ABSTRACT
This chapter analyses the evolution of the cracking pattern of San Giovanni Baptistery, combined to the stress measurements carried out on the tie-rods systems. It presents a brief comparison with the typology of wooden tie-rods inserted in Santa Maria del Fiore dome in order to better understand their fundamental role in the conservation process of these great structures. The chapter provides numerical analyses, carried out considering both simplified approaches and refined finite element models, to deepening the effectiveness of the "hidden" tie-rods. The insertion of tie rods around masonry domes had always represented the traditional strengthening technique employed to absorb their horizontal thrust. The final result of the combined numerical and historical analysis has clarified the crucial role of traditional hooping - often "hidden" inside the structure - for great masonry domes in order to fight against their worst enemy: the horizontal forces.
