ABSTRACT
This chapter provides a qualitative approach of the structural behaviour of the basic structural forms of masonry monumental and historical buildings, which are met in Europe and particularly in the South, where the consequences of the seismic action are traumatic. The out-of-plane loading appears in the case of free-standing walls or masonry systems without diaphragmatic action of the floors. In the semicyclic arches of buildings, where loading is permanent and uniformly distributed, the load path method is the most suitable for an easy presentation of their behaviour. The diaphragmatic action is very usual in masonry buildings due to the fact that the decks are reinforced concrete slabs or solid systems of steel beams connected with concrete to a solid diaphragm. In the case of buildings, without diaphragmatic action of the floors, each wall acts as a free cantilever element in the out-of-plane direction.
