ABSTRACT
The limit analysis approach is an effective tool for the safety assessment of masonry arch-type structures under seismic actions. The load bearing capacity of masonry arches is dependent on their geometric features, such as thickness, rise and span. This chapter focuses on the geometrical uncertainties of the voussoirs and their influence on the horizontal loads bearing capacity of the circular arch. It presents the horizontal loads carrying capacity of circular masonry arches by an iterative procedure, which refers to limit analysis and assumes Heyman's hypotheses about the material. The chapter considers the effects of the number of elements in the discrete model, which can be related to the ratio between the size of the voussoirs and radius. In order to determine the horizontal load multiplier and the corresponding mechanism, three conditions are imposed together: equilibrium, resistance criterion and mechanism condition. The seismic safety assessment of arch-type structures should be done by taking into account the uncertainties related to the geometry.
