M. Zucca1, A. Franchi1, P. Crespi1, N. Longrarini1, and P. Ronca1
1) Dept. of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milan,
Italy, {marco.zucca, alberto.franchi,pietro.crespi,nicola.longarini,paola.ronca}@polimi.it

Keywords: Foundation system, Historical building, Seismic retrofitting.

Abstract. In the seismic retrofitting of historic churches, the realization of new foundations of collapsed elements represents an important aspect either for the interaction with the underground pre-existing parts or with the new structural elements to be rebuilt.

For the specific case study of the Basilica di Collemaggio, after an accurate geometrical survey and on-site geotechnical tests, a specific mixed structure foundation system is proposed in order to fulfill the seismic safety requirements and the Cultural Heritage Office’s conservation prescriptions.
Nonlinear analyses are performed considering the interaction between the soil and the foundation system, together with the new interaction between the main pillars and the triumphal arch. The analyses aimed to verify the capabilities of the new foundation system to bear the transversal seismic actions.
The analyses are also completed by some experimental tests on the micropiles, which represent the main underground-to-elevation connection elements.