On the Nonlinear Behaviour of Domes Subjected to Point Loads on the Crown

A new model for nonlinear static analysis of masonry domes subjected to point loads on the crown is presented. Its simplicity makes it usable in common practise by unexperienced users. Masonry is modelled with elastic hexahedral elements connected by 1D elements representing mortar joints, both meridian and horizontal, on which nonlinearities are concentrated. The aim is to simulate the nonlinear behaviour of domes under vertical loads by using a Finite Element commercial software equipped only with the simplest finite elements, namely point contacts and cutoff bars. The mortar joints nonlinearity is reproduced by two different models. The first of which accounts for elastic perfectly brittle point contacts under Heyman’s hypothesis of no-tension material. Whereas the second exploits elastic perfectly ductile cutoff bars, by which different tensile strengths and masonry orthotropy are considered. In this last model, to evaluate the increase in load carrying capacity, Fibre Reinforced Polymers (FRP) strips are applied. While in the first model, the position of plastic hinge is well defined at the expense of the ultimate load, in the second model, the plastic hinge is smeared in favour of a major precision and accuracy in the computation of collapse load. The models are benchmarked on a masonry dome experimentally tested. The procedure is validated by comparison of results with a wide range of Finite Elements, numerical approaches and limit analysis available in the literature for the same dome. By the analysis of nonlinear behaviour emerging from load-displacement curves, the robustness and simplicity of the procedure is proven.