Fragility functions for local failure mechanisms in unreinforced masonry buildings: a typological study in Ferrara, Italy

Abstract

Unreinforced masonry buildings undergoing seismic actions often exhibit local failure mechanisms which represent a serious life-safety hazard, as recent strong earthquakes have shown. Compared to new buildings, older unreinforced masonry buildings are more vulnerable, not only because they have been designed without or with limited seismic loading requirements, but also because horizontal structures and connections amid the walls are not always effective. Also, Out-Of-Plane (OOP) mechanisms can be caused by significant slenderness of the walls even if connections are effective. The purpose of this paper is to derive typological fragility functions for unreinforced masonry walls considering OOP local failure mechanisms. In the case of slender walls with good material properties, the OOP response can be modeled with reference to an assembly of rigid bodies undergoing rocking motion. In particular, depending on its configuration, a wall is assumed either as a single rigid body undergoing simple one-sided rocking or a system of two coupled rigid bodies rocking along their common edge. A set of 44 ground motions from earthquake events occurred from 1972 to 2017 in Italy is used in this study. The likelihood of collapse is calculated via Multiple Stripe Analysis (MSA) from a given wall undergoing a specific ground motion. Then, the single fragility functions are suitably combined to define a typological fragility function for a class of buildings. The procedure is applied to a historical aggregate in the city center of Ferrara (Italy) as a case study. The fragility functions developed in this research can be a helpful tool for assessing seismic damage and economic losses in unreinforced masonry buildings on a regional scale.

EQ-DIRECTION Procedure towards an Improved Urban Seismic Resilience: Application to the Pilot Case Study of Sanremo Municipality

“…The choice considers damage levels that could cause interference with the system by means of partial or total collapses. In the case of URM, this mainly refers to the complete activation of out-ofplane mechanisms [82][83][84], while, in the case of RC, it is mainly associated with the response of infills. As far as the last point is concerned, indeed, various works highlighted how the response of infills may strongly affect the first DLs in the response of RC structures [85][86][87].…”

Fragility Curves for Rocking Masonry Façades of Churches: A Sensitivity Study of Vulnerability Parameters

“…the randomness of a certain phenomenon and are classified as irreducible uncertainty referring to a property of the system associated with more variability [18]. The aleatory variables herein involved are the dimensions related to the slenderness values of both the facade and the sidewalls (Table 1) and are treated by the MCS [19].…”

Fragility curves of masonry buildings in aggregate accounting for local mechanisms and site effects

“…: holistic approach (Cardinali et al 2021); heuristic approach (e.g. Ferreira et al 2013;Vicente et al 2014;Brando et al 2017;Sandoli et al 2022;Moretic et al 2022), analytical-mechanical approach (Cocco et al 2019;Cima et al 2021;Nale et al 2021; analytical-numerical approach (Ramos and Lourenço 2004;Senaldi et al 2010;Vicente et al 2011;Fagundes et al 2017;Formisano and Massimilla 2019;Bernardini et al 2019;Degli Abbati et al 2019;Valente et al 2019;Greco et al 2020;Grillanda et al 2020;Angiolilli et al 2021;Battaglia et al 2021;Valluzzi et al 2021;Bernardo et al 2022); large-scale approaches based on empirical evaluations obtained from post-earthquake data (Del Gaudio et al 2019;Penna et al 2022a;Sisti et al 2019); as well as hybrid methods (Kappos et al 2006;Maio et al 2015) combining the previous approaches through the individuation of representative building classes. Comparisons between different approaches for specific case studies are reported in Chieffo et al 2019 andChiumiento and.…”