This research project, funded by the Florida Department of Transportation (FDOT), evaluates the use of Glass Fiber Reinforced Polymer (GFRP) bars to address the significant risk of deterioration in the waterline pile cap footings that support bridge piers built in tidal zones. Traditionally, concrete foundations are reinforced with steel bars up to #11 (36-mm diameter) with thick concrete cover and durability-enhanced concrete mix designs. Both current design standards ACI CODE-440.11(2022) and AASHTO LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete (2018) do not include the use of #11 or larger bars, which are ideal for pile cap footings or elements that may be susceptible to large design forces including vessel collision or hurricane wave and wind loadings. Additionally, existing literature lacks scientific research and experimental testing for large diameter FRP bars. The objective of this research project is to perform a comprehensive physio-mechanical characterization of #11 or larger GFRP bars including tensile strength, transverse and horizontal shear and other relevant properties such as bond strength to concrete. To achieve this objective, a series of different tests were carried out in accordance with ASTM standards on #11 GFRP bars, produced from two different manufacturers.

Bridge digitalization increasingly relies on scan-to-BIM techniques to generate accurate as-built models from point-cloud data; however, existing approaches mainly focus on geometric reconstruction or standardized model export, providing limited support for engineer-controlled and editable infrastructure modelling workflows. This paper presents a parametric scan-to-BIM framework for existing box-girder bridges that combines automated geometric extraction with interactive modelling and real-time BIM generation. The proposed workflow starts from drone-based photogrammetric point-clouds and reconstructs bridge components through parametric modelling, where cross-sectional geometry and longitudinal arrangement are controlled by structured parameters stored in a spreadsheet environment. A live synchronization mechanism enables real-time transfer of the parametric model to the BIM platform, while a dedicated user interface allows non-expert users to generate and verify bridge models through guided input of engineering parameters. Unlike previous reconstruction-oriented methods, the approach prioritizes controllable modelling, editability, and practical usability, enabling rapid generation of information-rich as-built models suitable for rehabilitation and asset management applications. The results demonstrate reduced manual modelling effort, improved consistency, and enhanced adaptability compared to traditional modelling workflows, supporting the integration of existing bridges into digital-twin-oriented infrastructure management processes.

Hybrid reinforced concrete (HRC) sections combining steel and fiber-reinforced polymer (FRP) bars provide a structural solution that balances durability, load-bearing capacity and energy dissipation. However, the absence of unified design provisions and the coexistence of distinct safety formats in European and American codes complicate the consistent assessment of ultimate limit state behavior under combined axial force and bending moment. In this study, a strain-based sectional model founded on compatibility and internal force equilibrium is implemented through a layer-by-layer numerical integration procedure to generate axial force-bending moment (N-M) interaction domains and moment-curvature (M-chi) relationships. The formulation is extended to a dimensionless framework in terms of normalized axial load, bending moment, total hybrid mechanical reinforcement ratio omega h and hybridization parameter R. The analysis is conducted within two regulatory formats: the European framework based on Eurocode 2 and CNR-DT 203 R1/2026 and the American framework based on ACI 318-25 and ACI 440.11-22. The results show that increasing omega h leads to a progressive expansion of the interaction domain and modifies the transition between FRP rupture-controlled and steel-yielding-controlled limit states. Increasing R shifts balanced conditions towards higher axial compression and bending levels. Differences between the two regulatory approaches are observed in terms of predicted curvature capacity and design resistance within the N-M domain, reflecting the distinct safety formats adopted. The proposed dimensionless parametric formulation enables consistent comparison of hybrid configurations and provides basis for interpreting failure-mode transitions and deformation capacity of HRC sections under combined axial and flexural actions.

Structural Health Monitoring (SHM) is an increasingly crucial issue in civil engineering. Many structures like bridges and viaducts nowadays are older and show signs of structural deterioration that can potentially affect structural safety. One of the most popular monitoring techniques is dynamic monitoring under environmental vibrations using Operational Modal Analysis (OMA) techniques.The application of OMA techniques usually requires the recording of accelerometer signals of consistent time duration. Consequently, a large storage space, expensive cabled solutions and lots of data traffic are required for such purpose.In the last years, cheap wi-fi accelerometers begun to be installed on bridges providing short length accelerograms. This paper explores the feasibility and the quality of dynamic identification of composite steel-concrete bridge decks based on short-duration accelerometer recordings (slightly longer than 100 seconds) recorded at specific times of day.Furthermore, the outcome of using a small number of sensors on the results of dynamic identification is studied.The article highlights the potential and critical issues of dynamic monitoring based on short-term accelerometer recordings and a limited number of sensors.The results obtained show that short duration of accelerometer recordings cannot be used with a traditional OMA approach but may allow for dynamic identification with acceptable results if properly treated.The second critical aspect is related to the limited number of sensors, which, for the purposes of a model-driven monitoring approach, makes the model updating of the digital twin particularly complex.

Structural Health Monitoring (SHM) of existing bridges increasingly relies on dynamic measurements to assess structural performance and detect potential damage. However, the practical implementation of long-term vibration-based monitoring is still constrained by the volume of data required and the complexity of continuous acquisition systems. In the context of ensuring the safety and performance of existing bridge infrastructure, vibration-based monitoring offers a powerful tool for detecting changes in structural behavior. This study presents an extended investigation of dynamic monitoring applied to composite steel–concrete viaducts, focusing particularly on the signal-analysis framework and methodological enhancements. Short-duration accelerometric records are processed through an automated signal-selection pipeline and advanced modal-parameter extraction algorithms to yield identification of modal features. Emphasis is placed on the statistical evaluation of modal-parameter stability, effects of operational and environmental variability, and the potential for long-term trend detection. The results highlight the limits of short-length recordings when OMA techniques are applied. Nevertheless, appropriate signal processing and data handling can provide acceptable insights into the dynamic characteristics of large bridge systems. The methodological findings provide a foundation for improved monitoring workflows, showing the amount of information that can be retrieved using a cost-effective hardware deployment and supporting further development toward structural digital twins.

Glass-Fiber-Reinforced Polymer (GFRP) bars are emerging as an alternative to steel reinforcement in concrete structures thanks to their high mechanical performance and intrinsic resistance to corrosion. Nevertheless, their actual sustainability must be verified through an assessment that considers long-term durability, life cycle environmental impacts, and economic feasibility. The replacement of steel reinforcement with GFRP in concrete bridge decks is herein evaluated through an integrated methodology. First, a comprehensive literature review examines the degradation processes observed experimentally and the associated long-term evolution of mechanical properties, providing the basis for defining realistic durability scenarios. Subsequently, a comparative Life Cycle Assessment is conducted adopting a cradle-to-grave system boundary and using Environmental Product Declarations to build the Life Cycle Inventory and perform the Impact Assessment. Normalization and weighting phases are included for a better understanding of the overall impacts of the two alternatives. In parallel, a Cost Analysis is performed consistently with the system boundaries and scenarios considered in the Life Cycle Assessment. Finally, the Envision protocol, a framework to evaluate sustainability and resilience of infrastructures, is applied to identify credits directly influenced by the adoption of GFRP reinforcement. The results show that steel reinforcement exhibits lower initial environmental impacts and remains more economical over short service life horizons. However, if the extended durability of GFRP is considered, the reduction in heavy maintenance activities allows this solution to achieve superior environmental performance and improved economic balance. The Envision-based evaluation further confirms the potential contribution of GFRP reinforcement to higher sustainability ratings in infrastructure projects.

This research project funded by Florida Department of Transportation (FDOT) provided the opportunity to characterize #11 (36-mm diameter) GFRP bars that are not currently considered in ASTM specifications, but recently added to the FDOT FY2024–25 sect. 932 material specification. Accordingly, and based on the experimentally-obtained properties of these large-diameter bars, a waterline pile cap footing was selected and designed. As a result, a comprehensive design philosophy and workflow is proposed for GFRP reinforced concrete (GFRP-RC) bridge footings. The case-study waterline pile cap footing is located in the Florida coastal zone and was originally designed in 2017 based on AASHTO LRFD Bridge Design Specifications, seventh edition (2014) using conventional carbon steel reinforcement. The main objectives of this study are to: (1) redesign the foundation with GFRP bars while keeping the cap geometry unchanged; (2) analytically validate the Ultimate Limit State (ULS) and Service Limit State (SLS) designs with the AASHTO LRFD Bridge Design Guide Specifications for GFRP (2018) using a commercial FEM software; (3) compare the amount of #11 GFRP reinforcement with that of carbon steel bars in the as-built drawings of the original steel-RC design; and, (4) discuss the challenges in detailing, including the anchorage length of GFRP #11 bars and minimum bent bar sizes to meet both SLS and ULS requirements. The foundation was designed using both the properties defined by the FDOT FY2024–25 Specifications and those obtained from experimental tests, highlighting that the design with GFRP bars is more restrictive at the SLS and in detailing compared to steel-RC.

In the last decades, composite retrofit technology has been introduced for structural applications in civil engineering. The advantage of reinforcing existing reinforced concrete (RC) members with glass fiber-reinforced polymer (GFRP) bars is to provide the required additional load bearing capacity, while improving maintainability and durability. Being corrosion of steel reinforcement a major cause of damage in ordinary RC structures, the retrofit of existing structures by arranging additional GFRP reinforcing bars externally to the steel ones leads the entire RC section to be less susceptible to subsequent corrosion degradation, thus limiting further repair costs. On the other hand, the use of GFRP rebars reduces the ductility of RC members in bending and, therefore, can be critical specially for structures subjected to seismic excitations. Therefore, a hybrid use of steel and GFRP reinforcement is mandatory, to keep a sufficient level of ductility. This research aims to highlight the advantages at the Ultimate Limit State (ULS) of the design of repairing/strengthening interventions, such as concrete jacketing, using the innovative retrofitting technique with hybrid steel-GFRP reinforcement. Design models are proposed, based on fundamental theories for RC beams and available literature on failure modes of GFRP reinforced sections. Different solutions are explored by cross-sectional analysis to evaluate the increase in load bearing capacity and the resulting ductility in the bending regime.

A key aspect of providing the structural safety of road infrastructure, such as viaducts, is seismic retrofitting and the taking up of horizontal actions prompted by aerodynamic and dynamic forces. This paper will focus on the retrofitting of a viaduct by introducing an innovative solution to reprise the shear action induced mainly by wind and earthquake on the existing supporting devices. Before any retrofitting intervention on specific elements of the structure under consideration, the conservative state and the knowledge level were to be defined. This analysis, which is covered in the first part of the paper, focuses on prior interventions, evaluations, and analyses. Subsequently, a later solution is suggested to lessen the viaduct's vulnerability to transverse actions. In this method, the existing supports continue working until the acting forces reach a certain threshold, surpassing their capacity. At that point, the transverse forces generated by wind and earthquake-which turned out to be dimensional-are absorbed by steel seismic arrestors that are set up at the supports and connected to the underneath bearing pedestals by means of anchorage systems and shear keys. By redistributing the transverse forces, this system enables a significant improvement in the viaduct's seismic resistance capacity without necessarily having for replacement of the supporting devices and provides adequate bearing capacity against aerodynamic action. The effectiveness of this system has been assessed through numerical analyses on FE models. This study presents an innovative approach to enhance the structural safety of current viaducts against transverse actions like wind and earthquake. Its primary advantage lies in avoiding the need to change supports, thereby preventing disruptions in traffic flow. This represents a significant contribution to civil engineering research in the field of road infrastructure design and retrofitting.

A new consolidation system for prestressed reinforced concrete (PSRC) beams of girder bridges is presented and evaluated. The system consists of two arch-shaped steel trusses placed alongside the lateral faces of the beam to be consolidated. The arches develop longitudinally along the entire span of the beam and in elevation using the available height of the PSRC cross-section. The consolidation system is characterised by its own external constraints, independent from those serving the pre-existing element. The efficiency of the system with respect to variable parameters is examined, focusing on the ratio between the load discharged by the consolidation system and the total applied load. Referring to a case study, consolidation of a PSRC beam adopting the proposed system is compared with the usually adopted external prestressing technique. The cross-sectional properties of the steel arch-shaped trusses are defined by means of a structural optimisation process using a genetic algorithm to identify the minimum steel consumption. Finally, a preliminary cost–benefit analysis is performed for the proposed solution and compared with other commonly adopted techniques.

Bridge designs usually exhibit significant geometric variations between different structural solutions, which implies a low degree of reuse of the models in similar projects. To overcome this limitation, a parametric approach is proposed as an answer. Generative design enhances the bridge design process, increasing efficiency by reducing time and effort. The proposed methodology is based on the creation of a flexible geometric model through the introduction of parameters and numerical relationships between them. Therefore, from a generic generative development, different geometric and structural solutions of composite bridges could be created by modifying the parameter values in a bridge model. The objective of the present work is to define the workflow for a multi-girder composite bridge project based on parametric design and optimization in Grasshopper/Rhino to model the bridge Karamba3D, for structural analysis, and Tekla Structures, for 3D representation. This article describes the methodology implemented, starting with the design of the script into a visual programming interface that runs inside Rhino. Thanks to Grasshopper-Tekla live link, the 3D model is generated by using a set of Grasshopper components that can create and interact with objects in Tekla Structures. Afterwards, the algorithm for FEM analysis is created with Karamba3D. Finally, an optimization process is defined to reduce material waste and achieve an efficient design.

Bridges are complex structures in several aspects, from design to construction, mainly due to their complicated and constrained geometry, high design loads and unique boundary conditions. Moreover, the narrow schedules and the demand for efficiency in the civil engineering industry require a new approach. The Parametric BIM approach removes repetitive time-consuming tasks by introducing parameters and numerical relationships between them. This enhances the design process, increasing efficiency and reducing time and effort. This paper presents a methodology for the development of the geometrical model of different bridge typologies through the modification of input parameters. The approach is applied to composite and concrete box girders bridges, enabling efficient analysis of different structural configurations to explore a range of innovative cost-effective solutions. Thus, the workflow is proposed as a supportive tool for decision-making in the design of new complex structures.

In professional practice, the design and verification of Reinforced Concrete (RC) and Prestressed Reinforced Concrete (PRC) structures are performed using a simplified calculation provided by the Eurocodes that limits resistance but that also includes a certain level of structural safety. Some aspects that directly affect the simplified methods involve the use of linear constitutive laws of materials. The use of non-linear laws is evident in the exploitation of reservoirs of strength and deformations of plastic materials in the Ultimate Limit State. The purpose of this research is to evaluate the increase in resistance to bending actions during the plasticization of the beam of existing bridges to support the decision-making process of the engineer in the assessment of existing structures. To achieve this, two codes (MEG Ductility, MEG Fiber Sections) were developed to provide the moment–curvature diagram of RC and PRC sections using non-linear bonds, and in this paper, the study of RC sections is reported. Furthermore, through a push-down analysis, two RC and PRC viaducts have been analyzed using the moment–curvature characteristics obtained from the realized codes and by varying the non-linear constitutive bonds. The results of this study provide valuable insights into the behavior of RC structures under bending actions and demonstrate the importance of considering non-linear material laws for accurate structural assessments. The findings contribute to the enhancement of the decision-making process of engineers when dealing with existing infrastructures.

Most of the infrastructural heritance will be monitored, in this very close future. Hence, one challenging aspects of Structural Engineering is the development of a successful monitoring strategy. However, a general solution that can provide concrete tools is not yet defined, since Structural Health Monitoring (SHM) is now studying “healthy” or “pseudo-healthy” existing structures. A second critical aspect that is now limiting the spreading of SHM is that most bridges and viaducts existing nowadays are old structures that were not inspected for most of their service lives and that now may show some criticalities whose cause is unknown. The present work marks the importance of monitoring recurrent structures that were designed according to similar criteria and that are exposed to similar weather conditions. This type of constructions can be luckily found in the structural patrimony since constructions that belong to the same site and period were usually built by the same company. The method proposed can build a robust mathematical model of a group of structures and alert in case of not-correspondent behaviour. In the pre-processing stage, data is cleaned and filtered, while in the post-processing stage the analysis is carried on with Gaussian Processes Regression. Lastly, if the data is in accordance with the original mathematical model, a process of data cleansing is carried on strengthening the model using the latter data of monitoring. The process can be applied on local or global scale, and in the present paper it is finally provided an application to a case study.

The stress-strain relationship characterizes the behavior of materials, and a critical investigation of the non-linear curve involves an adaptation of the classic use of the constitutive laws. Eurocodes permit the use of conventional behavior of concrete and steel, to simplify the calculation and also include a certain level of structural safety. In particular, for the Serviceability Limit States, it is allowed to consider a linear elastic behavior and for the Ultimate Limit State, the analysis is performed with plastic materials. The use of non-linear laws is evident in the exploitation of material’s reservoirs of strength and deformations. This analysis provides several aspects that are considering the maximum exploitation of materials' mechanical properties, some of which are related to the assessment of existing structural elements limiting the safety redundancy and reinforcement optimization. The purpose of this research is to evaluate the increase in resistance to bending actions during the plasticization of the beam of a bridge to support the decision-making process that assists the assessment of existing infrastructures and evaluate structural elements ductility. To provide a practical application, an existing RC grillage bridge of the Italian Highway infrastructural network have been modeled in commercial FEM and underwent the cross-sectional analysis to gather information on the nonlinear strength.

Bridges are geometrically complex infrastructures, and their designs usually exhibit significant geometric variations between different structural solutions. The modelling complexity implies a low degree of model reuse in comparable projects; moreover, with the development of new technologies and design ways, the AEC industry often requires computational cost reduction, less time for model developments and analysis, and little-to-zero material waste in the face of the environmental emergency. The present document proposes a generative approach to enhance the bridge design process, increasing efficiency by reducing computational costs and modelling efforts, tackling the aforementioned objectives. The following methodology relies on a workflow to create flexible geometric models, introducing parameters and numerical relationships between all the design variables. Therefore, from a generative development, different geometric solutions of a bridge’s family are created by modifying the parameter settings within the same model. Then, the present work aims to define a modelling and analysis strategy for a multi-girder composite bridge project based on parametric development, structural analysis, and optimization. The results integrate building information modeling (BIM) to explore and create high-potential designs with complex geometries and find cost-effective solutions.

Inspections is a noteworthy task inside the civil engineers’ community either in testing and maintenance phase of infrastructures. Nowadays, the need of fulfilling safety requirements is occupying a central role in the management of the infrastructure network, since most of the main structures date back to the 1960s and 1970s, when the design was performed with different and less restrictive codes and more limited knowledge regarding the structural behavior. The accomplishment of these requirements has taken an uplift by several strategies which permit a continuous evaluation of structures. Monitoring strategies provide a continuous dataset that gather valuable information on the structural performance in a time window sampling the information with a certain frequency. The data-driven analysis allows the identification of potential undesired behavior of the instrumented elements and the global structure in both, static and dynamic regime, granting fairly quick response and bringing awareness on the current state of the structure. The cutting-edge technique is evaluated with static analysis of the case study of a box-girder bridge characterized by an unknown static scheme, which underwent an intervention regarding the modification of the supports, where the dataset of the pre-intervention and post-intervention displacements of the joints are collected. In parallel with a finite element model, the data analysis brought to light the expected performance of the retrofitted infrastructure.

Orthotropic steel deck (OSD) bridges are lightweight constructions which are convenient, especially for the achievement of long spans. Conversely, due to the stress concentration in correspondence to the numerous and unavoidable welded construction details, this bridge typology is prone to fatigue cracking under the effect of cyclic loading with high-stress amplitudes. Existing OSD bridges are particularly vulnerable to fatigue damage accumulation because of the dated standards adopted at the time of their design and the fact that heavy lorries have increased in travel frequency and weight. In the present paper, a case study of a northern Italian existing highway viaduct, built in the 1990s, is presented and analyzed. The fatigue damage accumulation was carried out according to the fatigue load models for road bridges reported in Eurocode EN 1991-2 and the assessment criteria indicated in EN 1993-1-9. The stress amplitude, in correspondence to the critical details of the bridge, is assessed by means of detailed finite-element calculations carried out with the software MIDAS GEN®. The amplitude and frequency of the travelling weights are assessed based on real traffic monitoring from the highway. Moreover, an automatic “rain-flow” algorithm is implemented, which is able to detect each nominal stress variation above the fatigue limit. In general, the bridge is not fully compliant with today’s standards when considering the entire duration of the prescribed life of the design. Countermeasures, like lane number reductions and lane reshaping, are critically analyzed since their effectiveness is questionable as far as the reduction in heavy traffic is concerned. Other interventions, like the replacement of the pavement in order to improve the stress redistribution upon the connection details below the wheel footprint, and continuous bridge inspections or monitoring, look more promising.

Various theories and analytical formulations were implemented and exploited in the 1980s and 1990s for the design of bridge beams or decks curved in the horizontal plane and subjected to out-of-plane loads.Nowadays, the Finite Element Method (FEM) is a valid tool for the analysis of structures with complex geometries and, therefore, the development of sophisticated analytical formulations is not needed anymore.However, they are still useful for the validation of FE models.This paper presents the case study of an existing viaduct built in North Italy, aiming to compare analytical approaches and numerical modelling.The bridge is characterized by an axis curved in two directions and a rectilinear segment.The global analysis of the viaduct is carried out with special attention to the attributes that cause torque action and bending moment.The theoretical developments focus on a deeper understanding of the torsional response under different constraint and loading conditions and aspire to raise awareness of the mutual interaction of flexural and torsional behaviour, that are always present in these complex curved systems.The examination of the case study is also obtained by comparing the response of isostatic and hyperstatic curvilinear steel box-girders.