Angela Fiamingo

Recent developments in End-of-Life Tires (ELTs) reuse emphasize their value in civil engineering applications. Shredded rubber, when mixed with soils to form Soil-Rubber Mixtures (SoRMs), is particularly promising for Geotechnical Seismic Isolation (GSI) systems. Previous studies with poorly graded soils have confirmed the effectiveness of SoRMs through laboratory and field investigations, but their preparation requires expensive grain-size selection. Alternatively, well-graded soils provide a more practical and economical solution for SoRMs, while preserving good mechanical performance. This research investigates the seismic efficiency of GSI systems employing mixtures made by well-graded gravel and rubber from End-of-Life Tires (wgGRMs) applied underneath a historical bell tower in Bronte (Catania, Italy). Finite Element Method (FEM) analyses were conducted on the fully coupled soil–wgGRM–structure system, employing advanced constitutive models. Specifically, the Hardening Soil with Small Strain Stiffness (HSsmall) and the Generalised Hoek–Brown (GHB) models were adopted to represent nonlinear soil and mixture behavior. FEM analyses of laboratory tests on the wgGRMs were performed for the calibration of the HSsmall model parameters. Dynamic parametric analyses explore different GSI layouts, rubber contents, and seismic inputs. Results confirm the effectiveness of wgGRMs, highlighting their potential as cost-efficient materials for the seismic protection of slender, heritage structures.

The protection of historic buildings in seismic-prone regions is a critical challenge requiring strategies that balance structural safety with cultural preservation. This study proposes an integrated methodological framework for assessing seismic risk in heritage contexts by combining Geographic Information System (GIS)-based large-scale analyses with detailed Finite Element Method (FEM) simulations. At the urban scale, the framework is applied to more than 70 buildings in the historic center of Bronte (Eastern Sicily, Italy) to evaluate Soil–Structure Interaction (SSI) effects and identify priority areas for mitigation. At a detailed scale, the approach is validated through an in-depth investigation of the San Giovanni Evangelista bell-tower, a representative historic structure within the study area. For this case, sustainable Geotechnical Seismic Isolation (GSI) systems using well-graded Gravel–Rubber Mixtures (wgGRMs) are numerically tested as a low-impact retrofitting strategy. The results demonstrate that combining large-scale mapping with detailed structural modeling provides both broad urban insight and accurate site-specific evaluations, offering a replicable decision-support tool for seismic risk reduction in heritage environments. Additionally, wgGRMs-based GSI system significantly reduces seismic accelerations and drifts, offering a low-impact, sustainable retrofitting solution that reuses waste materials and fully preserves architectural integrity.

The reuse of rubber inclusions obtained from End-of-Life Tires (ELTs) offers both environmental and technical benefits in civil engineering applications, reducing landfill disposal and enhancing the dynamic properties of geomaterials. The use of well-graded Gravel–Rubber Mixtures (wgGRMs), produced by blending well-graded gravel with granulated rubber, has been investigated for use in different geotechnical applications. The percentage of rubber inclusions included in wgGRMs significantly modifies the mechanical response of these mixtures, influencing stiffness, strength, dilatancy and dynamic properties. Due to the material heterogeneity (i.e., stiff gravel and soft rubber), the effective implementation of wgGRMs requires the development of constitutive models that can capture the non-linear stress–strain response of wgGRMs subjected to representative in situ loading conditions. In this study, a critical state-based generalized plasticity model is presented and tailored for wgGRMs. Calibration is performed using experimental data from isotropically consolidated drained triaxial tests on wgGRMs with different rubber contents. It is shown that the model accurately reproduces key features observed experimentally, including post-peak strain softening, peak strength variation, and volumetric changes across different confining pressure levels and rubber content fractions. This model represents a useful tool for predicting the behavior of wgGRMs in engineering practice, supporting the reuse of ELT-derived rubber.

Shredded rubber from waste tyres has progressively been adopted in civil engineering due to its mechanical properties, transforming it from a troublesome waste into a valuable and low-cost resource within an eco-sustainable and circular economy. Granular soils mixed with shredded rubber can be used for lightweight backfills, liquefaction mitigation, and geotechnical dynamic isolation. Most studies have focused on sand-rubber mixtures. In contrast, few studies have been conducted on gravel-rubber mixtures (GRMs), primarily involving poorly-graded gravel. Poorly-graded gravel necessitates selecting grains of specific sizes; therefore, from a practical standpoint, it is of significant interest to examine the behaviour of well-graded gravel and shredded rubber mixtures (wgGRMs). This paper deals with wgGRMs. The results of drained triaxial compression tests on wgGRMs are analysed and compared with those on GRMs. Stress-strain paths toward the critical state and energy absorption properties are evaluated. The tested wgGRMs exhibit good shear strength and remarkable energy absorption properties; thus, they can be effectively utilised in several geotechnical applications.

Soil–rubber mixtures have been proposed as cost-effective seismic and dynamic risk mitigation techniques. The granulated rubber used for these mixtures is obtained from end-of-life tires, allowing for stockpiles of waste rubber tires to be recycled. To date, most of the research has focused on the mechanical properties of sand–rubber mixtures, while limited studies have been performed on gravel–rubber mixtures (GRMs). In particular, GRMs with well-graded gravel (wgGRMs), which are of significant practical interest due to their availability, have only been poorly characterised. As part of a wider investigation aimed at facilitating the use of wgGRMs as geotechnical dynamic isolation systems, this paper presents bender element and small-strain cyclic triaxial test results performed on mixtures with 25%, 40%, and 55% volumetric rubber content. It is found that, thanks to their excellent energy absorption properties, wgGRMs can be efficiently adopted as geotechnical dynamic isolation to mitigate seismic risk of and anthropically induced vibrations on existing and new structures/infrastructures. Their easy implementation, low-cost, and widespread availability further facilitate their use.

Based on criticisms raised in the past by researchers about the effectiveness of the design rules reported in the European seismic code for the design of concentrically braced frames, a new design procedure has been proposed and included in the upcoming version of Eurocode 8. The upcoming version of Eurocode 8 is in the enquiry stage. Hence, it is important to evaluate the effectiveness of the design procedure reported in the code using accurate numerical models and seismic inputs. In the present paper, a four-story building with concentrically braced frames in the chevron configuration is designed according to the upcoming version of Eurocode 8. A seismic performance assessment is carried out by the means of multiple-stripe analyses performed on refined numerical models. The seismic input is defined based on one-dimensional local site response analyses. The numerical analyses prove that the use of local site response analysis to properly account for the soil-filtering effects is of paramount importance, and that the design procedure reported in the upcoming version of Eurocode 8 for chevron concentrically braced frames leads to reasonably low probabilities of exceeding the considered limit states.

Worldwide, an increasingly huge number of end-of-life tires (ELTs) are disposed of in landfills, illegally dumped, or otherwise unaccounted for, which causes significant environmental and s...