Inadequate detailing in precast buildings designed under previous codes has proven to be a key factor in the seismic vulnerability of Italy's industrial heritage. Advances in structural assessment and refined hazard mapping have led to strategies now embedded in design guidelines; however, their actual probabilistic performance remains an open issue. This paper investigates the probabilistic seismic vulnerability of four single-story precast RC buildings constructed between the 1960s and 1990s, each emblematic of its decade, in a high seismic hazard area designed according to the codes of the time and retrofitted according to the current Italian code. A rigorous validation of standard code-compliant retrofit strategies is proposed, using a fully probabilistic framework that incorporates non-linear pushover analysis, multi-stripe analyses, and fragility derivation methods, which are typically not used in practical code-based design verification. For each case, the effectiveness of the designed retrofit measures is assessed through advanced analyses at two performance levels: usability preventing damage (UPD) and global collapse (GC). Results show that highly invasive global retrofit solutions achieve safety targets consistent with current code requirements for Global Collapse. Furthermore, all proposed interventions substantially reduce the mean annual failure rate for the UPD limit state, keeping retrofitted archetypes within safety margins. Overall, the study provides a concise quantitative benchmark for assessing the effectiveness of current retrofit standards for precast industrial buildings on a probabilistic basis, tailored to specific typologies from different decades.
This paper summarizes key aspects of the Guidelines for the Seismic Design and Verification of Masonry Infill Walls in Reinforced Concrete (RC) Buildings, developed through research coordinated by eight Italian institutions and mainly supported by DPC-Reluis. The Guidelines, primarily intended for RC structures, provide design and detailing criteria for masonry infills that interact with the surrounding frame. Applicable to ordinary buildings with typical story heights, they address different infill typologies, non-ductile, reinforced, and ductile, and propose modelling strategies (simplified and detailed) for both linear and nonlinear analysis. Particular emphasis is placed on in-plane displacement checks, local effects on RC elements, out-of-plane resistance evaluation (including in-plane/out-of-plane interaction), and the impact of infills on global structural irregularities. The Guidelines aim to support the seismic design and verification of masonry infills, complementing Eurocodes and Italian standards (NTC2018).
The topic of the seismic vulnerability of existing masonry bell towers is undoubtedly of paramount importance, considering the wide diffusion of these structures throughout European countries; nevertheless, despite the significant damages and collapses occurred even in low/moderate seismic events, there is still a lack of scientific experimental research concerning the dynamic response of these structural typologies. In order to reduce the vulnerability of masonry bell towers and improve their seismic behavior, the company ISAAC proposes an innovative “hybrid” approach, which involves the installation of Active Mass Damper (AMD) devices combined with “traditional” methods of repair/strengthening (e.g. FRCM in this case) located in some strategic points of the structure. The aim is to reduce the seismic demand on the tower through the benefits of AMD devices and, at the same time, to increase the masonry capacity locally, avoiding the impact of overall retrofit interventions, which are often unfeasible for reasons related to the conservation of the architectural/monumental heritage. In order to evaluate the seismic performance of the proposed enhancement system, an experimental campaign of dynamic shaking-table tests on a full-scale (12 m high) brick-masonry bell tower, representative of common historical solutions of northern Italy, has been carried out. A first phase involving the execution of dynamic tests on the bell tower with only the AMD device installed has been followed by a second phase with the addition of FRCM retrofit of the belfry. The shaking-table tests allowed to evaluate the benefit of the proposed systems in terms of seismic response.
This paper evaluates and discusses the seismic response of unreinforced masonry buildings accounting for soil-foundation-structure interaction. A new strategy to model soil-foundation-structure interaction is firstly developed adopting a lumped parameters approach. A case study masonry building is selected, together with the foundation layout and soil profile. Lumped parameters models for the foundation of each masonry panel are then calibrated from 3D frequency domain analysis and applied at the base of the considered building, modelled by means of an equivalent-frame strategy. The lateral capacity of the entire building is assessed by pushover analyses, also allowing the estimation of relevant thresholds of a properly selected engineering demand parameter. Multi-stripe nonlinear dynamic analyses, carried out for different earthquake’s return periods, are finally performed to define the demand. Results obtained allow to assess the building’s performance and its modification due to the consideration of soil-foundation-structure interaction.
An experimental campaign, conducted at the EUCENTRE Foundation in Pavia (Italy), aimed to assess the in-plane seismic behaviour of different typologies of traditional masonry, representative of Italy's building heritage, strengthened with innovative integrated dry solutions providing both seismic and thermal insulation performance. The campaign included comprehensive mechanical characterization of materials, masonry and reinforcement elements, as well as cyclic pseudo-static in-plane shear-compression tests on full-scale unreinforced and strengthened masonry specimens. The study investigated several masonry typologies, including solid clay bricks arranged in both header and English bond patterns, typical Italian hollow clay “Doppio UNI” units arranged in a Flemish bond pattern, and unconnected double-leaf rubble stone masonry. Various strengthening solutions, developed by the Italian company Progetto Sisma, were tested, consisting of modular steel elements anchored to the exterior surface of the masonry. Results highlighted their effectiveness, showing significant improvements in both strength and deformation capacity of the specimens compared to unreinforced panels. Notably, the systems successfully limited crack opening as the imposed displacement level increased. To extend the experimental findings, a numerical campaign using FEM/DEM modelling was conducted. The objective of this ongoing study is to establish deformation thresholds for code-compliant limit states in strengthened masonry and to develop an analytical formulation for quantifying the strength increase provided by the strengthening systems. These findings are essential for drafting guidelines for the design of strengthening interventions for existing masonry buildings with Progetto Sisma’s systems. This article details the main results from the experimental campaign, focusing on some significant cases.
