Design Of High-speed Railway Bridges Research Articles

Theoretical method of determining pier settlement limit value for China’s high-speed railway bridges considering complete factors

Reasonable pier settlement is an extremely important limit value in the design of high-speed railway bridges, which directly affects the service performance of bridges and the running safety of trains. Comprehensively considering complete factors affecting the determination of pier settlement limit value (PSLV), this paper presents a method to investigate PSLV for simply supported girder bridges in China’s high-speed railways. First of all, an investigation on PSLV written in China’s current codes is conducted to explain the necessity of this present work. Then based on the train-track-bridge dynamic interaction theory, the methodology for determining PSLV for China’s high-speed railway bridges is proposed, in which the complete factors affecting the determination of PSLV are emphatically discussed and summarized. Adopting the established model, the bridge deformations caused by different factors are calculated, and the PSLV for China’s high-speed railway bridges is then obtained according to the running safety and ride comfort of high-speed trains. Results show that important factors written in codes, including self-weight, prestress, creep, shrinkage, temperature and rail random irregularity, should be fully considered in determining PSLV due to these factors greatly affect bridge deformations and dynamic behaviors of running trains. According to the running safety and ride comfort of high-speed trains, the PSLV for simply supported girder bridges in China’s high-speed railways is suggested to 12.7 mm.

Shaking table test of a high-speed railway bridge with a new isolation system

With the rapid development of high-speed railway bridge construction in seismic areas, it is necessary to investigate the seismic performance of these bridge structures. A new type of seismic isolation system with function separation is presented in this study. By considering an actual high-speed railway bridge as a representative example, the performance parameters of the new type of isolation system were numerically optimized. Based on the results of optimization design, a shaking table test was performed on a reduced scale high-speed railway bridge specimen employing the new isolation system. The comprehensive optimization design and the experimental results demonstrate that the new isolation system can minimize the bending moment of pier while ensuring that the pier’s seismic response in terms of acceleration and displacement is within the allowable range of normal operation of high-speed railway bridges. The proposed new isolation system is expected to offer a cost effective and safe solution in the design of high-speed railway bridges.

Train-speed sensitivity approach for maximum response envelopes in dynamics of railway bridges

The design of high-speed railway bridges is strongly conditioned by vibrations and resonance amplifications induced by rail traffic. Furthermore, most current dynamic analysis approaches are computationally expensive, what poses an obstacle to the study of structural alternatives at early design stages. In order to address this limitation, this paper presents a semi-analytic meta-model based on train speed sensitivity analysis. This technique exploits the sensitivity of the dynamic response of bridges to train speed variations or, in other words, the slopes of the maximum response envelopes. The only approximation of this technique stems from the spatial discretization by finite element modelling and modal superposition, while the formulation is closed-form in the time domain. In this way, it is possible to efficiently compute envelope values and sensitivities with moderate train speed sampling frequencies and, afterwards, approximate the remaining speeds through a cubic spline interpolation. Four case studies are presented in order to illustrate the potentials of the proposed technique, including from simply supported beams to complex three-dimensional models. The numerical results report substantial reductions in the computation time and storage requirements, proving the present approach to be a valuable tool for rapidly assessing the performance of design alternatives.

Design of High-Speed Railway Bridges with Earthquakes in the United States

The California High-Speed Train (CHST) project is located on the west coast of the United States, which is one of the areas around the Pacific plate that has high earthquake risks. Generally, high-speed rail requires rigid structures to satisfy tight limits on deflection and vibration control. But in earthquake areas, flexible and ductile structures are often preferred to resist seismic excitations efficiently, creating additional challengers in the design of the bridge structures. This paper highlights design criteria associated with these conflicting demands and presents some optimal design solutions that best balance these requirements.

Considering dynamic soil-structure interaction in design of high-speed railway bridges

This article presents preliminary theoretical results on the influence of dynamic soil-structure interaction (SSI) of slab foundations. Impedance functions, representing the dynamic SSI, were obtained from FE-models depicting the soil for a few cases of different geotechnical preconditions. The obtained impedance functions were attached to single-span bridges and HSLM-A analyses were performed. The effect of the impedance functions on the bridge response was studied and compared to the ultimate case of a bridge on rigid supports. The influence of SSI seems to have a significant effect on railway bridges. This study shows that by including this effect in bridge design, the damping ratio of the system is largely increased, giving lower acceleration amplitudes in the bridge, while the natural frequencies are less affected.

The Response Analysis of the Train-Bridge System under Seismic Action

This article based on bridge structural dynamics, vehicle dynamics and soil dynamics theory, set up the practical space mode, with an example of a dual-line 32 m single box section beam on Beijing-Shanghai Railway Line. According to the typical soft soil sites of Shanghai, the dynamic response of the bridge was analyzed by the large finite element software ANSYS under seismic action. Moreover the impact about the dynamic interaction of pile-soil-structure affecting on the design of high-speed railway bridges was got which will provide reference and basis for the construction and design similar project.

Dynamic Considerations in the Design of High-Speed Railway Bridges

Research was done concerning the dynamic performance checks required for bridges carrying high-speed rail traffic, and it presents practical numerical simulation techniques for the prediction of performance at the design stage. The sensitivity of the predictions to different modeling assumptions is illustrated. The procedures are described in the context of an example structure, a four-span continuous steel-composite bridge for the new Channel Tunnel Rail Link in southern England. This structure was analyzed with the proposed method, and its dynamic performance has subsequently been measured in the field. The dynamic properties of the bridge and the vibrations predicted at the design stage are compared with measurements made during commissioning tests with Eurostar trains at speeds of up to 300 km/h (190 mph). The principal dynamic concerns relate to dynamic load factor for the structural design, ballast stability, carriage acceleration, and radiated noise. The simulation method is shown to provide realistic predictions.

Experimental analysis of a high-speed railway bridge under Thalys trains

In this paper dynamic experiments on the Antoing Bridge located on the high-speed railway line between Paris and Brussels are reported. The experiments were co-operatively carried out by the Northern Jiaotong University from China, the Catholic University of Leuven, the Free University of Brussels and the Belgium Railway Company NMBS-SNCB from Belgium. The bridge is composed of multi-span simply supported PC girders with spans of 50 m and U-shaped sections. The loads are the high-speed Thalys trains with articulated vehicles. The speeds of the Thalys trains were between 265 and 310 km/h. In the experiments, the dynamic responses of the bridge such as the deflections, the accelerations and the strains that were measured by a laser velocity displacement transducer accelerometers and strain gauges, respectively. Many useful results have been obtained from the analysis of the recorded data. The tests and the measured results can be a reference for the study and the design of high-speed railway bridges.