Advanced nonlinear analysis of masonry arch bridges

Abstract

This research investigates the nonlinear response up to collapse of masonry arches and arch bridges using advanced numerical descriptions. Past research has shown that the mesoscale modelling approach for brick-masonry, where bricks and mortar joints are modelled separately, may offer a realistic representation of the mechanical behaviour of masonry components. However, because of the significant computational cost, thus far the use of this modelling strategy has been mainly restricted to 2D analysis of masonry arches and arch bridges. In some cases this may lead to a crude representation of the response which is inherently three-dimensional, especially when the analysed structure is subjected to eccentric loading or is characterised by a complex geometry (e.g. skew arches). In this work, masonry arches and arch bridges are analysed using a partitioned mesoscale approach, which enables the use of a detailed model for describing material nonlinearity at structural scale. This is combined with a partitioned approach allowing for parallel computation which guarantees computational efficiency. In the 3D mesoscale description, brick units and mortar interfaces are modelled separately accounting for the actual texture and arrangement of masonry. 3D elastic continuum solid elements are used to model brick units while mortar interfaces are modelled by means of 2D nonlinear interface elements. In analysing masonry bridges, the backfill material is modelled as an elasto-plastic continuum, while the physical interface between the continuum and mesoscale domain for masonry is represented by nonlinear zero-thickness interface elements allowing separation and plastic sliding. The proposed modelling approach has been applied to the analysis of multi-ring square and skew arches and masonry arch bridges. The numerical results, which also include numerical-experimental comparisons, confirm the accuracy of the adopted numerical strategy. Moreover numerical simulations have been performed to investigate the effects of the arch geometry, loading positions, material characteristics and potential settlements at the supports. The results obtained offer important information and a detailed description on the complex response of these critical structural systems under different loading and boundary conditions.