The Effect of the Associative Friction in the Seismic Limit Analysis of Masonry Arches with Uncertain Geometry

In this work, a limit analysis procedure for the estimation of the collapse conditions of masonry arches in presence of horizontal seismic actions is presented. The contribute evaluates the effect of the associative friction on the collapse load and the related mechanism of the masonry arch affected by geometrical uncertainties. Adopting rigid block limit analysis, considering rocking and sliding interface failure modes, a procedure was developed in order to evaluate the horizontal loads multiplier, taking into account the effects of geometrical uncertainties related to irregularities of construction, shape defects of the voussoirs and/or the deterioration levels. The procedure outcomes are the collapse configuration of the structure and the limit horizontal loads multiplier, whose statistical moments up to second order and probability density functions are evaluated in function of specific geometrical parameters considered as random variables. The horizontal limit load multipliers obtained taking into account uncertainties effects are compared with those obtained considering the nominal geometry and the comparison shows that the uncertainties effects could reduce significantly the nominal load capacity of the structure.