Fundamentals of Statics of Masonry Solids and Structures

Groundings of statics of masonry solids and structures are the subject of the chapter. Masonry behavior is strongly influenced by the dramatically lower strength in tension than in compression. Masonry structures can thus suffer cracks generating displacement fields, called mechanisms, which develop without any internal opposition of the material. Collapse can occur without any material failure. The Heyman masonry model, the idealized rigid in compression no tension material, is fruitfully assumed as basis of the approach followed in the chapter. The extension of this model to the masonry continuum is then developed. Strains and detachments occurring in a no tension masonry solid can thus obtain a suitable mathematical definition together with the admissible equilibrium. Both a proper virtual work equation, that considers the boundary of the body including the crack surfaces, as a condition on the loads, necessary and sufficient to the existence of the masonry equilibrium, can be formulated. This last condition governs the collapse strength of masonry structures. The notion of the minimum thrust, from both static and kinematical approaches, is then introduced, widening the field of application of the Limit Analysis also to the study of the actual stress states. A critical analysis of the recent failure of the cathedral of Noto, in Sicily (Italy), useful to a better understanding of the above discussed mechanical concepts, ends the chapter.