Flexural behaviour of cover plated CFS built-up beams composed of lipped channels: Comparison of test and design strengths

Abstract

Built-up members are efficient in developing adequate resistance against large load demands, and their efficiency largely depends on how adequately the built-up sections are designed. This paper discusses the flexural behaviour of cover plated cold-formed steel (CFS) built-up beams made up of lipped channels. Lipped channels were placed at an adequate distance in the back-to-back arrangement and were connected at the flanges with self-drilling screws by means of cover plates, on both the tension as well as the compression faces. Simply supported end conditions were adopted in all the specimens. Both three-point loading as well as four-point loading was considered to study the influence of moment gradient and constant moment loading of theses built-up beam specimens. The sectional compactness of the channel section and the aspect ratio of the built-up section were varied to assess the behavioural effect in the specimens with respect to the variations incorporated. This study deals with the tests conducted to generate the test data. Prior to the testing of the specimens, tensile coupon tests were carried out as per the relevant standards to acquire the actual material properties of the steel used for the specimen fabrication. Both the European code as well as the North American Standards were used for developing the theoretical strengths and were compared with the test results.