ABSTRACT
The present paper deals with the assessment of the load-bearing capacity of existing masonry arch bridges by means of numerical models. The problem related to the selection of uncertain parameters is addressed by reproducing a past experimental test performed on a reduced-scale bridge prototype vertically loaded until its collapse. The test is reproduced in Abaqus software by representing masonry elements through the Finite Element macro-modelling approach, in which masonry is considered as a homogeneous material having a plastic-damage constitutive behaviour in the nonlinear field. The fill material is introduced by means of a nonlinear continuum behaving under similar Mohr-Coulomb hypotheses. An appropriate interaction law that entails a frictional response in the tangential direction, avoids interpenetration, and allows for the separation between the two materials, is also considered. A wide parametric investigation is performed to obtain a good fitting with the experimental evidence by varying the uncertain mechanical parameters (i.e. Elastic Modulus of backfill, tensile strength of masonry and contact law between the two materials). Thus, a reliable numerical model exhibiting a response consistent with the experimental outcome in terms of both failure mode and force-displacement curve is proposed. The influence of each investigated parameter on the overall response of the bridge is then deeply analysed and discussed, also with the aim to identify possible retrofitting strategies.
