Assessment on the Behaviour of Cold-Formed Steel Built-up Beams

Abstract. Cold-formed steel, thin-walled steel product finds a wide application in construction worldwide. It has many advantages such as flexibility, convenient handling and fabrication and so on. The CFS is commonly used in structures like bridges, railway coaches etc., as it is economical when compared with hot-rolled steel. It can be used as single or built-up flexural members. Generally, the open section beams are susceptible to failure by lateral- torsional buckling due to the position of its centre of shear and centroid of the cross-section. To overcome this issue, open doubly-symmetric built-up sections or built-up closed sections have been used by many researchers. The parametric studies were conducted by many researchers to find the accuracy of the design strength predictions of the built-up beams. In parametric study, Eurocode specifications, the direct strength method and effective width method based on the North American specifications were used. The study reveals that there are no proper design guidelines available in the current Eurocode and North American specifications. Therefore, the paper provides an outline of research works done on various CFS sections by the researchers and their proposed design recommendations to the codal specifications were also reviewed.