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A variational model for irreversible quasi-static crack evolution in quasibrittlematerials is proposed in which, at each time step, the equilibrium crack paths areassociated with stationary points of a particular energy function, composed of bulk andsurface energy terms. The approach is similar to that proposed in [4-5] but, here, asubstantial modification of the energy function of [4-5] allows for the formation ofshear bands that may coalesce in mode II cracks, whereas the model of [4-5] can onlyaccount for cleavage fractures. The procedure has been numerically implemented andapplied to reproduce the characteristic fracture pattern observed in the ashlar masonryof the French Panthéon in Paris. The crack pattern theoretically predicted with themodel here proposed, being very similar to that observed in the French monument,gives an insight into the possible causes of damage.