dynamic simulation and critical assessment of a composite bridge in high speed railway

Abstract Evaluation of critical responses of a bridge including resonances in high-speed (HS) railway is a dominant issue in order to confirm the structural safety of bridge and the stability of ballast on bridge deck. In numerical way for critical assessment, it is important to make a sophisticated numerical model and considering the variation of actual properties of structural members. This study proposed a train-track-bridge interaction model focusing on Sesia viaduct, and calibrated the model properties as matching these modal characteristics and dynamic responses to measured ones. By the numerical and experimental comparison, calibrated model could reproduce accelerations up to 30 Hz both of on the time and frequency domains accurately. Especially, good agreements on sleeper accelerations can indicate the high reproducibility of interaction force, which is one of key factors of train-track-bridge interaction simulation. Numerical computation by calibrated model clarified that the deck acceleration up to 30Hz increases by seventh and eighth resonances between passing vehicle length and structural modes, not only global third bending or third torsional but also high order local deck modes. In addition, high performance computing technique based on super computer in RTRI was adopted for parametric analysis in order to investigate the requirements to realize highly accurate estimation for the maximum deck acceleration by the numerical way. As the results of parametric study focusing on design assumption, calculation modal order and train/bridge interaction, it was clarified that the design model causes overestimation by twice maximum acceleration on the deck, and the amplification of excitation forces caused by passage on deflected rails, which is considered in high-order modes and train/bridge interaction, is a key factor to achieve accurate deck acceleration evaluation

Influence of Local Deck Vibrations on the Evaluation of the Maximum Acceleration of a Steel-Concrete Composite Bridge for a High-Speed Railway

Abstract European design standards have established an upper limit on the deck acceleration of the high-speed railway bridges, however the influence of local vibrations of the deck members is rarely considered when modelling the vibrational responses of bridges. To evaluate how the inclusion of local deck vibrations might influence predictions of the maximum acceleration, detailed measurements were taken from a steel-concrete composite box-girder bridge on the Italian high-speed railway, and a numerical model of the system was developed. Deck vibrations were measured during high-speed train passages at the maximum train speed of 374 km/h, and compared against a numerical model of the vehicle-bridge system. This analysis revealed that the maximum deck acceleration is 1.3 times greater than the acceleration of the bridge girders, because of the sixth- and seventh-order resonance between the deck's local vibration modes and the structure with a train running at high speeds over 300 km/h. Moreover, when considering local deck vibrations in the numerical model, we found that the interaction between transient local rail deformations and the vehicle travelling on the rails can increase the acceleration of the deck through resonance

Seismic Train-Running Safety on Structures

In this study, using the analysis program DIASTARS III that is able to take into account the dynamic interaction between railway vehicles and railway structures, we conducted seismic train-running analysis on a model line that is about 4.8 km long. And we identified the relative weak structures of seismic train-running safety in the model line

Damage detection method for sleepers based on vibration properties

In order to detect the damages of PC sleeper in the ballast track which cannot be inspected visually, the damage detection method using vibration mode characteristic of PC sleepers was developed. As a result of the vibration measurement test that conducted in parallel to the bending test, it was confirmed that natural frequencies begin to decrease when more than 1.2 times of the cracking load acted. In Addition, as the results of measurements PC sleepers with actual damages and measurements at the full-scale test rail line, 3rd mode natural frequency in which the effect of damage appears greatly and the variation of ballast does not affect is a suitable indicator for detection of the cracks. Furthermore, focusing on the application on the routine patrol, the high workability damage detection by single point measurement and simple signal processing was considered. As a result, it can be confirmed that the same detection accuracy as the damage detection based on the multipoint measurement was securable

Vibration Reduction Countermeasures of Railway Concrete Viaduct

In this paper, numerical experiments about the structure borne sound countermeasures were conducted, by paying attention to the structure vibration of RC girder. Numerical experiments for the vehicle/track system model was carried out using the DIASTARSIII program, developed by the Railway Technical Research Institute, which analyzes dynamic interaction between the vehicle and railway structure. Also, numerical analysis for the track/structure system model was carried out using the DIARIST program for the track structure. As a result, we elucidated the vibration reduction effect of various countermeasures. First, vibration reduction effect of soft track pad of 30MN/m is recognized in the frequency band above about 70 Hz by measurement results and analysis results. Second, the frequency band which obtained reduction effect depends a great deal on natural frequency of vibration-reducing track