AN INCREMENTAL PROCEDURE FOR DEFORMATION ANALYSIS OF ELASTIC PLASTIC FRAMES

An incremental procedure is formulated for elastoplastic analysis of plane frame structures discretized into a finite number of beam members and described by piecewise linear elastic-perfectly plastic constitutive laws, under the assumption of both reversible and irreversible behaviour of material and using piecewise linear yield conditions at any desired degree of discretization in the space of the active stress resultants (axial force, shear force and bending moment). The incremental procedure presented in this paper allows geometrically linear analysis of elastoplastic frames, but it can be easily extended in order to account for the effects of geometrical non-linearities by means of the 'fictitious' generalized forces in the framework of the matrix force method for large deflections, and for the influence of finite spread of yielding zones.