Long-span Suspension Bridge Research Articles

Influence of Main Cable Displacement-Controlled Device of Long-span Suspension Bridge on Seismic Performance of Structure

Influence of Main Cable Displacement-Controlled Device of Long-span Suspension Bridge on Seismic Performance of Structure

Deep learning-based automated identification on vortex-induced vibration of long suspenders for the suspension bridge

Large amplitude vortex-induced vibration (VIV) of long suspenders, caused by vortex-shedding and wake flow, will decrease the service life of high-strength wires and its anchorage systems, hence listed as an essential monitoring indicator of the structural health monitoring system in the suspension bridges. Traditionally, a static vibration amplitude limitation is usually predefined and used to identify VIV from continuously monitored acceleration data of bridge suspenders. Due to the complexity of the starting vibration of the suspenders, it may not be able to flexibly adapt to the suspenders VIV under different conditions. In addition, transient but significant vibration events may not be captured since it relies only on static vibration amplitude limits without considering the temporal information of vibration. To address the above-mentioned issues, a novel framework to autonomously identify the suspenders VIV is proposed using the multimodal fusion techniques with deep neural networks. The main contributions of the methodology are: i) by calculating the wind field and vibration characteristic, two vibration response parameters are identified as indexes for the identification of suspenders VIV based on the significant difference method of big data analysis; ii) Two different modal information of time history images and power spectral density (PSD) sequences are used as inputs to the convolutional neural network (CNN) and bidirectional long short-term memory (BiLSTM) to extract the suspenders vibration response features from the time and frequency domain perspectives, respectively; and iii) The multimodal information is concentrated and enhanced by the multi-head attention (MHA) mechanism to achieve automated identification of the suspenders VIV. The proposed framework is validated with data collected from a full-scale long-span suspension bridge in comparison with the base model. The results show that the proposed framework can efficiently identify the full-cycle development process of the suspenders VIV. This study provides a convenient strategy for suspenders VIV identification, which can be used for bridge management and vibration mitigation device design.

Ride comfort assessment of road vehicles on a long-span truss girder suspension bridge under crosswinds

The precise identification of the aerodynamic loads on vehicles is a fundamental concern in assessing the ride comfort of vehicles crossing long-span bridges in the presence of strong crosswinds. However, the consideration of aerodynamic interference between vehicles and truss girder bridges is limited in existing studies. Furthermore, in practical engineering, wind barriers are commonly installed to enhance the ride comfort of vehicles crossing long-span bridges, but previous studies have primarily focused on the impact of wind barriers on the aerodynamic coefficients and dynamic responses of vehicles. This paper focuses on the aerodynamic interaction between trucks and truss girder bridges, through wind tunnel testing. The aerodynamic coefficients of the vehicle with three different ventilation ratios and four different heights of wind barriers were obtained. The dynamic response of road vehicles on a truss girder suspension bridge with a main span of 965 m was numerically calculated using the coupled analysis of wind-vehicle-bridge system and measured aerodynamic coefficients considering aerodynamic interference. On this basis, the comfort of road vehicles was investigated with different section types of the girder and different wind barrier parameters, and it was evaluated accordance with the overall vibration total value (OVTV) recommended in the ISO 2631–1. It is found that the aerodynamic coefficients of road vehicles are sensitive to the type of wind barrier. Wind barriers can reduce the road vehicle’s aerodynamic loads at high wind yaw angles. Wind barriers can also improve the ride comfort of road vehicles on the long-span truss girder suspension bridge.

Analytical model analysis of suspension bridges with tower-girder-connected dampers

Recently the tower-girder-connected damper has been utilized to suppress multi-mode vertical vortex-induced vibration (VIV) of long-span suspension bridges. In this paper, an analytical solution is proposed for the damping ratio of vertical bending modes of a single-span suspension bridge, with a vertical or/and a rotational damper mounted near the end of the stiffening girder, which significantly simplifies the design procedure for tower-girder-connected dampers on suspension bridges. The damping effect and the accuracy of the analytical solution are validated for Humen Bridge. It is found that both the vertical and rotational damper with an appropriate parameter selected can supply significantly additional damping ratio to multiple bending modes of the suspension bridge. The rotational and vertical dampers work in a similar way and provide nearly the same maximum additional damping ratio for each mode. In particular, for the first two symmetric modes, regions of reduced motion near the ends of the stiffening girder are developed due to the effects of cable geometry and elasticity, and this reduces the effect of the tower-girder-connected damper. Excluding these modes, the damper effect on a suspension bridge is similar to that on a tension beam with the same beam stiffness and horizontal tension forces.

A Study on Post-Flutter Characteristics of a Large-Span Double-Deck Steel Truss Main Girder Suspension Bridge

To investigate the nonlinear flutter characteristics of long-span suspension bridges under different deck ancillary structures and configurations, including those with and without a central wind-permeable zone, as well as to analyze the hysteresis phenomenon of a subcritical flutter and elucidate the mechanisms leading to the occurrence of nonlinear flutter, this paper studies first the post-flutter characteristics of the torsion single-degree-of-freedom (SDOF) test systems and vertical bending–torsion two-degree-of-freedom (2DOF) test systems under different aerodynamic shape conditions are further analyzed, and the role of the vertical vibration in coupled nonlinear flutter is discussed. The results indicate that better flutter performance is achieved in the absence of bridge deck auxiliary structures with a central wind-permeable zone. The participation of vertical vibrations in the post-flutter vibration increases with the increase in wind speed, reducing the flutter performance of the main girder. Furthermore, the hysteresis phenomenon in the subcritical flutter state is observed in the wind tunnel experiment, and its evolution law and mechanism are discussed from the perspective of amplitude-dependent damping. Finally, the vibration-generating mechanism of the limit oscillation ring is elaborated in terms of the evolution law of the post-flutter vibration damping.

Investigation on nonlinear flutter modes competition of a long-span suspension bridge based on full-bridge aeroelastic model tests

Nonlinear flutter has attracted wide attention due to the bottleneck caused by linear flutter theory on flutter-resistant design of super-long-span bridges. The longer the span, the more closely spaced the natural modes, which may cause competition among flutter-modes in a nonlinear flutter, but it is rarely reported so far. To this end, this study experimentally investigates the 3D nonlinear flutter characteristics of a long-span suspension bridge with closely spaced natural modes based on full-bridge aeroelastic model wind tunnel tests. Since there are two unstable flutter-modes within the interested post-critical regime and thus various complex but interesting flutter-modes competition processes were observed, such as continuous modes competition where the vibration amplitude evolution exhibits various different types of “sawtooth” shapes during stable vibration stages. Meanwhile, the complex nonlinear bifurcation behaviors caused by modes competition were also observed. The evolutionary characteristics of flutter-modes competition are analyzed in detail and relevant mechanisms are discussed. As the wind speed increases, the flutter of the studied bridge mainly undergoes a transition from being dominated by the symmetric mode to being dominated by the antisymmetric mode, accompanied by a continuous modes competition zone in between as a transitional zone. The results show that the continuous modes competition will result in a decrease in the maximum amplitude RMS of the full-span, which is beneficial for the structure. But it may also lead to a transient increase in the maximum amplitude of the full-span due to the coupling vibration shape formed by the two significant flutter-modes, which may be bad for the structure.

Wake-induced vibration of ultra-long suspenders adjacent to bridge tower

The tower wake usually induces large-amplitude vibrations in adjacent suspenders of a long-span suspension bridge. In order to interpret the underlying mechanism of the significant wake-induced vibrations of ultra-long suspenders, the wake-induced vibration characteristics of tandem suspenders beside the bridge tower are investigated using computational fluid dynamics based simulation. First, the computational model of the bridge tower and suspenders is established. Subsequently, the effect of tower wake on suspender vibration is analyzed considering the inflow velocity and relative position between the tower and suspenders. Based on the proper orthogonal decomposition (POD), the flow characteristics behind the tower and around the suspenders are investigated, and the governing mechanism of wake-induced vibrations of the suspenders is revealed ultimately. The results indicate that the wake-induced vibration of the suspender exhibits a lock-in phenomenon with large cross-wind amplitudes at specific incoming wind velocities. The wind loads on the suspender in both along-wind and cross-wind directions exhibit components with frequencies that are multiples of the vortex shedding frequency. The flow field can be accurately constructed using the first four POD modes with the largest energy. The symmetric POD modes are the primary components that contribute to the significant wake-induced vibrations of the suspenders.

An analytical method for thermal behavior analysis of long-span suspension bridges: Based on elastic catenary cable and gradient optimization

The thermal loads of suspension bridges will change the unstrained length of the main cable and hanger and lead to significate variation of the cable shape. Since the main cable is the main load-bearing structure of the suspension bridge, the change of cable shape will lead to significant bridge deformation. Hence, the thermal behavior analysis of suspension bridge is crucial. This paper introduces an analytical method to calculate the temperature-induced deformation and internal force changes of suspension bridges. Comparing to the prevalent Finite Element Method (FEM), this method has the advantage of clear calculation process and physical significance. First, the deformation of the cable-hanger structure is estimated based on the elastic catenary theory. Based on the differential relationship between curvature and force, the deformation of the pylon and beam is calculated. Finally, optimization equations are established by closing the coordinates of key nodes. The Levenberg-Marquardt (LM) method is employed for solving. In a numerical example bridge with a main span of 1700 m, the maximum error of deformation calculation based on this method is only 5.8 mm. This proves the effectiveness and accuracy of this method. Additionally, this paper analyzes the influence of various temperature loads and the mechanical property of bridge members on the thermal behavior. These works will provide valuable insights to engineers in bridge design.

Geometrical morphology and deformation measurement of long-span suspension bridge based on terrestrial laser scanning

Long-span suspension bridges necessitate deformation measurements for proper evaluation and upkeep. However, conventional approaches are unable to collect continuous spatial deformation data, which severely restricts their application in structural research. This paper presents a reliable and efficient method for measuring the deformation of suspension bridges using 3D laser scanning, including planning the scanning route, preprocessing the point cloud data, and extracting the deformation indicators. The method plans the scanning route based on experience and basic path planning principles to achieve both efficiency and precision, preprocesses the point cloud data by 3-stage denoising and curvature-based downsampling to preserve valuable point data better, and then proposes an extraction procedure for different types of deformation indicators. A field test on a typical long-span suspension highway bridge is performed, and the data processing and results extraction details are introduced. The accuracy and consistency of measurement results are discussed to verify the reliability of the proposed approach. The verified data provides useful information for the evaluation and maintenance of the bridge.

Analytical solutions for static longitudinal displacements of suspension bridges under a moving vertical concentrated load

The longitudinal displacement at the girder ends of long-span suspension bridges is a crucial issue that affects structural safety, durability, as well as traffic safety and ride comfort. The primary cause of these reciprocating displacements is the action of moving live loads, which induces quasi-static displacements in the longitudinal direction. This paper theoretically investigates the static longitudinal displacements of suspension bridges under a moving vertical concentrated load and elucidates the underlying deformation mechanisms. Considering geometrical nonlinearity, analytical equations are established for the longitudinal deformations of the main cable and stiffening girder under a vertical concentrated load. By analyzing the geometrical deformation conditions of the suspenders, the relationship between the longitudinal displacements of the stiffening girder and the main cable is derived. Due to the coupling between longitudinal and vertical displacements, the vertical displacement of the stiffening girder must be solved to obtain its longitudinal displacement. Based on deflection theory and considering the bending stiffness of the stiffening girder, this paper derives the vertical deformations of the stiffening girder for single-span suspension bridges and those with short continuous side spans under a vertical concentrated load, which is then used to calculate the longitudinal displacement. Finite element models are used to verify the accuracy of the analytical solutions. Differences between the proposed solutions and previous solutions neglecting the bending stiffness of the stiffening girder are compared and analyzed. The effects of neglecting the longitudinal displacement at the bridge tower top and the presence of short continuous side spans on the longitudinal displacement of stiffening girder are also investigated. The results demonstrate the high accuracy of the proposed analytical solution for the longitudinal displacement at the girder ends of suspension bridges. Importantly, the bending stiffness of the stiffening girder cannot be neglected in calculating the longitudinal displacement. The longitudinal displacement at the girder ends is primarily caused by the longitudinal deformation of the main cable, while the contribution from the flexural deformation of the girder is negligible. Furthermore, the longitudinal displacement at the bridge tower top has a negligible effect on the longitudinal displacement of the girder, and the presence of short continuous side spans is beneficial for reducing the longitudinal displacement of the stiffening girder. The proposed analytical solution method provides a rapid approach for calculating the static longitudinal displacement at the girder ends of suspension bridges under passing live loads and reveals the deformation mechanism. This is beneficial for preliminary design and structural optimization, as it avoids the complex finite element modeling and solution process.

Finite Element Modeling and Calibration of a Three-Span Continuous Suspension Bridge Based on Loop Adjustment and Temperature Correction.

Precise finite element modeling is critically important for the construction and maintenance of long-span suspension bridges. During the process of modeling, shape-finding and model calibration directly impact the accuracy and reliability. Scholars have provided numerous alternative proposals for the shape-finding of main cables in suspension bridges from both theoretical and finite element analysis perspectives. However, it is difficult to apply these solutions to suspension bridges with special components. Seeking a viable solution for such suspension bridges holds practical significance. The Nanjing Qixiashan Yangtze River Bridge is the first three-span suspension bridge in China. To maintain the configuration of the main cable, the suspension bridge is equipped with specialized suspenders near the anchors, referred to as displacement-limiting suspenders. It is the first suspension bridge in China to use displacement-limiting suspenders and their anchorage system. Taking the suspension bridge as a research background, this paper introduces a refined finite element modeling approach considering the effect of geometric nonlinearity. Firstly, based on the loop adjustment and temperature correction, the shape-finding and force assessment of the main cables are carried out. On this basis, a nonlinear finite element model of the bridge was established and calibrated, taking into account factors such as pylon settlement and cable saddle precession. Finally, the static and dynamic characteristics of the suspension bridge were thoroughly investigated. This study aims to provide a reference for the design, construction and operation of the three-span continuous suspension bridge.

Effect of Track Spectrum on the Dynamic Responses of Passenger–Train–Bridge System

To study the influence of the Chinese high-speed railway ballastless track spectrum and the German low-interference spectrum on riding comfort, a long-span highway-railway suspension bridge is studied as an example, and a passenger–train–bridge coupling model is established based on the structural dynamics. The vibration responses of the passenger–train–bridge system during the CRH2C train running on the bridge are studied by a combination of the self-written computer program and general finite element software, considering the hunting movement, and the riding comfort of trains and passengers is evaluated using [Formula: see text] and ISO-2631 standard, respectively. The results show that track irregularity has a few effects on the lateral vibration of the bridge. Compared with the German low-interference spectrum, the Chinese high-speed railway ballastless track spectrum has less exciting effects on the vibration of the passenger–train–bridge system and better riding comfort. Passengers in the middle of the train and on the middle seats of the same train have better riding comfort, and with the increase of train speed, the riding comfort of passengers will gradually reduce. Instead of passenger responses, the riding comfort classification based on the car body is overestimated.

Over 25-year monitoring of the Tsing Ma suspension bridge in Hong Kong

AbstractBridges in service are subjected to environmental and load actions, but their status and conditions are typically unknown. Health monitoring systems have been installed on long-span bridges to monitor their loads and the associated responses in real time. Since 1997, the Tsing Ma suspension bridge in Hong Kong has been the world’s first of the type equipped with a long-term health monitoring system. For the first time, this study reports the first-hand field monitoring data of the bridge from 1997 to 2022. The 26-year data provide an invaluable and rare opportunity to examine the long-term characteristics of the loads, bridge responses, and their relationships, thereby enabling the assessment of the bridge’s load evolution and structural condition over time. Results show that traffic loads have remained stable after 2007, highway vehicles kept increasing until the COVID-19 pandemic in 2020, the annual maximum deck temperature continued to increase at a rate of 0.51 °C/decade, typhoon durations increased by 2.5 h/year, and monsoon speeds decreased and became dispersed and variable. For the bridge responses, deck displacement is governed by the varying temperature. Natural frequencies in the past 26 years were almost unchanged. The overall condition of the bridge is very satisfactory. Current status and recent update of the health monitoring system are also reported. Lastly, prospects of bridge health monitoring are discussed. This study is the first to report the over one-quarter century status of a structural health monitoring system and the behavior of a long-span suspension bridge. This research provides a benchmark for many other bridge monitoring systems worldwide.

Vulnerability of suspension bridges to spatially variable vertical ground motions

This study investigates the vulnerability of long-span suspension bridges to spatially variable vertical ground motions (SV-VGMs). While of recognized importance, a comprehensive understanding of this topic has been traditionally limited by the unavailability of an adequate number of arrays of motions. In this work, 10 simulations of a large-magnitude Hayward Fault earthquake are utilized to perform site-specific structural response assessments of a suspension bridge under different load scenarios. A detailed nonlinear model representative of the West San Francisco-Oakland Bay Bridge is employed as the case study structure. Four sets of nonlinear time-history analyses are performed with and without VGMs and with and without the incorporation of spatial variability to offer the basis for a complete comparison of the demand distributions across different load cases. Results indicate that VGMs largely influence the response of the bridge decks in the vertical direction, with an increase in drifts up to 2× for the case of synchronous input and up to 2.5× for the case of asynchronous inputs. The analysis of the bridge response in the time and frequency domain across all load cases reveals a high sensitivity of the decks’ response to minor time lags in input motions of comparable amplitude, which are seen to activate the contribution of higher modes to the structural response. Evidence from this study points to the potential of severely underestimating structural demands if the (even limited) spatial variability of the input motions is not incorporated correctly. For the case study structure, the probability of exceeding the onset of nonlinearity in the short decks at the design earthquake level is seen to increase by a factor of about two when considering SV-VGMs as opposed to synchronous horizontal motions only.

Investigation of the modal frequency of a long-span suspension bridge under multiple environmental conditions

This study employs advanced techniques, namely the improved multi-synchrosqueezing transform (IMSST) and the Fourier synchrosqueezed transform (FSST), to extract the instantaneous frequency of the Humber Bridge, in the UK, in operational conditions. First, a brief overview of the relevant theories behind the techniques used is provided. These techniques are then applied to track the instantaneous frequencies within the monitored vertical acceleration data of the bridge. The instantaneous frequencies extracted by both techniques are verified against each other. The investigation further encompasses the development of three distinct regression models: a simple regression model, an expanded regression model and a regression model based on principal component analysis (PCA). The efficacy of the PCA-based model is scrutinised by generating and testing datasets that mirror the monitored data, with the Kolmogorov-Smirnov (KS) test confirming their validity. The findings of this research indicate a statistically significant inverse relationship between modal frequency and acceleration intensity. Furthermore, by incorporating wind effect considerations into the regression analysis, the R-squared values in both the expanded and PCA-based models exhibit substantial improvements. This demonstrates the performance of the enhanced model in capturing the dynamics of the bridge. The robustness of the PCA-based model is further corroborated by its performance during testing, proving its potential as a reliable tool in structural health monitoring (SHM).

Effects of combined-type wind barriers on the aerodynamic characteristics of train–bridge system for a long-span suspension bridge

The development tendency of lightweight and higher-speed regarding trains goes against the safety and comfort requirement of high-speed trains, especially in the scenario of the train running on bridges within crosswind environments. Wind barriers have been proven to be an effective measure to guarantee the train's operation security. In this paper, a new type of wind barrier consisting of the fence-type wind barrier form and open hole-type wind barrier form has been proposed. Then, a series of wind tunnel tests about the large-scale section model of a large-span suspension bridge installed with different wind barriers have been conducted. The effects of three different forms of wind barrier including fence-type, open hole-type, and combined-type on the aerodynamic characteristics of the train-bridge system have been analyzed. The windproofing effectiveness and the protection mechanism of the combined-type wind barrier on the train-bridge system have been revealed through the measured aerodynamic characteristics. The results show that the installation of open hole-type, fence-type, and combined-type wind barriers at a height of 4 m and a ventilation rate of 19% yields a maximum reduction in the train drag coefficient of 67.70%, 72.92%, and 97.21%, respectively. Moreover, the combined-type wind barrier can improve the train-bridge system's aerodynamic performance and trains' running safety on bridges when comparing with the open hole-type and fence-type wind barriers. The proposed combined-type wind barrier can provide a more efficiency and practical way for the high-speed train's running safety on the bridge.

BOPVis: Bridge Monitoring Data Visualization for Operational Performance Mining

Bridges are fundamental facilities in the transportation system, and their operational performance is crucial for economic and social development. Many large bridges are now equipped with structural health monitoring (SHM) systems that collect various types of real-time data. However, our user study found that despite the accumulation of massive amounts of monitoring data, current analysis methods cannot efficiently process large-scale, high-dimensional data. To address this, we have developed BOPVis, a visualization system for bridge monitoring data. BOPVis allows users to intuitively locate sensors and extract corresponding data from a 3D digital model of a bridge. It also provides convenient and flexible interactions for examining trends over time and correlations across hundreds of monitoring channels. A real-world long-span suspension bridge in China is used as a case study to demonstrate the advantages of the BOPVis system for operational performance mining. Through BOPVis, the global temperature deformation behaviors of the bridge are explored and found to align with the physical mechanism documented in the SHM literature. The BOPVis system, with its interactive visualization analysis capabilities, offers a new method for analyzing bridge monitoring data.

Study on the Influence of Wind Fairing Parameters on the Aerodynamic Performance of Long-Span Double-Deck Steel Truss Suspension Bridge

A long-span double-deck steel truss suspension bridge is easy to produce vortex-induced vibration (VIV) at low air velocity, which affects bridge service life. Additional aerodynamic measures play a role in suppressing VIV by changing the aerodynamic shape, which is a common control method. As the main aerodynamic measure to suppress the VIV response, wind fairing is widely used in engineering practice. In order to obtain the optimal additional position and shape parameters of the fairing, Huangjuetuo Yangtze River Bridge is the research target. Through the combination of a wind tunnel test and numerical simulation, the VIV response of the original and fairing section is studied. Based on data analysis, it is revealed that these additional fairings to the upper chord can significantly reduce the VIV response. When the shape parameters of the fairing are h/D = 1/4 and l/D = 1, the VIV inhibition efficiency is the highest, which can reach 65.51%. By analyzing the flow distribution, it can be seen that VIV is caused mainly by vortex separation in the upper bridge board area. Although this wind fairing does not change the original vortex shedding forms, it changes the first separation point and movement direction of the airflow, making the vortex scale generated by the airflow smaller and the vorticity lower, thus effectively suppressing VIV.

Simulation of multivariate ergodic stochastic processes using adaptive spectral sampling and non-uniform fast Fourier transform

The simulation of multivariate ergodic stochastic processes is critical for structural dynamic analysis and reliability evaluation. Although the traditional spectral representation method (SRM) has a wide application in many areas, it is highly inefficient in simulating stochastic processes with many simulation points or long durations due to the significant computational cost associated with matrix factorizations concerning frequency. To address the encountered challenge, this paper presents an efficient approach for simulating ergodic stochastic processes with limited frequencies. Central to this approach is a fusion of the adaptive spectral sampling and the non-uniform fast Fourier transform (NUFFT) techniques. The adaptive spectral sampling of the envelope spectrum enables the determination of limited non-equispaced frequencies, which are randomly sampled according to a uniform distribution. Thus, the Cholesky decomposition is only required at limited specific frequencies, which dramatically reduces the computational cost of matrix factorizations. Since the randomly sampled frequencies are not equispaced, utilizing FFT to accelerate the summation of trigonometric functions becomes impractical. Then, the NUFFT that adapts the non-equispaced sampling points is employed instead to expedite this process with the non-uniform increment approximated through reduced interpolation. By taking the wind field simulation of a long-span suspension bridge as an example, a parametric analysis is conducted to investigate the effect of random frequencies on the simulation error of the developed approach and the convergence of spectra. Finally, the developed approach is further validated by focusing on the spectra and probabilistic density functions of the simulated wind samples, and the simulation performance is compared with that of the traditional approach. The analytical results demonstrate the efficiency and accuracy of the developed approach in simulating ergodic stochastic processes.

Girder quasi-static cumulative displacement-based suspension bridge nonlinear damper leakage diagnosis by eliminating stochastic traffic effects

Fluid viscous dampers (FVDs) are the key energy dissipation devices for long-span suspension bridges, and their leakage poses a threat to the stable and reliable operation of bridge restraint systems. Therefore, this paper proposed an FVD fluid leakage diagnosis method based on girder longitudinal displacement monitoring data. First, the longitudinal vibration equation of the main girder under traffic loads was derived to reveal the displacement characteristic of girder-end motion. On this basis, considering that different displacement components under traffic loads are coupled and transient analysis directly utilizing traffic loads as the excitation is complicated and inefficient, an analysis framework focusing on the influence mechanism of FVD leakage on quasi-static displacement was established. Second, an equivalent mechanical model for simulating the hysteresis relationship of leaked FVD was proposed and verified. Then, the influence of variations in the location, number, leakage level and parameters of the leaked FVD on the quasi-static displacement was studied. Third, the equivalent traffic load (ETL) indicator was constructed to characterize the traffic volume. Furthermore, a quasi-static cumulative displacement and ETL correlation model, which can effectively eliminate the interference of traffic flow variations, was proposed for the leakage diagnosis of FVD. Finally, the proposed method was verified by real suspension bridge monitoring data. The results demonstrated that the proposed method can effectively detect a mild increase in the girder-end cumulative displacement due to FVD fluid leakage.