Search

In this study, dynamic receptance analysis (DRA) is proposed and combined with hybrid finite element (FE)-statistical energy analysis (SEA) method to accurately predict structural noise from long-span cable-stayed bridge (LSCB) with steel box composite girder (SBCG) in urban rail transit (URT). To begin with, a vertical vehicle–track coupling model in frequency domain is established based on DRA, in which the rail is represented by an infinite Timoshenko beam supported by a series of fasteners that are regarded as springs with complex stiffness. The floating slab is regarded as the Euler beam with both ends free supported by steel springs. Using this model, the spectrums of the wheel–rail force and the forces transferred to the bridge can be efficiently obtained by taking rail roughness as the excitation. Due to the low modal density of the concrete deck, the hybrid FE-SEA method is introduced to establish the noise prediction model, in which the discontinuity caused by using distinct models for different frequency bands is avoided. Then the on-site noise tests of a LSCB with SBCG in URT are carried out to verify of the proposed method. Finally, based on the prediction method, the acoustic contributions of the bridge components are analyzed in detail. The force transfer characteristics as well as the noise reduction effects of different track structures are thoroughly investigated, so as to provide reference for the future research on bridge-borne noise control. [ABSTRACT FROM AUTHOR]

To excite sufficient vibrations of bridges for more effective modal experiments to take place, traveling vehicles were utilized in many bridge field inspection campaigns in history. However, the dynamics of a bridge subjected to the traveling vehicles are of changed resonant properties compared with those of the same structure with the ambient excitation in nature. Therefore, the field modal experiments employing vehicle excitations might unfavorably lead to shifted measurement results of low-order natural frequencies for long-span bridges of large mass. Using Xinjiang Bridge (a single-tower pre-stressed concrete cable-stayed bridge with spans 40m + 150m + 150m + 40m) as the engineering background, this paper validates this technical notion based on reliable physical experiments and numerical simulations and seeks a practical approach to deal with the issue. It is found that the maximum deviation between the low-order modal frequencies measured on Xinjiang Bridge for the vehicle excitation case and those measured for the ambient excitation case (the accurate values) reaches 0.65Hz, and the deviation between the lower limit of the usual vehicle excitation’s energy band and the modal frequency measured (factor 1) and the traveling vehicles’ speed (factor 2) are the two key factors influencing the modal frequency shifts. An empirical model to compensate for modal frequencies’ deviations is formulated considering the two key factors accordingly, which is of high-practical significance in future applications of the modal experiments using vehicle excitations to other long-span bridges. [ABSTRACT FROM AUTHOR]

During the swivel construction of a large-tonnage cable-stayed bridge, a single spherical hinge is susceptible to be damaged from excessive force. Consequently, this paper suggests a multi-point support swivel method of gear rails. The paper introduces a multi-point support swivel system of large-tonnage gear-tooth-rail, along with the swivel construction and monitoring technology. Models of the spherical hinge are established. Results indicate that the force applied to the spherical hinge is reasonable, exhibiting a gradual increase in contact stress from the center to the outer edges. The distribution of Mises stress differs from the distribution of contact stress. The force applied by the driving device is reasonable, ensuring the safety and feasibility of the proposed approach. The findings have guiding significance for future engineering. [ABSTRACT FROM AUTHOR]

The Shennong Lake Bridge stands as a prominent landmark in Changzhi City, located in Shanxi Province. Constituting the primary span is a "herringbone" configuration, employing a single tower double cable plane cable-stayed design with spans of 2 × 130 m and a deck width of 47 m. The complex bridge tower structure poses a challenge to the design of the bridge. This study elucidates the procedural intricacies of employing a three-dimensional parametric approach in shaping the cable tower. By leveraging the merits of history-based parametric modeling and skeleton-template design, a comprehensive landscape blueprint has been developed, with a primary focus on the architectural layout of the cable tower. The collision rectification issue between the bridge tower and the cable has been resolved using a 3D parametric model. Following the culmination of construction efforts, the final structure harmoniously aligns with the initially envisioned landscape depictions. Through meticulous optimization of design protocols for intricate landscape-integrated bridges, this endeavor extends its potential utility as a salient reference for akin undertakings. [ABSTRACT FROM AUTHOR]

The excessive main girder displacement responses of the large-span cable-stayed bridges during seismic events may precipitate collisions between the main girder and the approach bridge. The viscous dampers (VDs) have been extensively employed in the seismic response control of long-span bridges, yet their effectiveness is limited. To augment the seismic-induced vibration control performance of the VD, inerter element, negative stiffness (NS) element, and spring element have been incorporated into the VD to achieve energy dissipation capacity enhancement. The equations of motion for the simplified cable-stayed bridge-damper systems are established under stochastic seismic excitation, and the design parameters of inerter and NS-based damper are optimized by using the genetic algorithm. The seismic control performance of the VD and five types of dampers are systematically compared, demonstrating that these dampers can substantially enhance the main girder displacement mitigation performance in cable-stayed bridges. Owing to the NS characteristics attributes of the inerter element and NS element and the tuning effect of the spring element, the tuned viscous mass damper (TVMD) with NS achieves a 24.56% higher efficiency in control performance compared to the VD. [ABSTRACT FROM AUTHOR]

AbstractSeismic uplift of a high-speed rail (HSR) cable-stayed bridge’s bearing affects train safety. Existing technique lacks improved seismic isolation in the vertical direction due to the bearing’s vertical stiffness. Based on the on-site dynamic test and train derailment table experiments and different software, the train running safety of the semi-floating system of the cable-stayed bridge-rail-train system was analyzed using different damping and isolation control strategies. The larger vertical seismic component increases the danger of flange climb derailment when subjected to near-fault earthquakes. After installing lateral/or viscous fluid dampers (VFDs) and magnetorheological (MR) bearing (A = 3.0), the bridge has an obvious bearing uplift response. Still, it is not enough to threaten the structure, and the seismic damping capacity of the bridge structure is improved, making the train ride safe. This research presents discoveries on the impact of bearing uplift on train operational safety. Specifically, it reveals that the lifting of the end bearings on both sides of the main girder is not synchronized. This investigation presents a technical reference for comparable initiatives. [ABSTRACT FROM AUTHOR]

Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems, including rigid system (RS), floating system (FS), and passive energy dissipation system (PEDS), is conducted to study the effects of connection configurations on seismic responses and fragilities. Finite element models of bridges are established using OpenSees. A new ground motion screening method based on the statistical characteristic of the predominant period is proposed to avoid irregular behavior in the selection process of ground motions, and incremental dynamic analysis (IDA) is performed to develop components and systems fragility curves. The effects of damper failure on calculated results for PEDS are examined in terms of seismic response and fragility analysis. The results show that the bridge tower is the most affected component by different structural systems. For RS, the fragility of the middle tower is significantly higher than other components, and the bridge failure starts from the middle tower, exhibiting a characteristic of local failure. For FS and PEDS, the fragility of the edge tower is higher than the middle tower. The system fragility of RS is higher than FS and PEDS. Taking the failure of dampers into account is necessary to obtain reliable seismic capacity of cable-stayed bridges. [ABSTRACT FROM AUTHOR]

This article investigates the challenges of maintaining the Machico Cable-Stayed Bridge in a marine environment, focusing on its implications for urban mobility. The primary problem addressed is the impact of harsh marine conditions on the structural integrity of the bridge, which poses significant challenges for ongoing maintenance and safety. The research highlights unique aspects such as the effects of saltwater exposure on materials and the interplay between infrastructure and urban transit dynamics. By emphasizing these critical issues, this study aims to provide insights into effective maintenance strategies and contribute to the broader discourse on urban mobility in coastal regions. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & 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.)

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 construction duration of long-span arch bridges is excessively prolonged due to insufficient closing precision and the non-convergence of traditional cable adjustment calculation methods. This study investigates cable force management in long-span concrete-filled steel tubular (CFST) arch bridges during cable-stayed buckle construction, aiming to improve construction safety and precision in arch rib alignment. Using the Pingnan Third Bridge and Tian'e Longtan Bridge as practical examples, the research develops a multi-objective optimization method for cable forces that integrates influence matrices, constrained minimization, and a forward iterative approach. This method offers a robust strategy for tensioning and cable-stayed buckling, enabling real-time monitoring, calculation, and adjustment during the construction of large-span CFST arch bridges. The results reveal that the iterative approach notably enhances calculation efficiency compared to conventional methods. For instance, field measurements at the Pingnan Third Bridge show a minimal arch closure error of only 3 mm. Additionally, the study addresses concerns about excessive stress in exposed steel tubes during concrete casting. By optimizing the sequence of main arch closure and concrete casting, stress in the exposed steel tube is reduced from 373 MPa to 316 MPa, thus meeting specification requirements. In summary, the multi-objective cable force optimization method demonstrates superior efficiency in determining cable tension and controlling rib alignment during cable-stayed buckle construction of long-span CFST arch bridges. [ABSTRACT FROM AUTHOR]

In the construction process of mass concrete structures, the large temperature gradient due to exothermic hydration makes the mass concrete highly susceptible to cracking. This paper carried out research on temperature control methods of mass concrete for the purpose of ensuring construction quality based on the construction of Fengyi cable-stayed bridge caps. Firstly, the temperature and stress change rule in the concrete pouring process of the caps was analyzed though the finite element method (FEM). Then, targeted-oriented comprehensive temperature control schemes were formulated according to the structural characteristics and construction environment of the cap, including the optimization of the material ratio, the arrangement of crack-resistant reinforcing steel, the design of a water pipe cooling scheme and reasonable maintenance. Finally, the whole bridge cap construction process using the optimized water pipe cooling solution was monitored, and the temperature gap between inside and outside the concrete satisfied the specification requirements rigorously. In the concrete demolding session, the concrete surface was smooth and no cracks were found, which indicates the temperature control scheme is reasonable and effective. The research results have reference significance for the pouring and temperature control of mass concrete for bridge caps. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working 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.)

With the recent growth of electrical and electronic systems such as electric vehicles, the demand for automatic cable routing for electrical wiring design is increasing. However, real industry use cases of automatic cable routing are still rare especially in three-dimensional design. In this study, we propose a new pathfinding algorithm, JPS–Theta*, which combines the existing pathfinding algorithms, Jump Point Search and Theta*, that is better suited for cable routing. In addition, we propose a B-spline optimization algorithm to create natural cable shapes while avoiding collisions. In the experiments, it was found that the proposed pathfinding algorithm complements the existing algorithms and is thought to be more suitable for the purpose of automatic cable routing. Additionally, ant colony optimization for continuous domains, a meta-heuristic algorithm, was successfully used for optimizing the B-spline to obtain cable shapes without collision. Lastly, as a case study, the proposed method was directly applied to the electrical panel design to show its effectiveness. We expect that the proposed method will be able to improve the efficiency and quality of electrical wiring design. [ABSTRACT FROM AUTHOR]

Urban rail transit is rapidly evolving, with long-span cable-stayed bridges becoming increasingly popular among engineers because of their adaptability. However, as the operation time of bridges with tracks increases, the combined effects of repeated wheel loads and various bridge system excitations, including temperature changes and shrinkage–creep, gradually alter the alignment of the main beam. Similarly, the track structure on the bridge deck also undergoes vertical displacement, leading to corresponding degradation in rail alignment. This study applies singular function theory and verifies its effectiveness in bridge mechanical analysis. For the steel spring floating plate track cable-stayed bridge system, the mapping relationship between the deformation of the bridge’s main beam and the track’s deformation under bridge system excitation is derived, integrating singular function theory with the theory of train–track–bridge dynamic interaction. By analyzing the force transfer mechanism of the track–bridge system under system excitation, this research examines the effects of different excitations on the coupled dynamic response of the train–track–bridge. These findings suggest that system excitations increase the dynamic response of the train–track–bridge system, which is crucial for improving the durability and reliability of urban rail transit infrastructure. [ABSTRACT FROM AUTHOR]

The wind-resistant performance of cable-stayed bridges under construction deteriorates sharply as the cantilever length increases, and the arrangement of the temporary pier is an effective measure to improve aerodynamic stability. To investigate the effect of the temporary pier on buffeting response of a long-span three-tower cable-stayed bridge under construction, the nonlinear buffeting analysis and wind tunnel test of aeroelastic model methods are adopted in this paper. The influence of the type and arrangement positions of temporary piers on mean wind response and the nonlinear buffeting response of double-cantilever construction are studied, and the arrangement of the temporary pier is optimized based on the buffeting response. The results show that the reduction rates of the RMS of the torsional moment at the tower bottom and the lateral buffeting displacement at the girder end with the rigid pier are 35.6% and 59.2% compared to those without the temporary pier. Further, the buffeting response will decrease as the distance between the rigid pier and the tower increases in the state. On the contrary, in the double-cantilever construction state before the constraint of temporary piers, the buffeting response will become significant as the distance increases. Therefore, it is necessary to consider the buffeting response under two construction states when optimizing the arrangement position of the temporary pier. [ABSTRACT FROM AUTHOR]

The Partially Concrete Filled Steel Tube (PCFST) structure has gradually been applied to bridges as the main load carrying components in recent years, owing to the advantages of light weight and high stability. The failure mechanism and load carrying capacity of PCFST structure highly depends on the concrete filling ratio. For this purpose, the failure mechanism and parametric analysis of a single arched PCFST cable stayed bridge tower are investigated by using both refined solid element simulation and quasi-static experiment. The results shows that the PCFST arched tower experiences asymmetrical instability failure subjected to quarter span symmetrical loading, and the plastic hinges appears firstly at the tower arch closely above the tower columns, and then the bottom of the tower columns, forming a rotating mechanism leading to the instability failure. Filling concrete or not will result in two opposite deforming propagations of the plastic hinges, and when the concrete filling length exceeds the length of plastic hinge, the initial rigidity and ultimate load carrying capacity of the PCFST structure will sharply increase. Finally, according to the results of the extended parametric analysis based on the real size simulation, an improved initial stress reduction coefficient of PCFST structure is then suggested. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature 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.)

When a large-span cable-stayed bridge is affected by external conditions, it is easy to cause changes in the plane coordinates of the encrypted CP II and CP III on the bridge. To solve this problem, a real-time coordinate prediction method based on the Beidou high-precision positioning system was adopted. Firstly, the encrypted CP II on the large-span cable-stayed bridge was set as a Beidou high-precision fixed antenna with a prism. This positioning antenna could measure the encrypted CP II coordinates in real time and connect the prism under the antenna with CP III for measurement. The real-time coordinates of CP II and the first phase coordinates were encrypted on the bridge, and the real-time conversion parameters were solved using four parameter transformation. The real-time coordinates of CP III were obtained through real-time conversion parameter calculation. By comparing the measured and calculated results of a large-span cablestayed bridge CP III for four consecutive periods, the maximum difference value in the X direction is 3.0 mm, the minimum difference value is -3.0 mm, and the maximum difference value in the Y direction is 2.9 mm, and the minimum difference value is -3.0 mm, which meets the requirements of the Code for Engineering Survey of High-speed Railway. The research results indicate that the real-time coordinate prediction method for CP III is feasible and suitable for real-time coordinate prediction of high-speed railway large-span cable-stayed bridges, providing a new method for track engineering construction. [ABSTRACT FROM AUTHOR]

The bridge influence line can effectively reflect its overall structural stiffness, and it has been used in the studies of safety assessment, model updating, and the dynamic weighing of bridges. To accurately obtain the influence line of a bridge, an Empirical and Variational Mixed Modal Decomposition (E-VMD) method is used to remove the dynamic component from the vehicle-induced deflection response of a bridge, which requires the preset fundamental frequency of the structure to be used as the cutoff frequency for the intrinsic modal decomposition operation. However, the true fundamental frequency is often obtained from the picker, and the testing process requires the interruption of traffic to carry out the mode decomposition. To realize the rapid testing of the influence lines of bridges, a new method of indirectly identifying the operational modal frequency and deflection influence lines of bridge structures from the axle dynamic response is proposed as an example of cable-stayed bridge structures. Based on the energy method, an analytical solution of the first-order frequency of vertical bending is obtained for a short-tower cable-stayed bridge, which can be used as the initial base frequency to roughly measure the deflection influence line of the cable-stayed bridge. The residual difference between the deflection response and the roughly measured influence line under the excitation of the vehicle is operated by Fast Fourier Transform, from which the operational fundamental frequency identification of the bridge is realized. Using the operational fundamental frequency as the cutoff frequency and comparing the influence-line identification equations, the empirical variational mixed modal decomposition, and the Tikhonov regularization to establish a more accurate identification of the deflection influence line, the deflection influence line is finally identified. The accuracy and practicality of the proposed method are verified by real cable-stayed bridge engineering cases. The results show that the relative error between the recognized bridge fundamental frequency and the measured fundamental frequency is 0.32%, and the relative error of the recognized deflection influence line is 0.83%. The identification value of the deflection influence line has a certain precision. [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 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 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 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.)

A beam's Neutral Axis (NA) is a parameter that has been utilized to detect damage. Its position depends on the geometry of the cross-section and also a member's axial loads. Shifts in its position can indicate changes in either load distribution or geometric characteristics. When considering structures such as cable-stayed bridges where the inclined cables induce significant axial forces, the effect of axial loads on NA position is significant. In this research, a simplified analytical model was developed consisting of the key elements of a cable-stayed bridge (beam, cable, and bearing). The model was loaded with a vertical point load representing a vehicle load. The NA position was calculated beneath the load as it moves over the length of the beam. By changing element properties, one can observe how the NA position behaves in different locations of the beam, due to simulated damage in the beam, cable, or bearing. It was found that changes in NA position can capture not only whether damage has occurred, but also in which component of the structure the damage is located (beam, cable, or bearing). This ability to use NA position for damage identification renders it an excellent parameter for monitoring cable-stayed bridges. [ABSTRACT FROM AUTHOR]

Excessive vibration of stay cables in strong winds has been a concern for bridge operators, which impairs the durability of both the cables and the bridge structure. This paper develops a data-driven approach to predict the amplitude of the cable vibration using an ensemble learning model. The model aims to predict cable vibrations in both in-plane and out-of-plane directions, with the wind speed, wind direction, turbulence intensity, and deck acceleration as input variables. Especially, the deck acceleration is included considering the deck-cable interaction and vehicle effects, which significantly improved the accuracy of the prediction. Furthermore, the model is interpreted with local interpretable model-agnostic explanations (LIME) and partial dependence plot (PDP) methods. The former demonstrates the relative importance of input variables on a global scale, and the latter indicates the correlation between individual input variables with the prediction target. The investigation is validated using the data harnessed from structural health monitoring (SHM) of a 1088-m cable-stayed bridge during three typhoon events. The adopted Gradient boosting regression tree (GBRT) model demonstrated better performance than other state-of-the-art machine learning models. The developed approach can provide guidance on preventive maintenance of stay cables to avoid damage due to excessive vibration. [ABSTRACT FROM AUTHOR]

Abstract In order to identify the time-varying frequency and amplitude of structural vibration based on the bridge structural health monitoring data and obtain the cable force of cable-stayed bridges in real time, a spectrum analysis method based on amplitude and phase estimation (APES) was proposed in this study. The amplitude spectrum of the acceleration data is first calculated by the APES method, the real-time spectrogram of the cable is obtained by the sliding window method. Then the modal frequency and amplitude are automatically extracted from the real-time spectrum by using a frequency extrusion post-processing technique, which can be regarded as the average value of the instantaneous frequency and amplitude respectively. Next, the fundamental frequency of the cable is extracted by using an automatic identification method, and the performance of the proposed method is verified. Finally, real-time scoring of cable forces and structural condition assessment is achieved with consideration of the moderation index model as well as the material strength. The results show that the APES method can use shorter calculation samples than the traditional Fast Fourier Transform (FFT) to obtain higher resolution and more accurate amplitude, which provides a theoretical basis for the real-time identification of fundamental frequency based on short-term monitoring data. The frequency extrusion post-processing-algorithm can reduce the spectrum recognition delay and improve timeliness of the cable force evaluation. The time-varying cable force with an interval of 10 s can be used to reflect the health status of the cable in time. The research results can provide technical support for the real-time extraction of cable force of long-span cable-stayed bridges, and can also provide an effective basis for component condition evaluation and bridge maintenance decision-making.

Due to the harsh working environments of certain bridges, the bridge structural health monitoring systems (SHMs) are prone to error warning because of anomaly data. Therefore, it is of great significance to accurately classify and locate the anomaly data for effectively addressing these issues. This paper proposes a method for classifying and locating anomaly data utilizing one-dimensional monitoring data based on convolutional neural networks. Compared to previous research reliant on visual features, the proposed method has lower computational costs. By incorporating the anomaly data localization network, manual localization operations for data restoration are replaced. The analysis in this paper is based on monitoring data from a large-span cable-stayed bridge, along with artificially generated anomaly data. The two neural network frameworks proposed in this paper are trained and validated, showcasing precise classification and localization of anomaly data. Furthermore, the paper discusses the impact of common errors in labeling data categories and locating training samples in practical operations. The results demonstrate that even in the presence of noticeable yet non-extreme labeling errors in the training set, the proposed method still achieves accurate classification and localization, highlighting its robustness. [ABSTRACT FROM AUTHOR]

A semi-floating cable-stayed bridge can swing longitudinally to absorb seismic energy in an earthquake for the purpose of reducing structural response. However, the large transverse (lateral) seismic response of such large-span cable-stayed bridges must be controlled to avoid severe bridge damage and ensure train safety. This study investigates the dynamic response and associated damping mechanism of a coupled high-speed rail (HSR) vehicle and cable-stayed bridge system subjected to various ground motions. A comprehensive vehicle–track–bridge interaction system is first established. Then, the dynamics of a semi-floating cable-stayed bridge-HSR vehicle system equipped with magnetorheological bearings (MRBs) and fluid viscous dampers (FVDs) is examined with various inputs of near-fault (NF) pulse-type, NF non-pulse-type, and far-field (FF) ground motions. To effectively mitigate the bridge internal force response and enhance train running safety, the transverse and longitudinal FVDs need to be concurrently utilized along with MRBs. This research presents a novel mitigation approach for simultaneously reducing the transverse vibrations of cable-stayed bridge and the derailment risk of running train. [ABSTRACT FROM AUTHOR]

Aiming at the problems of large capacity, narrow transverse width, large excitation, high safety level, and difficulty in accurately grasping the working state of the cable-stayed bridge for the long-span track, this research obtains the structural response data in real time by establishing a health monitoring system. The adaptive filtering method was employed to separate the train load response and the temperature load response. Then, a train load effect analysis method based on the influence line and a temperature load effect analysis method based on the correlation were proposed to assess the operational status of the bridge in real time and objectively. The Chongqing Nanjimen Railway Track Bridge (hereinafter Chongqing Nanjimen track bridge) project was utilized as a case study to demonstrate the application of these methods. The results show that the adaptive filtering method can effectively separate the response of train and temperature loads. The normalized cross-correlation (NCC) results of the measured train load response and the influence line's finite element calculation show a high degree of fit between the measured values and the theory, proving that no significant anomalies are found in the bridge. There is a strong correlation between the ambient temperature difference and the Pearson correlation coefficient of structural response, which indicates that the Chongqing Nanjimen track bridge is currently in normal working condition. [ABSTRACT FROM AUTHOR]

The data quality determines the reliability of big data‐based bridge condition assessments. However, rapidly discerning data conditions and identifying low‐quality data segments pose considerable challenges. This study introduces a transformer‐based autoencoder neural network for rapid data quality assessment in bridge health monitoring. The average Euclidean distance was used to quantify the dispersion of multiple hidden variables, and the overall quality of the multiple data fragments was quantitatively evaluated. Moreover, a method was introduced to calculate the adaptive thresholds based on the Euclidean distance. The application to the acceleration data of a cable‐stayed bridge demonstrates that the proposed method can extract hidden variables from acceleration data segments of length 3000. The network achieves a high compression rate of 1/1500, and the extracted hidden variables retain pertinent information regarding data quality. The proposed approach is data‐driven and exhibits significant advantages in efficiency, accuracy, and user‐friendliness. [ABSTRACT FROM AUTHOR]

Cables are vital load-bearing components of cable-stayed bridges. Surface defects can lead to internal corrosion and fracturing, significantly impacting the stability of the bridge structure. The detection of surface defects from bridge cable images faces numerous challenges, including shadow disturbances due to uneven lighting and difficulties in addressing multiscale defect features. To address these challenges, this paper proposes a novel and cost-effective deep learning segmentation network, named Trans-DCN, to detect defects in the surface of the bridge cable. The network leverages an efficient Transformer-based encoder and integrates multiscale features to overcome the limitations associated with local feature inadequacy. The decoder implements an atrous Deformable Convolution (DCN) pyramid and dynamically fuses low-level feature information to perceive the complex distribution of defects. The effectiveness of Trans-DCN is evaluated by comparing it with state-of-the-art segmentation baseline models using a dataset comprising cable bridge defect images. Experimental results demonstrate that our network outperforms the state-of-the-art network SegFormer, achieving a 27.1% reduction in GFLOPs, a 1.2% increase in mean Intersection over Union, and a 1.5% increase in the F1 score. Ablation experiments confirmed the effectiveness of each module within our network, further substantiating the significant validity and advantages of Trans-DCN in the task of bridge cable defect segmentation. The network proposed in this paper provides an effective solution for downstream cable bridge image analysis. [ABSTRACT FROM AUTHOR]

For some long span cable supported bridges, the longitudinal diaphragms in main girder are designed as steel truss to reduce structural self-weight. However, unanticipated fatigue cracking in critical details of longitudinal steel truss diaphragm may occur after only a few years of service, resulting in stiffness weakening and stress redistribution. Based on an actual cable-stayed bridge, this paper presents a fatigue analysis of longitudinal steel truss diaphragms and provide an effective strengthening measure to elongate the fatigue life. Using traffic information from bridge toll station, the fatigue vehicle models were established. Then, a multi-scale finite element (FE) model was developed to help determining critical details of potential cracking and calculating the vehicle induced stress. After obtaining the required parameters, fatigue life of the specific critical detail was estimated base on damage accumulation law. The result agrees well with field observation. To ensure the performance of steel girder, the strengthening measure that replace diagonal tubes in longitudinal steel truss diaphragm with bolted channel steels was proposed and then applied. The assessment result indicated that the provided strengthening measure achieves satisfactory effects. It can also provide experience and partial reference for maintenance of similar structures. [ABSTRACT FROM AUTHOR]

Current research on overvoltage in trains can be divided into field tests and circuit simulations. The circuit simulation study focuses on the overvoltage amplitude distribution, the oscillation frequency of the main operating overvoltage is also an important characteristic, and the amplitude and frequency characteristics of the overvoltage need to be considered in the study of its suppression method. However, there is currently limited research on the frequency distribution of overvoltage. To provide guidance for the study of overvoltage suppression in the operation of the main circuit breaker, a new simulation model of train operating main break overvoltage is proposed based on the three-dimensional structure of the car body, high-voltage cables and rails. The model is used to simulate the transient overvoltage characteristics of the high-voltage cable core and each car body during the operation of the main circuit breaker, and the distribution of the overvoltage in each car body is obtained. The simulation results show that the maximum overvoltage amplitude during the operation of car 1 is 6.10 kV, while it is the smallest for car 4. The overvoltage amplitudes of cars 1 to 4 are all above 1 kV, and it was found that there are two main oscillation frequencies of the main overvoltage during the operation of the car body, which are 0.70 MHz and 1.30 MHz. Furthermore, the accuracy of the distribution characteristics and spectral characteristics of the train operating main break overvoltage is verified by static tests on the existing trains, and the test data show that the simulation results are extremely accurate in terms of overvoltage amplitude distribution, and the error between simulation and test does not exceed 5% in terms of amplitude, except for car 4. In terms of spectral characteristics, both simulation and experiment have two main oscillation frequencies, which can be considered consistent between simulation and experiment. Therefore, it can be concluded that the simulation model based on the three-dimensional structure has the ability to simulate the characteristics of operating overvoltage with high accuracy and provides guidance for overvoltage suppression research. [ABSTRACT FROM AUTHOR]

Structural health monitoring (SHM) of cable-stayed bridges requires periodic assessment for the deteriorating stay cables to ensure a long-term service life of the bridge. However, conducting the non-destructive SHM for operating cable-stayed bridges and analyzing the safety statuses of all the working cables are still challenging, due to the lack of in situ cable data for previously constructed bridges. This study developed an innovative framework of health condition assessment for stay cables based on cable vibration frequencies from an interferometric radar (IBIS-FS) using engineering reliability analysis (ERA). Taking a cable-stayed bridge in Victoria, Australia as a target structure for the case study, it shows that the presented framework can remotely monitor the accurate real-time load bearing conditions of stay cables by calculating tension forces, and effectively assess their health conditions. The results show that the natural frequency (up to the fifth mode) of a healthy cable remains constant under different external loadings but varies for damaged cables. The measured reliability index of all the stay cables is higher than the safety threshold factor at ultimate limit states, while one carries tension force higher than the maximum design load (lower than the minimum breaking load) and other three cables need to be monitored regularly due to their low reliability indices. This is attributed to an integrated effect of applied tension force, cable diameters, and minimum breaking loads. [ABSTRACT FROM AUTHOR]

In this paper, the reliability of a cable-stayed bridge with a span of 640m is investigated and compared in three different scenarios. While both the first and second scenarios assumed a fixed end for the bridge supports used, they differed in terms of material and geometric behavior. Finally, the third scenario differed from the second by incorporating a soil–pile–structure interaction (SPSI) to account for the flexibility of the underlying support. This study accounts for uncertainties in the structure, pile, and soil parameters. The Latin hypercube sampling (LHS) method and dynamic time history analysis were used to estimate the structural responses. Artificial earthquake records at four different risk levels are used for the dynamic time history analysis. Using the machine learning method, several additional results were generated and used in the seismic reliability evaluation. In the case where the SPSI was a simulation, the reliability analysis showed a higher probability of cable failure than other criteria. The element of the tower in the fixed support case also has a high probability of failure. The results of the reliability analysis of the nonlinear models showed a higher probability of failure for a cable-stayed bridge on flexible support than on fixed support. [ABSTRACT FROM AUTHOR]

Utilizing the high strengths, toughness, and durability of ultra-high-performance concrete (UHPC), a segmentally prefabricated orthotropic steel–UHPC composite deck (POSUCD) system has been developed for long-span cable-stayed bridges. The deck system combines an orthotropic steel deck (OSD) with a reinforced UHPC layer using notched perfobond strips (NPBLs). The UHPC layer is prefabricated onto the OSD of the girder segment in the factory to form the POSUCD. After the precast UHPC layer is cured, the girder segments are transported to the bridge site and assembled. The precast UHPC layers are then connected via transverse wet joints before tensioning stay cables. Against the background of the Danjiangkou Reservoir Bridge with a main span of 760 m, finite element (FE) analysis was conducted to examine the stress state and flexural tests were carried out on local full-scale models to verify the feasibility of POSUCD. The results show that the prefabricated UHPC layer reduces the maximum static compressive stress of the steel deck in the girder system by 21%, and the stress ranges at fatigue-prone details of the steel deck are decreased by 28%–90% compared to traditional OSDs with asphalt overlay. Since the prefabricated UHPC layer helps withstand dead axial load in the main girder, the high compressive strengths of UHPC can be utilized more effectively than in deck systems with UHPC only used as a cast-in-situ overlay to resist vehicular wheel loads. The transverse wet joint interfaces were identified as the weakest aspect of the POSUCD, whether under tension or compression; however, their nominal flexural strengths along the longitudinal direction meet the required design standards. The shear resistance of NPBLs was also well confirmed by the minimal interfacial slip on the specimen when it reached the ultimate capacity under positive bending moment. [ABSTRACT FROM AUTHOR]

During strong earthquakes, pounding may occur on large-span bridges and their approach bridges. The effect and mitigation measures of such pounding have rarely been explored in previous studies. This paper primarily uses finite element models to investigate the pounding effects at the expansion joints between the main cable-stayed bridge and its approach bridge. Friction pendulum bearings (FPBs) and fluid viscous dampers (FVDs) are used to alleviate poundings. Furthermore, a detailed analysis is conducted on how the pounding effect of the isolated main bridge with FPBs and FVDs is affected by the wave passage effect, ground motion type, and soil type. This study reveals that FPBs and FVDs can effectively reduce pounding effects and the associated risks. Even with the installation of FPBs and FVDs, lower seismic wave velocities and near-fault seismic motions with pulse effects can significantly increase the pounding effects between the cable-stayed bridge and its approach bridge. [ABSTRACT FROM AUTHOR]

In recent years, the safety of cables of cable‐stayed bridges has attracted extensive attention, and the rise of radar technology has provided new possibilities for the performance testing of cable‐stayed bridges. In this regard, this paper introduces the principle of microwave radar measurement technology and uses the microwave cable force measuring instrument to perform noncontact microwave radar cable force measurement on a total of 72 stay cables in Shifeng Bridge and San‐Jiadian Bridge compared with the measurement results of the cloud smart collector. The results show that the fundamental frequency deviation rate of 71 cables is within 3%, and the cable force deviation rate of 67 cables is within 5%. This shows that the microwave radar cable force measurement method has a high degree of reliability and accuracy; meanwhile, it is also found that the forces on the left and right sides of the two bridges are in a symmetrical state, and the structure is in good condition; the signal characteristics are obvious, and the simultaneous measurement of multiple cables can be realized, and it is not limited by weather, site, and the length of the stay cable and has strong practical value. [ABSTRACT FROM AUTHOR]

This article proposes an innovative concept of an intelligent bridge system that integrates sensors, a processing unit, and an actuator to maintain bridge safety and performance even in the face of unexpected environmental changes and disturbances. Although technically challenging, this system is an exciting prospect for young engineers who aspire to contribute to cutting-edge technological advancements. As a practical example, this article presents an ICT-based bridge remote monitoring system called the "Intelligent Bridge," which allows real-time monitoring and control during extreme events such as earthquakes and typhoons. The Intelligent Bridge comprises a stand-alone monitoring system and a web-based internet monitoring system for bridge maintenance, which is introduced as an intelligent structure integrated into the intelligent bridge system. To verify the validity of the proposed system, it is investigated the ability to adjust cable forces on a 2-span continuous cable-stayed bridge model to control its structural performance. The development of an intelligent bridge system represents a significant advancement in bridge engineering and has the potential to improve the safety and longevity of bridges, particularly in areas prone to extreme environmental events. The system proposed in this article has practical applications that can benefit both engineers and the general public. [ABSTRACT FROM AUTHOR]

The transverse seismic behavior of a long-span cable-stayed bridge with two inverted Y-shaped reinforced concrete towers is investigated in this study. To accomplish this, a 1/35-scale model of a cable-stayed bridge with a span of 1088 m was designed, constructed, and tested until failure on four shake tables; the test was conducted at Tongji University, China. A site-specific artificial wave was applied in the transverse direction. Moreover, the input peak ground acceleration was increased from 0.1 g to 1.3 g until the test model failed. The transverse displacement, force, rebar strain, and curvature responses of the bridge model are obtained and studied. The test results showed that the transverse displacement response of the tower was significantly affected by high-order modes. This resulted in the maximum seismic displacement of the tower at the middle – upper level of the middle column except for the tower top. The ratio of the transverse seismic forces acting on the towers significantly exceeded that of the forces acting on the piers. In the final test case, severe damage, including concrete crushing and rebar exposure, occurred at the bottom of the middle column – the most critical part of the tower – leading to the inclination of the tower. Damage to the cables or deck was not observed. The finite element model captured the elastic transverse seismic behavior of the test model. [ABSTRACT FROM AUTHOR]

Studies on cable-stayed bridges exposed to blast loads encounter significant challenges arising from the complex interaction among different structural elements. Despite extensive investigation into how buildings respond to explosive loads, there is limited literature on the dynamic response of prestressed concrete bridge decks to blast loads. Single plane cable stayed bridges are very sensitive to cable loss or degradation. This study investigates the response of a prestressed concrete cable-stayed bridge with a single plane under blast loads, utilizing a comprehensive Finite Element (FE) model that incorporates nonlinear effects. The investigation considers blast weights of 230 kg, 680 kg, and 2270 kg of TNT. The analysis reveals that even small explosions cause damage to the deck, with more significant effects observed under higher blast loads, resulting in a damaged region measuring 12 m x 10 m with a 2270 kg TNT weight. Forces in cables near the detonation point increase by 19% during a 2270 kg TNT explosion. Notable changes are observed in pylon moments under different explosion charges. Maximum Bending Moment (BM) values are observed at the base under dead loads, while BMs at mid-height increase under various blast weights, with no discernible change at the base. This study provides valuable insights for designers, emphasizing the importance of incorporating explosion-resistant design principles into cable-stayed bridges. [ABSTRACT FROM AUTHOR]

The regular monitoring of cable forces is essential for ensuring the safety of cable structures both during construction and throughout their lifetime. This paper aims at developing a vibration-based identification procedure of the axial forces, bending stiffness, and, secondarily, the crossing point position of cable networks. A model constituted by two crossing stays having small bending stiffness and negligible sag effects is considered. The in-plane direct dynamic problem is solved both numerically and through a perturbation approach. The obtained results are compared to the outcomes of a finite element model for verification purposes. The theoretical studies are also supported by experimental tests performed on a real cable-stayed bridge (Haccourt bridge), which provide insights into the dynamics of the system showing that models of cables with small bending stiffness are more appropriate than taut string models. The inverse analysis based on non-linear Bayesian regression is developed and the closed-form asymptotic formulations are used to prove that the bending stiffness, the cable forces, and the crossing point position can be separately identified from a set of observed frequencies. The implemented procedure is then applied to the tested bridge as a proof of concept, showing that the proposed in-plane identification strategy provides satisfactory results. [ABSTRACT FROM AUTHOR]

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced vibrations. However, complicated finite element (FE) modeling, together with repetitive and computationally intensive nonlinear time-history analyses (NTHAs) are generally required in conventional design methods. To streamline the preliminary design process, this paper developed a simplified longitudinal double degree of freedom model (DDFM) for single and symmetric twin-tower cable-stayed bridges. Based on the proposed simplified longitudinal DDFM, the analytical equations for the relevant mass- and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy methods. Modeling of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization method. Additionally, the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were derived. Based on the developed simplified DDFM and suggested analytical equations, this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper parameters. Moreover, the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed bridge. Finally, the results indicated the following. 1) For the obtained fundamental period and longitudinal stiffness, the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05% and 1.5%, respectively. 2) Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%. 3) The equivalent damping ratio of nonlinear viscous dampers and the applied loading frequency had significant effects on the longitudinal seismic responses of the bridge. Findings of this study may provide beneficial information for a design office to make a simplified preliminary design scheme to determine the appropriate nonlinear damper parameters and longitudinal seismic responses for long-span cable-stayed bridges. [ABSTRACT FROM AUTHOR]

This study addresses the issue of inaccurate single damage fingerprint recognition during the process of bridge damage identification. To improve accuracy, the proposed approach involves fusing displacement mode difference and curvature mode difference data for single damage identification, and curvature mode difference and displacement mode wavelet coefficient difference data for two damage identification. The methodology begins by establishing a finite element model of the cable-stayed bridge and obtaining the original damage fingerprints, displacement modes, curvature modes, and wavelet coefficient differences of displacement modes through modal analysis. A fusion program based on the D-S evidence theory criterion is then developed using Matlab to calculate the displacement mode difference (DMD), curvature mode difference (CMD), and wavelet coefficient difference of displacement mode (WCDM) for data fusion. The recognition effect of a single fingerprint is analyzed using modal data for both single and two damage conditions. Additionally, the fusion of multiple fingerprint initial data is performed, and the recognition effect of the data fusion method is quantitatively analyzed through sub peak to peak comparison. It is observed that when the fusion index is used as the recognition index, the sub peak to peak ratio is smaller compared to using the curvature mode as the damage index. Consequently, the reduction in single damage is more significant, ranging from 12% to 48%, while the reduction in multi damage is approximately 2%. This method demonstrates the ability to accurately identify the location of damage, yielding satisfactory recognition results and showing promising feasibility. [ABSTRACT FROM AUTHOR]

In order to explore the failure mode of the cable-stayed pipe bridge under earthquake action, taking the structural system of an oil and gas pipeline–cable-stayed pipe bridge as the research object, the full-scale finite element calculation model of the cable-stayed pipe bridge–oil and gas pipeline structural system as well as the finite element calculation model considering the additional mass of the oil and gas medium and the fluid–structure interaction effect were established by using ANSYS Workbench finite element software. The stress and displacement of the cable under the earthquake action were analyzed in the time history, as were the response characteristics of the cable when subjected to both methods. The calculation results show that the overall failure of the pipeline is basically the same under the two methods. Compared with the additional mass method, the solution for the fluid–structure coupling method can be derived through a comprehensive analysis of the flow field and structure, respectively, avoiding the sudden change caused by model simplification or calculation error so that the analysis results can better simulate the actual situation. In summary, the fluid–structure interaction method enables a more precise prediction of the dynamic response of the structure, and the findings of this research can provide a theoretical foundation and technical guidance for optimizing the seismic performance of cable-stayed pipe bridges. [ABSTRACT FROM AUTHOR]