Very High Cycle Corrosion Fatigue Study of the Collapsed Polcevera Bridge, Italy

A possible scenario is proposed to put into evidence how the combined effect of fatigue at very high number of cycles and corrosion could have been responsible for the failure of one of the strands and the subsequent collapse of the so-called balanced system of the Polcevera Bridge designed by Morandi. The analysis accounts for an actual estimation of the heavy-lorry traffic and load spectrum, as well as for the European Standards prescription for the fatigue damage accumulation assessment. In addition, the effective construction phases of the viaduct are considered. The structural analysis is carried out by means of analytical models, in order to simplify the structure complexity without prejudice to the description of the most relevant aspects of the structural behavior. The main purpose is to warn the scientific community and the public administrations that the combined effects of low-amplitude fatigue and corrosion can be dangerously underestimated, and that the existing assets of 20th century bridges deserve special attention in this respect.