Polyhedral yield surfaces in the element nodal force space

In contrast to the usual procedure of formulating constitutive material laws in a number of integration points within each element, the approach presented here proposes using the element nodal forces and their associated nodal displacements as generalized stress and strain components. The procedure is restricted to elasto-plastic constitutive laws, and requires the formulation of linearized yield conditions in the nodal force–displacement space. Some examples related to the ultimate load analysis of reinforced concrete slabs modelled by plate-bending elements are discussed.