ABSTRACT
Railway bridges are carrying increasing volumes of traffic and carrying loads significantly in excess of those envisaged by the bridge designers. Experience over the last 30-40 years has indicated that long term cyclic loading from the repeated application of heavy traffic loads, can accelerate the deterioration of masonry arches, however, much of the existing research has focused on the behaviour of the arch under
monotonic loading conditions. The failure of masonry arch bridges is typically associated with three modes:
• formation of a hinge mechanism; • snap through failure prior to the full formation of
hinges; and • crushing failure
These failure modes generally relate to single span, single ring square arches without taking the effects of soil-structure interaction, possible abutment movements, mortar washout, long-term fatigue deterioration, etc. into account. In addition to the classical failure modes, masonry arches may also fail by a number of alternative failure mechanisms, such as ring separation, sliding, abutment movement, etc. Figure 1 shows typical arch failure modes.
