Evaluation of static collapse multiplier for masonry walls subjected to out-of-plane loading

The analysis of mechanical behaviour of masonry structures has been the subject of a rich literature until now. The results of lots of these works pointed out the particular importance of the limit analysis to estimate the safety of the masonries, when they are modeled as discrete systems of rigid blocks. We now take back a very simple numerical method, already described in our previous works regarding walls subjected to loads in the middle plane. The objective of this work, instead, is 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 the limit analysis. The walls are shaped as systems of rectangular or triangular rigid macroblocks. 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 the respect of kinematic compatibility conditions.