Nonlinear analyses of the medieval "Ponte del Diavolo", Borgo a Mozzano, Italy

Structural analyses are particularly difficult to conduct on masonry constructions as a result of the lack of knowledge of the material mechanical properties. However, one well-established peculiar characteristic of masonry is its radically different behavior under tensile and compressive stresses. A suitable constitutive equation has been developed that models masonry as an isotropic elastic non-linear material with zero tensile strength and either infinite or bounded compressive strength. This constitutive equation, which is known as the masonry-like model, has been implemented in the finite element code NOSA-ITACA, which has been successfully applied to the static analysis of several historical masonry buildings as well as the dynamic analysis of masonry pillars, beams and towers. In the work, described in this paper, the Maddalena bridge, known as the "Devil's Bridge" ("Ponte del Diavolo"), on the Serchio river in Borgo a Mozzano, Italy is studied. The paper presents several structural analyses performed using the NOSAITACA code by means of finite element models composed of plane or threedimensional elements. Initially, the structural behavior of the bridge under permanent loads is investigated using non-linear static analysis. Then, a non-linear dynamic analysis is performed using a time-dependent three-dimensional acceleration recorded during the earthquake that occurred in the nearby "Lunigiana" area on the 21 June in 2013. The results are analyzed and the differences between the linear and nonlinear behavior are highlighted.