102 - str - mus stiffening of cold - formed steel section at plastic hinge formation

Abstract

This study is carried out to investigate the method that can be used to stiffen the cold-formed steel section so that the section becomes a plastic section and thus can be used for plastic design of portal frame. In this study, experimental works have been done to study the formation of plastic hinge of cold-formed sections of various slenderness ratios. In the first series of tests, 2 numbers of lipped channel steel sections with the size of 75 x 30 mm and 0.65 mm thickness had been tested. The beams were simply supported at each ends. In the second series, rectangular sections were built-up each from two 75 X 30 mm single channel sections connected fece to face, to have different slenderness ratio of their elements. From the test, it was found that the formula used for the determination of design bending moment provided in the BS 5950 has not been proved reasonably comparable with that of experimental results. Two point bending method was used in the test. At high deflection, warping of the compression flange was determined. The failure was in the mode of local flange buckling, followed by budding of the web. The stiffener made of splice plates were used to stiffen the section and thus transforming the section into plastic section at the plastic hinge location. Two sections were combined and jointed together face to face to make it into a single section. From the study, it is concluded that stiffening of cold-formed steel section by the use of splice plate stiffeners needs to be improved to form plastic hinge