A complete analysis for reinforced concrete slabs and shells, which analyses a structure for successive loads, is formulated.

For each load a simulated structure is formed from anisotropic (or isotropic) finite elements whose stiffnesses are degraded if they are not compatible with the current stress system. The material constants for the anisotropic finite elements are determined by an analogy with the degradation of the load-moment-curvature relationships of an equivalent beam cross-section.

The method of analysis gives results which compare favourably with existing results of two rectangular slabs, an L-shaped slab, and a cylindrical shell roof model. The comparisons include crack patterns, load-displacement curves 9 and displacement profiles. The theoretical crack patterns include the direction and area of cracking. They are similar to the experimental crack patterns, and they follow the directions indicated by the yield-line theory, though the theoretical yield regions have substantial width. The theory predicts stiffer behaviour for some points on the structures and more flexible behaviour for the other points.