The tragical collapses of the Annone overpass in 2016, the Morandi bridge in 2018 and the motorway bridge on Magra river in 2020 have established the need of detailed regulations regarding bridge maintenance in the Italian territory. The first guidelines were issued in 2020 and after a revision in 2022 are subjected to further investigations to ensure the most effective and safer outcomes. The guidelines for risk classification and management, safety assessment and monitoring of existing bridges were used with the updated version of 2022 as issued by the relevant Italian Ministry. The first three levels of the analysis were applied to data coming from 19 reinforced concrete bridges of a highway located in northern Italy. These include, the census of all structures, the visual inspections with defects sheets, as well as the gross analysis of relevant risk with classification on a territorial scale. Based on this procedure, the outcomes are analysed and discussed, underlining the common defects that are present in specific bridges with their correlations. With the use of visual inspections of consecutive years, deteriorations that have occurred are highlighted. Specific examples of bridges maintenance thought the regulation process are presented and the significance of the new procedures of the guidelines on existing bridges is emphasized.

This paper presents an experimental investigation into the uniaxial tensile behaviour of hybrid textile-reinforced concrete (h/FRCM). The study focuses on the synergy between an Alkali-Resistant (AR) glass fabric and four different High Performance Fibre-Reinforced Concrete (HPFRC) matrices, varying by supplier and rheology. An experimental program was conducted, including uniaxial tensile tests on hybrid composites, HPFRC and Textile-Reinforced Concrete (TRC) without steel fibres (SF) to isolate the contribution of each component. The results consistently showed that fabric inclusion transformed the quasi-brittle, strain-softening failure of HPFRC into a quasi-ductile, strain-hardening response with multiple cracking and significant deformation capacity. A synergistic effect between SF and the fabric was observed in the hybrid systems, leading to higher tensile capacity. A clear correlation between the matrix's post-cracking flexural performance and the composite's efficiency was established, highlighting that matrix properties are a key factor for material selection in structural retrofitting.

Steel fiber reinforced concrete (SFRC) enhances the flexural capacity of flat slabs and, due to its effectiveness in statically redundant bi-dimensional elements, represents a viable alternative to conventional reinforcement. Although numerous studies have investigated the flexural behavior of SFRC slabs with and without bonded reinforcement, experimental data on their punching shear behavior are quite few. Moreover, only limited research has addressed the interaction between steel fibers and post-tensioning, a common and effective technique for flat slabs. To investigate the punching behavior of unbonded post-tensioned SFRC slabs, flat slabs with different fiber contents were tested. The post-tensioning system consisted of straight unbonded strands arranged in a uniform-banded layout. This paper discusses the results of the experimental campaign and compares the behavior of SFRC slabs with plain concrete slabs, highlighting the role of fibers in the failure mode. Finally, the experimental results are compared with predictions from the Yield Line Theory, the fib Model Code 2020 and the second generation of Eurocode 2.

Bridges are vital components of transportation networks, supporting economic, social, and emergency response functions. Their long service lives, however, expose them to multiple hazards, including fire, impact, and blast events. Although these anthropogenic events are low in probability, their consequences can be severe, especially when cascading effects occur. This paper presents a foundational framework for estimating the risk profile of existing road bridges under such scenarios, addressing a recognised gap in current national risk management procedures. Three risk models from the literature are applied to a representative sample of 50 Italian road bridges to evaluate their capacity to capture the complexity of low-probability, high-consequence (LPHC) events. Shared risk components-hazard, exposure, and vulnerability-are analysed to identify critical gaps and areas of convergence. The study also explores the role of subjective judgments, data limitations, and methodological assumptions in shaping risk estimates. A comparative analysis reveals the variability and sensitivity of outcomes across different hazard-specific risk models. The proposed framework supports a harmonised approach to risk estimation aligned with Italy's 2020 national bridge guidelines. Ultimately, the work aims to enhance decision-making, strengthen infrastructure resilience, and improve the integration of anthropogenic risk assessment in bridge management practices.

Half-joints in reinforced concrete girder bridges are generally considered critical elements, susceptible to degradation and potentially impacting the overall structural behavior. An Italian project carried out by ReLUIS interuniversity consortium addresses theoretical, numerical, and experimental studies on critical aspects of existing road bridges. One task is aimed at investigating existing half-joints. The paper offers a comprehensive assessment of finite element numerical simulations applied to a reinforced concrete dapped-end beam through an Italian benchmark study. Leveraging recent experimental campaign data as a reference, the study conducts partially blind numerical simulations. The benchmark procedure follows a systematic approach across three subsequent phases. Emphasizing the comparison between experimental data and numerical simulations, the paper introduces discrete and continuous error indicators to gauge numerical prediction efficacy across phases. Global synthetic indices are proposed to measure performance at serviceability and ultimate limit states. The discussion section integrates insights from eight research units, presenting a comprehensive analysis of simulation outcomes. Conclusive remarks outline implications and potential research directions in the realm of reinforced concrete dapped-end girder bridges.

As part of a regional research project started in 2011, the Politecnico di Milano coordinated a research consortium aimed at developing a cement‐based multi‐layered roof element designed to achieve structural safety, lightness, thermal efficiency, and compatibility with photovoltaic systems. During the initial project phase, full‐scale prototypes made with high‐performance cementitious materials were designed and tested to evaluate their structural response under longitudinal and transverse bending, as well as shear forces. To assess the solution's energy performance, three additional roof panels were installed on a demonstration canopy and exposed to an unsheltered environment for approximately 7 years. Following this extended exposure period, full‐scale mechanical tests were conducted on the panels to evaluate their aged performance. Additionally, corrosion potential mapping was carried out to determine the condition of the embedded steel reinforcement. For a detailed assessment, cylindrical cores of the tested panels were sliced along the rebar direction, and the carbonation depth was measured using a phenolphthalein solution. This test aimed to reveal if pre‐existing cracks, mainly caused by shrinkage and experimental manufacturing processes, had led to corrosion initiation. The steel bars were also visually inspected to detect any signs of corrosive attacks. The results presented in this paper indicate that exposure to natural environmental conditions for over 7 years did not significantly impact the steel reinforcement, even in the presence of cracks that could potentially accelerate degradation. The longitudinal and transverse bending tests on the roofing panels demonstrated a mechanical response that remained consistent with the unaged prototypes, confirming the durability and reliability of the design.

Extreme loads can arise from accidents such as vehicle collisions or airplane crashes, as well as deliberate acts of terrorism or military attacks involving blasts and fragmentation. Blast overpressure can also occur accidentally, for example, from explosions of hazardous materials such as gas. Distinguishing between accidental and deliberate loads is crucial for designing appropriate protection measures. The repercussions of extreme loading events can be devastating, leading to injuries, loss of life, economic setbacks, and significant social disruption. These consequences result not only from the direct effects of impacts or explosions, but also from secondary factors such as structural collapse, which is particularly concerning due to its potential for widespread devastation and substantial losses. Efforts to enhance the protection of concrete structures have focused on understanding the properties of construction materials and how structures respond to impact and blast loads. This document presents a comprehensive overview of RILEM TC 288-IEC, aiming to provide essential guidance for designing concrete structures to withstand extreme dynamic loads. This emphasizes the importance of a thorough understanding and accurate modelling of loading scenarios and material behaviour. By implementing the strategies outlined in this document, engineers can enhance the safety and resilience of structures facing such challenges.

As part of the "Grande Brera" project, a reinforcement intervention was carried out involving the floors of Palazzo Citterio", a historic building located in the centre of Milan, to house the new gallery dedicated to 20th century paintings by Lombard artists. Diagnostics and preliminary safety checks highlighted the need to perform a consolidation intervention to increase the shear resistance of the floors. In particular, FRCM-SRG composite systems with steel fabrics combined with rolled steel profiles were adopted; solutions that also offer a better fire resistance than FRP systems. The article illustrates the project, technologies, materials, executive details and acceptance tests. Each floor is characterized by a grid slab with a span of 11.25 m and a width of 20 m. Italian technical qualification and design guidelines were followed. The on-site test used to check the adhesion between the FRCM layer and the properly pre-treated support is also illustrated, the results of which confirmed the predictions made during the calculation.

This study compares the blast performance of reinforced concrete (RC) slabs with and without strengthening on the impact-facing side. The strengthening strategy employed the application of two thin layers of materials with a high mutual stiffness offset, i.e., high-contrast layers. The first is a low-strength, low-modulus damping layer made of infra-lightweight concrete, followed by a second layer of high-ductility fiber-reinforced concrete. The plain RC slabs under investigation vary in thickness of either 40 mm or 100 mm. The layered specimens consist of a 40 mm thick RC slab strengthened with a 40 mm damping layer and a 20 mm cover SHLC3 layer. This configuration enables a comparison of its behavior with the unstrengthened specimen (a plain 40 mm thick RC slab) and a specimen with a similar eigenfrequency (the plain 100 mm thick RC slab). The employed shock tube subjects the specimens to two rapidly rising areal pressures: a low-pressure wave reaching approximately 0.4 MPa and a high-pressure wave peaking at around 1.2 MPa. The study assesses the specimens' response in terms of accelerations, velocities, and deformations. Additionally, it evaluates damage by analyzing crack patterns, Ultrasonic Pulse Velocity (UPV) measurements, and damping analysis. Overall, the layered specimens exhibited performance nearly equivalent to the 100 mm thick specimens, displaying similar deformations and velocities despite having lower mass and bending stiffness. The high-pressure shock wave hardly damaged layered specimens, unlike the 40 mm thick slabs.

This paper presents the development and analysis of a bridge bearing database consistent with the 2020 Italian Guidelines (LG2020), currently enforced by the Italian law for risk classification and management of existing bridges. The database was developed by putting together the contribution of 24 research teams from 18 Italian universities in the framework of a research project foreseen by the agreement between the High Council of Public Works (CSLP, part of the Italian Ministry of Transportation) and the research consortium ReLUIS (Network of Italian Earthquake and Structural Engineering University Laboratories). This research project aimed to apply LG2020 to a set of about 600 bridges distributed across the Italian country, in order to find possible issues and propose modifications and integrations. The database includes almost 12,000 bearing defect forms related to a portfolio of 255 existing bridges located across the entire country. This paper reports a preliminary analysis of the dataset to provide an overview of the bearings installed in a significant bridge portfolio, referring to major highways and state roads. After a brief state of the art about the main bearing types installed on the bridges, along with inspection procedures, the paper describes the database structure, showing preliminary analyses related to bearing types and defects. The results show the prevalence of elastomeric pads, representing more than 55% of the inspected bearings. The remaining bearings are pot, low-friction with steel–Teflon surfaces and older-type steel devices. Lastly, the study provides information about typical defects for each type of bearing, while also underscoring some issues related to the current version of the LG2020 bearing inspection form.

The preservation of reinforced concrete masterpieces from the 20th century poses a complex challenge. These structures often combine architectural, historical, and technological value, which standard engineering codes and conservation practices are not fully equipped to address. The Erasmus+ REcube project responded to this gap by promoting an integrated, interdisciplinary approach that brings together technical knowledge, design thinking, and heritage awareness. In parallel with ongoing developments in international codes, such as the fib Model Code 2020, REcube explored ways to translate current research into effective tools and guidelines for assessing, protecting, and reusing existing concrete structures. The project also created an educational framework involving architecture and engineering students from multiple European universities. This included a MOOC, on-site interdisciplinary workshops, and collaborative design activities, aiming to foster critical skills for addressing real-world conservation scenarios. This paper outlines the key elements of the REcube methodology and reflects on the educational outcomes and operational challenges encountered. Results show that hands-on, context-driven formats supported student engagement and interdisciplinary dialogue, while also offering a valuable testing ground for emerging technical solutions.

The use of Textile Reinforced Concrete is becoming more and more important both in retrofitting of existing structures and in new constructions. This asks for reliable approaches for the design of structural members. In particular, referring to bending behavior, traditional approaches for Reinforced Concrete structures that account for a perfect bond between concrete and reinforcement cannot be adopted for these kinds of composites where the interaction between reinforcement fabric and concrete plays a key role in the global tensile response of the solution. General characterization approaches refer to the composite as awhole providing a tensile behavior that already takes into account the specific interaction between reinforcement and concrete. The present paper aims at presenting a design approach for bending behavior of these composites that propose the use of an equivalent reinforcement layer of reinforcement, whosemechanical properties are defined by tensile tests on the composite, and that is considered as embedded in the cross section under design. The paper discusses the reliability of the approach, also discussing the dimension and definition of the equivalent reinforcement layer comparing the prediction of the model with experimental results.

The maintenance of existing bridges sometimes requires an intervention to increase their residual bearing capacity during their service life. The bridge strengthening can modify significantly the original structural behaviour, but, in many cases, the lack of a specialized standard for existing structures in the past prevented the designer to operate a suitable check of the updated performance. In the paper, an example of a three-span overpass, built in the sixties in Lombardia, is investigated. Around ten years ago a significant restoration was carried out due to the bad conditions of the infrastructure: the P/C beams were retrofitted by means of CFRP strips and the top slab over the two internal piers was also strengthened by additional reinforcement. After a basic diagnostic aimed at verifying the mechanical characteristics declared in the documentation attached to the drawings and the pictures of the retrofitting intervention, a load test driven by a preventive structural analysis carried out by means of a linear elastic approach allowed to fix a control procedure aimed at guaranteeing the safety conditions in the future time. The discussion on the adopted procedure is the main goal of the paper.

Considerable research efforts have been dedicated to understanding the resistance of buildings against progressive collapse. However, these efforts have been relatively limited in the context of bridges, despite the equal, if not more, critical importance of robustness criteria in bridge engineering. In the context of existing bridges, it is crucial not only to assess safety, but also to evaluate robustness using reliable metrics. These metrics can aid managing authorities in prioritizing necessary interventions. Considering this, the paper applies various robustness measures to a specific type of reinforced concrete (RC) girder bridge known as half-joint bridges. As a case study, the Annone viaduct is examined, which collapsed in 2016 due to the passage of a heavy truck. A notional removal approach of critical elements to quantify structural robustness is proposed. This approach considers several load configurations, some envisioned during the design stage, and others representing abnormal loads. The study results reveal specific scenarios that may lead to potential progressive collapse and highlight the preferred metrics for this type of bridges. Ultimately, the assessment of robustness can play a key role in choosing a retrofitting solution over other intervention options for existing bridges.

Innovative high-performance cementitious materials lead the way for the development of advanced structural systems, characterized by improved durability, mechanical performance, and construction efficiency. In this paper, we introduce a partially precast unidirectional ribbed slab system, featuring very high-performance fiber-reinforced concrete (VHPFRC) I-beams, textile-reinforced concrete (TRC) stay-in-place formworks, and ordinary steel fiber-reinforced concrete (SFRC) finishes. Engineered to maximize the advantages of these innovative materials, the system achieves a lightweight configuration, minimizing the need for on-site steel reinforcement placement. After outlining the conceptual design of the proposed structural system, the paper thoroughly examines the characterization of materials and details the prototyping procedures employed. The theoretical framework is substantiated by an extensive experimental campaign on individual components, offering insights into the full-scale response of the precast elements, and is supplemented by simplified sectional analyses aimed at estimating the flexural behavior of the full composite slab. Additionally, a preliminary assessment of the environmental sustainability of the solution is provided.

In the framework of the conservation of twentieth-century heritage, the re-functionalization of the Manifattura Tabacchi in Bologna into technopole represents an opportunity to reflect on intervention strategies and materials for the preservation of concrete-based architecture. Focusing on the Fabbricato Lavorazioni, a building of the industrial complex realized by Pier Luigi Nervi during the 1950s, the paper presents structural measures that involve the use of innovative and fibre reinforced cementitious materials as a sustainable alternative to traditional strengthening interventions. The proposed structural solution involves the use of prefabricated elements made of high-performance and fibre reinforced concrete, thus ensuring an optimized use of materials. For the local shear strengthening, the use of carbon fibre reinforced polymer rods is proposed, according to the near-surface mounted technique. The presented interventions are compared with the actual steel-based design, following environmental and economic sustainability criteria including the life cycle of the materials and the cost estimation. The results show that the reinforced concrete solution is more advantageous both in economic and environmental terms. Indeed, the introduction of reinforced concrete shear walls mitigates the seismic actions on the original structure, with a consequent reduction of local interventions and the improvement of the overall sustainability.

As wind farms age, owners encounter pivotal decisions about either extending the operational lifespan of their facilities or pursuing complete decommissioning and repowering. Apart from the commercial factors guiding these choices, technical considerations must be assessed to gauge the risks associated with the continued operation of an aging fleet. In the context of onshore wind turbines, reinforced concrete shallow foundations stand as crucial components. Typically designed for a 20-year lifespan, there exists a pressing need to extend the life of foundations installed over 15 years ago. Both foundations and other structural turbine components endure cyclic fatigue loads. The utilization of fibre-reinforced concrete (FRC) presents enhanced competitiveness by reducing the need for traditional reinforcement, expediting construction, and delivering sustainability benefits. Furthermore, incorporating fibres can enhance fatigue behaviour, thereby positively impacting the service life of the foundation. This paper presents a preliminary numerical investigation into the influence of added fibres on the fatigue behaviour of wind tower foundations. The fatigue performance of the FRC foundation is compared with the standard behaviour of a conventional reinforced concrete foundation.

In 2018 a collaborative project between Politecnico di Milano (PoliMI) and Regione Lombardia (RL) was launched to join forces and expertise toward the improvement of the regional transport infrastructures maintenance management. One of the project goals was the development of regional guidelines aimed to support the design and implementation of monitoring systems for bridges. The focus of this paper is on the illustration of the Monitoring Regional (MoRe) guidelines and of their implementation on nine pilot monitoring systems designed and deployed within the project. The (MoRe) guidelines tackle the entire monitoring process from the analyses of the monitoring goals and the preliminary investigations needed to the identification of the phenomena and relevant indicators to monitor, up to the selection of monitoring devices and the presentation of results. A short illustration of the permanent monitoring systems installed on nine exemplary bridges in the Lombardia region concludes the paper.

Given the present landscape of existing bridges in Italy, a significant portion of which dates back to the mid-20th century, the need to conduct detailed investigations on the current deterioration state and on the safety of these infrastructures becomes indispensable. This work, focusing on a case study involving reinforced concrete tie rods removed from a 70-year-old arch bridge and preserved for mini-invasive diagnostics, addresses the critical need of estimating the current condition of these elements while verifying whether the common non-destructive techniques can be used to monitor the progress of deterioration. Both electrochemical measurements (e.g. corrosion potential and electrical resistivity) were used to detect the current corrosion conditions of steel bars; small core samples were also extracted to assess the presence of carbonation. In addition, this study allowed to investigate the effectiveness of the past restoration interventions, determining whether they achieved the designed outcomes. This research questions the effectiveness of these diagnostic measures to propose their repetition in situ for reliable, non-continuous monitoring of the structural health of these elements over time. The next steps involve visual inspection and mechanical characterization of the reinforcement to demonstrate the effectiveness of the diagnostics presented.