The figure illustrates the applied forces and external constraints on the masonry arch model. Brick and Mortar are in frictional contact. nnThe solution shows that as the friction coefficient increases, the model offers a greater capacity to resist, in the sense that the breaking load takes on higher values. This is, for example, a force-displacement diagram.nSo far everything is ok, but the problem arises when, instead of the load, I cheque for increasing displacements.nIn this case, however, the solution is always convergent and contrasts the model examined before, that is, with increasing force, which showed a breaking load. Therefore, with  Solution>Insert>Probe>Force reaction ( Y component of the Reaction Force at the fixed supports), I obviously get this diagram and not what I would have expected and that we have defined as the goal of the research. nnIs this a modeling problem or what?nThanks in advancen