LAUSR

Abstract The cold-formed steel members often require web openings to allow for building services such as mechanical piping, electrical wiring, and air conditioning systems pass through the ceiling and therefore reduce the building overall height and as a result, lateral forces induced on the building. Stress distribution in members with openings is different from members without holes and therefore characteristics, shape and modes of their buckling are dissimilar which results in reduced buckling capacity and ultimate strength. In order to compensate some of the lost capacity, edge and intermediate stiffeners are fabricated into the web which complicates the characteristics and buckling mode. In this study, a set of analytical solutions for the local buckling of cold-formed steel webs with rectangular openings stiffened by intermediate and edge stiffeners subjected to compression, bending and their combination is developed, and summarized. The main variables are elastic modulus, Poisson's ratio, height of openings to height of web, aspect ratio of openings, moment of inertia of intermediate and edge stiffeners to moment of inertia of reduced web section, and stress distribution gradient above or under the hole. The proposed solutions can be used for a wide range of rectangular web openings. Analyses are conducted using energy based methods and the results are compared with numerical data obtained from the commercial finite element software (Abaqus). The numerical results demonstrate that one of the eight proposed formulas with minor modification can be successfully used to predict the critical buckling stress.