Analisi limite agli elementi finiti di archi in muratura interagenti col riempimento

The limit analysis of masonry bridges is faced/tackled by considering the interaction between arches, piers and fill. The former are modelled by beams made of no tensile resistant material while the latter as a heavy rigid-plastic material in the simplifying hypothesis of plane strain. On the upper surface of the fill traction distributions are applied and upper bounds of the load multiplier at collapse are ricercati/pursued by applying the kinematic theorem. The collapse mechanisms considered are based on approximations of the velocity field from a finite element discretization. The fill is modelled by triangular constant strain elements and the arches and piers by two node beams. In order to take into account possible discontinuities in the velocity field in the fill, four nodes rigid-plastic interfaces are located between the triangular elements. Once linearized the limit domains in the generalised stress space, externally tangent to the effective limit domains, a linear programming problem is defined and upper bounds for the applied increasing loads are obtained. Two example are analysed and discussed from which the relevant effects of the fill on the collapse mechanism and multiplier are shown; finally, the sensitivity of the collapse multiplier on the mechanical parameters of the fill such as the coesion coefficient and the angle of internal friction is obtained