Ultimate Limit State Design Of Sheet Pile Walls By Finite Elements And Nonlinear Programming

Limit analysis has been used for decades in civil and mechanical engineering practice as a means of analyzing structures of materials which with reasonable accuracy can be described as being rigid-perfectly plastic. Such materials include steel, concrete and soils. Traditionally, most attention has been given to the problem which consists of determining the ultimate magnitude of a given set of loads acting on a structure with a given geometry. This problem is relevant when determining e.g. the necessary extrusion pressure in metal forming problems, when evaluating the bearing capacity of reinforced concrete slabs or the stability of slopes, and generally, whenever all information about the structure, except for the ultimate magnitude of the load set, is known. However, in the design of structures the situation is the opposite. Here the loads are known whereas the necessary dimensions, boundary conditions, material strengths, etc. must be determined in such a way that the structure is able to sustain the given loads. Thus, limit analysis embraces two different scenarios, one where everything except the maximal permissible load intensity is known, and one where all that is known is the load intensity.
In the paper we consider the latter of these problems with particular reference to the design of sheet pile walls.