Spherically-Hinged Cold-Formed Steel Equal-Leg Angle Columns: Experimental Investigation and DSM Design

Recently, Dinis & Camotim (2017) performed an in-depth numerical investigation aimed at developing, validating and assessing the merits of a novel Direct Strength Method design approach for short-tointermediate cold-formed steel simply supported equal-leg angle columns -- the end cross-sections are prevented from warping and torsion, and pinned with respect to major and minor-axis bending, which amounts to being rigidly attached to rigid plates resting on spherical hinges ("spherically-hinged columns"). However, a shortcoming of the above investigation was the lack of experimental validation, due to the fact that no available experimental failures loads concerning these columns were found in the literature. The research work reported in this paper provides a contribution towards filling this gap, since it consists of an experimental study, carried out at COPPE (Federal University of Rio de Janeiro), on the behavior and load-carrying capacity of cold-formed steel spherically-hinged equal-leg angle columns. After addressing the selection of the columns to be tested, the experimental set-up and test procedure are described in detail and the results obtained are presented and discussed. Such results comprise (i) initial geometrical imperfection measurements, (ii) equilibrium paths relating the applied load to key column displacements, (iii) deformed configurations (including the collapse modes) and (iv) failure loads. Next, attention is turned to assessing the merits of the DSM-based design approach proposed by Dinis & Camotim (2017). The comparison between the (i) experimental failure loads obtained in this work, as well as the previously available numerical ones, with (ii) their estimates provided by the novel DSMbased strength curves shows a very good correlation -- thus, it may be rightfully argued that the validation and calibration of this design approach has been successfully achieved.

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