mm³. the main studied parameters were the stub height (200, 300, 400, 500 mm), the effect of the in filled concrete, the continued weld and the eccentric force. The tests were carried out 28 days after the date of casting. A total of 20 stubs were tested in a 50 tf machine up to failure, 4 stubs subjected to axial load compression and 16 stubs subjected to eccentric load compression along the minor and major rigidity axis. The aim of the study is to provide some evidences that the use of crushed slag could be integrated in the manufacturing of non-conventional concrete. All failure loads were predicted by using the Euro code 4 and the design method proposed by Z. Vrcelj and B. Uy. From test results, it was confirmed that the length of stubs and the eccentric load had a drastic effect on the load carrying capacity. The failure mode of composite stubs was a local buckling mode with all steel sides deformed outwards. The Euro code 4 loads predictions were generally in good agreement compared with experimental loads and on safe side. The loads results of design method proposed by Vrcelj and B. Uy were generally on safe side compared with experimental load except the columns subject to eccentric load with 400 mm and 500 mm height.