A new masonry arch bridge assessment strategy (SMART)

About 40% of the European railway bridge stock comprises masonry arch bridges and over 60% of these are over 100 years old. All are ageing and most are carrying loads well in excess of those envisaged by their builders. The maintenance and assessment of these bridges is a constant concern for the bridge owners. Although current masonry arch bridge assessment methods are able to predict the ultimate carrying capacity of the bridge with some confidence, serious concerns have been identified with respect to predicting long-term behaviour and residual life. A new assessment procedure (sustainable masonry arch resistance technique (SMART)) is presented which differs philosophically from all the current techniques in as much as it takes a holistic approach in considering all possible modes of failure that the structure may experience under any given loading regime. Limit states are discussed and a new permissible limit state that is specific for masonry is proposed. The method advocates consideration of the permissible working loads, longterm behaviour and residual life of the bridge. This enables the assessing engineer to prioritise conflicting maintenance demands on limited budgets. The method is based upon recent research related to the long-term fatigue performance of masonry arch bridges subjected to cyclic loading.