ABSTRACT
Iron tie-rods have been widely used geographically and historically as the most intuitive and simple solution to reinforce vaults and arched structures, both to make them able to withstand unexpected actions and to allow them to be supported by slender abutments. This chapter analyses the tie-rods found in a paradigmatic case-study, the Santa Casa di Tresivio, which underwent several reinforcement interventions through the last two centuries according to the contextual physical understanding of the arch mechanics. The structure is modelled taking into account to the nonlinear and cracking nature of masonry vaults, and the interaction between the masonry and the tie-rod. The mathematical and physical models that explained the collapse and damage of masonry arched structures implied mostly different decisions on where the tie-rods should be implemented in order to make their best structural performance, and sometimes even on the appropriateness of its use. The masonry is composed by slightly carved stone blocks, complemented with small ashlars.
