Column base-plates under biaxial bending moment: Fid-Bau Portal

Column base-plates under biaxial bending moment

Da Silva Seco, Laura / Couchaux, Maël / Hjiaj, Mohammed / Neves, Luis Costa

Highlights • Test results of column base-plates subjected to uni/bi-axial bending moment. • The failure mode is not affected by the orientation of the bending moment axis. • Prying effect depends strongly on the orientation of the bending moment axis. • Plastic redistribution between tensioned anchor bolts occurs under biaxial bending.

Abstract This paper investigates the behaviour of exposed column base-plates with four outer anchor bolts subjected to monotonic loading. The results of six full-scale tests on steel column base-plate connections subjected to uni/biaxial bending moment are presented. The influence of the base-plate thickness and the bending moment axis orientation on the connection response is thoroughly investigated. In addition to standard measurements, Digital Image Correlation has been used to closely monitor the evolution of the contact area that develops in the tensile and compressive zones. Furthermore, a detailed finite element model has been developed using the software Abaqus and used to explore additional orientations of the bending moment axis. This numerical model allows to investigate the evolution of the anchor bolt forces, the contact pressure distribution and the lever arm, that strongly influence the bending resistance and rotational stiffness. An Analytical model is suggested for the calculation of the bending resistance of a column base-plate connection whatever the orientation of the bending moment axis. The position of the centre of compression directly depends on the base-plate thickness. A plastic redistribution is also considered between the anchor bolt rows when biaxial bending moment is applied to the column base-plate.