Railway Bridge Research Articles

Deflections and frequencies of long-span steel railroad truss bridges under passenger train excitation using laser Doppler vibrometer

ABSTRACT Given the critical challenge of aging infrastructure, it is imperative to adopt novel techniques that utilize modern technology to assess the structural integrity of existing bridges. This study presents a methodology to estimate the loading frequency of the train passing over the bridge and bridge dynamic responses, such as the acceleration and displacement response of long-span open-deck steel railroad truss-type bridge under the passenger train excitation using a Laser Doppler Vibrometer. The selected bridges for this study were the Cos Cob and Devon Railroad bridges in southern Connecticut, both in the Northeast Corridor. The structural response of the bridge floor system was collected during the field test using a single-point laser Doppler vibrometer and uniaxial accelerometers for reference under passenger trains, such as Metro-North M8, Amtrak Regional, and Amtrak Acela. The recorded data were analyzed using the moving load theory, interpreted, and discussed in the time and frequency domain. The study findings indicate that the bridge response and displacement align with the theoretical and vehicle axle loads. Also, it should provide valuable information about the behavior of the considered bridges under typical operating conditions.

An index-based multi-hazard risk assessment method for prioritisation of existing bridge portfolios

In recent years, several catastrophic collapses of existing bridges have highlighted the need for rapid risk analysis methods aimed at supporting infrastructure managers in the prioritisation of detailed assessments and, if any, risk mitigation actions. A large percentage of existing road bridges were built between the 1960s and 1980s, having thus already reached or even exceeded their design lifetime. Several studies have also shown that bridges often collapse due to either natural or human-related events, such as floods, collisions or overloading that, in addition to earthquakes, should be duly considered in risk assessment. This calls for multi-hazard approaches that provide an integrated perspective of the risk of bridge portfolios, to identify critical structures to support decision-makers. This study proposes a multi-hazard risk-based prioritisation methodology for application to a large number of bridges under limited level of knowledge. Specifically, the risk level is quantified through indices, accounting for uncertainties, that are used for comparative purposes among bridges. The methodology is applied to a highway bridge portfolio located in northern Italy, producing a risk-based ranking that is critically discussed. Analysis results are then compared with the outcome of the current Italian guidelines for safety assessment and maintenance of existing bridges.

MODERN TRENDS AND INNOVATIONS IN THE MODERNIZATION OF RAILWAY LINES BASED ON EXPERIENCE IN THE REPUBLIC OF BULGARIA

The modernization of the Bulgarian railways has been underway for over 20 years. Hundreds of kilometres have been rehabilitated with funds from the European Union. The aim is to join the main Trans-European network, according to Regulation No. 1315/2013 [1] of the EU. Given the complex mountainous relief, the specific engineering objects are now the design and construction of a large number of tunnels (in the Sofia-Plovdiv section alone, over 16 tunnels are planned, the longest of which is 6 km long); the design and construction of railway bridges, some of which have unique dimensions; the rehabilitation of bridges; and the construction of drainage facilities, including drains, ditches, and culverts (some of the culverts have a unique length of about 80 m). The report analyses the main railway projects with a critical analysis of strengths and weaknesses, according to the EU cost-benefit analysis methodology. The analysis presented in this report is unique for Bulgarian railways, as it includes a large volume of projects in the field of designing and building railway infrastructure according to European and world rules, which have not been used in Bulgaria until now. This is only the first stage of scientific research, which involves collecting data, examining the data, and building a working hypothesis. After the completion of the construction (supposedly by around 2029), there will be measurements of the railway and a diagnosis of its condition. At this time, data will be collected again, and the credibility of the presented hypotheses will be verified. The conclusions will serve for the more adequate preparation of the technical assignments for future infrastructure projects in the field of railways.

Data-Driven Relationship for Reduction Factor of Ballasted Railway Bridge Deflections Due to Load Distribution Within Track

Increasing the operating speed of the trains on modern networks necessitates performing dynamic analyses to assess the performance of bridges under passage of trains. The detailed investigation of their responses requires constructing complex computational models capable to take the train–track–bridge interaction effects into account. Such models have successfully been developed; however, employing those elaborated models for practical engineering applications, or to perform studies that require a large number of analyses may become infeasible. Among such situations are conducting probabilistic investigations, screening of entire networks, or sensitivity analyses. These concerns have been addressed by employing simplified models mostly relying on moving load modeling strategy which disregards the train–track–bridge interaction effects. Those neglected contributions can be compensated by implementing additional correction factors. The distribution of loads within track is one of those disregarded effects where a reduction factor is recommended by design guidelines to take its contribution into account. It has been shown that the existing relationship for these reduction factors delivers an acceptable performance for vertical accelerations, while showing a less favorable performance for displacements. Then, a data-driven strategy is adopted in this study to propose easy-to-apply relationships for reduction factors of deflections, due to load distribution within the track. In this context, three different distributive lengths of triangular load footprints have been considered, namely 2.0, 2.5 and 3.0[Formula: see text]m. The procedure employed has trained and tested for more than 1[Formula: see text]200 train configurations, comprising conventional, articulated and regular vehicles, and including several tens of thousand data points for each distributive length. The performance observed in the new models revealed a considerable improvement with respect to the existing relationship.

Systematization of the application of polymer composite materials in the design of bridge structures

Background. This study systematizes the principles of using polymer composite materials in bridge structure design, outlining the fundamental principles for calculating load-bearing structures of bridge spans featuring these materials. Aim. The goal is to enhance the strength and durability of bridge spans during construction and maintenance, while optimizing costs through the use of polymer composite materials. Materials and Methods. The research employs a modern approach to bridge structure design, utilizing mathematical statistics for experimental data analysis and numerical methods for calculating bridge structures using nonlinear deformation models of anisotropic materials. Results. Developed principles for designing bridge spans with polymer composite elements include methods for strengthening and reinforcing concrete bridge structures. These methods account for operational factors such as long-term constant and temporary loads, low and elevated temperatures, as well as methods for designing all-composite spans pedestrian and road bridges Conclusion. The principles of designing bridge spans with elements made of polymer composite materials have been introduced into the practice of transport construction in the Russian Federation. The technical and economic efficiency of using polymer composite materials in bridge structures of transport infrastructure has been confirmed.

Confounder-adjusted covariances of system outputs and applications to structural health monitoring

Automated damage detection is an integral component of each structural health monitoring (SHM) system. Typically, measurements from various sensors are collected and reduced to damage-sensitive features, and diagnostic values are generated by statistically evaluating the features. Since changes in data do not only result from damage, it is necessary to determine the confounding factors (environmental or operational variables) and to remove their effects from the measurements or features. Many existing methods for correcting confounding effects are based on different types of mean regression. This neglects potential changes in higher-order statistical moments, but in particular, the output covariances are essential for generating reliable diagnostics for damage detection. This article presents an approach to explicitly quantify the changes in the covariance, using conditional covariance matrices based on a non-parametric, kernel-based estimator. The method is applied to the Munich Test Bridge and the KW51 Railway Bridge in Leuven, covering both raw sensor measurements (acceleration, strain, inclination) and extracted damage-sensitive features (natural frequencies). The results show that covariances between different vibration or inclination sensors can significantly change due to temperature changes, and the same is true for natural frequencies. To highlight the advantages, it is explained how conditional covariances can be combined with standard approaches for damage detection, such as the Mahalanobis distance and principal component analysis. As a result, more reliable diagnostic values can be generated with fewer false alarms.

Comparison of interaction study between the double channel and Y-shaped railway sleeper tracks on steel girder railway bridge

Comparison of interaction study between the double channel and Y-shaped railway sleeper tracks on steel girder railway bridge

Impact of Shield Tunnel Construction on Adjacent Railway Bridge: Protective Measures and Deformation Control

With the rapid development of urban rail transit networks, constructing shield tunnels often requires passing underneath existing buildings, which can potentially impact their safety. This study examined the impact of constructing a double-line shield tunnel underneath a railway bridge on the adjacent pile foundation via numerical simulation. Protective measures, including construction parameter control, grouting methods, monitoring, and early warning systems, were implemented to mitigate impacts. The results indicated that the bridge deformation fell within acceptable limits, with maximum horizontal and longitudinal displacements of 0.06 mm and a maximum vertical displacement of −0.31 mm. The railway bridge pile foundation experienced maximum horizontal and longitudinal displacements of 0.47 mm and vertical displacements of −0.23 mm during construction. Enhanced construction quality control and monitoring effectively controlled deformation to ensure the railway safety. This study provides valuable guidance for similar projects and future urban rail transit developments.

Status of Construction Safety in Local Road Bridge Construction and its Consequences in Project Implementation: A Study in Gandaki Province, Nepal

After federalization of Nepal, bridge construction in local roads by provincial levels is in increasing trend. Being highly technical and of risky nature, construction safety needs to be ensured in bridge construction. However, in countries like Nepal, safety issues are considered, with follow up measures, only after the accidents occur at construction sites. In this context, this study aims to assess the present status and consequences of construction safety in local roads bridge project implementation and explore some improvements measures. A quantitative descriptive design was adopted for the study and 30 completed bridge samples from Gandaki province were selected using convenience sampling. Data were collected using questionnaire survey with 56 participants directly related to bridge construction and policy implementation. This study revealed that most of the bridge construction sites have poor workplace safety and worker’s welfare, inadequate provision and use of PPE, lack of trainings and awareness to workers as well as the absence of safety plans and method statements. Similarly, provisions for unsafe supports, shoring, formworks, concreting, and demolition were not noticed. While the absence of safety supervisor, job safety analysis, recording and reporting accident and diseases was observed, abundant cases were found where less importance was given to construction safety and use of PPE undermining the engineering and administrative hazard control methods in road bridge construction. Slip/trip/low falls, hand/leg/head injury, falling from height, eye problem, injury during erections, vehicle and electric current, cost and time overrun, substandard quality, reduced workers’ productivity, increased workers turnover, low construction safety reputation of contractor, loss/damage of land, irrigation canal, drinking water scheme, dust/noise have been found as consequences of poor safety practices. This clearly indicates that present bridge construction safety practices are inadequate and need substantial improvements for better project implementation. The major areas of improvements include safety as first priority, willingness, awareness and commitment of management, contractor and worker, selection of competent workers, formulation of specific safety rules, regulations, codes and their strict enforcement, good communication, safety training and inspection, motivation, adequate budget provision in contract for safety, provision of PPE, feeling safety as self-responsibility and use of technologies as well.

Developing and evaluating a risk-informed decision support system for earthquake early warning at a railway bridge

Earthquake early warning (EEW) systems provide timely information on the arrival of strong seismic waves at a site. Such information can help mitigate the consequences of earthquakes on the operation of infrastructure assets. EEW-informed mitigation actions should stem from risk-based decision-making protocols, and EEW benefits should be evaluated for the range of possible rupture scenarios that affect an asset of interest. This paper addresses these challenges specifically for railway bridges by: (1) developing a risk-informed EEW decision support system (DSS) for these assets; and (2) quantifying the effectiveness of the proposed EEW-DSS in mitigating seismic risks for railway bridges across relevant rupture scenarios. The proposed EEW-DSS combines information on site-specific seismic hazard, time-dependent EEW algorithm outputs, probabilistic seismic demand modeling, damage/derailment fragilities, and seismic loss models. These modeling components compose a multi-criteria decision-making framework. Value of information theory is then proposed to estimate the loss-mitigation benefits of the EEW-DSS, accounting for varied stakeholder risk priorities as well as dynamic lead-time/accuracy tradeoffs related to EEW performance. A railway bridge with multiple piers is adopted for the case study, which demonstrates the importance of risk-based, uncertainty-informed decision-making to the overall effectiveness of EEW in potentially reducing seismic losses.

Analysis of concrete damage at anchorage end of the high-speed railway bridge sound barrier under the 400 km/h train-induced wind loads

The sound barrier installed on high-speed railway bridges withstands repeated train-induced wind load, which may lead to concrete damage at its anchorage end. This paper focuses on the assessment of concrete static damage at the sound barrier anchorage end under train-induced wind loads. The nonlinear finite element model of the sound barrier anchorage system is established to analyze the stress distribution, strain distribution and static damage of concrete structure at the anchorage end under 400 km/h train-induced wind loads in respect of different bolt preloads. The simulated results illustrate that both mortar and concrete near bolt holes suffer a certain degree of tensile and compressive damage. The maximum tensile and compressive damage factor values for mortar and concrete are 0.930, 0.643 and 0.892, 0.434 respectively. In addition, the effects of train-induced wind load on the internal force of the sound barrier anchorage take nearly no account, with a maximum of only 0.68 %. The results indicate that bolt preload is the most significant factor for concrete static damage, while the train-induced wind load appears negligible. An appropriate bolt preload can avoid the concrete static damage of the sound barrier anchorage end, and guarantee the structural stability of the sound barrier.

Analytical Solution for Dynamic Response of a Reinforced Concrete Beam with Viscoelastic Bearings Subjected to Moving Loads.

To provide a theoretical basis for eliminating resonance and optimizing the design of viscoelastically supported bridges, this paper investigates the analytical solutions of train-induced vibrations in railway bridges with low-stiffness and high-damping rubber bearings. First, the shape function of the viscoelastic bearing reinforced concrete (RC) beam is derived for the dynamic response of the viscoelastic bearing RC beam subjected to a single moving load. Furthermore, based on the simplified shape function, the dynamic response of the viscoelastic bearing RC beam under equidistant moving loads is studied. The results show that the stiffness and damping effect on the dynamic response of the supports cannot be neglected. The support stiffness might adversely increase the dynamic response. Further, due to the effect of support damping, the free vibration response of RC beams in resonance may be significantly suppressed. Finally, when the moving loads leave the bridge, the displacement amplitude of the viscoelastic support beam in free vibration is significantly larger than that of the rigid support beam.

Study on Fracture Delay of High-Strength Bolts in Road Bridge Maintenance

In the maintenance work of highway and bridge engineering structures, the fracture delay of high-strength bolts is a content that needs to be focused on and researched. Based on this, the paper analyzes the fracture delay of high-strength bolts in highway bridge maintenance, including an overview of the fundamental research on fracture delay and related specific studies. It is hoped that this study can provide scientific reference for the reasonable maintenance of high-strength bolts, so as to ensure the overall maintenance effect of highway bridge projects.

Parametric modeling and engineering application of the high-speed continuous beam bridge based on Building Information Modeling.

To improve the informatization and intelligence level of high-speed railway (HSR) bridge construction, a parametric modeling method for continuous beam bridges based on Building Information Modeling (BIM) is proposed in this study. By this method, the parametric families of continuous beam components and key construction machinery are established, and the rapid modeling of overall continuous beam bridge and the simulation of critical construction process are realized as well. Taking the Caoxian-Shangqiu bridge of Xiong'an-Shangqiu HSR as a case study, the parametric modeling method is applied to conduct the engineering application on the prestressed duct layout and rebar clash detection. The results indicate that the modeling efficiencies of HSR continuous beam bridge and construction machinery are significantly increased by the established parametric modeling method. Based on the BIM model of continuous beam bridge, the improvement in the precision of prestressed duct layout and the elimination of rebar clash points can be achieved. The research achievement can guide the visualization of construction disclosure, enhance construction efficiency, and provide reference and technical support for the construction management and control of HSR continuous beam bridges.

Comparison of Different Modeling Approaches and Their Influence on the Dynamic Calculation of Four Single-Span Railway Bridges

Various approaches to mechanical modeling are available in practice to calculate the dynamic response of railway bridges under high-speed traffic, differing significantly in their complexity and accuracy. Very simple models often overestimate the vibrations occurring in reality but are much more computationally efficient and dependent on only a few input parameters than more complex and accurate models. Modeling the high-speed train as a multi-body system can represent the beneficial vehicle-bridge interaction, but it requires knowledge of numerous vehicle parameters, which manufacturers rarely disclose. In contrast, the track-bridge interaction can also be depicted by a simple coupling beam modeling of the structure, requiring only a few input parameters representing the dynamic stiffness and damping of the track. Several calculations on different single-span steel girder bridges demonstrate the influence of different model variants and input parameters on the acceleration results of the structure. Additionally, an approach for determining a dynamic distribution of the train axle loads affecting the bridge depending on the assumed vertical track stiffness is presented.

Research and Modification on the Park-Ang Damage Index for Railway Rectangular Piers

ABSTRACT This study addressed the issue of distortion in evaluating the seismic damage state of railway bridge piers using the original Park-Ang damage index. By constructing a parameterized co-simulation program with two finite element models, OpenSees and Abaqus, five sets of flexural failure and five sets of flexural-shear failure rectangular pier quasi-static test results were selected to validate the rationality of the calculation program. Four hundred and eighty parameterized calculations were conducted using this program. The combination coefficient β and critical damage index DI within the Park-Ang damage index were modified using nonlinear regression algorithm and convolutional neural network algorithm. The adaptability of the damage index calculation was ultimately verified through an engineering case study of a simply supported beam bridge. The research findings are as follows: 1) The main factor influencing β is the longitudinal reinforcement ratio, while the axial compression ratio, shear span ratio, volumetric stirrup ratio, aspect ratio, concrete strength, and steel strength are secondary parameters influencing β. 2) Compared to the nonlinear regression algorithm, the convolutional neural network algorithm can better establish a calculation model between pier structural parameters and β, clarifying their relationship. 3) It is recommended to use critical values of 0.11, 0.29, 0.49, and 1.00 for assessing pier damage as no, slight, moderate, severe, and collapse damage when using the damage index calculation model. 4) The Park-Ang index corrected by convolutional neural networks demonstrates improved accuracy and computational stability, making it suitable for practical assessment of seismic damage in bridge structures.

Influence of pier height and ground motion parameters on seismic response and energy dissipation of isolated railway bridges

The overlap between high-speed railways and earthquake areas makes it necessary to implement isolation design for railway bridges. At present, the variation of seismic energy of railway bridges with structural and ground motion parameters is not clear. In this paper, the finite element models of railway bridges with different pier heights are established and verified by shaking table tests. Then, the nonlinear time history analysis of isolated and non-isolated models is carried out, and the differences in seismic response and energy dissipation between the two models under different parameters are compared. Finally, the isolation effect of hyperbolic friction pendulum bearing (HFPB) is evaluated by using the efficacy coefficient method. Results demonstrate that HFPB can not only reduce the seismic response of the girder and the pier, but also effectively reduce the seismic input energy, structural damping energy, and pier hysteretic energy. In addition, HFPB has a better seismic isolation effect when pier height is 3–15 m, site characteristic period is 0.25–0.45 s, and earthquake PGA is 0.2–0.5 g.

Impacts of bridge constructions on channel dynamics and sediment aggradation: An integrated discussion, West Bengal, India

Channel dynamics, including channel migration, erosion, and deposition, is a significant geomorphological phenomenon. It has been noted that the Gish River exists with its widest extension between 1913 and 2021, causing a bottleneck situation. The section G4 (Gish-4) experienced the most significant squeezing character over time. The catchment landslide-induced sediments, mostly transported in the monsoon by 1st and 2nd order streams, deposited at the beds near the rail and road bridges of the rivers Lish, Gish, and Chel. Landslide susceptibility mapping (LSM) and sediment transport index (STI) maps specify the zones of sediment generation and aggradation. Results of low ‘b” value 0.77 + /−0.04 specify active tectonics and instability of the area. A petrographic analysis of landslide samples and river bed sediments justifies that the landslide connected streams are continuously transported and deposited in the river bed. In the Himalayan foothill rivers like Lish, Gish, and Chel, channel planform dynamics may be the result of landslide occurrences, that induce huge sediments in the rivers and sediment transport index indicates the deposition of the sediments near rail and road bridges in spatio-temporal scale.

Railway bridge “Under Vyšehrad” in Prague, preparation of reconstruction

AbstractThe 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.

Prediction of fatigue life of a bolted joint in railway steel arch bridge using multiaxial fatigue criteria

Fatigue represents a critical condition for infrastructure subjected to repeated cyclic loads, such as steel railway bridges. The literature offers several methods to estimate fatigue life, consisting of three main phases: cycle counting, fatigue damage criterion, and damage accumulation criterion. Applying S-N curves might not be conservative in the case of railway bridges subjected to traffic because the stress-time history is complex and cannot be reduced to a sinusoidal history. Additionally, the presence of a multiaxial stress state must be considered. Therefore, this work compares eight multiaxial fatigue damage criteria for evaluating fatigue life in a scenario between high and low-cycle fatigue. Specifically, the authors considered four low-cycle fatigue criteria, namely Smith–Watson–Topper (SWT), Kandil, Brown and Miller (KBM), Glinka, Fatemi and Socie (FS), and four high-cycle fatigue criteria, Crossland, Basquin and the methods recommended by Eurocode 3 and British Standard. The rainflow counting method in ASTM E1049-85 (2011) and Miner’s rule for damage accumulation were used. The Polcevera railway steel bridge was selected as a case study. A 3D numerical model was developed for this purpose using Midas Civil software, taking into account the material non-linearity of the bridge’s elements. Once the area with the highest stress concentration was identified, a detailed analysis was conducted to estimate the stress and strain time histories induced by train traffic. A sensitivity analysis was conducted after critically comparing the eight methods for predicting fatigue life to assess the impact of traffic parameters, train velocity, axle load, and convoy length on fatigue life. It has been found that the criteria considering axial stress tend to overestimate the number of fatigue cycles to failure compared to the criteria, including the effect of shear stress components.