Vulnerability Assessment of Italian Unreinforced Masonry Churches Using Multi-Linear Regression Models

Abstract

The extensive damage occurred to the Italian historical and architectural heritage during the 2016-2017 earthquake sequence, and particularly to unreinforced masonry churches, highlights the need to better recognize the vulnerability of religious buildings. A sample of 158 churches belonging to the four stricken regions is studied and their performance analysed statistically. Structural behaviour of these churches is described in terms of mechanisms affecting the so-called macroelements, being portions of the building behaving more or less independently. In order to define fragility curves correlating the damage related to each collapse mechanism against ground motion intensity and churches’ specific characteristics, the observed behaviour of the sample is herein analysed by means of statistical procedures accounting for possible local collapse mechanisms. Several regressions strategies are considered, accounting for vulnerability modifiers increasing/reducing the vulnerability of each macroelement, since the severity of shaking alone is not capable to fully explain the observed damage, strongly influenced by structural details that can worsen the seismic performance or improve it through earthquake-resistant elements. A synthetic damage index, purely based on observed data, is used to summarise the overall severity of damage related to relevant mechanisms, highlighting the contributions of ground shaking and building vulnerability. Results show the relevance of the proposed multi-linear regression models for the national heritage of churches and the advisability of extending mechanism-based regressions to other countries besides Italy. The proposed global damage index can be used as predictive tool to support seismic vulnerability mitigation at a territorial scale.

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References

[1] Penna, A., Calderini, C., Sorrentino, L., Carocci, C.F., Cescatti, E., Sisti, R. et al. Damage to churches in the 2016 Central Italy earthquakes. Bulletin of Earthquake Engineering (2019) 17: 5763–5790. https://doi.org/10.1007/s10518-019-00594-4

[2] D’Ayala, D. Establishing Correlation Between Vulnerability and Damage Survey for Churches. Proc 12th World Conference on Earthquake Engineering, Auckland, New Zealand (2000) Paper No.: 1–8.

[3] Sorrentino, L., Bruccoleri, D. and Antonini, M. Structural interpretation of postearthquake (19th century) retrofitting on the Santa Maria degli Angeli Basilica, Assisi, Italy. Structural Analysis of Historic Construction: Preserving Safety and Significance (2008) 217–25. https://doi.org/10.1201/9781439828229.ch23

[4] Giuffré, A. Restoration and safety in sismic areas. The Cathedral of S. Angelo dei Lombardi (in Italian). Palladio1 (1988) 95–120.

[5] Doglioni, F., Moretti, A., Petrini, V. and By), (Ed. (1994) Le chiese e il terremoto. Dalla vulnerabilità constatata nel terremoto del Friuli al miglioramento antisismico nel restauro. Verso una politica di prevenzione. (1994) Lint Editoriale Associati, Trieste.

[6] Lagomarsino, S., Podestà, S., Cifani, G. and Lemme, A. The 31st October 2002 earthquake in Molise (Italy): a new methodology for the damage and seismic vulnerability survey of churches. 13th World Conference on Earthquake Engineering (2004) 1–11.

[7] Borri, A., Corradi, M., Castori, G., Sisti, R. and De Maria, A. Analysis of the collapse mechanisms of medieval churches struck by the 2016 Umbrian earthquake. International Journal of Architectural Heritage (2019) 13: 215–28.

[8] DPCM. (2011) Direttiva del Presidente del Consiglio dei Ministri “Valutazione e riduzione del rischio sismico del patrimonio culturale con riferimento alle Norme tecniche per le costruzioni di cui al DM 14 gennaio 2008. (2011).

[9] Dolce, M., Kappos, A., Masi, A., Penelis, G. and Vona, M. Vulnerability assessment and earthquake damage scenarios of the building stock of Potenza (Southern Italy) using Italian and Greek methodologies. Engineering Structures (2006) 28: 357–71. https://doi.org/10.1016/j.engstruct.2005.08.009

[10] Vicente, R., Ferreira, T. and Maio, R. Seismic Risk at the Urban Scale: Assessment, Mapping and Planning. Procedia Economics and Finance (2014) 18: 71–80. https://doi.org/10.1016/S2212-5671(14)00915-0

[11] Azzaro, R., Tertulliani, A., Bernardini, F., Camassi, R., Del Mese, S., Ercolani, E. et al. The 24 august 2016 amatrice earthquake: Macroseismic survey in the damage area and EMS intensity assessment. Annals of Geophysics (2016) 59: 1–8. https://doi.org/10.4401/ag-7203

[12] Galli, P., Peronace, E., Bramerini, F., Castenetto, S., Naso, G., Cassone, F. et al. The MCS intensity distribution of the devastating 24 august 2016 earthquake in central Italy (Mw6.2). Annals of Geophysics (2016) 59. https://doi.org/10.4401/ag-7287

[13] Grünthal, G. (1998) European Macroseismic Scale. Eur. Cent. Geodyn. Seismol. (1998).

[14] Marotta, A., Sorrentino, L., Liberatore, D. and Ingham, J.M. Vulnerability Assessment of Unreinforced Masonry Churches Following the 2010–2011 Canterbury Earthquake Sequence. Journal of Earthquake Engineering (2017) Taylor & Francis. 21: 912–34. https://doi.org/10.1080/13632469.2016.1206761

[15] Marotta, A., Sorrentino, L., Liberatore, D. and Ingham, J.M. Seismic Risk Assessment of New Zealand Unreinforced Masonry Churches using Statistical Procedures. International Journal of Architectural Heritage (2018) Taylor & Francis. 12: 448–64. https://doi.org/10.1080/15583058.2017.1323242

[16] Draper, N.R. and Smith, H. (1998) Applied regression analysis, Volume 1. 3rd ed. (1998) Wiley.

[17] Marotta, A., Goded, T., Giovinazzi, S., Lagomarsino, S., Liberatore, D., Sorrentino, L. et al. An inventory of unreinforced masonry churches in New Zealand. Bulletin of the New Zealand Society for Earthquake Engineering (2015) 48: 171–90.

[18] Roselli, G., AlShawa, O., Liberatore, D., Sorrentino, L., Di Girolami, G., Cinaglia, P. et al. Mortar analysis of historic buildings damaged by recent earthquakes in Italy. The European Physical Journal Plus (2019) 134.

[19] Giresini, L., Casapulla, C., Denysiuk, R., Matos, J. and Sassu, M. Fragility curves for free and restrained rocking masonry façades in one-sided motion. Engineering Structures (2018) Elsevier. 164: 195–213. https://doi.org/10.1016/j.engstruct.2018.03.003

[20] AlShawa, O., Liberatore, D. and Sorrentino, L. Dynamic one-sided out-of-plane behaviour of unreinforced-masonry wall restrained by elasto-plastic tie-rods. International Journal of Architectural Heritage (2019) 13: 340–57. https://doi.org/10.1080/15583058.2018.1563226

[21] Lagomarsino, S. and Podestà, S. Seismic vulnerability of ancient churches: II. Statistical analysis of surveyed data and methods for risk analysis. Earthquake Spectra (2004) 20: 395–412. https://doi.org/10.1193/1.1737736

[22] Rovida, A., Locati, M., Camassi, R., Lolli, B. and Gasperini, P. CPTI15, the 2015 Version of the Parametric Catalogue of Italian Earthquakes. Istituto Nazionale Di Geofisica e Vulcanologia (2016).