The Recorded Seismic Response of the Santa Maria Di Collemaggio Basilica to Low-intensity Earthquakes

ABSTRACT

The seismic response of masonry monumental structures is a debated matter. In this paper, the authors compare the dynamic response of the Santa Maria di Collemaggio basilica under low-intensity earthquakes to the dynamic response under operational conditions. A permanent number of accelerometers records the dynamics of the Santa Maria di Collemaggio basilica under both operational and seismic excitation. It is questioned whether the earthquake intensity and the ambient parameters affect the modal parameters. The Least-Squares Complex Exponential (LSCE) method leads to the FRF function estimation. The stable frequencies identify the linear modal parameters which are likely to reproduce the seismic response. The authors endeavour to discuss whether the detected variations of the modal parameters are due to possible structural or material non-linearities. A time-frequency analysis confirms the results of the linear identification method. Further, the estimate of the dynamic amplification factors gives a glance over the global response by evidencing the possible existence of a macro-element response pattern.

KEYWORDS:

• Dynamic identification
• earthquake engineering
• experimental seismic response
• masonry
• nonlinear dynamics

Acknowledgments

The authors thank ENI (Ente Nazionale Idrocarburi), who financed the restoration of the basilica and the monitoring system.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ The CLT roof, installed during the restoration works, is 10 cm thick and is made of five layers. The CLT panels are connected to the nave walls, the facade, and the transept (Figure 11(a)) using threaded steel bars (Figure 11(b)), anchored in the masonry underneath. Additional steel plates unite all the panels together, see (Figure 11(c)).