Analytical-empirical relationships for the estimation of flexural frequencies in reinforced concrete bridge decks

Several in-service reinforced concrete bridges within the Italian and worldwide infrastructure network exhibit significant structural deficiencies. In this context, structural monitoring based on dynamic identification serves as a valuable tool for detecting early signs of deterioration, enabling timely maintenance, and preventing potential failures that could threaten 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 recognised. This study reviews and compares experimentally identified vibration modes and natural frequencies of a number 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. Empirical-analytical correlation laws for the two flexural frequencies as functions of geometrical parameters are developed, showing good capability in predicting the fundamental frequencies of reinforced concrete bridges.