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With the continuous expansion of the high-speed railway network in China, long-span railway bridges carrying multiple tracks demand reliable and fast testing procedures and techniques. Bridge dynamic behavior analysis is a critical process in ensuring safe operation of structures. In this study, we present some experimental results of the vibration monitoring of a four-track high-speed railway bridge with a metro–track on each side: the Nanjing–Dashengguan high-speed railway bridge (NDHRB). The results were obtained using a terrestrial microwave radar interferometer named IBIS-S. The radar measurements were interpreted with the support of lidar point clouds. The results of the bridge dynamic response under different loading conditions, including high-speed trains, metro and wind were compared with the existing bridge structure health monitoring (SHM) system, underlining the high spatial (0.5 m) and temporal resolutions (50 Hz–200 Hz) of this technique for railway bridge dynamic monitoring. The detailed results can help engineers capturing the maximum train-induced bridge displacement. The bridge was also monitored by the radar from a lateral position with respect to the bridge longitudinal direction. This allowed us to have a more exhaustive description of the bridge dynamic behavior. The different effects induced by the passage of trains through different tracks and directions were distinguished. In addition, the space deformation map of the wide bridge deck under the eccentric load of trains, especially along the lateral direction (30 m), can help evaluating the running stability of high-speed trains.

A novel numerical methodology is presented to solve the dynamic response of railway bridges under the passage of running trains, considering soil–structure interaction. It is advantageous compared to alternative approaches because it permits, (i) consideration of complex geometries for the bridge and foundations, (ii) simulation of stratified soils, and, (iii) solving the train-bridge dynamic problem at minimal computational cost. The approach uses sub-structuring to split the problem into two coupled interaction problems: the soil–foundation, and the soil–foundation–bridge systems. In the former, the foundation and surrounding soil are discretized with Finite Elements (FE), and padded with Perfectly Match Layers to avoid boundary reflections. Considering this domain, the equivalent frequency dependent dynamic stiffness and damping characteristics of the soil–foundation system are computed. For the second sub-system, the dynamic response of the structure under railway traffic is computed using a FE model with spring and dashpot elements at the support locations, which have the equivalent properties determined using the first sub-system. This soil–foundation–bridge model is solved using complex modal superposition, considering the equivalent dynamic stiffness and damping of the soil–foundation corresponding to each natural frequency. The proposed approach is then validated using both experimental measurements and an alternative Finite Element–Boundary Element (FE–BE) methodology. A strong match is found and the results discussed.

The construction deviations of super-long span bridges in high-speed railways during the construction phase directly affect the track smoothness after bridge completion, thereby impacting the operational quality of high-speed trains. This study analyzes the main influencing factors of smoothness control in super-long span bridge construction based on their technical characteristics, proposes a construction-phase bridge smoothness control strategy combining segmental assembly control with holistic assessment and adjustment, and investigates smoothness control methods during segmental assembly using the virtual chord measurement method, supported by case studies. The research demonstrates that implementing smoothness control during construction is essential to ensure post-completion track smoothness of super-long span bridges. The proposed strategy effectively translates smoothness control objectives into key construction phases. The virtual chord measurement method proves highly operable and effective for segmental assembly smoothness control. Post-completion multidimensional evaluations using chord measurement and other techniques can guide track smoothness adjustments. Conducting construction-phase smoothness control for super-long span bridges lays the foundation for achieving high track smoothness objectives on high-speed railway bridges.

Masonry arch bridges are an integral part of the European transportation infrastructure. Regular inspections are critical to ensure the safe operation of these bridges and also to preserve historical heritage. Despite recent advancements in assessment techniques, monitoring masonry arch bridges remains a difficult and important research topic. This paper describes a proof-of-concept study carried out on a masonry arch rail bridge in Gavirate, Italy, to investigate the dynamic responses of the bridge to train-induced moving loads. The dynamic measurements are obtained by a distributed fiber optic sensing system that enables a novel inspection of the integrity of masonry arch bridges. The focus of this field study is to quantify the dynamic strain induced by train moving loads and reveal the masonry arch bridge’s dynamic behaviors through the use of an innovative distributed fiber optical sensing-based technique. The results may provide a useful guideline for the application of distributed fiber optical sensing to monitoring masonry arch bridges.

•First large-diameter shield tunnel built under an active high-speed railway bridge.•Innovative steel casing method ensures safety under limited construction height.•Detailed monitoring tracks impacts on soil, bridge piers, and isolation piles.•Advanced 3D modeling predicts pier displacements, guiding protective measures.•Offers vital reference for future tunnels under high-speed rail infrastructure. This case study examines a landmark engineering project in Suzhou, China, involving the construction of two large-diameter (13.2 m) shield tunnels beneath an active high-speed railway (HSR) bridge. This pioneering project is the first of its kind in both China and the world. Advanced numerical simulations were conducted to rigorously assess construction risks. To ensure the operational safety of the existing HSR bridge, an innovative protective system, consisting primarily of segmental steel casing concrete pile barriers, was employed. A comprehensive network of monitoring sensors was strategically deployed to track soil, pile barrier, and pier displacements throughout both the protective and tunnelling phases. Simulation results indicated that tunnelling without protective measures could cause pier displacements of up to 3.1 mm along the bridge—exceeding the maximum allowable displacement of 2 mm in accordance with regulations. Monitoring data revealed that the maximum pier displacement during protective scheme installation was limited to 0.5 mm. With these protective measures, pier displacement during each tunnelling phase remained consistently below 0.5 mm, representing an approximate 80% reduction compared to the unprotected scenario, thereby ensuring the continued safety of the HSR bridge.

High-speed railway bridges are essential components of any railway transportation system that should keep adequate levels of serviceability and safety. In this context, drive-by methodologies have emerged as a feasible and cost-effective monitoring solution for detecting damage on railway bridges while minimizing train operation interruptions. Moreover, integrating advanced sensor technologies and machine learning algorithms has significantly enhanced structural health monitoring (SHM) for bridges. Despite being increasingly used in traditional SHM applications, studies using autoencoders within drive-by methodologies are rare, especially in the railway field. This study presents a novel approach for drive-by damage detection in HSR bridges. The methodology relies on acceleration records collected from multiple bridge crossings by an operational train equipped with onboard sensors. Log-Mel spectrogram features derived from the acceleration records are used together with sparse autoencoders for computing statistical distribution-based damage indexes. Numerical simulations were performed on a 3D vehicle–track–bridge interaction system model implemented in Matlab to evaluate the robustness and effectiveness of the proposed approach, considering several damage scenarios, vehicle speeds, and environmental and operational variations, such as multiple track irregularities and varying measurement noise. The results show that the proposed approach can successfully detect damages, as well as characterize their severity, especially for very early-stage damages. This demonstrates the high potential of applying Mel-frequency damage-sensitive features associated with machine learning algorithms in the drive-by condition assessment of high-speed railway bridges.

Documentation of structural visual inspections is necessary for its monitoring, maintenance, and decision about its rehabilitation, and structural strengthening. In recent times, close-range photogrammetry (CRP) based on unmanned aerial vehicles (UAVs) and terrestrial laser scanners (TLS) have greatly improved the survey phase. These technologies can be used independently or in combination to provide a 3D as-is image-based model of the railway bridge. In this study, TLS captured the side and bottom sections of the deck, while the CRP-based UAV captured the side and top sections of the deck, and the track. The combination of post-processing techniques enabled the merging of TLS and CRP models, resulting in the creation of an accurate 3D representation of the complete railway bridge deck. Additionally, a 3D as-designed model was developed based on the design plans of the bridge. The as-designed model is compared to the as-is model through a 3D digital registration. The comparison allows the detection of dimensional deviation and surface alignments. The results reveal slight deviations in the structural dimension with a global average value of 9 mm.

Fabricated ballastless track has witnessed increasingly wide application in large-span bridges of municipal railways. The current ballastless track standard is applicable to bridges with a main span of 200 m to 400 m. For the main span is longer than 400 m, it is necessary to ensure the travelling safety and comfort on the fabricated tracks. In this study, static and dynamic analysis models of train-track-bridge are established to explore the influence of complex ambient temperature changes and concrete shrinkage and creep on bridge deformation, followed by the analysis of the deformation coordination between long-span bridge and fabricated ballastless tracks, thereby revealing the dynamic response of the train-track-bridge system under the complex influence of temperature. The results show that when a train runs at a speed of 160 km/h, the existing ballastless track design standard is still applicable to a bridge span of 688 m. Compared with CRTS type III track, the adoption of the novel prefabricated ballastless track on long-span urban bridges provides higher safety and greater comfort, with comprehensive power performance improved by more than 10%. This design comprehensively takes into account the deformation coordination and dynamic performance of the rail bridge, providing a basis for the design and application of fabricated ballastless tracks on long-span bridges of urban railways.

With the development of life and its requirements increasing, it has become necessary to find means that reduce the time to meet them, and one of these means is high-speed trains. Many previous studies have dealt with different properties affecting the dynamic behavior of railway bridges. In this research, the effect of changing the structural material of part of the main bridge structure on its dynamic behavior were be studied. Two types of bridges were studied. The first is the steel-girder bridge, and the second is the polygonal concrete bridge. The bridge modeling was done through the program SAP2000 and the structural analysis of the study model was done by using the finite element method. Material and mechanical properties from laboratory experiments were used for previous studies. The results for the two dynamic behavior parameters that were tested showed larger values in the polygonal model of the bridge. It increases in the steel beam model by 59% for vertical displacement and by 45% for vertical acceleration. The vertical displacement values were within the limits of the international standard L/600, and the vertical acceleration was within the limits of the European standard 3.5 g. The best design for each speed should be determined by conducting more study, which should include testing models at various speeds.

To mitigate and control the seismic damage risk of high-speed railway bridges and enhance their post-earthquake reparability, a prefabricated multi-layer parallel-connected slit steel plate shear damper is proposed by utilizing the energy absorption capacity of flexure–shear coupled deformation in dampers. A theoretical model for calculating the stiffness and load-bearing capacity of the proposed damper was established and validated through detailed finite element simulations. The results demonstrate that the damper exhibits stable energy dissipation efficiency under cyclic loading, along with a gradual reduction in post-yield stiffness. Subsequently, a numerical model of the high-speed railway track–bridge-damper systems (HSRTBDS) was developed, incorporating the contribution of the proposed damper to quantify its control over the seismic response of the HSRTBDS. The findings indicate that the damper effectively reduces the seismic responses of the girders, rail fasteners, and track slabs, with a maximum deformation reduction exceeding 30% in the supporting structures. However, the deformation and damage of the bridge piers slightly increased, though they remained within acceptable safety limits. The damper showed limited influence on the damage to rails, fasteners, and shear key slots. Overall, the effectiveness of the proposed damper in controlling the structural response of HSRTBD has been demonstrated and validated, providing insights for the seismic design of high-speed railway bridges in high-intensity seismic zones.