Cap model for limit analysis and strengthening of masonry structures

Abstract

This paper presents a general method for the limit analysis of structures made of rigid blocks, which can be used in the assessment of ancient masonry structures. This method takes into account nonassociated flow rules and limited compressive stresses for masonry. The mathematical programming problem resulting from the formulation is a nonlinear optimization problem. The feasible initial solution is obtained by solving a mixed complementarity problem while, in a second step, the complementarity constraint is temporarily relaxed to allow for optimizing the load factor. A tie element added to the rigid block formulation permits the analysis and design of strengthening. Several results, obtained by a computer implementation of the method, are presented and discussed. The results show the validity of the method by comparison with experimental data, and also show the benefit of the approach in providing a better insight into the behavior of ancient masonry structures.