Initial post-buckling of submerged slender vertical structures subjected to distributed axial tension

This paper proposes an analytical solution for determining the initial post-buckling behaviour of submerged slender vertical steel structures. These structures may have significant bending stiffness and self-weight so that the axial force varies linearly from one end to the other. Such structures constitute main components of drilling and production platforms used for the offshore exploitation of hydrocarbons. An understanding of their structural behaviour after buckling offers opportunities for cost reduction and design optimisation. The initial post-buckling behaviour is evaluated by retaining non-linear curvature terms and using an expansion in series to reduce the governing equation to a set of linear ordinary fourth order differential equations, which are then solved sequentially by power series functions. The paper also presents results from buckling and non-linear large deflection finite element analyses. The numerical results validate and establish a range of application for the analytical formulation. This solution technique is employed to explore the behaviour of slender structures dominated by geometrical (tension) or flexural stiffness.