Assessment of masonry bridges: numerical and theoretical approaches

The mechanical response of masonry bridges is still only partially known. Recent tests on reduced scale models and on real scale bridges showed that masonry bridges are complex structures in which all the elements take part in the load carrying system. The assessment procedures rely on some commonly accepted assumptions and make largely use of Limit Analysis, which assumptions are not fulfilled by brickwork. Recent tests showed that only deep arches can be reasonable dealt with Limit Analysis procedures while the collapse of shallow arches is not a bending collapse, that is typical of collapse mechanisms, but it is ruled by the axial force, collapse being attained because of compressive crushing of some sections. In this paper a comprehensive view of the assessment procedures is given underlying pros and cons of every approach. An example provides an application of the discussed issues