ABSTRACT
To assess the performances of existing Reinforced Concrete (RC) bridges, the current structural analyses need the definition of material properties, and in particular of concrete strength. Such parameter is usually measured by means of destructive tests on concrete cores drilled form a bridge, or by means of indirect non-destructive analyses, such as the acoustic techniques or the rebound hammer test. Nevertheless, in several cases, a rough estimation of the compressive strength of concrete is sufficient, without performing any test on the structures. This is the case of some historical RC bridges, which date back to the early ages of last Century and are currently in service in Italy. Accordingly, the strength-for-year curves have been introduced to calculate the average strength (and the percentiles) of a concrete cast in a specific year. They are based on the results of tests performed on concrete cubes, and stored in a database available at the Politecnico di Torino (Italy). The use of the strength-for-year curves improves the effectiveness of the rapid assessment procedures. As a result, the priorities of retrofitting, necessary to mitigate the risks associated with the prolonged service of RC bridges, can be better identified.
