VAULT-FILL INTERACTION IN MASONRY BRIDGES: AN EXPERIMENTAL APPROACH - 2: DYNAMICS

This paper is the continuation of a companion paper presented in this conference by the same authors. It is first demonstrated that scaled models may reproduce the dynamic response of masonry bridges if proper scaling criteria are set. The comparison of the natural frequencies of the real bridge to the ones expected on the basis of structural models may provide important information on the inner structure of the bridge, which is often known only approximately or is unknown at all and is only postulated. A series of laboratory tests are discussed to identify and quantify the contributions to the natural modes, shapes and frequencies of the different elements of a masonry bridge. 1:4 prototypes have been used; dynamic tests have been performed at different levels of load-induced damage and in different settings: bare arch and arch + fill. It is showed that the structural elements, and their effective contribution to the load bearing structure, may actually be identified by means of dynamic identification techniques. Damages, mainly due to material degradation or overload, instead, may be identified on the basis of dynamic testing only if their extent is large enough to be detected also visually