Ultimate limit state design of sheet pile walls by finite elements and nonlinear programming

The design of sheet pile walls by lower bound limit analysis is considered. The design problem involves the determination of the necessary yield moment of the wall, the wall depth and the anchor force such that the structure is able to sustain the given loads. This problem is formulated as a nonlinear programming problem where the yield moment of the wall is minimized subject to equilibrium and yield conditions.

The finite element discretization used enables exact fulfillment of these conditions and thus, according to the lower bound theorem, the solutions are safe.