  This work presents an extended formulation of maximal stiffness design,
within the framework of the topology optimization. The mathematical formulation
of the optimization problem is based on the postulated principle of equal
dissipation rate during inelastic deformation. This principle leads to the
enforcement of stress constraints in domains where inelastic deformation would
occur. During the transition from the continuous structure to the truss-like
one (strut-and-tie model) the dissipation rate is kept constant using the
projected gradient method. The equal dissipation rate in the resulting truss
and in the original continuous structure can be regarded as an equivalence
statement and suggests an alternative understanding of physical motivation
behind the strut-and-tie modeling. The performance of the proposed formulation
is demonstrated with the help of two examples.
