PSI - Issue 44

Alessandro Lubrano Lobianco et al. / Procedia Structural Integrity 44 (2023) 910–917 A. Lubrano Lobianco et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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improve the efficiency and effectiveness of maintenance work, as well as identify the best option for the decision maker (Iannacone et al., 2022). The basic in selecting the features to be monitored is that seismic damage can significantly alter the stiffness, mass or energy dissipation properties of a system, which in turn alter the measured dynamic response of that system. For a typical civil building in the case of seismic damage, many codes and studies (Mayes, 1995) correlate the damage to a structure with the maximum displacement (interstorey drift ratio, IDR) reached during an earthquake and this is correlated with a damage level (DL) or, in other words, with a damage limit state. In fact, design procedures limit the interstorey drift for the serviceability limit state (SLS) to 0.5% to avoid damage to the infill walls. An ongoing challenge in SHM is to correlate the change in modal properties of a building with the relative level of damage (DL). In other words, one of the major issues is to define threshold values to assess through SHM whether a structure has been slightly, moderately or severely damaged by one of the possible causes of damage. Some authors have experimentally identified the modal parameters of existing bridges (Cunha et al., 2001), RC buildings (Regni et al., 2018) and masonry structures (Casapulla et al., 2019; García-Macías & Ubertini, 2020; Ramos et al., 2010); others have evaluated also the changes in vibration characteristics with experimental laboratory tests (Lorenzo et al., 2016; Maria Feng et al., 1999), without correlating those variations to a damage scale. A first attempt to correlate the variation in modal properties of structural members with a damage scale has been proposed by the authors for reinforced concrete columns (Lubrano Lobianco et al., 2021). The aim of the present work is to assess and quantify the global damage occurred in a reinforced concrete (RC) 3D building after earthquakes of increasing intensity via SHM data. The methodology adopted to assess and quantify the seismic damage is first illustrated. Then, a numerical study is performed on a case-study building subjected to non linear dynamic analyses to simulate the seismic damage. Methodology framework In the present study, a numerical framework is adopted to correlate global and local structural damage of a building after a seismic event through SHM data. Previous studies performed by Lubrano Lobianco et al. (2021) provide a correlation between the variation of vibration period of RC columns at different damage levels and the maximum interstorey drift (IDR max ) experienced by a structure during an earthquake. However, the relationship between the local damage of single structural members (and their variation in vibration period) and the global structural damage (and the variation of the vibration period of the entire structure) has not been assessed yet. The methodology framework adopted herein consists in two phases: (i) assess the local damage level of single structural members (i.e., columns) by using the IDR max and (ii) correlate the global damage of the building with the local damage of structural members. Then, ranges of variation of vibration period of the entire building are derived for each DL. The methodology is depicted in Fig. 1. 1

Fig. 1 – Scheme of methodology framework