Vehicle-Bridge Interactions (VBI) in High-Speed Rail Corridors

Abstract

Moving railway vehicles on the bridges cause excitation in the bridge components and owing to this there is increase in the forces like (bending, shear, torsion, displacement, etc). This increase in the forces in the bridge components are computed using Dynamic impact factor. Dynamic impact factor is applied on to the axles to get the dynamic effect on the bridges. Our Indian Railway codes provide the value DIF (called Coefficient of Dynamic Augment) for speed up to 160 kmph. Most of the railway and metro lines are operating with speed lesser than that, therefore, Coefficient of Dynamic Augment (CDA) can be conveniently taken from codes. For any speed greater than 160 kmph CDA shall need to be computed as per the dynamic analysis as per available international codes. As mentioned earlier that there is imminent need of high-speed rail network in India due to increase in economic activity, increase in travel choices, improvement in mobility, reduction in congestion and to boost productivity. Our objective of this thesis is to study dynamic response of a various types of bridges under high-speed trains currently being used in India for high-speed rail projects like RRTS (Delhi to Meerut and other corridors) and High-speed rail project from Mumbai to Ahmedabad to accurately assess the DIF in bridges under the effect of different governing factors (vehicle speed, vehicle load, bridge superstructure type, etc). This study could be beneficial in upcoming projects of high-speed rail as it is our future need.

Introduction

The dynamic interaction between vehicles and bridges (Vehicle-Bridge Interaction or VBI) significantly affects bridge response during vehicle movement, often producing greater dynamic effects than static loads. Factors such as vehicle speed, bridge span length, mass, natural frequency, damping, train axle configuration, track irregularities, and vehicle suspension influence this dynamic behavior. Traditional bridge design uses a Dynamic Impact Factor (DIF) to account for these effects, primarily based on bridge length or natural frequency.

VBI is a two-way interaction where the vehicle influences the bridge’s motion and vice versa, which is critical for modern infrastructure supporting high-speed trains, heavy freight, and extreme events like earthquakes. Static design approaches often underestimate dynamic effects such as resonance, fatigue, and passenger discomfort, necessitating dynamic analysis for accurate prediction, design, and maintenance.

The literature shows that especially in Europe, with its extensive high-speed rail network, dynamic analysis is essential. Problems like high vertical accelerations at high speeds led to more rigorous standards. In India, current codes lack provisions for speeds above 160 km/h, making it necessary to refer to international standards such as Eurocode when designing for high-speed trains.

The study aims to develop a procedure to analyze dynamic responses of different bridge superstructures (steel truss, steel composite plate girder, and prestressed concrete box girder) under moving high-speed trains (up to 180 km/h, such as Delhi-Meerut RRTS). The methodology employs finite element modeling (using ETABS) to simulate and evaluate responses including acceleration, displacement, and structural forces at various train speeds (144 to 216 km/h).

Results show peak accelerations and displacements at different nodes of the bridge models, providing insight into the dynamic effects of high-speed rail loads on bridge structures, helping optimize design for safety, comfort, and durability.

Conclusion

This study is based on the current semi-high-speed rail network i.e. Delhi Meerut Rapid Rail Transit System (RRTS) being constructed and other corridors are to be implemented. Design speed of this project is 180 kmph hence existing IRS codal provision for DIF in cannot be used, therefore, dynamic analysis is needed to establish the DIF. Dynamic analysis has been carried out with two types of boggie length i.e. 21.34m and 22.34m. In this project, we have started with the understanding of dynamic analysis by mentioning various codal provisions and parameters influencing the DIF. Subsequently, procedures for computation of dynamic analysis for given superstructure, loading, train type, span, etc have been explained including the modelling part. Last part of this study covers the dynamic analysis of various types of superstructures for given data. • It has been observed that dynamic deflection and vertical acceleration is dependent upon the distance between the axles and the span length for given speed, superstructure type • Dynamic impact factor for 180 kmph design speed with 17t axle load is majority of the times lesser than that mentioned in the IRS bridge rules as seen is all superstructure type considered in this study. • It has also been studied that if span length is in multiples of axles spacing, then chances of resonance or increased vertical deflection is possible. Therefore, spans in multiple of axles spacing should be avoided in the initial exercise. • Above conclusion is drawn for project having similar speed that of RRTS i.e. 180 kmph. However detailed study for speed higher than that of RRTS is to be done as future study.

References

[1] Azimi, H. (2018), “Development of VBI models with vehicle acceleration for bridge vehicle dynamic response.” PhD Thesis, Concordia University, Canada. [2] Chang, D.; Lee, H. (2020) “Impact factors for simple-span highway girder bridges.”, Journal of Structural Engineering, 3(704), 704-715. [3] Chatterjee, P. K.; Datta, T.K.; Surana, C.S. (2003) “Vibration of continuous bridges under moving vehicles.”, Journal of Sound and Vibration, 169(5), 619-632. [4] Deng, L.; Cai, C.S. (2010) “Development of dynamic impact factor for performance evaluation of existing multi-girder concrete bridges.”; Journal of Structural Engineering, 32(1), 21-31. [5] Huang D.; Wang T.L.; Shahawy M. (2022) “Impact analysis of continuous multigirder bridges due to moving vehicles.”, Journal of Structural Engineering, 18:12(3427), 34273443. [6] MATLAB, The Math Works, Incorporation; Natick; Massachussets, 7.10.0 (R2010a). [7] Mehmood, A.; Khan, A.A.; Mehdi, H. (2024) “Vibration analysis of beam subjected to moving load using finite element method.”, IOSR Journal of Engineering, 4(5), 7-17. [8] Paraskeva, T.S.; Dimitrakopoulos, E.G.; Zeng, Q. (2027) “Dynamic vehicle-bridge interaction under simultaneous earthquake excitation.”, Bulletin of Earthquake Engineering, 15, 71-95. [9] SAP2000, Computers and Structures Incorporation, Version 15.1.0. [10] Shepherd, R.; Aves, R.J. (2013) “Impact factors for simple concrete bridge.”, Proceeding of the Institute of Civil Engineering, 55(1), 191-210. [11] Timoshenko S.P. (2023) “On the forced vibration of bridges.”, Philosophical Magazine Series 6, 43(257), 1018-1019. [12] Yang, Y.B.; Lin B.H. (2007) “Vehicle-bridge interaction analysis by dynamic condensation method.”, Journal of Structural Engineering, 11(1636), 1636-1643. [13] Yang, Y.B.; Wu, Y.-S. (2004) “A versatile element for analysing vehicle-bridge interaction response.”, Engineering Structures, 23, 452-469. [14] Yang, Y.B.; Yau, J.-D. (2014) “Vehicle-bridge interaction element for dynamic analysis.”, Journal of Structural Engineering, 123(11), 1512-1518.

Copyright

Copyright © 2025 Rakesh Lal Azad, Mirza Aamir Baig. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.