Train-induced vibrations on the Maddalena Bridge in Borgo a Mozzano (Italy)

De Falco A., Galletto A., Girardi M., Pellegrini D.

Masonry-like model  Masonry bridges  Dynamic analysis 

This paper deals with the Maddalena Bridge, also known as the "Devil's Bridge", in Borgo a Mozzano (Italy). This particularly fascinating structure was built in the 11th century as a strategic infrastructure for trade routes. Due to the changing needs and new lifestyles of modern society, its importance as a thoroughfare has been progressively lost over the centuries. The construction of a new railroad line in the early 20th century called for demolition of the bridge's right shoulder in order to build the railway embankment and a new arch for the passage of trains. Nowadays, the vibrations of passing convoys are transmitted to the bridge, and current conservation requirements for this national monument require assessments of the interaction effects with the railway infrastructure. This document reports on a vibration measurements campaign aimed at evaluating the effects of train transit in terms of stresses and accelerations on the bridge structure. To this purpose, many acceleration time-histories have been acquired on the railway and bridge both under ambient vibrations and during the passage of convoys. The analysis of the experimental data has also enabled calibration of a finite element model of the bridge. Furthermore, in order to assess the overall stress field in the structure and its dynamic behaviour, several structural analyses have been performed by modelling masonry as a nonlinear elastic material, with zero tensile strength and infinite compressive strength, according to the masonry-like model. In particular, the accelerations recorded on the railway during the transit of a cargo train have been applied to the finite-element model. Dynamic analysis was then performed and the results compared with those actually recorded on the bridge. All analyses have been performed by means of the NOSA-ITACA code (http://www.nosaitaca.it/en), in which the masonry-like model has been implemented. This study provides information on both the dynamic response of the structure and the effects produced by the passage of trains on the adjacent railway tracks.

Source: ISTI Technical reports, 2015