Author
C ANSELMI, E DE ROSA and L FINO
Dipartimento di Costruzioni e Metodi Matematici in Architettura, Università Federico II, Naples, Italy

Abstract
The analysis of the mechanical behaviour of masonry structures has already been the subject of a rich vein of literature. The results of much of this work pointed out the particular importance of limit analysis for estimating the safety of masonry when it is modelled as discrete systems of rigid blocks.
We now return to a very simple numerical method, already described in our previous work regarding walls subjectedto loads in the middle plane.
The objective of this new work is now to evaluate the load collapse multiplier for masonry walls subjected to out-of-plane seismic forces through a linear formulation founded on the static theorem of limit analysis.
The walls are shaped as systems of rectangular or triangular rigid macro-blocks. Their main mechanical features are: provision for blocks to slide with dilatancy; inability to carry tension and limited compressive strength for the contact interfaces. The collapse load is evaluated making use of Excel’s solver. Then, the evaluation of the collapse mechanism is pursued with respect to the kinematic compatibility conditions.