Stochastic distribution of compressive strength: effects on the load carrying capacity of masonry arches

The standard assessment procedures for masonry arches assume the compressive strength of masonry as a deterministic variable. In this paper, the load carrying capacity of masonry arches is addressed by means of Kinematic Limit Analysis (Mechanism Method) assuming the material compressive strength as a random variable. Based on the failure probability of each admissible mechanism, the global collapse probability is provided by the Cornell approximation. The application of the procedure to a single span bridge shows that, for arch-type structures, the C.o.V. of the load carrying capacity is less than the C.o.V. of the compressive strength. Discussion is provided on the safety factors defined by masonry codes and their effect on the safety assessment of masonry arches