Transverse behaviour of masonry arch bridges

Research efforts in the assessment of masonry arch bridges have concentrated on the strength of the arch in the span direction. However, experience with these structures indicates that masonry arch bridges more often fail by sliding or overturning of the spandrel walls perpendicular to the roadway centreline, or by the development of longitudinal cracks in the arch barrel and eventual separation of the spandrels from the remainder of the arch barrel. The present paper reports results of a 3-dimensional non-linear finite element (FE) model of an arch bridge that uses a Drucker-Prager material for the fill and a brittle material for the masonry. The model predicts that most truck-loaded stone arch bridges will exhibit a premature failure due to lateral effects rather than a mechanism collapse. The predicted lateral failure modes include local spandrel wall failures, overturning of the spandrel walls, edge failure of the arch barrel, and local punching of the arch. Stone bridges with thin arches or bridges with very low tensile strengths were predicted to be significantly weakened by such lateral effects.