This paper discusses the modelling of simple supports using geometrically exact 3D thin-walled beam finite elements relying on the rotation vector parametrization of the cross-section rotation. This issue is quite relevant, as isolated simply supported members are widely employed in numerical and experimental studies aiming at developing design rules for steel members. In beam models these supports are usually defined as restraining the cross-section in-plane displacements and the rotation about the beam initial axis (herein designated as the “θ3=0” support), but in experimental tests and shell finite element models, a two-axis gimbal-type support is used instead. Consequently, this paper aims at (i) showing how the two-axis gimbal support can be modelled using beam elements based on the rotation vector and (ii) highlighting the differences between the two support types. Several numerical examples are presented to illustrate these differences, which are quite significant for moderate-to-large displacements but do not affect the collapse load of standard steel members.
- Fork support
- Geometrically exact beam theory
- Gimbal support
- Large displacements