Latest revision as of 12:44, 30 November 2021

Abstract

The definition of seismic risk scenarios necessarily depends on the attribution of a vulnerability class to each building of a stock. In the macroseismic scale (EMS-98) the vulnerability class – from A to F – results from the combination between horizontal and vertical structures. On the basis of post-event surveys carried out in Italy after the earthquakes occurred in the last 50 years, many rules for converting the masonry quality and the stiffness of horizontal diaphragms into a vulnerability class have been proposed. However, despite the now high number of retrofitted or strengthened buildings in Italy, structural interventions are not mentioned in these procedures, except for metal tie rods and r.c. tie beams. The paper proposes a critical approach to the definition of vulnerability classes, by the means of applying the conversion rules to the same sample of 525 masonry buildings located in five historical centres struck by 2016 Central Italy earthquake: Acquasanta Terme, Campi Alto di Norcia, Castelsantangelo sul Nera, Muccia and Vezzano. They have been chosen due to the extensive strengthening campaigns that had been carried out after earlier seismic events. The preliminary recognition of the structural features of each building happens at the terms of the MUSE-DV Masonry, a rapid visual screening procedure recently proposed by the authors. The damage probability matrices (DPMs), obtained from each conversion, are compared to those from a theoretical model proposed for the EMS-98. Given the same poor masonry quality, the existing rules classify buildings in class A or B depending only on floors’ stiffness and horizontal connections. As a result, both low and high damage may appear in the same vulnerability class causing a bimodal trend in the damage distributions. Conversely, the MUSE-DV procedure allows to reduce these two frequency peaks by considering interventions. In fact, overall interventions, even on very poor masonry structures, may lead to a very low damage and, consequently, to low vulnerability classes (even C or D), while uncontrolled interventions could obtain a high damage and a high vulnerability. The twofold consequence is that a) structural interventions have a ‘relative’, i.e. positive or negative, contribution; b) the usual limitation to A and B vulnerability classes for random masonry buildings needs to be widened to better explain the damage observed in the 2016 Central Italy earthquake.

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Reference

[1] Grünthal, G. European Macroseismic Scale 1998. Cahiers du Centre Européen de Géodynamique et de Séismologie, Vol. XV, Luxembourg, (1998).

[2] Sieberg, A. Geologie der Erdbeben. Handbuch der Geophysik (1930) 2(4):552-555.

[3] Medvedev, S.V. Seismic Intensity Scale MSK-76. Publications of the Institute of Geophysics, Polish Academy of Sciences (1977) A-6(117):95-102.

[4] Molin, D. Considerazioni sull’eventuale adozione in Italia della scala macrosismica europea (EMS-1998). XXII GNGTS “Gruppo Nazionale di Geofisica della Terra Solida”, Rome, 18-20 November (2003).

[5] Bernardini, A., Giovinazzi, S., Lagomarsino, S. and Parodi, S. The vulnerability assessment of current buildings by a macroseismic approach derived from the EMS-98 scale, Asociaciòn Espanola de Ingenierìa Sismica. Girona, 8-11 May (2007).

[6] Locati, M., Camassi, R., Rovida, A., Ercolani, E., Bernardini, et al. Database macrosismico italiano (DBMI15), version 2.0, INGV (2019).

[7] Rovida, A., Locati, M., Camassi, R., Lolli, B. and Gasperini, P. Catalogo Parametrico dei Terremoti Italiani (CPTI15), version 2.0, INGV (2019).

[8] Saretta, Y., Sbrogiò, L., Molinari, F., Vettore, M. and Valluzzi M.R. Proposta di un nuovo strumento multilivello per la valutazione del danno e della vulnerabilità a scala urbana: la procedura MUSE-DV Masonry per la valutazione empirica del comportamento di edifici consolidati. Progettazione sismica (2020) no.1, Quaderno 1.

[9] Dolce, M., Speranza, E., Giordano, F., Borzi, B., Bocchi, F., et al. Observed damage database of past Italian earthquakes: the Da.D.O. WebGIS. Bollettino di Geofisica Teorica ed Applicata (2019) 60(2):141-164.

[10] Braga, F., Dolce, M. and Liberatore, D. A statistical study on damaged buildings and an ensuing review of the MSK-76 scale. Proceedings of the 7th ECEE, Athens (1982).

[11] Gruppo Nazionale per la Difesa dai Terremoti & Consiglio Nazionale delle Ricerche. Scheda di esposizione e vulnerabilità di primo livello e di rilevamento danni, GNDT (1994).

[12] Baggio, C., Bernardini, A., Colozza, R., Corazza, L., Della Bella, M. et al. Manuale per la compilazione della scheda di 1° livello di rilevamento danno, pronto intervento e agibilità per edifici ordinari nell’emergenza post-sismica (AeDES). PCM-DPC, (2014).

[13] Zuccaro, G., Papa, F. and Baratta, A. Aggiornamento delle mappe a scala nazionale di vulnerabilità sismica delle strutture edilizie. In: Bernardini A. (Ed.): La vulnerabilità degli edifici: valutazione a scala nazionale della vulnerabilità sismica degli edifici ordinari. Roma, CNR-GNDT, (2000), pp. 133-166.

[14] Dolce, M., Masi, A., Marino, M. and Vona, M. Earthquake damage scenarios of the building stock of Potenza (Southern Italy) including site effects. Bull. Earthquake Engineering (2003) 1(1):115-140.

[15] Di Pasquale G., Orsini G. and Romeo R.W. New Developments in Seismic Risk Assessment in Italy. Bull. Earthquake Engineering (2005) 3(1):101-128.

[16] Sisti, R., Di Ludovico, M., Borri, A. and Prota, A. Damage assessment and the effectiveness of prevention: the response of ordinary unreinforced masonry buildings in Norcia during the Central Italy 2016-2017 seismic sequence. Bull. Earthquake Engineering (2019) 17:5609-5629.

[17] Dolce M. and Goretti A. Building damage assessment after the 2009 Abruzzi earthquake. Bull. Earthquake Engineering (2015) 13(8):2241-2264.

[18] Valensise, G., Tarabusi, G., Guidoboni, E. and Ferrari, G. The forgotten vulnerability: A geology-and history-based approach for ranking the seismic risk of earthquake-prone communities of the Italian Apennines. Int. J. Disaster Risk Reduction (2017) 25:289-300.

[19] Valluzzi, M.R., Sbrogiò, L., Saretta, Y. and Wenliuhan, H. Seismic response of masonry buildings in historical centres struck by the 2016 Central Italy earthquake. Part 1-feature recognition and damage evaluation. International Journal of Architectural Heritage (n.d.) Submitted.

[20] Fiorentino, G., Forte, A., Pagano, E., Sabetta, F., Baggio, C., et al. Damage patterns in the town of Amatrice after August 24th 2016 Central Italy earthquakes. Bull. Earthquake Engineering (2018) 16:1399-1423.

[21] Vettore, M., Saretta, Y., Sbrogiò, L. and Valluzzi, M.R. (2020). A New Methodology for the Survey and Evaluation of Seismic Damage and Vulnerability Entailed by Structural Interventions on Masonry Buildings: Validation on the Town of Castelsantangelo sul Nera (MC), Italy. Int. J. Architectural Heritage (2020) Published Online.

[22] Gavarini, C. (ed.) Costruzioni e terremoto. Roma, Nisa, (1983).

[23] Sbrogiò, L., Saretta, Y. and Valluzzi, M.R. Seismic response of masonry buildings in historical centres struck by the 2016 Central Italy earthquake. Part 2-calibration of a vulnerability model for strengthened conditions. Construction and Building Materials (n.d.) Submitted.

[24] Giovinazzi, S. The vulnerability assessment and the damage scenario in seismic risk analysis. PhD Thesis, University Carolo-Wilhelmina and University of Florence, (2005).

[25] D’Ayala, D. F. and Paganoni, S. Assessment and analysis of damage in L’Aquila historic city centre after 6th April 2009. Bull. Earthquake Engineering (2011) 9(1):81-104.

[26] Sbrogiò, L., Valluzzi, M. R. and Cardani G. Recenti sviluppi sulle previsioni di vulnerabilità sismica di Campi Alto di Norcia alla luce degli interventi di riparazione e/o consolidamento e del sisma Centro Italia 2016, XVIII Congresso Nazionale ANIDIS “L’ingegneria Sismica in Italia”, Ascoli Piceno, 15-19 settembre (2019).

[27] Borri, A. and De Maria, A. Alcune considerazioni in materia di analisi e di interventi sugli edifici in muratura in zona sismica. XI Convegno Nazionale ANIDIS “L’ingegneria sismica in Italia”, Genova, 25-29 gennaio (2004).