LOAD BEARING STRUCTURE OF MASONRY BRIDGES

Masonry bridges are often considered arches to which the fill, retained by the spandrels, contributes as a stabilizing dead load. Recent research demonstrated that the arch-fill interaction is a fundamental contribution to the load carrying capacity of these bridges. To highlight this aspect, several tests on reduced scale models were performed but improper scaling rules introduced a bias on the results making them often unreliable. In this paper, test results on reduced scale models, according to proper scaling rules, are discussed providing an estimation of the amount of load carrying capacity increase due to the arch-fill interaction. Up to now, only a deep arch model has been tested, showing also that the classic assumption of hinge-mechanism is not fulfilled, being anticipated by compressive crushing of the materials. This raises some questions on the standard procedures for the bridge assessment