Numerical Study of Bolted Moment Connections in Cold-Formed Steel Frames

Abstract

Bolted moment connections for cold-formed steel frames are considered very important and complicated items which need in depth studies. This paper studies the behaviour and strength of eave connections for members that consist of back to back cold-formed double channels in portal (right angle) steel frames. Relatively new configuration is suggested to facilitate the construction and reduce the cost of this type of connections. The connection is comprised of two stubs (welded built-up I shape) connected with two head plates, each stub is welded to its head plate, keeping in mind that the rafter stub is tapered I-shape. The web and flanges of cold-formed members are connected to the connection accessories by bolts. Numerical study is carried out using a finite element software package (ANSYS). The analysis accounts for geometric and material nonlinearities, large deformation and Elastic-plastic behaviour. Different parameters such as width to depth ratios and, width to thickness ratios of web and flange for the connection accessories and the cold-formed channels are considered. Different failure modes, including local yielding, flexural-distortional buckling, bearing failure as well as combined local yielding and bearing failures are observed. Moreover, moment-rotation relationships for this type of connection are deduced. The rigidity of this connection type is compared with EC3 classifications and generally it can be classified as a semi-rigid connection