Plate Girder Bridge Research Articles

Damage detection for railway bridges using time‐frequency decomposition and conditional generative model

AbstractA novel damage detection model, which utilizes the spatiotemporal characteristics of the acceleration data, is proposed to assess the structural integrity of railway bridges. For this, the measured acceleration data are decomposed into several intrinsic mode functions (IMFs) using the sparse random mode decomposition model. The generated IMFs are subsequently integrated into the enhanced time series conditional generative adversarial network model to identify possible damage in bridges across various frequency bands. The influence of environmental and operational variables (EOVs), particularly temperature fluctuations, was also investigated. The proposed model was verified using both numerical and experimental data from a plate girder bridge. Further validation was conducted using the Z24 bridge dataset, and damage cases under the influence of EOVs were successfully predicted. Throughout the validation process, various anomaly metrics were introduced to establish a threshold value, and a covariance‐based time domain metric was proven to be the most effective in our cases.

Design and Analysis of Curved Steel Bridges Using 3D Shell Modelling

AbstractSteel bridge designers and erectors primarily rely on approximate methods, such as 1D line girder analyses and 2D grid analyses. For curved or skewed bridges, this can give erroneous indications of the structure's true behaviour. Refined methods of analysis, such as 3D shell modelling, aim to bring a significant change in the practice of bridge engineering. By moving the industry away from simplistic design assumptions, refined analysis methods lead to more accurate, less conservative results, which in turn brings true benefits such as improved structural safety and increased economy. In this paper, several case studies on curved plate girder and tub girder bridges are presented, which cover the full bridge life cycle, from erection of the steel structure and placement of the concrete deck, down to live load analyses using influence surfaces and load rating. The case studies will be modelled with mBrace3D, a dedicated FEA software for curved steel bridges.

Stress characteristics and cracking mechanism of web-to-stiffener weld in steel plate girder bridges under bending-shear action

The web-to-stiffener weld was subjected to bending-shear action, which was always neglected in previous research and affected the accuracy of fatigue evaluation. In this study, multi-scale FEMs (finite element models) of steel plate girder bridges were established to investigate the deformation characteristics, thus revealing the generating mechanism of bending-shear action. The fatigue comparison tests under bending-shear load and bending load were conducted to identify the cracking mechanism and its impact. The stress characteristics at the weld end were further explored through the structural mechanical model and verified by FEMs. The results show that the bending-shear action was caused by the inward and downward pulling by the stiffener on the web, and would lead to a premature transition from fatigue cracking to brittle fracture. The ratio of shear stress to normal stress was independent of load, inversely proportional to gap height, and positively related to web thickness, which could provide support for the accurate fatigue evaluation of web-to-stiffener weld.

A simplified method for estimating bridge frequency effects considering train mass

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.

Estimation of the Minimum Lateral Resistance of Continuous Welded Rail Tracks Installed on Ballastless Railway Plate Girder Bridges

Estimation of the Minimum Lateral Resistance of Continuous Welded Rail Tracks Installed on Ballastless Railway Plate Girder Bridges

Optimal Reinforcement Model based on the Shape and Installation Position of the Lower Horizontal Bracing of a Ballastless Railway Plate Girder Bridge

Optimal Reinforcement Model based on the Shape and Installation Position of the Lower Horizontal Bracing of a Ballastless Railway Plate Girder Bridge

Elastic-plastic flexural behavior of hybrid steel girder bridge considering welded residual stress

Hybrid steel girders use a section type that fully utilizes the strength performance of steels, which are widely used in steel plate girder bridges with multiple spans. In this paper, the distribution of the welded residual stress in hybrid I-shaped steel girders was investigated by the hole drilling test, and the unified model was analyzed and revised. Considering welded residual stress, the elastic and plastic design method for calculating the flexural capacity of hybrid I-shaped steel girders was put forward. Experiments and numerical simulations were conducted to analyze the elastic-plastic flexural behavior of the hybrid I-shaped steel girders using multi-scale models. The influence of welded residual stress, geometry of section, steel grade, and initial geometrical imperfections on the elastic-plastic flexural capacity of hybrid I-shaped steel girders were discussed through the parameter analysis adopting the dimensions commonly used in bridges. Analysis results show that the welded residual stress reduces the value of the elastic and plastic bending moments by almost 25% to 40% and 3%, respectively. The geometry of the section should be paid attention to clarify the value of the flexural capacity of the hybrid I-shaped steel girder. The width-to-thickness ratio limit of the flange should be adjusted according to the severity of initial geometrical imperfections.

Buckling Strength Analysis of Railway Plate Girder Bridge According to the Transverse Reinforcement at the Lower Flange

Buckling Strength Analysis of Railway Plate Girder Bridge According to the Transverse Reinforcement at the Lower Flange

Performance of Composite Plate Girder Bridges with Full-Depth Precast Concrete Deck Systems

Performance of Composite Plate Girder Bridges with Full-Depth Precast Concrete Deck Systems

Case Study on Collision Accident Analysis and Repair·Reinforcement of Old Plate Girder Bridge

Case Study on Collision Accident Analysis and Repair·Reinforcement of Old Plate Girder Bridge

Vibration characteristics and load-carrying capacity of multiple steel plate girder bridges with corroded girder ends

This study investigates the effects of corrosion on the vibrational characteristics and load-carrying capacity of steel plate girder bridge ends, which are extensively used in many bridges. First, eigenvalue and static analyses were performed using the finite element method, and the following main parameters were considered: the number of main girders, corrosion locations, and corrosion levels. The correlation between the results of the eigenvalue analysis and load-carrying capacity was examined; furthermore, to serve vibration-based health monitoring purposes, the selected parameters were investigated. The results indicated that the natural frequencies of the torsion-transverse coupling mode changed considerably as the corrosion ratio increased in the case of the corroded girder end and double-sided pin-bearing conditions. Additionally, a correlation between the natural frequency and load-carrying capacity was observed regardless of the number of main girders, indicating that the natural frequency and maximum load factor were related. In conclusion, the load-carrying capacity of corroded girder bridges can be estimated by measuring the transverse mode using an acceleration sensor installed on the upper flange and slab.

Dynamic Responses of Spread Slab Beam Bridges Considering Inconsistent Road Roughness Conditions

In order to deeply study the dynamic response of a new type of low section short span bridge system, the numerical analysis of the extended plate girder bridge under the action of moving vehicles was carried out. In the study, the inconsistent road roughness conditions are considered, and the influence of vehicle speed on the influencing factors is discussed. The analysis results show that under various load conditions, the structural response of the outer plate beam is more critical. In addition, the amplification effect of external plate beam caused by consistent pavement roughness is greater than that caused by inconsistent pavement roughness. The torsional mode of the vehicle can be activated by the input excitation of inconsistent pavement roughness conditions, which should be handled carefully in the design.

Fatigue Life Assessment of a Plate Girder Bridge Using an Uncoupled Iterative Scheme for Bridge–Vehicle Interaction

Most commercial software allows moving-load analysis to be performed on finite-element bridge models. However, the available software does not allow the incorporation of the dynamic load induced by vehicles due to vibration resulting from pavement roughness. The present study, aims to utilize an uncoupled iterative scheme to incorporate road roughness into the numerical model in order to overcome this problem. The vehicle-induced stress history obtained using the uncoupled iterative scheme is then used to determine the fatigue life of a plate girder bridge. A fatigue damage model is proposed, which incorporates the load sequence effects and the segregation of load cycles into crack-initiation and propagation stages. Investigation of various influencing parameters reveals the significance of vehicle speed, vehicle arrival time, pavement category, and the eccentricity of the load and girder design variables on the fatigue life of the bridge.

STUDY ON DETERIORATION OF THERMAL SPRAYED ALUMINUM COATING BY BRIDGE SURVEY

Since aluminum spraying has excellent corrosion resistance, it has been applied to many steel bridges in Japan since 2000s. However, in recent years, partial degradation has been observed in steel bridges with the thermal sprayed aluminum coating. This study aims to clarify the degradation mechanism of thermal sprayed aluminum coating. This study investigates thermal sprayed aluminum coating on-site on a steel plate girder bridge. In the bridge (constructed 17 years ago at estuary) investigation, the aluminum coating is generally in good condition, but the partial degradation is concentrated inside of the girder where the corrosion environment is severe. It was also confirmed that there were many corroded parts in the lower flange weld zone. Partial degradation occurs evenly throughout the bridge, but there is a tendency for more degradation to occur on the piers, where the corrosive environment is considered to be the most severe. A large amount of salinity was detected in the results of the attached salt content measurement near the corroded parts, and it is presumed that the salt content is a major factor in promoting the deterioration of the thermal sprayed aluminum coating.

Field Testing and Refined Load Rating of a Load-Posted Continuous Steel Girder Bridge

Load-posted bridges have potential effects on traffic, commerce, and emergency egress due to detours in routes between origins and destinations. Posted bridges can also be problematic for state departments of transportation from a management standpoint because they may call for more frequent maintenance, monitoring, and inspection. For these reasons, it is beneficial for states to minimize the number of load-posted bridges. This study investigates a continuous steel plate girder bridge superstructure and proposes a methodology for exploring the refined load rating of this bridge type in a safe manner through refined modeling and load testing. Load test results were used to examine live load distribution factors, and finite-element models were developed to refine load ratings. It was determined that the refined load-rating factors for the bridge are significantly higher than the currently posted limits, and therefore, the posting could be removed. The methodology presented in this paper can potentially be used to increase the load-rating factors for similar continuous steel girder bridges.

Buckling and Bearing Capacity Variation Caused by Local Corrosion at Support in Steel Bridge

The local corrosion of steel plate girder bridges at supports is a major issue affecting the safety. To clarify its effect on the buckling characteristics and bearing capacity, the static tests were carried out. The bearing capacities and local deformation were compared. The local buckling characteristics were refined by stress testing. To further investigate the effect mechanism of corrosion, the global finite element models (FEMs) of bridge were established. Separate corrosion of each component was considered. By comparing the strength and ultimate loads, the key member on bearing capacity reduction was specified. The influence of corrosion scope including the parameters of length, height, and depth on the bearing capacity was clarified. The results show the effect mechanisms of different-member corrosion on bearing capacity reduction were completely diverse. The web corrosion was the main cause of the bearing capacity reduction, which was the first to buckle. The relative position between corrosion scope and the support should also be considered during the evaluation of bearing capacity.

A New Proposal for Live Load Distribution Factors of Bridges with Transverse Beams

Many bridge superstructures use transverse beams as load carrying components. In these systems, usually the transverse beams are connected to the main longitudinal girders or trusses on the two sides of the bridge. Such systems are commonly used in plate girder, box girder, cable-stayed and truss bridges. The live load distribution factor (LLDF) for bridge superstructures with transverse beams in AASHTO-LRFD bridge design specification has remained unchanged for decades and is prescribed as a function of the distance between the transverse beams. However, for slab-beam superstructures in which longitudinal beams at close spacing carry the loads to the substructure, the LLDFs have gone through many changes throughout the years and in their current forms depend on many parameters such as concrete slab thickness, beam span, longitudinal beam stiffness as well as the distance between the longitudinal beams. This study investigates the factors affecting the LLDF for transverse beams and intends to obtain new equations similar to AASHTO’s longitudinal beam equations. For this purpose, 3D finite element models of different sample bridges were developed and critical parameters affecting the LLDF were identified and varied. Accordingly, the LLDFs for moment and shear forces of transverse beams were obtained through regression analyses. The proposed equations have less than 3.1% of average error for the cases considered.

Data Normalization and Anomaly Detection in a Steel Plate-Girder Bridge Using LSTM

Modal properties are recognized as indicators reflecting structural condition in structural health monitoring (SHM). However, changing environmental and operational variables (EOVs) cause variability in the identified modal parameters and subsequently obscure damage effects. To address the issue caused by EOV-related variability, this study investigated the variability of modal frequencies in long-term SHM of a steel plate-girder bridge. A Bayesian fast Fourier transform (FFT) method was used for operational modal analysis in a probabilistic viewpoint. Bayesian linear regression (BLR) and Gaussian process regression (GPR) models were utilized to capture the variability in the identified most probable values (MPVs) of modal frequencies as temperature-driven models, and the limitation of these models for data normalization with latent EOVs is discussed. To overcome the interference of latent EOVs indirectly, a long short-term memory (LSTM) network was established to trace the variability as an autocorrelated process, with a traditional seasonal autoregressive integrated moving average (SARIMA) model as a benchmark. Finally, an anomaly detection method based on residuals of one-step-ahead predictions by LSTM was proposed associating with the Mann-Whitney U-test.

Cost comparison of steel plate girder and RCC girder bridge

Most of the part of nation especially city areas facing problem of traffic congestion due to unplanned increasing traffic intensity that is why requirement of elevated road access come into picture. The railway and road crossing is also required the elevated intersection. Most part of the country having superstructure of pre-stressed or RCC structure being heavy in weight creation expensive cost of sub-structure and foundation as well as bearing. A study has been conducted regarding the cost comparison of steel plate Girder Bridge and Reinforced Concrete Girder Bridge and found that steel plate girder is a sustainable option as being light in weight and are more efficient in compression and tension both.

Influence of Fatigue Crack Formation and Propagation on Reliability of Steel Members

During the years of bridge exploitation, many degradation processes and external influences attack its structure. Therefore, bridge reliability and durability is decreasing in time. On the other hand, the traffic load remains almost the same or even higher than in the past. However, bridges should not to become the limiting component of communication capacity and traffic reliability. Regarding to reliability, bridges should be assessed from the viewpoint of the Ultimate Limit States (ULS) and Serviceability Limit States (SLS). Within the ULS, cross-sections and members are verified for various types of stressing and their combinations, and also for fatigue at the same time. The cross-sectional verification, e.g., for bending stresses and fatigue, is done independently according to corresponding criteria of the ULS determined for strength verification a fatigue assessment separately. The presented article deals with the steel railway plate girder bridge with bottom member deck, in which there is an effort to prove the effect of the crack in tension bottom flange due to fatigue stressing on the change of bending resistance over time. The analytical calculation was derived and at the same time, the probabilistic approach of the influence of the fatigue crack size on the change of the cross-sectional resistance and reliability over time was used.