Identification and Model Update of the Dynamic Properties of the San Silvestro Belfry in L’Aquila and Estimation of Bell’s Dynamic Actions

Angelo Aloisio,Rocco Alaggio,Franco Di Fabio,Riccardo Cirella,Ilaria Capanna,Massimo Fragiacomo

doi:10.3390/app10124289

Abstract

The authors investigated the dynamic behaviour of the San Silvestro belfry in L’Aquila (Italy). The 2009 earthquake in L’Aquila caused severe damages to the entire masonry complex. Extensive rehabilitation works, ended in 2019, repaired the structure and enhanced its seismic safety. In this paper, the authors discuss three aspects typical of masonry towers by interpreting the outcomes of Operational Modal Analysis carried out on December 2019: the interactions between the tower and the masonry complex, the dynamic effects of the bell, and the seismic reliability assessment of the tower. Specifically, the experimental mode shapes drive the estimation of an equivalent cross-section, whose principal axes of inertia match with the directions of oscillation of the mode shapes, and the parameters of an equivalent cantilevered beam roughly representative of the tower dynamics. In a second step, a two-degrees-of-freedom analytical model simulates the dynamic coupling between the tower and the more massive bell. The response of the system to a set of seven strong-motion earthquakes yields the assessment of the bell effects over the seismic performance of the masonry tower.

Highlights

The study of masonry towers attracts numerous scholars
On December 2 2019, the authors measured the response of the masonry tower to ambient excitation
The covariance-driven Stochastic Subspace Identification (SSI) method yield the estimate of the experimental modal parameters [15,16,17]

Summary

Introduction

The study of masonry towers attracts numerous scholars. Many research on their seismic performance, which can be quite diverse depending on the dynamic features of the tower.in some cases, masonry towers are the first structures to suffer damages or collapse, see Figures 1a and 2, while in some instances they are the sole to endure, see Figure 1b.For these reasons, the assessment of the dynamic response of masonry towers is essential before any retrofitting intervention. The study of masonry towers attracts numerous scholars. Many research on their seismic performance, which can be quite diverse depending on the dynamic features of the tower. In some cases, masonry towers are the first structures to suffer damages or collapse, see Figures 1a and 2, while in some instances they are the sole to endure, see Figure 1b. For these reasons, the assessment of the dynamic response of masonry towers is essential before any retrofitting intervention. Dozens of papers present the dynamic response of masonry towers to ambient excitation Practitioners are still not acquainted with dynamic identification, which can provide useful information, especially in the case of slender structures, like belfries.

Results

Discussion

Conclusion