2D-DEM modelling of the formwork removal of a rubble stone masonry bridge

• On-site measurements showed a singularity for voussoirs very close to the keystone.
• A DEM modelling is required to retrieve the patterns observed on site.
• Transfer of stresses between the voussoirs does not involve the total contact area.
• The reduction of the contact zone must be settled to a value close to 20%.
• Local stresses larger than those predicted by a FEM may exist within the voussoirs.

This study aims to determine the mechanical behaviour of a stone arch bridge during the phase of the formwork removal. This operation is the most delicate during construction, because it puts in charge the arch which must work in compression for stability. On-site measurements of the displacement of the arch voussoirs during the process of the formwork removal were carried out. Then, some mechanical tests were performed with the stones used in the construction to determine the mechanical properties required for modelling the structure by a discrete element method. This numerical approach has the ability to find the specific pattern of the displacement field observed on-site that could not have been found with a finite element method. The key feature is the rotation of the voussoirs which changes the location of the zones of contact from one to another. Therefore, the contacts from one to another are restricted to a small zone for the voussoirs close to the keystone.