Tests, modelling and design of cold-formed steel moment resisting joints with bolts in the web and outer flange

This paper presents an experimental and numerical investigation into cold-formed steel portal frame moment-resisting joints, having bolts in both the web and outer flange. The bearing resistance and stiffness of threaded bolt shanks in single and double shear lapped connections are determined experimentally. A total of seven four-point bending tests on jointed back-to-back channel beams, and one on a continuous beam, are then reported. In these tests, three types of joint arrangements were considered. A finite element model is then described and validated against the experimental test results in terms of ultimate moment capacity, failure mode and initial stiffness of the moment–displacement curve. The accuracy of existing design recommendations presented in the codes of practice (i.e., BS 5950-5; EN 1993-1-3; AS/NZS 4600; AISI S100-16) were compared against test results. Existing models for calculating the moment resistance and the rotational stiffness of the moment connections were updated for the different joint configurations tested. From this comparison, it was found that the models from the design standards can provide safe predictions of the joint capacity, albeit only if the bolt group length-to-width ratio is less than 3.5.