Search

The rapid development of high-speed railway bridges in China has brought enormous challenges to the ballast bed stability on the bridge. With the increase in the bridge span, the bridge deformation under the temperature load increases gradually, as well as the stability difference of ballast bed between different regions. Moreover, the track vibration response under high-speed driving conditions is larger, which can easily cause differential settlement, flying ballast, and deterioration of the ballast bed, thereby affecting the bearing capacity and stability of the ballast bed. In view of this, this article summarizes relevant research work on a ballast bed on the bridge from the perspectives of the resistance, deformation, and acceleration response of the ballast bed. In addition, this study discusses the existing measures for improving the ballast bed stability on the bridge, including the optimization of the sleeper and ballast bed structures. Finally, the main issues that need to be addressed to improve the ballast bed stability on the bridge are pointed out, and ideas for future research on ballast beds on bridges with different spans and structures are proposed. [ABSTRACT FROM AUTHOR]

In order to study the influence law of rockfall on the train running safety of railway bridges, a simply supported box girder bridge on a railway in western mountainous area was taken as the research object. A rockfall impact simulation model and a vehicle-track-bridge coupling dynamic analysis model, which fully considered material nonlinearity and contact nonlinearity, were established. The characteristics of rockfall impact force on bridge piers were clarified, and the train running safety on the bridge under rockfall impact was analyzed. The influence of rockfall impact speed, angle, height, and rockfall diameter on running safety was also revealed. The results showed that: (1) The peak impact force value of rockfall increased with the speed and diameter of the rockfall, while the impact height and angle had little effect on the peak impact force. (2) The increase in rockfall diameter enlarged the damage range of the pier structure, characterized by the appearance of multiple impact force peaks and an extended impact force time history. (3) The faster the rockfall impact speed and the greater the impact energy, the more significant the threat to train running safety on the bridge. The closer the rockfall impact height was to the top of the pier and the larger the diameter of the falling rock, the greater the lateral dynamic response of the train, posing a higher threat to train safety on the bridge. (4) The variation patterns of the time-history curves of each safety evaluation index of the train under different working conditions were similar across different impact angles of rockfall, with minimal changes in their impact on train safety. (5)The wheel load reduction rate was highly sensitive to rockfall diameter and impact height. The wheel load reduction rate exceeded the standard limit when the rockfall diameter reached 2. 5 meters. The research results will provide a reference for the whole life cycle design and safe operation and maintenance of railway bridges in western mountainous area. [ABSTRACT FROM AUTHOR]

In order to evaluate the post-earthquake condition of railway bridges, this study develops a method for evaluating the traffic function of railway bridges based on vulnerability. Taking common railway bridges in China as references, 20 four-span simply-supported beam bridges with varying structural parameters were modeled in OpenSees for full-bridge finite element analysis. Seismic timehistory analysis was employed to evaluate both the vulnerability and traffic function of the bridges, clarifying the key factors influencing seismic damage and traffic function. The findings indicated that the longitudinal reinforcement ratio and shear span-to-depth ratio were the core factors affecting seismic damage, with the axial compression ratio also playing a significant role, while the volumetric stirrup ratio served as a secondary factor. To control seismic damage of the bridges, increasing the longitudinal reinforcement ratio and reducing the shear span-to-depth ratio were recommended. A higher reinforcement ratio significantly enhanced traffic capacity, while an increased shear span-to-depth ratio reduced it. Additionally, slight improvements in traffic capacity were observed with increases in the reinforcement ratio and axial compression ratio. The longitudinal reinforcement ratio and shear span-to-depth ratio were the main factors affecting the traffic function of the bridges, while the volumetric stirrup ratio and axial compression ratio were secondary. To ensure optimal traffic capacity, the longitudinal reinforcement ratio should be appropriately increased or the pier shear span-to-depth ratio be reduced, with modest increases in the volumetric stirrup ratio and axial compression ratio. The traffic capacity evaluation method proposed in this study provides an effective tool for assessing bridge functionality and is suitable for post-earthquake assessments. [ABSTRACT FROM AUTHOR]

A railway bridge is located in a high-intensity seismic zone near a fault, with asymmetric deep-cut valleys. To determine the optimal bridge design, three types of bridge structures were proposed, taking into account climatic, topographical, geological conditions, and other relevant factors. The proposed schemes included a (95+160+95+59) m prestressed concrete continuous rigid-frame bridge, a (60+200+106+50) m partial cable-stayed bridge and a (253+145) m continuous steel truss flexible arch. Each scheme's structural dimensions and construction methods were introduced in detail. Finite element analysis models for the bridges were established using BSAS and Midas Civil software, and analyses were conducted on the main beams, pylons, piers, pile foundations and dynamic characteristics. Comparisons of the three schemes were performed based on structural stiffness, construction difficulty, construction period, seismic performance, maintenance requirements and engineering cost. The results showed that: (1) Under static load, the continuous rigid-frame bridge exhibited a vertical displacement of 38 mm, with a span-to-deflection ratio of 1/4 210; the partial cable-stayed bridge had a vertical displacement of 135. 4 mm, with a span-to-deflection ratio of 1/1 477; and the continuous steel truss flexible arch showed a vertical displacement of 78 mm, with a span-to-deflection ratio of 1/3 231. (2) The first-order period of the continuous rigid-frame bridge was 2. 02 s; the partial cable-stayed bridge was 2. 4 s; and the steel truss flexible arch was 2. 58 s. (3) All three bridge schemes met the design specifications and were proven to be safe and feasible, but the continuous rigid-frame bridge was significantly more cost-effective than the other two options. ( 4) Prestressed concrete continuous rigid-frame bridge, with its large stiffness, mature construction technology, superior seismic performance, low engineering cost and minimal maintenance requirements, was considered the optimal scheme. [ABSTRACT FROM AUTHOR]

The effective monitoring of railway facilities is crucial for safety and operational efficiency. This study proposes an enhanced remote monitoring technique for railway facilities, specifically bridges, using satellite radar InSAR (Interferometric Synthetic Aperture Radar) technology. Previous studies faced limitations such as insufficient data points and challenges with topographical and structural variations. Our approach addresses these issues by analysing displacements from 30 images captured by the X-band SAR satellite, TerraSAR-X, over two years. We tested each InSAR parameter to develop an optimal set of parameters, applying the technique to a post-tensioned PSC (pre-stressed concrete) box bridge. Our findings revealed a recurring arch-shaped elevation along the bridge, attributed to temporal changes and long-term deformation. Further analysis showed a strong correlation between this deformation pattern and average surrounding temperature. This indicates that our technique can effectively identify micro-displacements due to temperature changes and structural deformation. Thus, the technique provides a theoretical foundation for improved SAR monitoring of large-scale social overhead capital (SOC) facilities, ensuring efficient maintenance and management. [ABSTRACT FROM AUTHOR]

The restrainers in the friction pendulum system (FPS) may experience brittle failure during an earthquake. Strong nonlinear behavior should be considered to precisely assess the seismic performance of the railway beam bridge under an earthquake. A seismic vulnerability assessment was performed based on a typical simply supported railway beam bridge. Three different models of the FPS in fixed direction were considered: elastic restrainer model, brittle restrainer model, and nonrestrainer model. Through dynamic analysis, the responses of the railway beam bridge were obtained, including the force and displacement of the FPSs, the curvature ductility at the pier bottom, and transverse dislocation at the beam gap. The analysis results pointed out when the earthquake intensity exceeded the fundamental intensity, the brittle failure of the restrainers was very likely to happen. The sudden release of energy introduced a displacement pulse to the FPS. The elastic restrainer model overestimated the force demand and damage probability of the substructures but underestimated the FPS displacement and dislocation at the beam gap. The nonrestrainer model seriously underestimated the force demand of the substructure and the FPS displacement under strong earthquakes. The brittle restrainer model could reflect the nonuniform failure of the restrainers and provide a more accurate estimate of the transverse dislocation at the beam gap. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The construction of a new double‐track steel railway arch bridge over the Elbe river, which replaced the original single‐track bridge from 1966, has significantly increased the capacity, speed, and smoothness of railway traffic in Pardubice. This 140‐meter‐long, three‐span bridge was realized as part of the modernization and double‐tracking of the Pardubice ‐ Hradec Králové line between 2021‐2024. Its construction, coupled with the provisional use of the original bridge, represents a remarkable engineering feat [ABSTRACT FROM AUTHOR]

An increasing number of arch and suspension bridges have been built in railway networks. Suspender cables serve as the critical load-transmitting component in these cable-supported bridges, which are subjected to a combination of the adverse impacts of train-induced fatigue stress and a corrosive environment. However, little research effort has been made on the corrosion fatigue performance of railway bridge suspender cables. This paper proposes an approach for the corrosion fatigue evaluation of the suspenders that integrates a sophisticated fatigue stress computational model and an enhanced corrosion fatigue model. The dynamic stresses of the suspenders are computed using a three-dimensional (3D) train–bridge interaction (TBI) model, which is established to consider the train-induced flexural vibrations on the suspender. Then, the corrosion fatigue damage of steel wires is characterized by a continuum damage mechanics-based model. The condition for the transition from pitting to fatigue crack is derived. Based on this, the corrosion fatigue assessment framework for suspenders is formulated, which can describe the time-dependent damage evolution that considers significant effects. A tied-arch railway bridge is investigated to showcase the effectiveness of the proposed approach and gain insights into the corrosion fatigue performance of the suspender cables in railway bridges. The field test data are employed to validate the stress computational model. In addition, the time-dependent corrosion fatigue evolution and service life of the suspenders are obtained. The results show that the suspender flexural vibrations cause considerable variations in the equivalent stress range and number of stress cycles. The corrosion fatigue life (CFL) of the critical suspender is reduced by 25% on average due to train-induced flexural vibrations. [ABSTRACT FROM AUTHOR]

The interest on the dynamic behavior of railway bridges has grown in recent years due to the emergence of high-speed trains that induce a significant dynamic effect. A correct understanding of the dynamic behavior of a railway bridge is essential, as an accurate prediction of the structure’s response contributes to cost-effective design for new bridges and rational operation of existing ones.

Abstract In this work, we studied the near-surface flow field structure of railway bridges with different heights through field investigation and wind tunnel simulation experiments. Meanwhile, we simulated the distribution of sand accumulation around a bridge via CFD software based on the sand accumulation around the Basuoqu bridge in the Cuona Lake section of the Qinghai–Tibet Railway. Results show that the sand around this railway bridge is mainly from the lake sediment on the west side of the railway and the weathered detritus on the east side. The height of the railway bridge in the sandy area affects the distribution of the near-surface flow field and the variation in speed on both sides of the bridge. The wind speed trough on both sides of the 6 m high bridge is higher, and the horizontal distance between the wind speed trough and the bridge section is 1.5 times that of the 3 m high bridge. Wind speed attenuates in a certain range on the windward and leeward sides of the bridge, forming an aeolian area; under the beam body, it is affected by the narrow tube effect, forming a wind erosion area. The height of the bridge determines its sand transport capacity. Under certain wind conditions, the overhead area at the bottom of the 3 m high bridge and its two sides do not have the sand transport capacity, so sand accumulates easily. Nevertheless, the sand accumulation phenomenon gradually disappears with the increase in bridge clearance height. The objectives of this study are to reveal the formation mechanism of sand damage for railway bridges, provide theoretical support for the scientific design of railway bridges in sandy areas, and formulate reasonable railway sand prevention measures to ensure the safety of railway running, which have certain theoretical significance and practical value.

Abstract In the conceptual design stage of railway bridge, the beam type of the bridge at the main control point must be modified repeatedly to satisfy varying requirements. Thus, the demand for design efficiency is high. However, railway bridge design relies heavily on professional knowledge and experience and is typically completed manually by senior designers, thereby requiring considerable time. An intelligent beam type recommendation algorithm named AutoDis Graph Ontology Attention Matching (AGOAM) is proposed to rapidly generate bridge design plans for railway route main control points. This method acquires the node embeddings of the main control point and beam type attribute graphs through graph neural networks (GNNs) and predicts the score of each beam type through graph matching technology. The beam type with the highest prediction score is recommended. In addition, the accuracy of the recommendation results is improved through ontology-enhanced attribute interaction and attention mechanism-based graph pooling. The efficiency of the proposed method is demonstrated with a real-world railway bridge design dataset, and ablation study is conducted to evaluate the effectiveness of the ontology-enhanced attribute interaction and attention mechanism-based graph pooling.

The coastal salt pan of Shijiazhuang-Hengshui-Cangzhou-Huanghua Port Intercity Railway project is a highly corrosive environment. In order to ensure the long-term operation safety of the bridge structure, it is urgent to carry out relevant durability research and improve the durability of the bridge structure in this project. Through detailed investigation and analysis of the erosive environmental characteristics of the bridge engineering in this region, the exposed environment of the bridge structure is evaluated, durability design of the bridge concrete structure is carried out, and the following research results are presented. In view of the corrosive environment problems faced by railway engineering, the principle of overall design scheme is proposed. The mix ratio design of bridge pier pile-cap and castin- place pile in coastal corrosive environment is conducted, and the preparation technology of high durability concrete suitable for coastal salt pan corrosive environment is formed. The structural design of durability is studied, structural design principle and physical isolation design concept are proposed, the structural design control measures are proposed to improve durability, and the structural physical isolation measures are designed to effectively improve the durability of bridge structure. In view of the erosion characteristics of the project, additional strengthened protection measures are put forward, including the silane impregnation protection and the application of corrosion resistant reinforcement. The permeable formwork cloth is studied and applied to improve the construction quality and compaction of concrete. An exposure test station is set up in the engineering site and a wireless monitoring system for reinforced concrete durability is developed. The whole process of reinforcement corrosion monitoring is realized through the wireless monitoring system. Through the durability design and research of concrete structure of bridge in the coastal environment with strong corrosion, the purpose of improving the durability of railway concrete structure under the harsh service condition of coastal salt pan has been achieved. At the same time, The solid foundation has been laid for the later evaluation of the durability of the bridge structure during the service period. [ABSTRACT FROM AUTHOR]

In order to study the dynamic response of high-speed railway bridge under flood, a two-span high-speed railway simple-supported beam bridge with unequal 32-meter pier height is studied. A three-dimensional hydrodynamic model of the substructure and a finite element model of the bridge under flooding are built up to analyze the law of flow field distribution around and the hydrodynamic pressure. The influences of the change of velocity and height of flood and the foundation scour depth on the dynamic response of bridge and internal force of pile foundation are revealed. The study shows that: (1) The law of flow field distribution is basically the same when the bridge substructure is impacted by the flood with different velocities; (2) When the flood velocity exceeds 3 meters per second, the influence of the hydrodynamic pressure on the substructure cannot be ignored, and the pressure is positively correlated with velocity and height of the flood; (3) The depth of foundation scour has a significant influence on the hydrodynamic pressure. But when the depth of foundation scour is increased after the bearing platform is exposed, the increase of the pressure is not obvious; (4) When the bridge is impacted by the flood, the overall law of the dynamic response of the bridge with time is basically the same. The response is as follows: When t = 1.06 s, the lateral vibration acceleration of pier top reaches the peak value; When t = 1.16 s, the lateral displacement of pier top reaches the peak value. After the lateral displacement and vibration acceleration reach their peak values, they both tend to attenuate decay rapidly and periodically. With the velocity and height of flood increasing, the peak values and final stable values of displacement and acceleration at prier top as well as the pile bending moment increase; (5) With the increase of foundation scour depth, both the dynamic response and the pile bending moment increase, but the negative bending moment area of pile foundation is more sensitive to the impact of foundation scour depth. [ABSTRACT FROM AUTHOR]

During the long-term operation of high-speed railway in our country, affected by various factors such as surrounding environment changes and human engineering activities, large lateral deviation occurs in some line bridge sections, which seriously affects the normal and safe operation of the train and needs to be rectified urgently. Based on the analysis of the principle of bridge rectification by high pressure jet grouting, the theoretical calculation model of bridge rectification is established, and the differential equations of pile deflection, rotation angle, bending moment and shear force under the high pressure jet grouting rectification mode and the analytical formula of pier top displacement are deduced based on the elastic foundation beam theory. Then,by comparing the calculated displacement at the top of the pier with the actual offset of the line,the feasibility of high pressure jet grouting technology for bridge rectification is analyzed, and the rectification effect is verified by typical engineering cases on site. Research shows that the top displacement of pier is related to foundation coefficient and excess pore water pressure generated by high pressure jet grouting; when foundation coefficient and excess pore water pressure take 1 MPa/ m and 80.3 kPa respectively,the top theoretical calculated displacement of pier is 81.8 mm,which is much larger than the actual deviation of ballastless track line of common high speed railway;In the bridge rectification project of a high speed railway Songjiang Grand Bridge,the displacement at the top of the pier calculated by the average value of the measured excess pore water pressure 30.4 kPa 6. 4~31. 0 mm,which is also greater than the maximum deviation 18.2 mm of the line, indicating that the high pressure jet grouting technology is feasible for bridge rectification theoretically;After rectification construction,the bridge and track structure are stable,the line alignment is smooth,and there is no abnormality in the normal speed operation for many years. The theory and practice have proved that the high pressure jet grouting method is a practical and feasible technical measure for bridge rectification. [ABSTRACT FROM AUTHOR]

In railway tracks, additional stresses occur in rails due to interaction between the rail and the bridge superstructure, which is a phenomenon known as track–bridge interaction (TBI). The additional rail stresses (ARSs) develop primarily as a result of temperature effect, vertical bending of bridge superstructure, and braking/acceleration of trains traveling over the bridge. One of the major parameters affecting the TBI response is the behavior of interface elements simulating the coupling between the bridge superstructure and the rail. In TBI analysis this coupling is defined by the so-called longitudinal resistance-displacement curves (RDCs). The present study deals with the longitudinal aspect of TBI though a numerical investigation. The numerical modeling approach was verified with available analytical solutions and data obtained from bridge monitoring. The primary interest was to illustrate how sensitive the TBI response is to changes in RDCs with both separate and sequential analysis approaches, which has not been investigated thoroughly earlier. The parametric study was extended to investigate the effects of expansion length and substructure stiffness, in addition to RDC type. For simply supported precast girder bridges, RDCs that are experimentally proven specific to ballastless railway bridges can be used as an economic alternative to those specified by provisions. [ABSTRACT FROM AUTHOR]

The dynamic response of a railway bridge depends on several parameters; the primary parameter is the fundamental natural frequency of vibration of the bridge itself. It is considered a critical parameter of the bridge as the driving or the forcing frequencies arising from moving trains may coincide with the fundamental frequency of the bridge and initiate a resonant response amplifying the bridge load effects. This condition may adversely affect the stresses experienced on bridge members and, consequently, the remaining fatigue life of the structure. Because the train adds additional time-varying mass to the bridge, this introduces a time-varying change in the bridge's fundamental natural frequency of vibration. As a result, train critical speeds will have a certain range depending on the train configuration. This article presents a simplified method using a power-law relationship to predict the frequency characteristics of a bridge as a function of the train-to-bridge mass ratio. The method is presented in a generalized form, which enables the frequency characteristics to be determined for any given combination of trains and simply supported bridges of short to medium span typically found on the UK rail network. The method is then demonstrated in a case study of a single-span, simply supported plate girder bridge. By considering the BS-5400 train traffic types, the proposed method is used to calculate bridge frequency effects, dynamic amplification, and train critical speed bandwidth for each train type. The simplicity of the proposed method, as it does not require any complex computational modeling, makes it an ideal and effective tool for the practicing engineer to carry out a quick and economical assessment of a bridge for any given train configuration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the limitations of traditional bridge swivel construction attitude adjustment by relying on experience and trial and error, the potential advantages of the calculation model in attitude adjustment were analyzed, as well as the application prospects in improving construction efficiency and saving construction period, etc., a calculation model suitable for attitude adjustment of bridge swivel construction was proposed. Considering the actual constraints in bridge swivel construction and combining with the existing construction experience, the technical process of attitude adjustment was optimized to realize the optimization of attitude adjustment. The effectiveness and feasibility of the proposed optimization method have been verified through its application in the continuous beam swivel construction project of the Tianjin main canal of South-to-North Water Diversion Project. The practice proves that the optimization method can improve the construction efficiency while meeting the specification requirements. The successful application of the attitude adjustment optimization based on the calculation model in the swivel construction of bridge promotes the development of the field of attitude adjustment in the swivel construction, reduces unnecessary waste of resources, provides reference for optimization problems in other engineering fields, and provides strong support for the promotion of the calculation model and specific construction technology in the field of swivel engineering. [ABSTRACT FROM AUTHOR]

Partial cable-stayed bridges have the advantages of high rigidity, good economy and convenient construction. In recent years, they have been widely used in high-speed railway, but most of them are two-tower structures. In this paper, based on the main bridge of Ji'nan Yellow River Bridge on Zhengzhou-Ji'nan Railway, the structural system, side-to-middle span ratio and key parameters of beam-tower-cable are analyzed and studied for the long-span, five-tower, four-span and large-span partial cable-stayed bridge on high-speed railway. Through comprehensive comparison and study, the structure system of tower pier consolidation is selected for the Yellow River Bridge, which has the advantages of partial release of temperature force, bridge stiffness and track surface irregularity index to meet the requirements of ballastless track on high-speed railway. Vibration-reducing and isolation measures can be adopted for beam section, effectively reducing seismic force and improving overall economy of bridge. The main bridge uses a smaller ratio of mid-span at the edge to meet the requirement of no auxiliary span for flood control, and can effectively reduce the corner at the end of the beam, avoiding the increase of the investment of the whole bridge due to the use of large girder height. When the height of the tower is 38 m, the increase of the height of the tower can significantly reduce the internal force of the beam, but the deformation under temperature load will increase accordingly. Therefore, the selection of the height of the tower should take into account the structural forces and the requirements of track irregularity. AT - 61 cable is used. Increasing cable size has little effect on bridge rigidity, but it can significantly reduce beam bending moment, but increase beam irregularity and residual creep deformation. [ABSTRACT FROM AUTHOR]

The completed bridge alignment of super long-span railway bridges is prone to large deviation from the design alignment, which leads to the unrealization of the original rail surface design alignment, and it is usually necessary to change the rail surface alignment on the basis of the completed bridge alignment. In order to ensure that the changed rail surface alignment meets the requirements of train operation performance, it is particularly important to reasonably evaluate the completed bridge alignment of long-span railway bridges before laying the track. In this paper, the characteristics of the measured completed bridge alignment of a long-span railway bridge in China are analyzed. Combined with the adjustable capacity of ballast bed on the bridge, an evaluation method of completed bridge alignment of long-span railway bridges based on riding quality is proposed, and the amplitude of completed bridge alignment within the sensitive wavelength range of the vehicle body is taken as the evaluation index. Firstly, according to the evaluation principle that the vertical acceleration of vehicle body caused by line random irregularity, additional deformation of bridge under external loads and rail surface alignment does not exceed level I management standard, the maximum acceleration caused by rail surface alignment within the sensitive wavelength range of vehicle body is determined. Then the correlation between vertical acceleration of vehicle body and chord measurement amplitude, and the correlation between chord measurement amplitude and linear amplitude are studied to determine the maximum amplitude of rail surface alignment within the sensitive wavelength range of vehicle body. Finally, by deducing the correspondence between rail surface alignment amplitude and completed bridge alignment amplitude within the sensitive wavelength range of the vehicle body, the limit value of the evaluation index is formulated. Taking a kilometer-level suspension bridge in China as an example, the limit value of the evaluation index is determined to be 58 mm according to the method of this paper. The maximum value of the measured completed bridge alignment within the sensitive wavelength range of the vehicle body of this bridge is 36 mm, which does not exceed the limit value, indicating that the control effect of the completed bridge alignment is good, and on the premise of meeting the requirements of ballast bed thickness, the rail surface alignment which meets the riding quality can be laid on the basis of the completed bridge alignment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Civil Engineering & Architecture is the property of Journal of Beijing University of Civil Engineering & Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The railway bridge in Prague under Vyšehrad is a steel riveted structure with a lower deck from 1901 connecting the right and left banks of the Vltava River. The bridge is double‐track and is located on a national track included in the TEN‐T system. This is the transit corridor Nuremberg – Pilsen – Prague – Brno – (Vienna, Bratislava, Poland). It is therefore one of the busiest railway bridges in the Czech Republic. The bridge is a cultural monument. At the moment, it is also the best‐known and most discussed railway bridge in the Czech Republic. The bridge has been in service for more than 120 years and its expected lifespan has long been exceeded. The railway needs to increase the track capacity. At the same time, it is being discussed what to do with the heritage‐protected bridge. Repair? Replace? Shift? These are the questions and challenges facing the Railway Administration. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the change of the inclination angle of the main truss has a great influence on the aerodynamic characteristics of inverted trapezoidal steel trusses，taking a public-rail continuous steel truss as an example, the effect of main truss inclination on the aerodynamic characteristics of inverted trapezoidal steel truss was investigated. A simplified three-dimensional analysis model was established by using computational fluid dynamics (CFD) method for different main truss inclination angles to simulate the wind field of main turss sections with different main truss inclination angles. The differences of static wind aerodynamic coefficient, vortex vibration performance and flow field characteristics of main truss sections with different main truss inclination angles were analyzed. The results show that the lift and moment coefficients are significantly influenced by the change of main truss inclination, the lift coefficient of the steel truss is better when the inclination angle of the main truss is 10°, at this time the steel truss is subjected to smaller vertical wind load, and the moment coefficient of the steel joist is better when the inclination angle of the main truss is 0°, at this time the steel truss is subjected to smaller torsional wind load; the main truss inclination angle has a significant effect on its vortex excitation performance under 0° and 6° wind angle of attack conditions, and the vortex vibration performance is better at the main truss inclination angles of 2.5° and 5°;the deceleration phenomenon of wind velocity inside the steel truss decreases with the increase of main truss inclination, it contributes to internal traffic stabilization; the change of main truss inclination has obvious effect on the distribution of turbulent kinetic energy, the effect of increase of turbulent kinetic energy inside the steel truss decreases with the increase of main truss inclination and the effect of increase of turbulent kinetic energy on the leeward side of the steel truss strengthens. By comprehensively comparing multiple types of aerodynamic properties, the aerodynamic characteristics of steel trusses with main truss inclination angles of 5° are better. The influence of the change of main truss inclination angle on the aerodynamic characteristics and spatial flow field characteristics of inverted trapezoidal steel truss can provide a reference for the subsequent wind-resistant design of steel truss.

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The need for new railway bridges is driven by the growing volume of transportation demands for both passenger and freight traffic on railway networks. In the design of these bridges, the fatigue limit state is a criterion that usually limits the allowable applied load level and thus also the utilization of the high strength of the steel material. Therefore, improving the fatigue performance of welded details by high‐frequency mechanical impact (HFMI) treatment leads to a more efficient design. However, the fatigue performance of HFMI‐treated welds is known to be affected by the mean stress and this needs to be considered in the design of treated welded details in steel bridges. This is rather straightforward if the bridge is subjected to cycles from one type of train but becomes cumbersome when several different sets of trains (e. g. axle loads, axle distances) cross the bridge. In this article, a factor to take the mean stress effect (including self‐weight and traffic load variations) into account is derived from traffic data measured in Sweden. Moreover, the mean stress effect is also predicted using the different fatigue load models in the Eurocode. These models either consist of one‐load patterns such as LM71, SW/0, and SW/2 or are composed of different trains with different combinations. It was found that the mean stress effect is underestimated by the first group of models. On the other hand, the mean stress predicted by the light traffic mix is found to be close to that calculated using real traffic data, while other mixes (standard and heavy) underestimate the mean stress effect. Therefore, a correction factor to account for the mean stress effects in real traffic is derived (called here λHFMI). This factor can be used to correct the design stress range for fatigue verification of HFMI‐treated welded details in railway bridges. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study presents a measuring framework for railway transition zones using a case study on the Swedish line between Boden and Murjek. The final goal is to better understand the vertical dynamics of transition zones using hammer tests, falling weight measurements, and axle box acceleration (ABA) measurements. Frequency response functions (FRFs) from hammer tests indicate two track resonances, for which the FRF magnitudes on the plain track are at least 30% lower than those at the abutment. The falling weight measurements indicate that the track on the bridge has a much higher deflection than the track on the embankment. Two features from ABA signals, the dominant spatial frequency and the scale average wavelet power, show variation along the transition zone. These variations indicate differences in track conditions per location. Finally, the ABA features in the range of 1.05–2.86 m−1 are found to be related to the track resonance in the range of 30–60 Hz. The findings in this paper provide additional support for physically interpreting train-borne measurements for monitoring transition zones. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Technical rehabilitation and strengthening of the Chemnitz viaduct The Chemnitz viaduct, which was built between 1901 and 1909 for a four‐track operation, is being technically refurbished and reinforced for modern use in accordance with the requirements of the historical monument preservation. The two inner tracks will be used for future railway traffic, while the outer bridge structures will accommodate inspection, maintenance and emergency routes as well as technical equipment. The approx. 275 m long and 17.50 m wide bridge structure consists of two arch and ten beam segments. During the technical repair, the inner beam segments were renewed and constructed as a steel‐concrete composite structure. The other structures were repaired, strengthened and supplemented with a reinforced concrete structure above the hump plates. This article begins with an overview of the existing structure and its prospective use. This is followed by explanations of the planning, tendering and execution of the construction work. Subsequently, various measures for technical repair and reinforcement are described. The article concludes with a brief summary of the experience gained with the Chemnitz viaduct in terms of refurbishment and monument protection. [ABSTRACT FROM AUTHOR]

Train configurations give rise to a primary wagon pass forcing frequency and their multiples. When any one of these frequencies coincides with the natural frequency of vibration of the bridge, a resonant response can occur. This condition can amplify the dynamic response of the bridge, leading to increased levels of displacement, stresses and acceleration. Increased stress levels on critical bridge structural elements increases the rate at which fatigue damage accumulates. Increased bridge acceleration levels can affect passenger comfort, noise levels, and can also compromise train safety. For older bridges the effects of fatigue, and being able to predict the remaining life, has become a primary concern for bridge engineers. Better understanding of the sensitivity of fatigue damage to the characteristics of the passing train will lead to more accurate remaining life predictions and can also help to identify optimal train speeds for a given train–bridge configuration. In this paper, a mathematical model which enables the dynamic response of railway bridges to be assessed for different train configurations is presented. The model is based on the well established closed from solution of the Euler–Bernoulli Beam (EBB) model, for a series of moving loads, using the inverse Laplace–Carson transform. In this work the methodology is adapted to allow different train configurations to be easily implemented into the formulation in a generalised form. A generalised equation, which captures the primary wagon pass frequency for any train configuration, is developed and verified by presenting the results of the bridge response in the frequency domain. The model, and the accuracy of the equation for predicting the primary wagon pass frequency, is verified using independently obtained measured field train–bridge response data. The main emphasis of this work is to enable the practicing engineer, railway operators and bridge asset owners, to easily and efficiently make an initial assessment of dynamic amplification, and the optimal train speeds, for a given bridge and train configuration. This is visually presented in this work using a Campbell diagram, which shows dynamic amplification and compares this with those calculated based on the design code, across a range of train speeds. The diagram is able to identify train speeds at which a resonance response can occur, and the wagon pass frequency, or its multiples, which are causing the increased dynamic amplification. The model is implemented in Matlab and demonstrated by analysing a range of short- to medium-single span simply supported plate girder railway bridges, typically found on the UK railway network, using the standard BS-5400 train configurations. The model does not consider the effects of the train mass and suspension system as this would require a non-closed form numerical solution of the problem which is not practical for the purposes of an initial assessment of the train–bridge interaction problem. [ABSTRACT FROM AUTHOR]

In order To reduce the height of railway long span prestressed concrete continuous beams and expand their scope of application, this article proposes a reasonable span ratio and structural dimensions of a low height continuous beam with a main span of 100 m, and the calculation results meet the requirements of the specification. By comparing and analyzing the continuous beam with a main span of 100m in common high-speed railways, the effects of span mix ratio and structural parameters on the structure are systematically studied. The advantages and disadvantages of large span and low height continuous beams and the recommended construction values are summarized. The research results show that: (1) The concrete consumption of low height continuous beams is more economical compared to traditional continuous beams, with a reduction of about 20% per linear meter of concrete consumption with the same span; (2) Due to the decrease in beam height, the main beam stiffness of low height continuous beams has slightly decreased, but the creep camber value has significantly decreased after construction, with a reduction of about 60%; (3) For low height continuous beams with a main span of 100 m, it is recommended that the span length should be between 70 m and 80m, not less than 60 m; (4) The top beam height of a low height continuous beam pier with a main span of 100 m should not be less than 6m, and the recommended value range is 6. 0 m to 6. 5 m. The midspan beam height should not be less than 3. 0 m, and the recommended value range is 3. 0 m to 3. 5 m. [ABSTRACT FROM AUTHOR]

The newly built Wujiang Super Major Bridge on Weng-an-Zunyi Railway leaps over a deep valley between two mountains. The topography at the bridge site is complex and the bridge design is difficult. This thesis describes the conceptual considerations and structural design of the main bridge first, and then carries out the static and dynamic simulation analysis of the bridge by using the space finite element software. Research conclusions: The stiff skeleton deck-arch bridge with a main span of 337 m has the advantages of large rigidity, small creep and less maintenance work. The main arch is designed with small rise-span ratio, taking into account safety, economy, environmental protection and aesthetics. The arch rib is composed of concrete-filled steel tubular skeletons and the encasing nonshrinage C55 concrete, and the internal forces in different components of the arch are improved by means of casing concretet in layers and segments. The composite girder is consisted of two I cross-section steels and concrete slabs, and the steel girder are connected by bombination of bolting and welding, which is convenient for manufacture, transport and construction. The arch abutment is an expanded foundation with ladder-shaped section, and permanent and temporary measures are used in foundation excavation to reduce construction risk. The numerical analysis shows that the rigidity, strength and stability of the bridge structure can meet the requirements of the code and the safety and riding comfort requirements of the mixed passenger-freight line. It can provide some references for other mountain railway bridge design. [ABSTRACT FROM AUTHOR]

Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The dynamic response of a railway bridge depends on several parameters; the primary parameter is the fundamental natural frequency of vibration of the bridge itself. It is considered a critical parameter of the bridge as the driving or the forcing frequencies arising from moving trains may coincide with the fundamental frequency of the bridge and initiate a resonant response amplifying the bridge load effects. This condition may adversely affect the stresses experienced on bridge members and, consequently, the remaining fatigue life of the structure. Because the train adds additional time-varying mass to the bridge, this introduces a time-varying change in the bridge’s fundamental natural frequency of vibration. As a result, train critical speeds will have a certain range depending on the train configuration. This article presents a simplified method using a power-law relationship to predict the frequency characteristics of a bridge as a function of the train-to-bridge mass ratio. The method is presented in a generalized form, which enables the frequency characteristics to be determined for any given combination of trains and simply supported bridges of short to medium span typically found on the UK rail network. The method is then demonstrated in a case study of a single-span, simply supported plate girder bridge. By considering the BS-5400 train traffic types, the proposed method is used to calculate bridge frequency effects, dynamic amplification, and train critical speed bandwidth for each train type. The simplicity of the proposed method, as it does not require any complex computational modeling, makes it an ideal and effective tool for the practicing engineer to carry out a quick and economical assessment of a bridge for any given train configuration.

The arch foot structure of railway prestressed concrete continuous beam arch is complex, and in recent years, problems such as concrete cracking have occurred in the arch foot, which affects the quality of arch foot to a certain extent. In view of this situation, this paper takes a (90+180+90) m railway prestressed concrete continuous beam arch bridge as the research object by means of BIM technology. The optimization is based on the interference of main bearing components such as the vertical prestressing bar, the root support plate and the junction steel plate, the main reinforcement and the three-way prestressed beams, embedded arch rib positioning columns and longitudinal and transverse prestressed beams. The concrete pouring scheme of the foot, the type of steel reinforcement processing, the precise positioning of the component construction, and the concrete pouring vibration are further applied. The results show that a BIM model with construction drawing accuracy can be established by virtue of the advantages of BIM technology visualization and parameterization, which can effectively view the spatial relationship of each component in the arch foot of continuous beam arch, and then carry out detailed design and construction applications. In the aspect of the deepening design of the arch foot, a total of 5 key stress positions are optimized from the structural safety level, and a total of 4 places are optimized from the technical scheme level, which can effectively improve the design quality and safety performance. A total of 4 important key points about quality, efficiency and structural safety have been optimized to better improve the construction level of arch foot. The practical application of the results in projects such as Changjinghuang Railway and Shanshan Railway has effectively promoted the design and construction quality of the arch foot. [ABSTRACT FROM AUTHOR]