Railway Bridge Structures Research Articles

Automatic crack detection method for high-speed railway box girder based on deep learning techniques and inspection robot

Box girders serve as crucial upper-level load-bearing components in high-speed railway simply-supported bridges, requiring sufficient structural rigidity during operation. The occurrence of cracks compromises the overall stiffness of the structure, posing significant safety risks and potentially leading to substantial loss of life and property. Therefore, it is essential to rapidly and accurately detect cracks within the girder structure, particularly in the interior of box girders where access for maintenance by personnel is inconvenient. To address this issue, this paper proposes a robot-based framework for crack detection in high-speed railway box girder, and accurately evaluate the damage status of structures. This comprehensive framework includes an image generation network for generating high-quality crack images, a lightweight object detection algorithm for rapidly identifying crack targets, and a high-precision semantic segmentation algorithm for accurately extracting crack pixels. Comparative analysis with mainstream algorithms validates the superiority of the proposed methods. Moreover, preliminary validation through simulated tests highlights the feasibility of the proposed framework, offering novel method and theoretical support for the intelligent operation and maintenance of high-speed railway bridge structures.

Online Real-Time Monitoring System of A Structural Steel Railway Bridge Using Wireless Smart Sensors

In the transportation network, railway bridges are crucial for the transfer of both passengers and commodities. Railway bridges require continuous monitoring to observe their performance. A structural health monitoring system is one method for assessing the viability of a railway bridge structure. The functioning of railroad bridge structures has been extensively observed using wireless technology. This research aims to implement smart wireless sensors for monitoring the structural health of the railway bridge online in real-time during operation. Many sensor kinds were installed on the railway bridge, including strain gauges, accelerometers, linear variable displacement transducers, and proximity sensors. Geometric modeling and numerical simulation were performed to find critical frame locations on the railway bridge where the instrumentation sensors would be placed. In this study, MONITA® is employed for data acquisition modules. The MONITA® system consists of a combination of hardware and software that functions to retrieve, send, store, and process data. This paper describes the result of the establishment of this method to comprehend the performance of the steel railway bridge structure in real-time via the human-machine interface display dashboard. As a result, the monitoring system can appropriately be used to assess a structural railway bridge in real-time. This study may be helpful to practicing engineers and researchers in future studies of steel railway bridge evaluation. This could be a useful reference for future studies in implementing such systems as the railway bridge early warning system technique in detecting bridge damage.

BEHAVIOR OF A STEEL STRUCTURE RAILWAY BRIDGE UNDER DYNAMIC LOADINGS

Most old steel structure railway bridges in Indonesia have deteriorated throughout their service life since they were constructed almost a century ago. However, those bridges' performance must be maintained to have essential safety issues and live extension of the railway bridge structure. Therefore, inspecting and evaluating those steel railway bridges is necessary to maintain the service requirement. Vertical deformation of the steel railway bridge caused by dynamic loadings needs to be observed. The objective of the study is to assess the old steel railway bridge by evaluating the strength characteristics of the structures against the working forces, particularly the moving, wind, and seismic loads. In order to understand the phenomena impacted by the dynamic loadings, the steel structure railway bridge was instrumented using deformation sensors, strain gages, accelerometers, and passive infrared. The steel railway bridge was analyzed using a 3D finite element model. This study discussed the influence of dynamic loadings on the steel structure railway bridge. This paper elaborates and provides suggestions to solve problems and recommended action in practice for future study. This paper may be useful for researchers and practicing engineers.

UAV 3D Modeling and Application Based on Railroad Bridge Inspection

Unmanned aerial vehicle (UAV) remote sensing technology is vigorously driving the development of digital cities. For experimental objects such as large, protruding, and structurally complex steel truss railway bridge structures, commonly used oblique photography and cross-circular photography techniques can lead to blurring, missing, or lower accuracy of fine texture in the models. Therefore, this paper proposes a real-scene three-dimensional modeling method that combines oblique photography with inclined photography and compares it with oblique photography and cross-circular photography techniques. Experimental results demonstrate that the model generated by combining oblique photography with inclined photography exhibits clearer textures, more complete lines, and higher accuracy, meeting the accuracy requirements of 1:500 topographic map control points. This method plays a beneficial auxiliary role in the inspection of ailments such as steel structure coating corrosion and high-strength bolt loss in steel truss railway arch bridges.

Monitoring displacement, strain, and acceleration of a steel railway bridge

An evaluation of the existing steel railway bridge is necessary to obtain information in supporting policymakers to decide further strategies of the railway bridge maintenance process. The reliability and durability of the existing steel railway bridge were monitored regularly by installing instrumentations on the bridge. The railway bridge characteristics were reviewed by implementing a structural health monitoring system (SHMS). The advantages of the SHMS include an early warning system for the railway bridge structure in order to avoid failures. The objective of this study is to evaluate and monitor conditions of the railway bridge structure. The results of the study explained the vertical deflection of the railway bridge, the stress distribution of the entire truss, and the frequency that happens during loadings. This paper discusses and provides a recommendation to solve problems for users and necessary action in practice. This paper may be used by practicing engineers and researchers.

Development and Application of Linear Variable Differential Transformer (LVDT) Sensors for the Structural Health Monitoring of an Urban Railway Bridge in Vietnam

Measuring the structure's displacement plays a very important role in ensuring the safe operation of railway bridges in general and urban railway bridges in particular. In Vietnam, traditional methods using high-precision mechanical gauges have been used to measure the displacement of railway bridges. However, these methods need a lot of effort in installation and traffic control during implementation. These methods are based on the static principle: The test loads are placed on the bridge structure, and then the structure's displacement is observed. The safety assessment and analysis results are guaranteed by multiplying the dynamic coefficients, leading to some assessments that may not be close to the actual exploitation of the bridge structure. Therefore, the current study presents a new solution for measuring the displacement of railway bridge structures. This method uses Linear Variable Differential Transformer (LVDT) sensors to record the continuous displacement of the structure during the time the train passes over the bridge. Through field measurements combined with a finite element analysis model, the research focuses on developing and applying LVDT sensors in urban railway bridge structure health monitoring. At the same time, the potential of developing this method in Vietnam in the future is evaluated.

Seismic performance of precast hollow concrete bridge double columns with shallow socket connection

In this paper, a precast hollow concrete bridge double column with shallow socket connection (PHCBDCSS) is proposed for reducing the socket depth and achieving rapid construction of high-speed railway bridge structures. To investigate the mechanical properties and reliability of the PHCBDCSS under earthquake excitations, full-scale pier in-situ pseudo-static test and numerical simulation of a practical high speed railway PHCBDCSS are performed. Accordingly, the damage state and damage characteristics of PHCBDCSS are analyzed, and the seismic performance is assessed in terms of strain distribution, hysteresis curve, stiffness degradation and ductility, as well as the sensitivity of spigot and socket connection piers to the stiffness of spliced joints is revealed. The results show that the socket connection of PHCBDCSS can effectively and reliably transfer the applied load, which meets the design requirements. Similar to the cast-in-place integral pier, the failure mode of PHCBDCSS is a typical plastic hinge bending failure. Moreover, PHCBDCSS and cast-in-place integral pier have good plastic deformation capacity, bearing capacity and member ductility. The key points of the pier hysteresis curve obtained from fiber element simulation are in accordance with the test results. When the ratio of connection joints' stiffness to pier columns' stiffness exceeds 10, the mechanical properties of the socket connection pier and the cast-in-place integral pier are similar.

Numerical Simulation Study on the Applicability of Lightweight Foamed Soil Backfill of Railway Bridge Structure under Train and Seismic Impacts

The sudden bump at the transition area from the bridge usually cultivates to vigorous railway deterioration because of the variation in the railway's supporting foundation. Therefore, this study focuses on the development of an advanced lightweight backfill material that can resolve the serious settlement in the transition zone. Besides, due to the strict soil properties requirements for construction, some excavated local soils are not preferred. This issue leads to the expansion in the construction budgets and the consumption of natural resources. In this research, the usage of excavated locally silty soil can mitigate this issue. To improve the self-leveling of fresh material and further broaden the range of applications, the air-foam technique is integrated into this material with a ratio of 10% by volume. The resilient modulus test was conducted to investigate the engineering characteristic of the backfill mixture. The reinforcing effect of the lightweight backfill was then evaluated through the numerical simulation method under repeated trainloads and earthquakes. Overall, the laboratory and the simulation results suggest a potential application of lightweight soil as a sustainable material since this material can substantially enhance the durability of the railway structure and provide smoothness for train operation.

Braithwaite – in search of a sustainable turnaround

Learning outcomes The learning outcomes of this study are as follows: ■ understand organizational turnaround and its sustainability;■ applying the understanding of turnarounds to distinguish between operational and strategic levers of a turnaround strategy; ■ analyze and evaluate past and present turnarounds from a sustainability perspective; and ■ formulate managerial actions to make turnaround sustainable. Case overview/synopsis Braithwaite Company Ltd. (Braithwaite) was a specialized engineering firm headquartered in Kolkatta, India. It primarily undertook structural steel fabrication to make railway wagons and bridge structures. It was incorporated as a private enterprise almost a century back. However, since its nationalization five decades ago, it has been operating as a public sector undertaking (PSU) under the aegis of Indian Railways, a department of the Government of India. The case documents the past three decades of the firm’s journey, during which it experienced three episodic turnarounds. Details of the first two turnarounds are presented as the background, in light of which sustainability of the third turnaround is to be examined. The case explores the sustainability of organizational turnarounds from the perspective of the current Chairman and Managing Director (CMD), the case protagonist. Braithwaite underwent financial and operational distress in 1992, 2005 and 2015 and negotiated them under different leaders. These leaders from diverse backgrounds used distinct tactics and strategies to bring about organizational turnarounds. The case provides data and information to assess the sustainability of the third turnaround. Hence, it allows a class to explore the paradoxical observation that while “turnaround” inherently implies sustenance of good performance over time, turnaround sustainability is not spontaneous in the real world. The case deals with the performance issues of PSUs, which make significant contributions to the national economy in the case of emerging economies (for example, 5%–8% of the Indian National gross domestic product is contributed by PSUs; https://swarajyamag.com/ideas/psus-are-crucial-for-indias-growth-but-only-if-they-play-a-strategic-role). Under government ownership and management, the poor performance of PSUs is often attributed to bad decision-making by its top management. In contrast, Braithwaite’s top management’s sound contextual decision-making resulted in a jump in its performance during each turnaround phase, but unsound fundamentals resulted in the unsustainability of the turnarounds. Hence, the case enables an exploration of the unique challenges faced by PSU that emanate from legacy roles, monopolistic markets and dual purpose – the concurrent pursuit of profits and social welfare. Consequently, the case allows an examination of the reasons for the distress of PSUs and the viability of turnaround strategies in the context of the broader Business–Government–Society landscape in emerging economies. Complexity academic level The case is written for use in the MBA elective course covering “Strategic Revival and Turnaround Strategies.” It can be used at the beginning of the course to identify reasons for organizational failure/distress or in the later part of the course to discuss the implementation of operational and strategic turnaround strategies. Supplementary materials Teaching notes are available for educators only. Subject code CSS 10: Public Sector Management.

A simplified method to assess vehicle–bridge interaction for train-induced vibration of light-weight railway bridges

ABSTRACT Moving constant load (MCL) models, which neglect dynamic effects of moving vehicles, are widely adopted for train-induced vibration analysis of railway bridges in current high-speed rail codes, such as Eurocode or UIC code, for simplicity in modeling trainloads to carry out response analysis of bridges. However, for light-weight highspeed railway bridge structures, such as single-track steel bridges, train-induced resonance on bridges would be overestimated if the dynamic vehicle–bridge interactions (VBI) were neglected. To assess such VBI benefits on resonance reduction of railway bridges using MCL model, this paper presents an analytical strategy to determine the equivalent additional structural damping ratios and modal masses on the bridge deck. According to the numerical validation supplied by two types of bridges, i.e. simple beam and truss bridge, the proposed approach was successfully demonstrated to account for the VBI benefits on resonance reduction of light-weight bridges under moving trains using MCL models.

A combined review of vibration control strategies for high-speed trains and railway infrastructures: Challenges and solutions

People use trains as a means of transportation to travel to various nearby and distant destinations, resulting in an increasing amount of time spent inside such vehicles. Consequently, railway transportation sectors are focusing significantly more on enhancing passengers’ demand and level of satisfaction, including but not limited to high-speed travel, safety, and riding comfort. This paper provides a state-of-the-art review of available solutions for reducing undesired vibrations that have a substantial impact on improving the critical velocity limits of trains, maintaining the quality of riding comfort, and resolving safety concerns. In this regard, the solutions proposed for train vibration control are divided into two main categories: direct and indirect solutions. The direct solutions are those methods that are applied directly to trains’ bodies or bogies to attenuate the undesired vibrations, for example, improving the suspension/damper system, implementing active/semi-active control strategies, or applying various carriage optimization design modifications. Indirect solutions, on the other hand, are those that could indirectly affect trains’ vibrations, for example, controlling vibrations in railway bridge structures during train passages. Since the identification of vibration characteristics is assumed to be the first step in choosing proper solutions, particularly for active or semi-active control implementations, this review has examined the literature pertinent to modal identification of trains and railway infrastructures. Additionally, despite the installation of dampers between the bogie and suspension, the train’s equation of motion, and consequently, the vibration control of the bogie, has relied on the sky-hook model for decades. The fundamental problem for systems whose control strategies are based on the sky-hook concept is that the ‘sky’ does not actually exist. A solution to solve the sky-hook logic issue is using tuned rotatory inertia dampers and active rotatory inertia drivers which is addressed in this paper as well. Finally, it is concluded that these three solutions – employing a suspension/damper system in the bogie, an elastic connection for the train’s under-chassis-suspended equipment, and a ballastless railway – can practically mitigate vibration and noise in a train.

A Comprehensive Reliability Assessment Method for Existing Railway Bridges Based on Bayesian Theory

The increase in traffic volume and train load poses new challenges to the reliability assessment of existing railway bridges. To construct a comprehensive assessment method for the safety and reliability of existing railway bridges, firstly, the risk factors of railway bridge structures are analyzed and the evaluation criteria are determined; secondly, based on the accident tree theory, a multilevel Bayesian network model with key points is established, and the ability of the Bayesian network bidirectional reasoning and sensitivity analysis is used to evaluate the structural safety; finally, the result was applied to the marina northern Songhua River extra-large bridge to verify the applicability of the comprehensive evaluation of the reliability of an existing railway bridge. This approach provides a theoretical basis for the maintenance and reinforcement of the Songhua River Bridge along the Bin‐North Line.

Initial Implementation of Structural Health Monitoring System of a Railway Bridge

In order to determine the actual condition of the railway bridge structure in the field, predictive monitoring is needed by installing a structural health monitoring system (SHMS). In the process of applying the SHMS, a bridge design review was applied to have railway bridge characteristics. The purpose of conducting this design review is to determine the allowable threshold for deflection and vibration of the bridge. This paper will present the analysis of the steel frame structure; with a span of 51.60 meters, 4.45 meters wide, of 5.00 meters high, respectively. According to the applicable standards, the loads used following the function of the bridge on the railroad tracks are calculated. The purpose of this paper is to (1) analyze the strength of the attached profile against the working forces, especially the live load of the rail line, (2) to know the deflection that occurs, (3) to know the natural frequency that occurs, and (4) to develop expert systems. The simulation results are used as the basis for placing sensors on the bridge and as the basis for determining the threshold for the railway bridge SHMS.

Finite Element Analysis of I-Girder Bridge

Abstract: In India railway bridge structures are widely designed with the method suggested by IRS – Concrete bridge code 1997.This Code of Practice applies to the use of plain, reinforced and prestressed concrete in railway bridge construction. It covers both in-situ construction and manufacture of precast units. The Code gives detailed specifications for materials and workmanship for concrete, reinforcement and prestressing tendons used in the construction of railway bridges. After defining the loads, forces and their combinations and requirements for the limit state design, particular recommendations are given for plain concrete, reinforced concrete and prestressed concrete bridge construction. The design of I-Girder bridge superstructure (deck slab and PSC I-beam) are done by calculating bending moments, shear forces, bending resistance in transverse direction, bending resistance in longitudinal direction, checking flexural cracking. The Design of PSC I-Girders is done for Bending moments and Shear forces by Dead Load, Super Imposed Dead Load (SIDL) and Live Loads (LL). The Shrinkage strain, Creep Strain and effect of Temperature rise and fall are also determined. The design is complete for Pre-stressing cables, un-tensioned reinforcements, End cross girder, Shear connectors. I-girder superstructures are the most commonly used superstructures at cross-over location in metro bridges in india, as it has the wide deck slab and it easily permits metro’s to change tracks. I-Girder superstructure construction is component wise construction unlike U-Girders. I-Girders are constructed in casting yard and its deck slab is cast in situ, parapets are also installed on later stage. Keywords: SIDL effects, Live Load effects, Derailment effect, with or without 15% future PT margin

Dynamic response limit of high-speed railway bridge under earthquake considering running safety performance of train

Due to the wide railway network and different characteristics of many earthquake zones in China, considering the running safety performance of trains (RSPT) in the design of high-speed railway bridge structures is very necessary. In this study, in order to provide the seismic design and evaluation measure of the bridge structure based on the RSPT, a calculation model of RSPT on bridge under earthquake was established, and the track surface response measure when the derailment coefficient reaches the limit value was calculated by referring to 15 commonly used ground motion (GM) intensity measures. Based on the coefficient of variation of the limit value obtained from multiple GM samples, the optimal measures were selected. Finally, the limit value of bridge seismic response based on RSPT with different train speeds and structural periods was determined.

A model for investigating vehicle-bridge interaction under high moving speed

The speed of rail vehicles become higher and higher over two decades, and China has unveiled a prototype highspeed train in October 2020 that has been able to reach 400 km/h. At such high speeds, wheel-rail force items that had previously been ignored in common computational model should be reevaluated and reconsidered. Aiming at this problem, a new model for investigating the vehicle-bridge interaction at high moving speed is proposed. Comparing with the common model, the new model was more accurate and applicable, because it additionally considers the second-order pseudo-inertia forces effect and its modeling equilibrium position was based on the initial deformed curve of bridge, which could include the influences of temperature, pre-camber, shrinkage and creep deformation, and pier uneven settlement, etc. Taking 5 km/h as the speed interval, the dynamic responses of the classical vehicle-bridge system in the speed range of 5 km/h to 400 km/h are studied. The results show that ignoring the second-order pseudo-inertia force will underestimate the dynamic response of vehicle-bridge system and make the high-speed railway bridge structure design unsafe.

Numerical Study on Track–Bridge Interaction of Integral Railway Rigid-Frame Bridge

Track–bridge interaction (TBI) is an increasingly essential consideration for the design and operation of railway bridges, especially for the innovative bridge structure systems that constantly spring up over the years. This paper focuses on the characteristics of additional forces in continuous welded rails (CWRs) on the 3 × 70 m integral rigid-frame bridge of the Fuzhou–Xiamen High-Speed Railway, which is a novel high-speed railway (HSR) bridge structure system in China. The differential equations of rail stress and displacement are first investigated and an integrative analysis model comprising of rail, track, bridge and piers is then established. Secondly, the characteristics of representative additional forces are illustrated and the influences of different design parameters are discussed in detail. Furthermore, suitable rail fasteners, optimal layout schemes of adjacent bridges and reasonable stiffness of piers are also studied. The results indicate that the additional expansion force accounts for the largest proportion of additional forces in integral rigid-frame bridges and that resistance reduction obviously weakens the various additional forces caused by the TBI effect, while the broken gap of the rail increases greatly. Small resistance fasteners are recommended to be applied onto this new type of HSR line as these provide reductions in additional stresses of CWRs compared to WJ-8 fasteners. The additional rail stresses after adopting an adjacent span scheme of 4 × 32 m simply supported beams are less than the corresponding stresses in other schemes. The results also show that there is a strong correlation between the minimum threshold value of the pier stiffness and the longitudinal resistance of HSR lines for the integral rigid-frame bridge. This work could serve as a valuable reference for detailed design and safety evaluation of integral rigid-frame bridges.

Automated design of the railway bridge structure

This paper presents the design and calculations of bridge structures using modern computer technology. They provide the special capabilities necessary for the design of bridges, for example, the construction of influence lines for calculating moving loads, for calculating nodal interfaces, for checking local stability, for calculating the thermal stress state of supports, etc. The main purpose of the survey of the bridge structures was to obtain the initial data in accordance with GOST-v and SNiP-v for calculating the carrying capacity of the bridge superstructure, assessing the technical condition and developing recommendations for its further operation.

A New Model Updating Procedure for Reliability-Based Damage and Load Identification of Railway Bridges

In the current work, a new reliability-based method is presented for damage and load identification of railway bridge structures using finite element model updating in the presence of uncertainty. The bridge structure is modelled as an Euler-Bernoulli beam and the train is modelled as a series of axles in the form of sprung-mass with an unknown weight. Since the bridge-vehicle system is time-variant, the finite element model updating procedure is used as a response-based method. The effect of model and measurement uncertainties on identificationresults is investigated. The efficiency of the reliability-based method is compared with the deterministic and traditional probabilistic methods. In addition, the effect of critical parameters such as damping, speed and mass ratio on the accuracy of the proposed method is also discussed. It is observed in numerical models that the reliability-based method is the most accurate method for simultaneous identification of railway bridges in the presence of uncertainty. In addition to the damage index (DI), which indicates the location and the extent of damaged elements, the proposed method provides the probability and reliability of identified damages (RI) as well as the extent of unknown moving loads accurately.

Dynamic Response of Railway Bridges under Heavy‐Haul Freight Trains

In the freight railway bridge, the increase of the train running speed and train axle loads can enlarge dynamic response (DR) of the railway bridges, which leads to excessive vibration of bridges and endangers the structural safety. In this paper, a three‐dimensional coupled finite element (FE) model of a heavy‐haul freight train‐track‐bridge (HHFTTB) is established using multibody dynamics theory and FE method, and the DR for the coupled system of HHFTTB are solved by ABAQUS/Explicit dynamic analysis method. The field‐measured data for a 32 m simply supported prestressed concrete beam of a heavy‐haul railway in China are analyzed, and the validity of the FE model is verified. Finally, the effects of train formation number, train running speed, and train axle loads on DR of the heavy‐haul railway bridge structures are studied. The results show that increasing the train formation number only has an influence on DR duration of the bridge structure, rather than the peak value of DR, when the train formation number exceeds a certain number; besides, the train axle loads and train running speed have significant influence on DR of the bridge structure. The results of this study can be used as reference for the design of heavy‐haul railway bridges and the reinforcement transformation of existing railway bridges.