Assessment of the structural response of masonry cross vaults

Cross vaults have been used extensively in the roofing of medieval buildings. Knowledge of the behaviour of cross vaults under load is fundamental for the planning of structurally compatible and economic conservation programmes. A method is presented here to assess their safety under various loading conditions. A 1/4-scale model was built in wood, representing an aisle vault of the partially collapsed Abbey Church of Holyrood in Edinburgh. The structure was loaded with dead weight and deformations and strains were recorded. Subsequently, the abutments were allowed to move progressively to cause the collapse of the vault. Finite element modelling was employed to interpret the experimental pattern, confirming the collapse of the vault was due to the development of hinges along the transverse vertex and the front abutments and membrane cracks at the back groins.