Seismic response of the Circuit Wall of the Acropolis of Athens: Recordings versus numerical simulations

The Acropolis of Athens is one of the most prestigious ancient citadels in the world, and therefore, the structural integrity of its monuments and structures is of paramount importance. Since Greece is characterized by high seismicity, a seismic array of accelerographs has been installed on the Acropolis hill over the last decade in order to monitor the dynamic response and distress of monuments and structures in real time. One of the monuments is the Circuit Wall, which is actually an old perimeter masonry retaining structure. Undoubtedly, monitoring its seismic response comprises a very interesting and useful "real-scale experiment". Furthermore, records and analyses in the literature have shown that the seismic behaviour of any retaining structure is a complicated problem of dynamic soil-structure interaction, where many parameters seem to have a substantial impact on the overall dynamic response and distress. Based on the aforementioned, the current study aims to shed light on the seismic response and distress of the Acropolis' Circuit Wall. After a short description of the prevailing geological and geotechnical conditions of the Acropolis' hill and the available geometrical and mechanical properties of the Wall, an evaluation of the available seismic records is conducted. Subsequently, preliminary two-dimensional dynamic numerical simulations are being performed utilizing the finite-element method in order to estimate the seismic response of the Wall in terms of acceleration. Despite the various uncertainties of the numerical simulations (i.e. the input parameters), the results are in a good agreement with the available records.