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Many transportation infrastructures all around the world are facing new challenges in terms of ageing and loss of performance. The infrastructural asset managers are required to perform scrupulous control of the health condition of the infrastructures over time and to execute the required maintenance works. In this context, digital twin models of the infrastructures should have a key role to simplify and speed up the procedures for proper maintenance. This paper discusses the advantages of developing digital twin models for the management of infrastructures, with a focus on bridges. In particular, the role of dynamic tests performed on bridges for the development of digital twin models is addressed, paying attention to test procedures and requirements. Issues such as the quality of instrumentation, the numerosity, and layout of sensors, and the acquisition and post-processing procedures are addressed through applications to two real bridge case studies. Both infrastructures are multi-span pre-stressed RC bridges that were dynamically tested after the restoration and seismic upgrading works. Results of ambient vibration tests and operational modal analyses are described, providing an idea of dynamic test requirements, as well as their use within the framework of the digital twin model creation.

The failure behaviour of historic unreinforced masonry (URM) structures is strongly influenced by the properties of bricks and mortar. Over time, degradation processes compromise these materials, with significant effect on structural response and safety. Nevertheless, deterioration effects on the nonlinear behaviour of masonry have been only marginally investigated. This study investigates the mechanical behaviour and failure mechanisms of historic brick masonry with weak and irregular mortar joints, representative of Mediterranean traditional constructions. An extensive experimental programme was conducted on mortars, historic clay bricks, prisms, wallets, and triplet specimens, complemented by in-situ flat jack tests. Results confirm the critical role of mortar quality and joint irregularities in reducing compressive and shear strength and in influencing deformation capacity of historic masonry. The experimental findings served as a basis for the calibration of a Finite Element Model (FEM), subsequently employed to gain deeper insight into the governing failure mechanisms in a real study case. A critical discussion of compression and shear failure criteria is presented, focusing on historic masonry. Experimental and analytical comparisons show major discrepancies in classical criteria, especially with degraded mortars. The study shows that in historic masonry with weak joints, failure is often governed by compression rather than shear.

Operational modal analysis (OMA) is widely used for its simplicity and reliance on ambient noise. While commercial OMA software exists, they often limit user control. Some researchers develop their own tools, but independent software tools remain scarce. The number of such independent software is limited, and the development of new ones with enhanced features, better performance, and varied user interfaces would be beneficial to spread the informed use of dynamic identification techniques, leading to more reliable and valuable results for structural engineering applications. This work introduces the new DYMOS software for OMA from ambient vibration test recordings. DYMOS includes various state-of-art algorithms and tools for vibration-based modal identification and for optimal sensor placement (OSP), allowing for customization of analysis parameters and procedures with the aim of reducing the gap between the needs of professional practice and research. Additionally, a new graphical tool is introduced for visualizing results in both buildings and bridges. By using CAD drawings as input, it streamlines model construction, making the process faster, more intuitive, and efficient. The article aims to describe DYMOS and to demonstrate its potential for OMA and OSP in civil engineering through the application on two real case studies dynamically tested.

This paper deals with modelling strategies for the updating of Finite Element Models (FEMs) of infilled Reinforced Concrete (RC) frame buildings. As is known, this building typology is the most adopted worldwide for residential houses and strategic buildings, such as hospitals, schools, police stations, etc. The importance of achieving trustworthy numerical models for these kinds of structures, especially the latter ones, is clear. The updating procedure mainly consists in changing the geometrical and mechanical material properties of models until pre-determined convergence criteria are verified, the latter based on the comparison between numerical and experimental outcomes. In this work, the modelling strategies that can be adopted to refine FEMs of infilled RC buildings are treated in-depth, starting from the simple model usually developed for design purposes. Modelling techniques relevant to the geometry, the mechanical properties, the mass, and the restraint conditions of the model are discussed. Moreover, the approaches that can be adopted to calibrate numerical models during the construction process are addressed as well. Then, an application of the proposed strategies is provided with reference to a real building that was investigated during its construction. The proposed modelling strategies proved to be effective in the model updating of the considered building and provide useful support for the calibration of FEMs of this building typology in general.

Over the last couple of decades, significant efforts have been made to develop structural health monitoring solutions. The growing need for the dynamic characterization of structures supports the implementation of condition assessments, maintenance, and monitoring strategies for existing and new civil engineering structures, and to provide increased safety for the public. Wireless monitoring systems are still being improved as the technology is finding a wider use for the monitoring of civil engineering structures, thanks to their easier installation and reduced costs when compared to the wired counterparts. In this context, this paper presents a new wireless network system for the dynamic characterization of civil engineering structures, whose distinguishing features comprise combining cutting-edge accelerometers, excellent signal synchronization, low battery consumption nodes, and a cloud-based framework to support the monitoring operations. The performance characteristics are validated through laboratory tests and are demonstrated on a newly constructed 211 m tall building.

This paper presents the results and interpretations of static and dynamic tests that were executed on a newly built cable-stayed steel-concrete composite bridge during the final proof testing. A brief description of the structure, the testing methodology, and the used instrumentation are presented. Then, the test results are widely discussed and interpreted in order to evaluate the bridge performance during the proof test and also to understand the usefulness of each performed test in a proof test framework. All the collected experimental data are also compared to the numerical ones that were obtained through a refined finite element model, in order to check the behavior of the structure. The outcomes of the present work can offer references for the proof testing and monitoring of cable-stayed bridges.

This study explores the transverse response of bridge piers in riverbeds under a multi-hazard scenario, involving seismic actions and scoured foundations. The combined impact of scour on foundations’ stability and on the dynamic stiffness of soil–foundation systems makes bridges more susceptible to earthquake damage. While previous research has extensively investigated this issue for bridges founded on piles, this work addresses the less explored but critical scenario of bridges on shallow foundations, typical of existing bridges. A comprehensive soil–foundation structure model is developed to be representative of the transverse response of multi-span and continuous girder bridges, and the effects of different scour scenarios and foundation embedment on the dynamic stiffness of the soil–foundation sub-systems are investigated through refined finite element models. Then, a parametric investigation is conducted to assess the effects of scour on the dynamic properties of the systems and, for some representative bridge prototypes, the seismic response at scoured and non-scoured conditions are compared considering real earthquakes. The research results demonstrate the significance of scour effects on the dynamic properties of the soil–foundation structure system and on the displacement demand of the bridge decks.

The seismic assessment of existing bridges is of the utmost importance to characterise the main structural deficiencies, estimate the risk, prioritise retrofit interventions, or estimate losses and repair costs in case of earthquakes. The above tasks require information on the damage mechanisms likely to occur as well as on the damage extent over the structure. Such types of information are generally not provided by classical fragility analysis, which is mainly focused on the evaluation of the global performance of the bridge. In this paper, a systematic probabilistic methodology for the evaluation of bridge fragility is proposed. The methodology aims at offering insight into the failure mechanisms most likely to occur and the evolution and extent of damage within the bridge structure. First, a mathematical description of the proposed analysis methods is given, then an application to a realistic case study—a reinforced concrete multi-span simply supported deck link-slab bridge—is provided to illustrate the applicability of the tool. A nonlinear 3D finite element model is developed, and a multiple-stripe (nonlinear dynamic) analysis is performed by using a stochastic bidirectional seismic input. The results highlight the suitability of the proposed methodology to reveal the main structural deficiencies, the relations among different failure mechanisms (involving piers, bearings, abutments, etc.), and the expected damage extent.

Vibrations are an issue of increasing importance in current footbridge design practice. More sophisticated footbridges with increasing spans and more effective construction materials result in lightweight structures and a high ratio of live load to dead load. As a result of this trend, many footbridges have become more susceptible to vibrations when subjected to dynamic loads. The most common dynamic loads on footbridges, other than wind loading, are pedestrian-induced footfall forces due to the movement of people. This paper concerns the experimental and numerical dynamic characterization of a newly built steel and wooden cable-stayed footbridge. The footbridge was dynamically tested in situ under ambient vibration, and the results allowed the real dynamic behavior of the footbridge to be captured. The dynamic response under pedestrian dynamic loads was also investigated and compared with the limitations provided by the main international codes and guidelines for footbridge serviceability assessment. A numerical model of the footbridge was also developed and updated based on the experimental outcomes. Then, the calibrated model was used to numerically assess the footbridge’s serviceability following the guideline prescriptions for pedestrian load simulation, and the design accuracy was also validated. This paper aims to increase the state-of-the-art knowledge about footbridge dynamic testing so as to support the design of new and futuristic structures as well as prove the effectiveness of using the requirements of codes and guidelines for footbridge serviceability assessment by adopting a calibrated numerical model.

Europe faces many problems connected to ageing infrastructure which was built in the second half of the 20th century. Bridges are one of the crucial elements of these infrastructures. In recent years, European countries have witnessed many failures of bridges across the continent. For example, the collapse of Viadotto Polcevera in Genoa caught the attention of society regarding its tragic consequences. Therefore, engineers must deal with the assessment of existing bridges which is essential for proper decision-making. Condition rating systems for bridges vary from country to country. Consequently, these differences in the methodology can lead to different conclusions related to the future service of assessed structures. For these reasons, this paper briefly describes condition rating systems for road bridges in Italy, Slovakia, and Portugal and defines the differences in the methodology. Subsequently, the obtained conclusions are compared and discussed. The aim of the paper is to encourage standardization in the assessment of bridge health conditions within European countries, highlighting the differences in the current systems adopted by various countries.