Antonio Tralli

Bio: Antonio Tralli is an academic researcher from University of Ferrara. The author has contributed to research in topics: Unreinforced masonry building & Fragility. The author has an hindex of 1, co-authored 5 publications receiving 4 citations.

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.

Fragility Functions for Local Failure Mechanisms in Unreinforced Masonry Buildings

Abstract: The unreinforced masonry buildings can be present frequent local failure mechanisms and represent a serious life-safety hazard as recent strong earthquakes have shown. Compared to new building, existing unreinforced masonry buildings prone to be more vulnerable, not only because they have been designed without seismic or limited loading requirements, but also because horizontal structures and connections amid the walls are not always suitable. Out-of-plane collapse can be caused by important slenderness of walls also when connections are effective. The purpose of this paper is to evaluate fragility functions for unreinforced masonry walls in the presence of local failure mechanisms considering the out-of-plane response. The wall response, very often, can be idealized as rigid bodies undergoing rocking motion. Depending on its configuration, a wall is assumed either as a rigid body undergoing simple one-sided rocking or an assembly 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. Later, 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 very helpful tool for estimating damage and economic loss for unreinforced masonry buildings and for a seismic assessment on a regional scale.

Three-dimensional analysis of a damaged masonry arch bridge under horizontal load

Abstract: The aim of this paper is to study the vulnerability to horizontal loads of a severely damaged masonry arch bridge located in the province of Ascoli Piceno (Marche, Italy). The bridge is a traditional single-span masonry arch designated as road bridge. A wide fracture line has been observed along the longitudinal direction. The arch has been studied by applying two distribution of horizontal loads directed in the longitudinal and the transversal directions separately. A new upper bound limit analysis recently developed by the cooperation of the Polytechnic University of Milan and the University of Ferrara has been adopted. For the case of horizontal load acting along the longitudinal direction, the capacity curve and the associated fragility curve are presented.

Stochastic Seismic Assessment of Bridge Networks by Matrix Based System Reliability Method

Abstract: Infrastructure systems cover an important role for economic activities and emergency response after a disaster, such as an earthquake. Within these systems, bridges represent a crucial component. However, they are often considered a weak link because of their vulnerability to hazards. Indeed, the structural damage of a bridge can create a disconnection in a transportation network or reduce its functionality. A probabilistic approach is the natural environment in which to analyze a complex network system and carry out risk/loss assessment estimations and decision-making processes. This problem presents various computational challenges and usually, sampling-based approaches are used to account for the uncertainty. In this contribution, a prioritization methodology is developed using the matrix-based system reliability (MSR) approach. This method is capable of delivering component failure probabilities and estimating the probabilities of complex system events with parameters sensitivities through efficient matrix calculations.

Damage assessment in single-nave churches and analysis of the most recurring mechanisms after the 2016–2017 central Italy earthquakes

Abstract: Abstract Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage.

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.

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

Abstract: Abstract The seismic evaluation of masonry buildings in aggregate, largely diffused within the existing Italian and European building stock, represents a difficult and open task that has not been exhaustively investigated so far. The study proposes a procedure aimed at evaluating the potential impact of the combination of local mechanisms and site-amplification in terms of fragility curves on an existing unreinforced masonry (URM) aggregate which is made of five adjacent structural units mutually interacting with each other during seismic sequences. The case study is inspired by built heritage of the historic centre of Visso struck by the Central Italy 2016/2017 earthquakes. The in-plane (IP) response of URM buildings was simulated through nonlinear dynamic analyses performed on a 3D equivalent frame model of the structure, whereas out-of-plane (OOP) mechanisms were analysed by adopting the rigid-block assumption but assuming, as seismic input, the floor accelerations derived from the post-processing of data derived from the global 3D model. An innovative procedure considering the pounding effect to the global response of the building is also presented. Two soil conditions were assumed with (freefield) and without (bedrock) site amplification. The results showed that site effects strongly affected the seismic vulnerability of the aggregate, also altering the combination between IP and OOP mechanisms. In fact, for bedrock condition, especially for medium–high damage levels, local mechanisms were prevailing with respect to the IP response. Conversely, for freefield condition, IP mainly governed the overall behaviour for all the damage levels, consistently with the field evidence.