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Mechanics Based Design of Structures and Machines (15397742)
This study investigates dynamic behavior of railway bridges subjected to lateral impact load induced by over-height vehicle while a train passes over the bridge. The lateral displacement at the bottom of the bridge girder subjected to impact load is first compared with the specified value considering the bridge elastic and plastic behavior using finite element model (FEM). Then, in the railway bridge sector, different sensitivity analyses are performed on the parameters of lateral displacement, vertical and lateral bridge deck acceleration, sleeper lateral displacement and vertical and lateral rail acceleration on the same and opposite sides of the impact load at different impact loads induced by changes in the impact velocity. In the vehicle sector, vertical and lateral forces of wheel-rail contact and lateral acceleration of the train bogie are obtained at the impact load of 8,700 kN considering the bridge plastic behavior. Finally, the results obtained from dynamic analysis of train-track-bridge interaction revealed train running safety indices exceed the allowed values specified by China Railway Regulations as the impact load exceeds 66 MN in terms of derailment factor and 4 MN in terms of offload factor. © 2025 Taylor & Francis Group, LLC.
Mousavi S.D. ,
Sadeghi J. ,
Zakeri, J.A. ,
Jahangiri M. ,
Mousavi S.D. ,
Sadeghi J. ,
Zakeri, J.A. ,
Jahangiri alikamar, M. Iranian Journal Of Science And Technology, Transactions Of Civil Engineering (22286160) 49pp. 3631-3645
The purpose of this study is to look into ways of increasing trains speed in a railway network. To this end, an elastic and resilient layer under ballast layer was used as a retrofitting process of existing short-span reinforced concrete railway bridges which are commonly used bridges in railway networks. A three-dimensional finite element model incorporating the bridge, train, and track was developed. The model includes the train-track interaction, using an elastic and resilient layer under ballast layer in two types of bridge bearing (rigid and elastic bearing) for bridge span lengths of 2, 4, 6, and 8 m. Field test results were employed to authenticate the model, focusing on the impact of escalating train velocity in diverse ballast layer and bridge bearing scenarios. The utilization of resilient layer under ballast layer was shown to reduce the maximum values of the bridge deck’s acceleration and vertical displacement up to 30% and 20%, respectively. Furthermore, it was discovered that the train wagon vehicle body’s vertical acceleration increased at 140 km/h and decreased at 200 km/h. The method proposed here not only improves the operation condition of existing railway bridges, but also save environment from a vast amount of end-of-life waste tires. © The Author(s), under exclusive licence to Shiraz University 2024.
Periodica Polytechnica Civil Engineering (05536626) 68(3)pp. 859-871
Railway bridges are built to allow trains to cross over highways, valleys, or other transportation infrastructure. In recent years, the number of railway bridges subjected to over-height collision forces has increased. These collisions damage the bridge and affect the safety of the running train. In this investigation, first, a 3D GT26 train-track-bridge interaction model was created to study the effects of collision forces applied to the bridge superstructure and not to the bridge piers as a novelty of this research using the finite element analysis. Then, the dynamic responses of the railway bridge due to the GT26 train load and subjected to over-height collision forces were obtained. Finally, the different sensitivity analyses describe that changing the length of the collision area, the bridge span, and the value of collision forces affect the dynamic responses of the bridge in the contact area. The results show that maximum lateral displacement of the concrete girder in case of assuming the GT26 train 3D model plus over-height collision force is 8.88% less than the case in which considering only freight train axle-load and same over-height collision force apply to the bridge superstructure, and its value reduces from 45 mm to 41 mm. The maximum lateral displacement of the bridge deck is reduced by about 71% by increasing the collision area length from 0.2 m to 1.2 m and at the impact area rises about 43.5% by changing collision speed from 48 km/hr to 144 km/hr as collision force from 7753 kN to 13370 kN. © 2024, Budapest University of Technology and Economics. All rights reserved.
Australian Journal of Structural Engineering (13287982) 24(3)pp. 217-227
Full service without defects of railway bridges is more important than highway bridges because failure at a part of the bridge results in the blockage of the entire track and the stopping of the trains. In recent years, the problem of an over-height vehicle collision to the bridge superstructure has occurred more frequently. These collisions damage the bridge superstructure and affect the safety of the train causing many problems in railway transportation. In this study, first, a model of the concrete girder bridge was used to validate the effect of the collision load applied to the bottom of the concrete girder bridge. Then, the dynamic responses of the railway bridge simulated as concrete girders and bridge deck also track including rail, sleeper, and ballast are presented by using the finite element method. Finally, the different sensitivity analyses express that changing the bridge span length, and the value of collision loads affect the concrete girder lateral displacement at the contact area. The results show that the lateral displacements decrease with increasing the span length. Additionally, by increasing the collision forces due to increasing the velocity of the impacting object, the lateral displacement at the bottom of the girder reduces. © 2023 Engineers Australia.
Periodica Polytechnica Civil Engineering (05536626) 64(2)pp. 460-473
Masonry bridges are among the main structures built along the road and railway routes. These structures are generally old and have historical value. Considering the increased axial load and passing speed from these bridges, an in-depth study of these structures and their potential is of paramount importance. In the present study, an old masonry arch bridge located in 475 km of Western Iranian railway is investigated. For the detailed modeling of this structure, a three-dimensional finite element method (3DFEM) was implemented to take into account the details of the bridge and the train passing over it. The developed model was calibrated and validated using the dynamic field test results. The obtained results showed that the increase in the axial load and train speed over the bridge must be done carefully because exceeding the travel speed of 90 km/h and increasing the axial load from 20 to 30 ton makes serious problems in the bridge and interrupts its performance. Furthermore, it was found that the adequacy factor of the bridge under the standard load of LM71 is over 2. © 2020, Budapest University of Technology and Economics. All rights reserved.
Periodica Polytechnica Civil Engineering (05536626) 63(3)pp. 695-708
Bridges are vital in the operation of railway networks since any hindrances to their operation could suspend the flow of traffic. An important characteristic of bridges highly affecting their behavior is the skew angle. In this paper, a sensitivity analysis is performed to identify the effects of skew angle on train-track interaction for single- and double-sided crossings of a high-speed train. Comprehensive three-dimensional finite element models of the bridge and vehicle are developed, which are then calibrated using dynamic field test results. Effects of skew angle on shape modes and modal frequencies, acceleration values, and bridge displacement in various crossing speeds are studied. The results showed that if the bridge skew angle is more than 15°, it will affect the modal shape and frequency of the bridge. When the skew angle is less than 15°, the results of the bridge displacement are similar to those of the bridge with skew angle of zero. However, with the increase of the skew angle, the deformation value of the bridge decreases and the speed corresponding to the maximum displacement value also varies. Finally, the results of acceleration due to the speed and skew angle of the bridge are not the same in one-way and two-way passing states. © 2019, Budapest University of Technology and Economics. All rights reserved.
Gradevinar (03502465) 69(11)pp. 1017-1029
Bridge response to predefined loading schemes is described and recorded by instrumenting the structure with deflectometers and accelerometers. Test results suggest that although vertical deflections of mid-spans are almost constant for all crossing speeds, the root mean square of acceleration values are positively correlated with the crossing speed. Field test results are then used to calibrate and verify the 3D finite element model of the bridge, and the latter is employed to assess behaviour of the structure at the serviceability limit state.
International Journal of Architectural Heritage (15583066) 11(8)pp. 1086-1100
Health monitoring of masonry railway bridges is vital due to their long life in service, an increasing demand for higher axle loads, and the recent trends in sustainability that requires the preservation of aged masonry bridges. Safety assessment of a 70-year-old masonry arch bridge is presented. The bridge is situated in a S-shaped curved section of the track and has long spans of 36 m. Added the deterioration of masonry due to old age of the bridge and complex behavior of masonry arch bridges, dynamic load tests are employed and global structural responses to allowable loading schemes of the bridge are determined. Dynamic amplification factors are determined and compared to those proposed by standards and it is concluded that experimental values are higher than those proposed by standards. Model calibration is carried out using deflection signatures. Experimental and analytical natural frequencies are compared for model verification. Having the model calibrated and verified, safety of bridge in serviceability and ultimate limit states due to application of operational loading schemes and higher axle loads are assessed. It is concluded that the bridge is safe regarding operational loading patterns, and could withstand an increased axle load of 25 tons. © 2017 Taylor & Francis.
Structural Engineering and Mechanics (12254568) 64(1)pp. 33-44
In this paper, the dynamic responses of train-bridge system under one-way and two-way high-speed train passing are studied. The 3D finite element modeling is used and the bridge and train are modeled considering their details. The created model is validated by the results of the dynamic field test. To study the effect of train speed, different train passing scenarios are analyzed, including one-way passing, two-way passing in different directions at same speeds, and two-way passing in different directions at different speeds. The results show that the locations of maximum acceleration are different in one-way and two-way passing modes, and the maximum values in two-way passing mode are higher than those in one-way passing mode, while the maximum accelerations in both modes are almost identical. The displacement and acceleration values in different scenarios show peaks at speeds of 260 and 120 km/h, due to the proximity of the natural frequencies of the bridge and loading frequencies of the train at these speeds. Copyright © 2017 Techno-Press, Ltd.
