Structural analysis of unreinforced masonry spiral staircases using Discrete Element modelling

Unreinforced masonry spiral staircases have been built for more than two thousand years in castles, churches and palaces, these require structural assessment. For a few decades, the behaviour of “cantilever” has debated among scholars. Several methods used, but due to complex 3D geometry substantial number treads, priori assumptions made about magnitude point application contact forces between treads wall-tread connections. These influence calculation torsional moment, which, some methods, reaches high values that could generate shear stresses greater material’s strength. In this paper, model based on one helix staircase San Domingo de Bonaval, Spain, analysed using Discrete Element Method. The entire stair is without making location resultant forces, which are calculated each tread customised Python-based functions. connections modelled rigid blocks, several conditions investigated. Moreover, different friction angles geometrical imperfections simulate material tolerances assembly imprecisions. simulation results indicate perfect lead conservative predictions moment. Instead, gaps allow small displacements, reduce torque increase compression inner helical ring stair. Low moment values, while vertical settlements do not cause significant effect. Cantilever situations still occur consecutive suggests tread-tread area should be carefully inspected during restoration. More generally, paper demonstrates potential variability highly indeterminate structures when boundary uncertain, providing valuable context inform restoration strategies.