This paper considers a theoretical analysis of the inelastic response of tubular brace members of offshore jackets which are supported on nonlinear rotational end springs and subjected to axial load and generally applied end bending moments. The present analysis is based on the concept of 3-D plastic hinge formation. The method assumes that plasticity is confined to discrete plastic hinges while the rest of the member remains elastic. This allows a rapid nonlinear analysis of the axial behavior of the member by a sequence of elastic solutions of the classical beam-column equations. It is shown that the model is able to simulate closely and efficiently the 3-D inelastic behavior of brace members under the foregoing support conditions.