Behaviour of concrete-filled square section stub columns fabricated from mild steel plates and incorporating cold-formed tubes at the vertices

![CDATA[Recent research has investigated the behaviour of fabricated section stub columns made through welding facet plates but also incorporating small diameter circular hollow sections at the vertices. In 2000, Japanese researchers investigated the behaviour of empty fabricated triangular section stub columns made up of normal strength steel facet plates and normal strength steel tubes. The steel used for the facet plates and the tubes had a nominal yield strength 235MPa. Australian researchers in 2004 studied the behaviour of both empty triangular and square fabricated stub columns through the welding of very high strength steel tubes at the vertices to high strength steel plates. The high strength steel facet plates had nominal yield strength of 350MPa and tubes at the vertices with a nominal yield strength of 1350MPa. Further research in Australia extended the previous research on empty fabricated triangular and square sections through the determination of behaviour after concrete filling the fabricated stub columns. This paper investigates the behaviour of concrete-filled fabricated square section stub columns manufactured using mild steel plates, 250MPa yield stress, welded to cold-formed steel tubes, of 350MPa yield stress, at the vertices. Experimental results are analyzed and the strength compared to existing standards.]]