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With the continuous increase of bridge spans, wind-induced vibrations will pose serious problems to structural integrity and serviceability. Among the many vibration sources of long-span bridges, buffeting, which results from impinging turbulence, affects the fatigue life of the bridge structure, and when coupled with other wind-induced loads, might lead to severe structural problems. With climate change, buffeting-induced fatigue might significantly increase due to higher wind speeds and turbulence intensities. Therefore, it is important to assess the cumulative fatigue damage generated by buffeting loads under changing climate scenarios. In this study, the buffeting response of a single-span suspension bridge is investigated in the frequency domain under the Worst-case climate scenario RCP8.5. A simplified bridge model will be used to capture key dynamic and aerodynamic characteristics, with a time-dependent Weibull distribution accounting for nonstationarity in wind speed. The analysis of fatigue damage accumulation under buffeting will involve the rain-flow cycle counting method and the Palmgren–Miner damage law. Three Canadian cities, Montreal, Toronto, and Vancouver, will be included in the study to assess how location, along with the climate scenario, influences the life-cycle buffeting-induced accumulated damage over a 100-year period. [ABSTRACT FROM AUTHOR]

The large amount of data collected by structural health monitoring systems deployed in the bridge contains dynamic information about the structure. To enhance the prediction accuracy of the structural dynamic responses and to evaluate the frequencies from predicted restructured responses, this paper develops an approach of optimized variational mode decomposition (OVMD) combined with a genetic algorithm-back propagation (GA-BP) neural network. The procedure is first to establish the OVMD algorithm using relative root mean square error (RRMSE) and correlation coefficient to determine reasonable decomposition and retention of the intrinsic mode function (IMF) components in the response decomposition. Then each retained IMF component is used as input to the GA-BP for prediction. Finally, the frequencies and their characteristics of the structure are estimated from the predicted restructured responses. A damaged arch bridge test shows that OVMD overcomes the shortcomings of VMD, decomposes and reconstructs the signals effectively, and outperforms the other three methods in denoising. The experimental results of the long-span cable-stayed bridge prove that OVMD combined with GA-BP has higher prediction accuracy for the dynamic responses with high sampling rates. The structural frequencies are correctly determined from predicted recombined displacement and acceleration responses. This approach provides a useful tool for bridge dynamic response decomposition, reconstruction, prediction, and structural frequency evaluation. [ABSTRACT FROM AUTHOR]

Purpose – The bridge expansion joint (BEJ) is a key device for accommodating spatial displacement at the beam end, and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge. For long-span railway bridges, it must also be coordinated with rail expansion joint (REJ), which is necessary to accommodate the expansion and contraction of, and reducing longitudinal stress in, the rails. The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway (HSR) long-span bridges in China, and to propose a performance-based integral design method for BEJs used with REJs, from both theoretical and engineering perspectives. Design/methodology/approach – The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development. Results of a survey of typical BEJ faults were analyzed, and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load. Based on the above, a performance-based integral design method for BEJs with maximum expansion range 1600 mm (±800 mm), was proposed, covering all stages from overall conceptual design to consideration of detailed structural design issues. The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios, full-scale model testing, and field testing and commissioning. Findings – Two major types of BEJs, deck-type and through-type, are used in HSR long-span bridges in China. Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap, abnormally large longitudinal frictional resistance, and flexural deformation of the scissor mechanisms. These faults influence BEJ functioning, and thus adversely affect track quality and train running performance at the beam end. Due to their simple and integral structure, deck-type BEJs with expansion range 1200 mm (± 600 mm) or less have been favored as a solution offering improved operational conditions, and have emerged as a standard design. However, when the expansion range exceeds the above-mentioned value, special design work becomes necessary. Therefore, based on engineering practice, a performance-based integral design method for BEJs used with REJs was proposed, taking into account four major categories of performance requirements, i.e., mechanical characteristics, train running quality, durability and insulation performance. Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ; the latter factor in particular has a decisive influence on train running performance at the beam end. Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface. The static and dynamic performance of the newly-designed BEJ with expansion range 1600 mm have been confirmed to be satisfactory, via numerical simulation, full-scale model testing, and field testing and commissioning. Originality/value – This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China, along with novel insights into their design.

The complex deformation of large-span high-speed railway bridges, influenced by factors such as thermal load, poses a challenge in the acceptance inspection of track irregularity quality on the bridges. To quickly establish targeted maintenance and repair standards for kilometer-span high-speed railway bridges, time-frequency distribution characteristics of track irregularities were analyzed using dynamic and static track irregularity detection data from existing kilometer-span high-speed railway bridges in China as samples. The accumulated data over the course of a year was examined using the mid-chord method, vector distance difference method, and track irregularity power spectral method. The results showed that, in the time domain, the dynamic and static track irregularity over-limit points on suspension and cable-stayed bridges were mainly located at the bridge piers and mid-spans. The amplitudes of track irregularities were elevated at the rail expansion joints installed at the ends of the suspension bridges, requiring timely control of the irregularity amplitude at critical positions on the bridges. In terms of frequency-domain characteristics, the track spectra of kilometer-span high-speed railway bridges exhibited a change pattern roughly similar to the ballasted track irregularities on high-speed railways in China. A combined analysis of dynamic and static power spectra revealed that the track spectrum of kilometer-span high-speed railway bridges, in the medium-and long-wavelength frequency bands for high and low irregularities, was mainly located between the ballast spectrum of China and the low-interference spectrum of Germany. Among them, the overall performance of the kilometer-span suspension bridges was significantly inferior to that of the kilometer-span cable-stayed bridges in the long-wavelength band around 100 m and in the medium-and short-wavelength band below 10 m. Both bridge types commonly showed periodic wavelength components of 1 ~ 3 m and 8 ~ 12 m. Daily railway maintenance operations should continue to address rail smoothness issues caused by factors such as irregularities in new rails and weld joints. [ABSTRACT FROM AUTHOR]

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

A method based on particle swarm optimization algorithm-generalized regression neural network (PSO-GRNN) was proposed for high-precision updating of the finite element model of large-span bridges. In this method, the generalized regression neural network (GRNN) was employed to describe the complex nonlinear relationship between the output of the finite element model and the parameters to be updated, and the particle swarm optimization (PSO) algorithm was adopted to optimize the smoothness factor of GRNN. The proposed updating method was verified using the finite element model of a long-span steel box girder suspension bridge. The results indicate that the GRNN optimized by PSO can more accurately describe the nonlinear relationship between frequencies and the parameters to be updated, and the prediction errors are significantly reduced. Compared with the error back propagation neural network method, the updated frequency errors of the GRNN and PSO-GRNN method are smaller. Due to the optimization of PSO, the updated frequency error of the PSO-GRNN based updating method is further reduced, and the maximum error is less than 5% . The updating method based on PSO-GRNN can be used for updating finite element models of various large-span bridges. [ABSTRACT FROM AUTHOR]

The traditional nonlinear aerostatic instability of long-span bridges is based on a two-layer iteration method that accurately predicts the structural equilibrium path before the critical buckling point. Due to strong nonlinearity after buckling, this traditional method cannot easily calculate the structural equilibrium and possible bifurcation using either Newton–Raphson or arc-length methods. In this study, a reduced order modeling (ROM) method for long-span bridge aerostatic deformation is proposed to approximate the bridge aerostatic equilibrium path after the critical point. The structural deformation mode shapes are extracted through singular value decomposition performed on the deformation matrix, and the nonlinear structural stiffness matrix is determined through the indirect displacement-based method on the finite-element method (FEM) platform. The ROM method is validated through comparison against the aerostatic deformation by the traditional two-layer iteration method based on FEM. By extending to higher wind speed, the ROM method can approximate the bridge deformation after initial buckling, and pitchfork bifurcation is observed after the structure undergoes rapid deformation growth. The stability of the equilibrium paths is examined through the Jacobian of restoring force vector, and the "snap-through" phenomenon exists for the equilibrium path before the bifurcation point. [ABSTRACT FROM AUTHOR]

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Purpose – Express freight transportation is in rapid development currently. Owing to the higher speed of express freight train, the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge. Besides, the blunt car body of vehicle has poor aerodynamic characteristics, bringing a greater challenge on the running stability in the crosswind. Design/methodology/approach – In this study, the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test. The dynamic model of the train-long-span steel truss bridge coupling system is established, and the dynamic response as well as the running safety of vehicle are evaluated. Findings – The results show that wind speed has a significant influence on running safety, which is mainly reflected in the over-limitation of wheel unloading rate. The wind speed limit decreases with train speed, and it reduces to 18.83 m/s when the train speed is 160 km/h. Originality/value – This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems. It also provides a new theoretical basis for the safety assessment of express freight trains.

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

The comfort of maglev trains is related to the vibration in the passenger area of the vehicle and is determined by the acceleration and impact in three directions as the train passes over the track. The comfort of the maglev track is achieved by limiting the maximum acceleration and impact to not exceed specified limits. Unlike small-span maglev bridges, long-span bridges experience changes in deck alignment under the effects of temperature, wind load, and train load, which directly affect the vertical curve alignment of the bridge track. Based on the existing technical standards and related calculation principles and methods for vertical and horizontal curve minimum radii in current maglev track design, the relationships among the vertical acceleration, impact, and alignment and bending angles of the bridge track at the train operating velocity are determined. By verifying the instantaneous deformation curves of the bridge deck using the representative positions of the train's head, middle (center of the car length), and tail during travel, the technical index for the comfort of the bridge track during instantaneous bridge deformation are established. This paper provides the calculation loading method and results for the comfort of long-span bridges using a specific long-span maglev bridge as an example.

Long-span bridges, which are critical nodes of the nation's infrastructure system, are frequently exposed to extreme hazards, such as flood, scour, hurricane, earthquake, blast, and impact. In spite of their importance, the structural robustness of long-span bridges is not well understood and has not been adequately quantified. Traditional design approaches are unable to provide explicit measures of residual safety of long-span bridges. Current evaluation approaches to ensure safety through redundancy in the event of any localized damage are mainly intended for short- to medium-span bridges. Therefore, a new robustness evaluation approach that is well suited for short-, medium- as well as long-span bridges is proposed. Applicability and versatility of this approach is demonstrated on a three-span I-girder bridge and three long-span cable-supported bridges and the results are compared with those from available approaches. A significant advantage of this approach is its ability to account for and estimate structural robustness corresponding to different user-specified initiating events and different user-specified limit states on a common and unified basis. Thus, unlike existing approaches, our approach can be used as a comprehensive tool to assess the safety of bridges in their intact and damaged conditions to facilitate critical decisions on design and retrofit needs. [ABSTRACT FROM AUTHOR]

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

Wind-induced stress analysis is essential for evaluating the local failure and fatigue damage of long-span bridges in wind-prone regions. Nevertheless, the accuracy of stress-level analysis can be affected by the choice of wind loading and structure models. This study formulates three scenarios to calculate the wind-induced response of a long-span bridge, incorporating two types of wind load models (lumped force or distributed force) and two types of finite element (FE) models (spine-beam or substructure). Specifically, Case 1 employs the lumped force and beam model, Case 2 adopts the lumped force and substructure model, and Case 3 utilizes the distributed force and substructure model. The aerodynamic parameters for forces and POD pressure modes are obtained through wind tunnel tests. By comparing the wind-induced structural response in terms of global behavior (displacement, acceleration) and local behavior (stress), the influence of wind loading and structure models is discussed. The findings reveal that employing a simplified beam model underestimates local stress, and neglecting wind load distribution leads to further underestimation. Therefore, the refined FE model and distributed wind load models are recommended for the precise assessment of wind-induced stresses in long-span bridges. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the influence of geometric nonlinearity on post-flutter responses by developing a full-mode coupled nonlinear flutter analysis method (frequency-domain method) and a time-dependent nonlinear analysis scheme (time-domain method). This approach integrates the three-dimensional (3D) nonlinear finite element model and nonlinear self-excited force described by amplitude-dependent rational functions (RFs). By comparing post-flutter responses obtained from frequency-domain and time-domain methods, not only the influence of geometric nonlinearity on post-flutter responses is quantified, but also the underlying physical mechanism is revealed. The results show that the geometric nonlinear effect will become more significant with the increase of the amplitude and thus will induce a super-harmonic resonance behavior. The behavior is mainly characterized by the higher harmonic frequencies vibrations with higher-order mode shapes involved in the vertical and torsional displacement responses. Meanwhile, the larger the vibration amplitude, the more significant the super-harmonic resonance behavior. Besides, the geometric nonlinear effect will also cause a significant uplifting of the bridge deck in the vertical direction during 3D nonlinear flutter process. The main physical mechanism for the reduction in the amplitude of post-flutter response (dominated by the vibration with fundamental harmonic frequency) after considering the geometric nonlinear behavior is that the vibrations with higher harmonic frequencies play a role of absorbing energy and reducing vibration (similar to tuned mass damper effect) for the vibration with fundamental harmonic frequency. For the long-span suspension bridge with a main span of 1650 m studied in this study, the geometric nonlinear effect may need to be considered when the torsional amplitude at mid-span is only greater than 1.5°. [ABSTRACT FROM AUTHOR]

A key component of infrastructure seismic risk assessment is the execution of nonlinear time-history analyses with a suite of selected ground motions scaled to site-specific spectra. When interested in the evaluation of distributed systems residing near major active faults, such an approach is challenged by the scarcity of records adequately incorporating region and site-specific features known to impact the nonlinear response of distributed infrastructure substantially (pulses, spectral shape, spatial variability). This paper assesses the differences in the seismic demand posed to a suspension bridge as obtained from real ground motions selected based on state-of-the-art methods and arrays of site-specific simulated ground motions generated from physics-based wave-propagation models. The objective is to characterize the biases in structural response estimates introduced by the use of real ground motions in code-compliant approaches. A total of 15 realizations of an M7 Hayward fault earthquake and a detailed nonlinear simulation model representative of the West San Francisco–Oakland Bay Bridge are utilized as a case study. Damage limit states associated with structural drifts are defined for each bridge component as a function of the spread of plasticity. The results indicate that the median and variability of the demands posed by the simulated motions and real ground motions scaled to the same site-specific spectra are markedly different. Evidence from this study highlights the sensitivity of complex structures to multiple characteristics of the ground motions that might be biased by current scaling methods. Finally, fundamental characteristics of the scaled records leading to differences in the bridge response are discussed providing the basis to inform current ground motion selection and scaling procedures. [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.)

The time-lag effect between temperature and thermal displacement may induce the displacement-based safety assessment results of long-span bridges to derivate from the truth. In this paper, the typical characteristics of the time-lag effect between temperature and thermal displacement are firstly investigated by using the synchronously monitored temperature and displacement data from a long-span steel box-girder arch bridge. And then, the inherent reasons of the time-lag effect are found out by employing the Kendall correlation coefficient. Following that, a general method derived from the Bayesian function registration model and the Z-mixture preconditioned Crank-Nicolson algorithm is proposed to compensate the time-lag effect. Finally, the proposed compensation method is verified by data from three bridges and compared with the traditional method achieved through shifting a fixed time interval. The results show that thermal displacement may be ahead of or lag behind temperature, depending on the temperature and thermal displacement of concern. The lag time varies from a few minutes to several hours with temperature and displacement variables, as well as time instants. The time-lag effect between temperature and thermal displacement is caused by the asynchronous change of the dominant temperature for the specific thermal displacement and other temperatures because of different material thermodynamic parameters and geometric characteristics of different bridge components. The developed compensation method can completely eliminate the time-lag effect between temperature and thermal displacement of various long-span bridges without any pre-correlation analysis and prior knowledge. The correlation between temperature and thermal displacement compensated by the method proposed in this paper is much stronger than that compensated by the traditional method. [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.)

The outer lanes and emergency lanes of the bridge deck of long-span bridges in which orthotropic steel deck is adopted were replaced with Ultra-High-Performance-Concrete (UHPC) composite deck to create a hybrid bridge deck system. A transverse connection detail was proposed to connect the two different bridge deck forms. Static bending tests and theoretical analysis were conducted on the transverse connection detail to obtain failure modes, ultimate load-carrying capacity, crack resistance, and the collaborative bending performance under positive and negative moments. A calculation method for the ultimate load-carrying capacity considering residual stresses in the UHPC after cracking was provided. The results show that the transverse connection detail has good plastic deformation capacity and collaboratively supports both sides of the bridge deck. The error in predicting the ultimate load-carrying capacity of specimens under positive bending moments using the proposed theoretical calculation method is 3.9%, and for specimens under negative bending moments, the load-carrying capacity is controlled by local buckling of the steel, with a 3.1% difference between theoretical and measured values. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) of long-span bridges can be of large amplitude, which can influence serviceability. Therefore, it is important to predict the response of vortex-induced vibration to aid the management of long-span bridges. A novel data-driven model is proposed to predict the time history of the dynamic response of VIV events. Specifically, the proposed model consists of gated recurrent unit (GRU) neural networks and the Newmark-beta method. GRU neural networks can perform accurate sequential prediction, and the Newmark-beta method can complement the physical meaning of the middle output of the proposed model. To aid the accurate prediction of the amplitude of VIV events, the proposed model employs weighted mean square error as the loss function, which can put more emphasis on the amplitude. The proposed model is validated on measured VIV events of a long-span suspension bridge. The weighted mean absolute percentage error and Pearson correlation coefficient of the trained model indicate the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

Purpose: This study is an attempt to illustrate and discuss multi-hazard interactions in vibration control of long-span bridges subjected to wind and seismic loads. Such bridges, being flexible structures, are inherently vulnerable to wind loads. However, some response parameters of such bridges, for example, tower and deck acceleration, can be significant during large earthquakes which produce ground motions with low-frequency content. Methods: To illustrate this problem, a case study of the Runyang Suspension Bridge (RSB) is used. A finite element model of the bridge is created and verified against published literature. A set of ground motions from large worldwide earthquakes and spatially varying wind velocity time series, simulated as a realization of a random field, are used to evaluate the bridge's dynamic response with and without control devices. The control devices applied in this study are passive-tuned mass dampers (TMDs). Careful investigation of the uncontrolled response of the bridge shows that while wind load is mainly important for the displacement of the bridge deck, seismic loads can induce significant acceleration of the tower and the deck. Since the response of the tower and the deck are coupled at some higher modes of vibration, seismic action, although most critical for the tower, is also relevant for deck acceleration. These observations indicate the need for a multi-performance-based control strategy. Results: It is found that TMDs optimal for reducing seismic-induced deck acceleration can lead to amplification of wind-induced deck displacement. At the same time, TMDs optimal for reducing wind-induced displacement response are, in some cases, harmful to seismic-induced deck acceleration. These results clearly show multi-hazard interaction in control performance. Conclusions: To account for this problem, a control strategy for the deck and tower's seismic and wind responses is investigated. This consists of TMDs placed at the top of each tower and 4 TMDs placed on the deck. By tuning the TMDs to different vibration modes of the bridge, the system is shown to be effective for both seismic and wind actions. [ABSTRACT FROM AUTHOR]

Pile foundation is the most important foundation type of long-span bridges, of which the ultimate load-bearing capacity affects the safety and sustainable performance of bridges. When constructing large-span bridges, the bridge site may be close to the adjacent fault zones, which seriously affects the safety and long-term performance of pile foundations, causing the failure and unsustainability of long-span bridges in their life-cycle service life. At present, there are no engineering design rules or methods for assessing the load-bearing capacity of the pile foundation near the fault zones. To study the influence of the fault zone on the loading-bearing capacity and sustainable performance of pile foundations, triaxial compression tests were carried out on the mylonite at the Yanji suspension bridge site near the Xiangfan–Guangji fault zone in Hubei Province. The mechanical properties of mylonite were reflected by the Mohr–Coulomb yield criterion, and a topographic and geological modeling method based on the multi-platform was established. Then, the ABAQUS finite element software was used to study the deformation, stress, failure modes, and sustainable performance of the pile foundation under different bridge load levels, analyze the safety of the pile foundation in the fracture zone, and summarize the ultimate bearing characteristics of the pile foundation. The results show that the whole pile and surrounding rock are basically elastic under the pressure of the designed load, the plastic zone of the pile foundation is mainly concentrated at the pile bottom, and the shear stress concentration zone of the pile is mainly manifested in the joint of the cap and pile and the interface between soft and hard rock. When the load is increased to 4 times the designed load, the stress concentration area of the pile body gradually shifts upward from the pile bottom, and the surrounding rock at the bottom forms an "X-shaped" shear failure zone. After 100 years of operation, the maximum compressive stress of piles reaches 28.6 MPa, which is 120% higher than that at the beginning of the bridge construction, indicating that the sustainable performance of the piles can withstand the effect of the fault zone over the designed service years. [ABSTRACT FROM AUTHOR]

To overall investigate the mechanical performance of resilient wheels to suppress the vehicle–bridge (especially LSB) coupled vibration, the coupled dynamic characteristics of metro train–LSB considering nonlinear resilient wheels are studied. Firstly, the mechanical property test of rubber of resilient wheel is designed and conducted, the mechanical characteristics of the nonlinear resilient wheel (NLRW) and linear resilient wheel (LRW) are discussed, and the dynamic model of LRW and NLRW are established. Then, based on train–track–bridge dynamic interaction theory, the coupled dynamic models of metro train–LSB considering LRW and NLRW are established, respectively. Adopting the established model, the dynamic influences of NLRW and LRW on the metro train–LSB coupled system are investigated by long-short wave irregularity excitation. The effects of damping characteristics of LRW and NLRW on the metro train–LSB system are discussed from the time–frequency domain. Results show that the wheel–rail vertical force of NLRW is smaller than that of LRW. The acceleration of the web, axle box, bogie, and car body of the NLRW is smaller than that of the LRW. The main frequency of wheel–rail vertical force under the action of NLRW and LRW is about 4 and 22 Hz. The main frequencies of the rim and web of the NLRW are about 25 Hz, while those of the LRW are about 50 and 25 Hz, respectively. The acceleration of the web of the NLRW is significantly smaller than that of the LRW. The main frequency of acceleration of the LSB is about 10 Hz, and the acceleration of the LSB under the action of NLRW is significantly less than that of the LRW when the frequency is in the range of 22–62 Hz. Vibrations of the metro train and LSB increase with the increase of speed, and the dynamic response of the metro train–LSB system under the action of NLRW is smaller than that of LRW. [ABSTRACT FROM AUTHOR]

This article focuses on the construction monitoring and control of a pre-stressed concrete continuous beam bridge, consisting of 13 spans. The goal is to ensure that the bridge structure meets the design requirements throughout the entire construction process. By comparing the theoretical and measured values of the bridge's alignment and stress during the cantilever construction, closure, and completion phases, it can be observed that the deflection deformation of the bridge is generally in agreement with the theoretical calculations. After the completion of the entire bridge, the measured elevations of each section have an error range of -18mm to 20mm compared to the design elevations, which satisfies the specifications. A comparison analysis of the measured and theoretical stress values at the root and mid-span of the cantilever indicates that the stress difference at the root is within the range of -0.2MPa to 0.2MPa, and the stress differences at the mid-span after completion are 0.03MPa (upper) and 0.09MPa (lower), all of which meet the structural design and code requirements. By establishing a gray GM (1,1) model and using gray system theory, the deflection error during the construction process is predicted and controlled. The prediction accuracy of different methods is compared to determine a reasonable prediction method suitable for long-span pre-stressed continuous beam bridges, providing reference for similar engineering projects. [ABSTRACT FROM AUTHOR]

Fatigue cracks commonly occur on the steel box girders of long-span bridges, while are barely summarized and analyzed in a statistic way due to the non-standard records on reports. This paper proposes to establish a standardized database of cracks on steel box girders from multiple data sources. The data are collected from 7 bridges, while 4 of them provide the inspection reports for 28 years in accumulation. By conducting the data specification and standardization, a tuple containing 15 parameters is proposed to store the information of each crack. The crack categorization is then carried out, resulting in 6 series and 34 types. In addition, the analysis module is proposed for the database to show the crack properties in various aspects, including the longitudinal and transverse distribution of the cracks, and the growing process of the crack length. It can be concluded that the database in its current form can benefit bridge management and maintenance in practice. Moreover, it lays the foundation for building the knowledge graph of cracks on steel box girders in the future, which can be helpful in predicting the crack behavior in both data-driven and mechanical ways. [ABSTRACT FROM AUTHOR]

The Kosciuszko Bridge carries a 1.8 km long segment of the Brooklyn–Queens Expressway over Newtown Creek between Brooklyn and Queens in New York City, USA. The roadway is a vital link in the region's transportation network, carrying over 170 000 vehicles/day. Owing to structural and operational deficiencies, the existing structure was replaced. The new bridge consists of two parallel structures, one eastbound and one westbound, with main spans mirroring one another. Each structure consists of a single-tower cable-stayed main span over Newtown Creek with unbalanced main and back spans. This was the first cable-stayed bridge to be constructed in New York City, joining the ranks of the city's most iconic bridges. Here, two main span structures are discussed, with the focus primarily on the design and construction of the westbound, phase 2 bridge. Some key design aspects are outlined, including outboard cable anchorages, a concrete-filled counterweight and other details intended to facilitate construction, maintenance and inspection. The eastbound, phase 1 bridge was constructed under a design–build contract, and the westbound, phase 2 bridge as a design–bid–build. The paper also touches on some of the design aspects that were refined during the second phase. [ABSTRACT FROM AUTHOR]

Aeroelastic instability and buffeting are two wind-induced phenomena for long-span bridges. In the traditional method, aeroelastic instability and buffeting are analyzed separately. If geometric and aerodynamic nonlinearity are required, aeroelastic instability is normally calculated based on finite-element methods, and buffeting is carried out based on linearization of structural and aerodynamic nonlinearity. Then, the standard frequency-domain methods are utilized on the eigenvalue decomposition. However, for ultralong-span bridges, aerostatic deformation, aeroelasticity, and buffeting are strongly coupled. During buffeting, the bridge deck pitching will change both structural stiffness and aerodynamic loads; therefore, the nonlinearity should be included in the long-span bridge buffeting analysis. This paper establishes a reduced-order modeling procedure to simulate the wind-induced buffeting vibration for long-span bridges including the nonlinear aeroelasticity and buffeting force. First, the mode-based vibration formulas are derived to consider both structural and aerodynamic nonlinearity through polynomial expansion. Next, the numerically simulated turbulence is imported into the vibration governing equation, and the structural response can be calculated using the time-domain integration method. [ABSTRACT FROM AUTHOR]

Aerodynamic stability and buffeting response due to turbulent wind have a fundamental importance for long-span bridge design. However, there are no benchmark cases that can be used as a reference estimate for an independent validation of the numerical methods and theoretical approximations. Therefore, the IABSE Task Group 3.1 proposal is to fill this gap by defining a reasonably well predicted set case for the response to wind of long-span bridges, both in terms of aerodynamic stability and buffeting. Specifically, a statistical analysis was performed on the numerical results collected by the task group participants, who used their own methodology and tools (either in time domain and/or frequency domain) to predict the bridge stability to flutter and buffeting response to wind, sharing the same input data (wind conditions, bridge structural properties, and deck aerodynamic coefficients). The benchmark results presented in this paper can be used as a point of reference for other numerical codes, and they include the onset of flutter speed, damping ratio variation with mean wind speed and the root mean square of the displacements as a function of mean wind speed, power spectral density values, and time histories of displacements. [ABSTRACT FROM AUTHOR]

This study explored extending the performance-based seismic design method to three case study arch bridges with geometry and loading conditions representative of the long-span concrete deck arch bridge class. The force-based design method was first utilized to develop preliminary seismic designs of the three bridges and validate the assumption that bridges designed following the force-based design are protected against collapse under rare seismic events. The preliminary designs of the short spandrel columns failed to achieve code-specified performance objectives under longitudinal seismic loads and were thus revised. The three bridges with the revised details were analyzed using nonlinear time history analysis considering three suites of ground motions scaled to the code-specified hazard levels at the site of interest. The three suites of ground motions represented crustal, subcrustal, and subduction earthquakes. Under individual records associated with the subduction earthquakes, the revised designs of two bridges failed to achieve the code-specified performance objectives. Seismic fragility curves were generated for the bridges considering details based on force-based and performance-based design methods. The probabilities of the collapse of bridges designed following the force-based design method were near zero under rare events. The assumption that bridges designed following the force-based design method meet the collapse prevention limit state was thus found to hold true when extended to the special case of long-span concrete deck arch bridges. Such bridges, however, were found to be unlikely to meet low to intermediate levels of damage and performance criteria corresponding to low to moderate levels of seismicity. Despite being designed to achieve code-specified performance objectives, performance-based designed piers were also characterized by some probability of not meeting the damage levels and performance criteria, albeit to a much lesser extent than force-based designed piers. Considering demands associated with individual records with particular emphasis on those representatives of the dominating seismic hazard at the site of interest is thus recommended for performance evaluation of long-span concrete deck arch bridges. [ABSTRACT FROM AUTHOR]

The increasing number of suspension bridges has led to designs favoring greater length and flexibility, resulting in a common problem of vortex-induced vibration. While vortex-induced vibration typically does not cause structural damage, it diminishes the bridge's fatigue resistance and has a detrimental impact on ride comfort. Additionally, this study introduces a road–bridge–vehicle vibration model, proposing an evaluation method for assessing ride comfort during vortex-induced vibrations in long-span bridges. This method features simplified modeling and swift calculations, circumventing the need for intricate finite element modeling and iterative solving. Furthermore, it evaluates ride comfort for vehicles crossing a prototype long-span suspension bridge using the Overall Vibration Total Value (OVTV) and Motion Sickness Incidence (MSI) criteria. This study also analyzes the influence of various parameters on OVTV and MSI, including vehicle speed, road grade, vortex-induced vibration frequency, and amplitude. It establishes a reference limit for vortex-induced vibration amplitude based on OVTV and MSI values. Moreover, the study substantiates that, within the context of vortex-induced vibration, the MSI value is more suitable for evaluating driving comfort compared to the OVTV. [ABSTRACT FROM AUTHOR]