Progressive cracking of masonry arch bridges

Numerous methods are available for the assessment of masonry arch bridges at the ultimate limit state. However, there is a lack of suitable methods for assessing behaviour at service levels of loading. To address this, non-linear three-dimensional finite element (FE) models that consider constitutive material models enabling progressive cracking and failure of the complete structural system were used to investigate the development of damage for three masonry arch bridges at both service levels and at the ultimate capacity. All of the elements contributing to the strength of the structure were represented in the models, including the arch barrel, spandrel, abutments, fill and surrounding soil. This allowed for consideration of the longitudinal and transverse capacities, the stiffening effects of the spandrel walls, the restraint and load distribution provided by the fill, the frictional behaviour between the masonry and fill, movement at the abutments and multiple causes of failure. While complex non-linear FE models are able to identify the ultimate load capacity there are alternative simpler approaches available for this, and it is the investigation of damage and crack propagation at service level loads where their use is of greatest benefit.