On the service behaviour of masonry viaducts

Abstract

Railway viaducts are suffering damage short of collapse that is not predicted by current assessments, but which requires major interventions. This is a critical issue facing the UK rail network, where freight traffic is growing rapidly. This paper offers a new understanding of critical behaviour, which is not dominated by arching. Rather, the main section over each pier and extending well into the span either side behaves as a rigid block, rocking back and forth as loads pass. This behaviour explains spandrel cracks and horizontal cracks in spandrel walls and below parapets, which are both frequently seen in arch viaducts. With further research, including field measurement of behaviour under normal traffic loads, this understanding should lead to useful assessment guidelines and new methods of strengthening and repair.