Several in-service reinforced concrete bridges within Italy’s road infrastructure network—as well as those worldwide—exhibit significant structural deficiencies. In this context, structural monitoring serves as a valuable tool for detecting early signs of deterioration, enabling timely maintenance, and preventing potential failures that could jeopardize public safety. Although the relationship between dynamic identification and the presence of structural issues remains an open question, the potential of dynamic identification for preliminary and rapid assessment of bridge health is widely recognized.

This study reviews and compares the experimentally identified vibration modes and natural frequencies of existing reinforced concrete bridges, as reported in the literature, with the goal of developing simplified formulations for the preliminary estimation of their dynamic properties. A simplified numerical model is employed both as a reference and to expand the experimental dataset. Initial results show substantial agreement between analytical and experimental outcomes for the fundamental modes and highlight the cases where significant discrepancies in predicted versus observed frequencies occur.