Seismic events that have occurred in Italy in recent decades have shown the significant vulnerability of the Italian building stock. In particular, residential masonry buildings have suffered serious damage, highlighting the need to plan effective mitigation strategies as soon as possible. In this context, this study aims to evaluate the effectiveness of possible retrofit interventions for masonry buildings. Fragility curves of macro-classes of residential masonry buildings have been developed in both as-built and retrofitted conditions within the DPC-ReLUIS agreement (Department of Civil Protection—Network of University Laboratories for Earthquake Engineering). In particular, three sets of fragility curves, developed by the University of Padova (UniPD) and the University of Genova (UniGEa and UniGEb) are discussed and compared herein. The three models show similar estimates of the expected structural improvements for the examined retrofit interventions when applied to the building macro-classes, although some differences, due to the different analysis approaches, can be observed.

This paper focuses on the so-called “flange effect” in unreinforced masonry buildings when the connection among walls is good, thus forming a 3D assembly of intersecting piers (with L-, C-, T-, or I-shaped cross-sections). Given the direction of the horizontal seismic action, the presence of such flanges (the piers loaded out-of-plane) can influence the response of the in-plane loaded pier (the web) in terms of failure modes, maximum strength, and displacement capacity. Specific rules are proposed in codes to evaluate the effective width of the flange, for the in-plane verification of a single masonry wall. However, in the case of 3D equivalent frame (EF) modeling of the whole building, all the intersecting piers should be considered entirely, to model the response in both the orthogonal directions as well as the torsional behavior, but this may lead to overestimating the flange effect if a perfect connection is assumed. This paper investigates the capability of simulating the actual behavior in EF models by introducing an elastic shear connection at the intersection between two piers using an “equivalent beam”, coupling the nodes at the top of piers. A practice-oriented analytical formulation is proposed to calibrate such a flange effect on the basis of the geometric features and material properties of the web and the flange. Its reliability is tested at the scale of simple 3D assemblies and entire buildings as well. Finite element parametric analyses on masonry panels with symmetrical I- and T-shaped cross-sections have been performed to investigate the axial load redistribution between the flanges and the web and the consequent repercussion on the overall performance of the web. The results have proven that, after a calibration of the shear connection, the variation of axial force between the web and the flanges is correctly reproduced and the strength criteria for 2D panels provide reliable results. Finally, in the conclusions, some practical hints for simulating an imperfect wall-to-wall connection are also provided, since this case is relevant in historic masonry buildings, which are characterized by different masonry types, transformations over time, and already-cracked conditions.

This paper summarizes simple and practically attractive new methodologies based on validated and optimized strategies for preserving historical heritage towards natural or anthropic risks in order to assist public administrations and stakeholders involved at various levels in the protection of cultural heritage. This represents the outcome of the PRIN 2017 project DETECT-AGING—degradation effects on structural safety of cultural heritage constructions through simulations and health monitoring. Results were built on recent advances in structural performance modelling of historical masonry structures, interpretation of effects of degradation, advanced numerical simulations, and structural health monitoring, with the final aim to go beyond the state of the art in regard to assessing and establishing: (i) degradation effects from the level of materials to the scale of components; (ii) methodologies able to transfer information on mechanical behaviour from a micro-scale to a macro-scale; (iii) the use of ambient vibration measurements to address epistemic modelling uncertainties in historical masonry buildings; (iv) structural health monitoring (SHM) to detect the occurrence of damage and locate/quantify damage; (v) the capability of equivalent frame models (EFMs) to support the SHM of masonry structures in place of more refined 3D finite element models (FEMs); (vi) variations in the structural response that can be monitored by sensor networks as a function of simulated degradation.