Experimental Investigation of the New Built-up Litesteel Beams

A new cold-formed steel beam, known as the LiteSteel Beam (LSB), has found many applications in the building industry. When LSBs are used as back to back built-up sections, they are likely to improve their flexural capacity and thus extend their applications further. The built-up LSB sections can also reduce the detrimental effects of Lateral Distortional Buckling (LDB) that occurs with single LSB sections. However, the behaviour of built-up beams is not well understood. Many steel design codes include guidelines for connecting two channels to form a built-up I-section including the required longitudinal spacing of connections. But these rules were found to be inadequate in some applications. Therefore an experimental investigation was undertaken to study the flexural behaviour of back to back LSBs with various longitudinal connection spacings under uniform moment conditions. This paper presents the details of the experimental tests of back to back built-up LSB sections, and the results. It also discusses the effects of connector spacing on moment capacity, the behaviour and the applicability of current design rules to back to back LSBs.