Seismic assessment of stratified defensive walls with rubble stone infill

This paper presents a study on the behaviour of the walls of the Rocca Roveresca of Senigallia in Italy built in the 14th century AD on the ruins of a former Roman defensive structure. This is a peculiar example of a fortress that had undergone in the 15th century AD modifications of the plant to enhance its defensive performances. A TOF laser scanner survey complemented with an endoscopic survey was necessary to highlight all the traces and the architectural stratifications occurred over time. A linear finite element model is first developed in order to understand the dynamic behaviour of a generic portion of the wall and to detect the probable incipient failure mechanisms. A subsequent static nonlinear analysis is carried out to investigate the formation of the cracking layout and to detect the position of plastic hinges. The last analysis level is carried out with a tailored macro-element constituted by three bodies, namely the two external curtains and the inner fill for which a degradation of the behaviour is considered. The results obtained demonstrates the efficiency of the wall against earthquakes characterized by return times typical for ultimate limit states. Same issues that deserve further investigation are highlighted.