A unified design model to assess the shear behaviour and ultimate strength of a cold-formed steel welded and bolted clip-angle connection

Abstract

In the present research work, a series of 70 laboratory tests were carried out to investigate the shear characteristics of a CFS welded clip-angle (WS) connection. The WS connection primarily exhibits failure modes such as (i) local buckling and (ii) distortional buckling of the clip-angle, in addition to a CFS column bearing failure. The impact of column bearing failure on the ultimate shear strength of the WS connection is investigated. A detailed parametric study is undertaken to analyze the effects of design variables on the different failure modes and the ultimate strength of the WS connection. Following the conventional two-step process, a design approach for the WS connection is developed like (i) failure modes were classified using aspect ratio (width/depth) and (ii) a new design equation was developed to predict the ultimate shear strength. Nonetheless, it is important to note that these two design steps are not interrelated. Therefore, the present research introduces a unified design model to assess and relate the failure behaviour and ultimate strength using a failure index factor. Unlike conventional method that overlook thickness impact on failure mode categorization, the current failure index factor considers all relevant design variables. The suggested design methodology has been expanded to the CFS bolted connection and shows a good agreement with the literature data of 114 bolted CFS connection tests. A comparative study was executed on the welded and bolted CFS shear connection and design guidelines have been formulated. A reliability assessment of the developed design models for both welded and bolted CFS connections has been carried out. A design example is provided to elucidate the design methodology.