ABSTRACT
A large number of existing masonry arch bridges are still in use in the Italian roadway and railway networks. Most of them were built more than one hundred years ago, designed considering only gravitational loads without any seismic analysis. To keep these works in service, it is necessary to have tools that can describe and predict the structural behavior of the bridge when subjected to extreme actions. For this reason, a three-dimensional rigid-block analysis for masonry arch bridges has been developed. In the model, the main structural masonry elements (vault, pier, abutments, spandrel wall) are discretized as an assemblage of rigid blocks, which interact via no-tension contact surface with Coulomb friction. This approach allows reproducing with good accuracy the tri-dimensional collapses mechanisms of some real masonry arch bridges recently collapsed due to extreme events.
