Bridge Tower Research Articles

Engineering Mechanics Methods in Stability Studies of Bridge Structures and Innovations in Future Bridge Designs

Abstract With the development of science and technology and transportation, high pier and large-span bridges are rapidly rising. Due to the increase in span diameter and pier height, nonlinear and stability problems of bridges become more and more important. In this paper, the stability of large-span steel box-girder suspension bridges is investigated using engineering mechanics methods. Based on the finite element analysis method to solve the bridge structure of the first type of stability problems and the second type of stability problems, the use of the response spectrum method for bridge seismic response. Taking “Xiling Yangtze River Bridge” as the engineering background, the seismic response is analyzed by establishing a finite element model. The axial force of the bridge tower generated by the downstream earthquake is larger than that generated by the transverse earthquake. In the transverse direction, the bending moment MZ is larger than the bending moment MY in the transverse direction, and the bending moment of the pile foundation is larger than the bending moment of the pile foundation in the longitudinal direction. The Xiling Yangtze River Bridge plays a dominant role in transverse seismicity, and its downstream seismic excitation plays a dominant role in longitudinal seismicity. However, the energy-demand ratio corresponding to the transverse moment MY is only 1.83, and the strength of the pile section needs to be further improved. For the future innovation of bridge design, a high-performance bridge structure based on UHPC is an important direction for future development.

Discrete viscous dampers for multi-mode vortex-induced vibration control of long-span suspension bridges

Multi-mode vertical vortex-induced vibrations have been observed on several long-span suspension bridges, where several vertical modes of stiffening girder are excited in turn with increasing of wind velocity. This paper proposed a discrete viscous dampers solution and its optimization targeting multi-mode vortex-induced vibration control for long-span suspension bridges. The minimal modal damping ratio was used to evaluate the performance of the damper system. The wind tunnel test verified that the modal damping ratio is an alternative to the resonance response amplitude and can be obtained by complex modal analysis. The ternary search algorithm was adopted to find the optimal damper parameter for the Yingwuzhou Yangtze River Bridge, which is a suspension bridge that suffered excessive vortex-induced vibrations. Using linear damper elements to connect the bridge tower and the bridge girder directly turned out to be a feasible method of increasing multiple modal damping ratios. Four torsional eddy current dampers have been installed in the Yingwuzhou Yangtze River Bridge, based on the numerical optimization results calculated in this paper. Although the measured modal damping ratios were smaller than the numerical results, the structural damping increased by three times after dampers were installed, and the requirement of the current specification was satisfied.

Estimating design positions of suspension bridge tower saddles in the completed bridge state: An analytical approach

Saddle position is an essential parameter in the form-finding of main cables and for the construction control of suspension bridges. In actual suspension bridges, the center of the arc-shaped tower saddle in the completed bridge state may sometimes deviate toward the river and the river bank. However, the influencing factors and the judgment method for the deviation have yet to be thoroughly studied. This study proposes an analytical approach for estimating saddles positions in the completed bridge state of suspension bridges under two definitions of the intersection point (IP) of the main cable in the tower top: (i) IP between the two extended catenary segments of the main cable and (ii) IP between the two extended straight lines of the main cable. For catenary-based IP, the calculation of the saddle position is separable from the form-finding of the main cable. Once the shape of the main cable is derived, equations can be established based on the geometric compatibility conditions for the saddle and main cable, their solving required for deriving saddles positions. For straight line-based IP, the calculation of the saddle position is inseparable from the form-finding of the main cable, and the two processes are conducted simultaneously. Equations can be established based on mechanical equilibrium and the geometric compatibility conditions for the saddle and the main cable and then solved. The relationship between the position of the center of the arc-shaped tower saddle and the centerline of the tower is analyzed, proving that the saddle deviates toward the side with a smaller catenary parameter. The eccentric compression of the tower is analyzed, implying that the eccentric moment acting on the tower in the completed bridge state is primarily produced by the self-weight of the saddle and the main cable segment in the saddle. Finally, the feasibility of the proposed method and the correctness of the above findings are verified through a suspension bridge with a main span of 730 m.

Numerical simulations on flow control of the long hanger around a bridge tower based on active suction and blowing method

Long hangers around the bridge tower are subjected to severe vibrations caused by the tower wakes. This study adopted an active suction/blowing control measure at the tower corners to control hanger vibrations and included four combination measures: upstream suction (US), upstream blowing (UB), downstream suction (DS), and downstream blowing (DB). The effects of control cases on the near-wake flow structures of the tower were first studied in two-dimensional RANS simulation, and the vibration behaviors of the hanger and control mechanism were further analyzed. The cases associated with UB and DS cannot effectively suppress hanger vibrations, and both lead to unfavorable upward trends in the aerodynamic coefficients of the tower. Especially for the cases associated with DS, at a specific control speed, the second-order frequency of the drag coefficient of the hanger is very close to its natural frequency, resulting in significant longitudinal vibration. The cases associated with US and DB are effective control schemes with longitudinal peak amplitudes of the hanger reduced by 94.1% and 94.5%, and lateral peak amplitudes reduced by 95.8% and 97.0%, respectively, compared with the case baseline. This is because the dominant frequency of the lift of the hanger is away from its natural frequency, and the fluctuating wind loads on the hanger are effectively suppressed. Finally, the control effect and vibration suppression mechanism for typical cases were further reproduced in three-dimensional large eddy simulations.

Deformation monitoring of long-span railway bridges based on SBAS-InSAR technology

The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property. The interferometric synthetic aperture radar (InSAR) technology has the advantage of high accuracy in bridge deformation monitoring. This study monitored the deformation of the Ganjiang Super Bridge based on the small baseline subsets (SBAS) InSAR technology and Sentinel-1A data. We analyzed the deformation results combined with bridge structure, temperature, and riverbed sediment scouring. The results are as follows: (1) The Ganjiang Super Bridge area is stable overall, with deformation rates ranging from −15.6 mm/yr to 10.7 mm/yr (2) The settlement of the Ganjiang Super Bridge deck gradually increases from the bridge tower toward the main span, which conforms to the typical deformation pattern of a cable-stayed bridge. (3) The sediment scouring from the riverbed cause the serious settlement on the bridge's east side compared with that on the west side. (4) The bridge deformation negatively correlates with temperature, with a faster settlement at a higher temperature and a slow rebound trend at a lower temperature. The study findings can provide scientific data support for the health monitoring of long-span railway bridges.

A New Method for Correcting the Deviation of a Middle Pier Tower of a Long-Span Intermediate Arch Bridge

To control the deviation of a long-span concrete-filled steel tube (CFST) arch bridge during construction monitoring, a practical method for controlling tower deviation is studied and established. The form of construction of this bridge is an intermediate double-arch bridge, which differs from conventional bridges, thus requiring the urgent resolution of the issue of unbalanced middle piers. Therefore, the mechanical characteristics and construction process of an intermediate long-span, dual-coupled steel pipe arch bridge are meticulously examined by using a 1:10 scale model, with particular focus on discussing the deflection of the buckle tower during the installation of the arch rib segments. Construction control is implemented using a novel tower deflection control method that addresses unilateral torsion problems and difficulties in controlling the deflection of the tower. The model results are compared with the finite element analysis output, demonstrating that this new approach can resolve unbalanced tower deviations by maintaining absolute values within 0.5 mm. After correcting these deviations, the measured results from the model bridge tower align with the calculated analytical results and even surpass the theoretical expectations for tower deviation. This remarkable new method accurately resolves real-world bridge tower deviations.

Aerodynamic stability of high-speed vehicle passing bridge tower in different lanes under crosswind conditions

Large bridges' decks often exhibit different adhesion coefficients in complex environments, which are frequently accompanied by significant crosswind effects. This results in a complex and constantly changing flow field around vehicles, which can severely impact driving safety. In this study, the two-way coupling method is utilized to investigate the transient aerodynamic characteristics and dynamic response of vehicles passing through bridge towers at high speeds in different lanes with varied adhesion coefficients under crosswind conditions. The vehicle speed was 30 m/s, and the crosswind velocity was recorded at 11.33 m/s. The results indicate that the aerodynamic load fluctuates more significantly due to the influence of the bridge tower. In the same lane, the bridge deck with an adhesion coefficient of 0.4 produces a greater lateral displacement and yaw angle. When passing through the bridge tower, a vehicle in lane L1 is suddenly affected by vortex shedding, resulting in a larger lateral displacement and yaw angle compared to vehicles in L2 and L3 lanes. The lateral displacement measures 0.251 m, and the yaw angle measures 0.0205 radians at an adhesion coefficient of 0.4. This also indicates that driving in the L1 lane in a crosswind environment is relatively less safe.

Underwater shaking table tests of a sea-crossing cable-stayed bridge under combined earthquake and wave action

Sea-crossing cable-stayed bridges may encounter the combined effects of earthquakes, waves, and currents, seriously threatening their service safety. In this paper, the effects of the combined earthquake and wave action on the dynamic responses of a sea-crossing cable-stayed bridge are investigated through underwater shaking table tests. The coordinative similitude law is adopted to fulfil the similarity of hydrodynamic and wave force. The test results indicate that, the combined action of earthquake and wave has significant effects on the dynamic response of the bridge tower, while the effects vary with the height of the tower and the type of ground motion. The side pier exhibits greater dynamic responses at the same loading cases and is more susceptible to the combined earthquake and wave action than the auxiliary pier. On the whole, in comparison to earthquake excitation alone, the combined earthquake and wave action significantly enhances the dynamic responses of sea-crossing cable-stayed bridge in most cases, with a maximum magnitude up to 20%–30%. By comparing with previously conducted underwater shaking table tests of substructures, the effects of water-structure interaction on the full cable-stayed bridge and bridge tower foundation are close, both of which are obviously lower than the effects on bridge pier.

Flow field characteristics analysis of vortex-induced vibration of bridge tower based on dynamic mode decomposition method

As a high-rise structure, the tower of a suspension bridge has low stiffness due to the lack of cable system constraints when it is self-supporting. Wind-induced vibration is one of the key factors in design and construction. In this paper, the wind tunnel test of the bridge tower aeroelastic model is carried out in two different flow fields, and the wind vibration response under a self-supporting state is systematically studied. Meanwhile, numerical simulation of the unsteady flow field around the tower section is carried out, and the dynamic modal decomposition (DMD) method is used to study the modal frequency of the flow field, the surface pressure of the section, flow field reconstruction error, and the stability of the flow field around tower section is discussed. The results show that in the self-supporting state, the displacement of the tower top presents a quadratic curve relationship with the wind speed, and no galloping phenomenon occurs under the test wind speed. However, in the uniform flow, when the wind attack angle is 90°, the bridge tower has an obvious vortex-induced vibration (VIV) phenomenon. After decomposing the flow field by the DMD method, it is found that there is strong aerodynamic interference between the double rectangular column sections, the first seven orders of modal energy play a major role in the flow field, and when the main modal energy accounts for more than 90%, the reconstruction can realize the accurate restoration of the information such as the surface pressure. For the complex flow field structure, it shows that the method can more accurately identify the coherent structure and background part in the unsteady flow field. This paper provides an idea for future research on the characteristics of the flow field around complex sections and helps to further improve the understanding of the VIV mechanism.

Mechanism analysis on wake-induced vibration of parallel hangers near a long-span suspension bridge tower

To reproduce the vibration phenomenon and explore the mechanism of parallel hangers near a suspension bridge tower based on the practical engineering, a pair of hangers in the wake of the bridge tower were taken as the research object. The influences of different wind yaw angles on the flow patterns of the bridge tower and aerodynamic characteristics of parallel hangers were investigated using the computational fluid dynamics (CFD) method. Then, based on the amplitude spectrum results, the relationship between the aerodynamic interference intensities of the tower wake and the displacements of parallel hangers were quantitatively described. Moreover, the coherence between the bridge tower and the parallel hangers were studied. Finally, based on the surface pressure distributions, energy input analysis, and wind speed characteristics, the vibration mechanism of parallel hangers near the bridge tower were explored. The results show that when the wind yaw angle is in the range of 0° ∼ −30°, the tower wake and the vortex shedding from the hangers jointly affect the aerodynamic characteristics of the hangers, which leads to the vibration displacements and movement tracks are observed as a sawtooth shape with multiple frequencies and synchronous skewed ellipses, respectively. The aerodynamic interference intensities of the bridge tower are positively correlated with the displacements of the hangers, and the peak amplitude at the wind yaw angle of −30° with strong aerodynamic interference is 35 mm, which is about 9 times that at the wind yaw angles of ±60° with weak aerodynamic interference. Moreover, at the wind yaw angles with strong aerodynamic interference, the mean wind pressure coefficients of the parallel hangers tend to be negative and their root mean square (RMS) values of wind pressure coefficient exhibit an overall upward trend compared with those at wind yaw angles with weak aerodynamic interference. Based on the analysis of energy input and wind speed characteristics, it is found that the low-frequency vortex shedding from the tower wake is the internal factor that continuously maintain the large vibrations of the parallel hangers.

Analytical Solution for Longitudinal Anti-Push Stiffness of the Middle Tower of Cross-Cable Multi-Tower Cable-Stayed Bridge

The Queensferry Crossing in Scotland is the first multi-tower cable-stayed bridge with crossed cables in the world. This means that the conceptual design of a cross-cable multi-tower cable-stayed bridge has become a reality. In this paper, the cross-cable action mechanism is studied deeply. Suppose that the small displacement amount at the top of the side tower is ignored. The deformation coordination principle is used twice to analyze the relationship between the horizontal external force and the top displacement amount of the middle tower. Thus, derive the formula for estimating the anti-push stiffness of cross cables to the middle tower of the multi-tower cable-stayed bridge under the influence of the stiffness of the tower and beam. A numerical example is given to verify this. The research results show that the error between the analytical solution and the finite element solution is less than 8%, which meets the conceptual design requirements of cross-cable multi-tower cable-stayed bridges. The cross cables can reduce the deflection of the main beam and improve the stiffness of the bridge. After setting 10 pairs of cross cables, the displacement amount of the middle tower decreases by as high as 51%. The stiffness of the multi-tower cable-stayed bridge increases with an increase in the number of cross cables, but the increasing trend of stiffness gradually slows down. Increasing the stiffness of the tower or beam can improve the structural stiffness to a certain extent, but the effect is much less potent than that of the cross cable in the middle span.

Study on Earthquake Failure Mechanism and Failure Mode of Cable-Stayed Pipeline Bridge Considering Fluid–Structure Coupling

To investigate the failure mode of the cable-stayed pipeline bridge under seismic loading, this study focuses on an oil and gas cable-stayed pipeline bridge as the research subject. A full-scale finite element calculation model of the structural system is established using ANSYS Workbench 14.0 software, considering the stress characteristics and structural properties of the oil and gas pipeline. Additionally, a fluid–structure coupling effect finite element model is developed to account for the influence of medium within the pipeline. The analysis includes evaluating deformation, stress, strain, and other responses of the oil and gas pipeline subjected to seismic waves from different directions. The results indicate that the overall damage in the pipeline is consistent with maximum deformation, stress, and strain, concentrated at both the inlet/outlet ends and side spans; however, variations exist in terms of seismic damage depending on wave directionality. Furthermore, by considering interactions between various components within the oil and gas cable-stayed pipeline bridge’s structural system during strong earthquakes, this study analyzes failure mechanisms caused by the support–pipeline interaction as well as excessive displacement-induced failure patterns in bridge towers. Finally, a proposed failure mode for pipe bridge systems resulting from longitudinal slip between supports and pipelines, along with excessive displacement of bridge towers, is presented.

Laboratory Investigations on the Mode of Failure in Frictional and Low-Cohesive Materials Under the Load of a Ground Anchor

Ground anchors are widely used in many types of construction works, such as stabilization of rock slopes, wind turbines, concrete dams and bridge towers. Some of the modes of failure for these anchors still have an insufficient scientific basis, and that applies especially to what happens in the ground when overloaded. This paper presents investigations on the failure development in frictional and low-cohesive materials which are subjected to loading by an embedded anchor with a free length towards the surface. The failure development is demonstrated through a series of small-scale physical model tests performed in the laboratory. The physical model setup consists of a transparent PVC test chamber, a rigid «anchor block», and a hydraulic jack. The model is instrumented with a camera, an extensometer and a load cell to continuously record the failure development and resistance from the material as the anchor block is pushed through the sample material. The main question investigated is how the failure appears, as a failure along the whole pull-out body at once or as an advancing fracture along the plane, where in the first case the shear capacity of the material will be the main input in calculations, and for the second case, one also needs to take failure propagation into account.

Optimal Design of Crossbeam Stiffness Factor in Bridge Towers Using a Reliability-Based Approach

Optimal design of the crossbeam is essential for the economical design of bridge towers as the crossbeam could considerably enhance the lateral stiffnesses of these towers by providing a special bracing for the tower columns. By using a reliability-based approach, this paper studies the optimal design of the crossbeam stiffness factor in bridge towers; this is defined as a dimensionless crossbeam stiffness relative to the tower column stiffness. A novel second-order matrix stiffness method (MSM) is applied to obtain a closed-form solution of the lateral stiffness of the bridge tower. The structural second-order stiffness matrix consists of combinations of the second-order element stiffness matrices and coordinate transformations. Subsequently, a reliability analysis to study the optimal design of the bridge tower is performed by considering the uncertainties arising from the design and construction of the bridge tower. The lateral stiffness of the bridge tower is set as an objective function while the total usage of materials is set as a constraint condition. Then, the influence of the crossbeam stiffness factor on the lateral stiffness of the bridge tower, including the fragility curve and the probabilistic behavior, is examined. Based on the reliability analysis, optimal design recommendations on the crossbeam stiffness of the bridge tower are presented.

Dynamic analyses of long-span cable-stayed and suspension cooperative system bridge under combined actions of wind and regular wave loads

This paper presents the dynamic analyses of long-span cable-stayed and suspension cooperative system bridge under combined actions of wind and regular wave loads. First, the wind loads acting on the bridge deck are calculated based on the aerodynamic force coefficients which were obtained in the wind tunnel and wave flume tests. Then, the wind loads acting on the bridge towers, piers and suspension cables are calculated based on the aerodynamic force coefficients which are simulated in FLUENT software. Besides, the regular wave loads acting on the composite foundations are simulated in FLOW-3D software. Finally, the dynamic responses of the bridge subjected to the combined actions of wind and regular wave loads are calculated in the Mechanical APDL module of ANSYS 17.0 software. The results indicate that the root mean square (RMS) values rather than the mean values of the time histories of the aerodynamic force coefficients obtained in the wind tunnel and wave flume tests should be selected to calculate the wind loads acting on the deck to accurately evaluate the dynamic responses of the sea-crossing bridge. The maximum RMS values of the displacement responses of the deck midspan and 5# tower top increase with the increase of the regular wave heights for the wind-wave cases, which are larger than those for the wind-only case, respectively. In general, the linear superposition of the dynamic responses under the actions of wind-only and wave-only is a conservative choice compared to the consideration of the combined actions of wind and regular wave loads. The displacement spectrums of the deck midspan and 5# tower top, and the lateral base shear and lateral base bending moment spectrums of 5# tower are analyzed to reveal the contribution mechanism of the wind loads, regular wave loads and natural frequencies of the bridge.

Validation and application of pressure-driven RANS approach for wind parameter predictions in mountainous terrain

Computational Wind Engineering has undergone numerous developments over the past few decades and has been applied to solve a variety of wind engineering issues, but it cannot substitute wind tunnel testing and field measurements for accurately replicating wind characteristics in naturally hilly terrain. This paper is aimed at detecting the validity of the approach on numerical simulations by estimating wind flow behaviour at a bridge site in a Y-shaped valley and comparing the results from wind tunnel testing. Further, the terrain-induced effects on wind flow are investigated and the spatial distributions of wind parameters along the bridge structures are characterized. It is concluded that three Reynolds-Averaged Navier-Stokes (RANS) turbulence models, namely k-ε, k-ω and SST, make significant differences in the leeward regions and wind velocity, speed-up, and pitch angle profiles, with the k-model producing superior predictions within 20% error when compared to experimental results. The simulation results show that non-homogeneity of wind characteristics occurs frequently along bridge structures. One is significant rotations of the wind velocity profile up the height of both bridge towers, and then a practical equation for predicting wind deflection is proposed. The other is spanwise nonuniformities in mean wind speeds and pitch angles along the main girder, which necessitates the use of a modified terrain coefficient when securely predicting wind speed. The discussion of a few national bridge design codes reveals that most of them fall short of characterizing the wind load at the bridge site in mountainous areas.

Aerodynamic stability of vehicle passing through a bridge tower at high speed under crosswind conditions with different road adhesion coefficients

In a complex environment, large bridges will present different adhesion coefficient, often accompanied by large crosswind, which makes the flow field around the vehicle complex and changeable. It is easy to cause unnecessary lane change and sideslip of the vehicle, which will affect the driving stability and lead to serious traffic accidents. Therefore, this paper studies the aerodynamic stability of cars passing through the bridge tower at high speed under different road adhesion and crosswind conditions. The detached-eddy simulation (DES) model was employed and the reliability of the DES model was verified by wind tunnel tests. An overlapping mesh technique was adopted to realize the motion of the vehicle. A multibody dynamic (MBD) model of the vehicle was established, and its robustness was verified. A two-way coupling model was then established based on the aerodynamic and MBD models. Subsequently, the aerodynamic characteristics and dynamic response of the vehicle passing through the bridge tower at a high speed were compared and analyzed using one-way and two-way coupling methods, with road adhesion coefficients of 1.0, 0.6, and 0.4 under crosswind conditions. The results show that the aerodynamic characteristics of the vehicle passing the bridge tower at a low adhesion coefficient under two-way coupling change evidently, and the trajectory and body attitude of the vehicle change significantly. As the adhesion coefficient of the road surface decreases, the vehicle passes through the bridge tower with a large lateral displacement and yaw angle. The maximum lateral force of −1406 N and the maximum yaw moment of 803 N∙m are generated when the car passes through the bridge tower under the two-way coupling with the adhesion coefficient of 0.4. Under two-way coupling, the lateral displacement and yaw angle caused by the bridge deck with an adhesion coefficient of 0.4 are 0.265 m and 0.0205 rad, respectively, which is larger than those of the bridge deck with adhesion coefficients of 1.0 and 0.6. Because the coupling effect of aerodynamic and vehicle motion is not considered in the one-way coupling, the one-way and two-way coupling simulation results differ significantly. The results indicate that it is necessary to use a two-way coupling method to study the aerodynamic stability of vehicles passing through a bridge tower at a high speed under crosswind conditions.

Experimental Study on Effect of Water Depth on Earthquake Response of a Deep-water Cable-stayed Bridge Tower

With the aim of investigating the effect of water depth on the earthquake response of a deep-water cable-stayed bridge tower, this study designed and manufactured a large-scale bridge tower model, taking a cable-stayed bridge across a deep reservoir of a hydropower station as a reference. Under the boundary conditions similar to the reference, shaking table tests were conducted to reflect the structural response of the bridge tower under white noise and earthquake actions at different water depths. The time history curve of the bridge tower’s structural response was recorded and used to investigate the variations in the natural frequency, displacement, stress and strain of a deep-water cable-stayed bridge tower at different water depths under earthquake actions. The results showed that the natural frequency of the bridge tower decreased almost linearly with the increase in the water depth. The displacement at the tower top increased gradually with the increase in the water depth under earthquake actions. In addition, the stress and strain at the tower bottom increased almost linearly in the transverse direction and nonlinearly in the longitudinal direction with the increase in the water depth.

Analysis on Mechanical Behavior of Relay Vertical Rotation for Steel Arch Tower

The vertical rotation method is a special option for steel tower construction in fabricated bridge. The tall tower is prefabricated on the ground and then pulled to its designed position using steel wires. Traditional vertical rotation method always uses a taller temporary structure to provide an upward pull force to lift the rotation member; however, the temporary structure would spend much time, cost, and work high above the ground. For instance, the Jinwu Bridge tower’s weight was so heavy that the ordinary rotating method was not feasible. Therefore, a relay traction system with two auxiliary struts was employed to rotate the tower. The chief strut was first rotated to an inclined angle of 60° by an assistant strut to decrease the lateral component force of tension. Then, the tower was pulled from horizontal to vertical by the chief strut. Furthermore, a numerical model was established to analyze the mechanical behavior of the inner force, stress, and deformation of the chief strut, assistant strut, and tower. The study identified critical conditions such as the reverse of axial force for the assistant strut, intervention of back cables, and release of cable tension. The relay traction system effectively reduced initial pulling stress, spending less cost and time. Besides, the analysis method can be an innovate reference for other vertical rotating projects.

Performance Assessment of Structural Monitoring of a Dedicated High-Speed Railway Bridge Using a Moving-Base RTK-GNSS Method

At present, high-precision GNSS positioning technology is an important means to monitor the health of bridges and other structures. However, the GNSS signal of reference stations and monitoring stations used for bridge monitoring can easily be blocked by bridge towers, vehicles, or other objects, resulting in low positioning accuracy and insufficient availability of GNSS, which affects the effectiveness of bridge structural health monitoring. Therefore, according to the characteristics of bridge structure, this paper proposes to take the bridge tower monitoring station as a moving-base station to build the baselines with other monitoring stations and use the moving-base RTK-GNSS method to realize the relative positioning, so as to improve the availability of GNSS in the application of bridge structure health monitoring. In this paper, the moving-base RTK-GNSS model is derived and verified via GNSS monitoring data of the Ganzhou dedicated high-speed railway bridge. The results show that the ambiguity in the fixing rate can be improved using the moving-base RTK-GNSS method with the tower monitoring station as the reference station. The deformation and vibration characteristics of each monitoring point can be reflected, and the displacement and vibration amplitude estimation accuracy can achieve results better than 4 mm. Therefore, the moving-base RTK-GNSS method can be used as an alternative scheme when the observation environment of the base station is poor or the banded engineering monitoring is applied, so as to improve the monitoring capability of GNSS.