Keywords: masonry arch bridges, finite element modelling, crack modelling.

Determining the ultimate behaviour of masonry arch bridges has been a topic of interest to practising engineers and researchers for a number of years in the UK. The UK has a very large stock of these bridges that are still in use on road and rail links and has funded a large programme of assessment and refurbishment of these structures over the past 30 years. Research interest remains strong, however, due to increasing maximum vehicle weights and the concern that many current methods of assessment are too conservative.

The ultimate failure load of a masonry arch bridge is difficult to calculate with any accuracy since it depends on many factors, most of which are hard to quantify. Researchers have therefore tended to concentrate their modelling of these structures on the major load-carrying parts such as the arch barrel and the fill above. Finite element modelling applied to masonry encounters many difficulties not found in the modelling of materials such as steel and concrete. Masonry is a coarsely composite material, consisting of "voussoirs" (bricks or stones) and mortar. The behaviour is characterised by brittleness and cracking, features not well accommodated in conventional continuum finite element formulations.

This paper presents some new ideas for the modelling of masonry arch bridges using commercially available finite element software similar typically available in civil engineering consultants design offices. The approach avoids the use of macroscopic elasto-plastic constitutive modelling of masonry (e.g. [1]) and may therefore be more accessible to practitioners.

We show that finite element models of arch barrels can be built from a combination of elastic continuum elements, pseudo-gap elements (no-tension beams) and shear panels. The last two types of elements combined can be used to model cracking behaviour, which is both robust and easy to use. The model is demonstrated on simulations of two bridges tested to capacity in the 1980's under the TRL programme of research [2]. These barrel models are then built in to a more comprehensive model of the bridge including the overlying fill material.

The most useful output from this research are (a) indications of suitable material parameters to model cracking and (b) guidance on solution controls to ensure convergence.

1

Crisfield, M.A. 1985 Finite element and mechanism methods for the analysis of masonry andv brickwork arches, HMSO

2

Page, J. Masonry arch bridges - TRL state of the art review. HMSO, London, 1993

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £123 +P&P)