Cross-sea Bridge Research Articles

Wave-Current Loads on a Super-Large-Diameter Pile in Deep Water: An Experimental Study

Recently, the diameters and construction water depths of the pile foundations of planned and newly built sea-crossing bridges have been increasing greatly. Hydrodynamic loads are the key control factors in the design of super-large-diameter piles. However, most of the previous studies focused on the inline force on the pile with a small diameter, and there were few cases to consider the impact of the transverse force on the hydrodynamic load of the pile under wave-current actions. In this study, to understand the hydrodynamic loads on such deep-water super-large-diameter piles, the prototype was one of the 6.3-m piles used in the Xihoumen Rail-cum-Road Bridge, and 1:60-scale model tests were carried out in an experimental tank, with the actions of regular waves and waves combined with currents used as loads. The influence of the current velocity and static wave height on the inline and transverse forces on the pile was measured and analyzed. The experimental results indicate that with increasing current velocity, the fluctuation characteristics of the wave-current-induced inline and transverse forces change significantly, and their peak values increase obviously compared to those induced by only waves. In particular, the peak transverse force increases tens of times and can become equivalent to the inline force. The modified Morison formula and Kutta–Joukowski formula are used to derive the correlations between the drag coefficient CD, inertia coefficient CM, lift coefficient CL, and redefined Keulegan–Carpenter number KC*. Under wave-current action, the transverse force contributes quite significantly to the hydrodynamic load on a super-large-diameter pile, making it easier to trigger extreme structural loads. The results presented herein are an important reference for the engineering designs of such super-large-diameter piles.

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.

Application of the Electromagnetic Method to the Spatial Distribution of Subsurface Saline and Fresh Water in the Coastal Mudflat Area of Jiangsu Province.

Interfacial zones straddling terrestrial and marine realms, colloquially known as mudflats, epitomize a dynamic nexus between these environments and are fundamental to the coastal ecosystem. The investigation of these regions is paramount for facilitating infrastructural developments including ports, wharfs, cross-sea bridges, and the strategic utilization of freshwater resources sequestered from mainland islands amid ongoing economic progress. Terrestrial realms conventionally employ electromagnetic techniques as efficacious modalities to delineate subterranean geological information, encompassing structural details and water-bearing strata. However, the peculiar topographic and geological nuances of mudflat regions pose substantial challenges for the efficacious application of electromagnetic methodologies. The present paper endeavors to address these challenges by suggesting innovative modifications to the existing instrumentation and evolving novel data acquisition techniques specifically tailored for electromagnetic exploration within mudflat environments. This paper delves into the electrical characteristics of water-bearing layers within mudflats, and ascertains details pertaining to the subterranean structure and the spatial distribution of fresh and saline water resources, through the holistic interpretation of a multitude of profiles.

Study on multidimensional and multipoint seafloor spatial ground motion simulation under an ice-water layer and the dynamic response of a cross-sea bridge

A combined ice-water reflection coefficient is developed to measure the effect of saltwater and floating ice on seabed ground motions to explore the effect of floating ice on seafloor ground motions. The combined reflection coefficient is made up of three parts: the reflection coefficient of the seawater layer, the transmission coefficient of the water layer, and the reflection coefficient of the ice layer. The combined reflection coefficient analyzes the reflection, transmission, and refraction pathways of seismic waves from the soil layer to the water layer, then to the ice layer and air, and then reflects the attenuation principle of seismic waves in an ice-water layer based on the mechanical parameters of the soil layer, water layer, ice layer, and air. The spatial coherence effect, traveling wave effect, and local site effect are then addressed using the trigonometric series method, and the ice-water layer combined reflection coefficient is utilized to analyze the influence of offshore complex sites on seafloor spatial ground motion. Under the floating ice and seawater layer, an artificial synthetic approach of multidimensional multipoint spatial ground motion is described. The random ice load time history was artificially produced using the ice load spectrum theory and the recorded sea ice parameters. The random response of a long-span cable-stayed bridge is investigated under the combined action of seafloor spatial ground motion and random ice load, and the structural responses of the bridge and tower vary substantially under the combined action of ground motion and ice load.

Influence of seawater depth on offshore ground motion characteristics and seismic responses of sea-crossing cable-stayed bridges

This paper studies the effect of seawater depth on offshore earthquake motion characteristics and seismic response of bridges. By analyzing the offshore seismic data recorded by the K-NET during 2006–2021, the horizontal amplification coefficient spectrum and V/H spectral ratio of offshore ground motions were compared for various offshore stations at different seawater depths. Moreover, a numerical model simulating the propagation process of seismic waves in the seabed was developed to investigate the effects of seawater depth and site conditions on offshore ground motions. Finally, a site-seawater-pile foundation-cable-stayed bridge coupling model was created to study the influence of seawater depth on the seismic responses of sea-crossing cable-stayed bridges. The results reveal that the vertical response spectrum of offshore ground motion in deeper seawater is lower for periods longer than 0.3 s. The numerical models reveal that seawater has a suppression effect on the P wave near the resonance frequency of the seawater layer. Due to the hydrodynamic effect, the longitudinal bridge seismic response is significantly amplified. The amplification effect becomes more obvious with an increase in seawater depth. Therefore, it is important to consider the influence of the seawater layer in the seismic design of sea-crossing bridges.

Biosonar activity of the Indo-Pacific humpback dolphin (Sousa chinensis) near the tunnel section of the world’s longest cross-sea bridge—the Hong Kong-Zhuhai-Macao Bridge—is negatively correlated with underwater noise

Underwater noise pollution from the world’s longest cross-sea bridge—the Hong Kong-Zhuhai-Macao Bridge (HZMB)—which stretches across the Chinese White Dolphin National Nature Reserve (of the People’s Republic of China, PRC) in the Pearl River Estuary may affect the distribution of local humpback dolphins. In this study, static passive acoustic monitoring was applied to monitor biosonar activity of humpback dolphins and underwater noise adjacent to the tunnel section of the HZMB for more than one year. During the monitoring period, dolphin biosonar signals were detected on 88.5% of days. A significant temporal pattern occurred in dolphin biosonar activity and in anthropogenic noise. Biosonar activity was significantly higher at night than during the day, whereas underwater noise occurred more in the day than at night. Significantly more echolocation signals were detected in winter-spring than in summer-autumn, and highest acoustic activity occurred significantly more during high tide than at other tidal periods. In addition, the negative correlation between elevated underwater noise and dolphin sonar activity in winter suggests that dolphins may avoid noisy waters for short periods, perhaps due to auditory stress, but fish prey movement cannot be ruled out. These findings facilitate understanding activity patterns of humpback dolphins in the Pearl River Estuary and may contribute to conservation efforts.

Study On Identification of Construction Risk Pathways for Bridge Piers of Cross-Sea Bridges Based on FTA-BN Model

In order to explore the risks associated with the construction of bridge piers for cross-sea bridges, this paper presents a comprehensive analysis from five dimensions and proposes a model for identifying construction branch paths for cross-sea bridges based on Fault Tree Analysis (FTA) and Bayesian Network (BN). The model analyses, diagnoses, and evaluates system risks by using FTA structural inference and BN bidirectional inference. The research findings show that the probability of cross-sea bridge pier construction risk occurring is 36.8% from the perspective of the overall system's risk. From a sensitivity perspective, unexpected accidents and other risk situations are the most sensitive and are likely to cause top events to occur, with the probabilities of two nodes occurring being 36.0% and 37.5%, respectively. From a contribution perspective, poor construction conditions have the greatest impact, and when this node is in the most dangerous state, the probability of top events occurring is the highest at 81%. Poor construction conditions, physiological and physical degradation, and financial factors all have a risk occurrence probability exceeding 50%, and are significant risk factors leading to the occurrence of cross-sea bridge pier construction.

Design and BIM-based technology on a new cross-sea bridge in Xiamen, China

The Xiamen Second East Cross-Sea Bridge in China is a continuous steel box-girder bridge completed in September 2022. Innovative design and construction technologies helped to improve design, delivery and long-term performance. Building information models were extended from design and construction process simulation to systems for safety, quality management, monitoring and maintenance. This paper describes how whole life-cycle digital modelling significantly improved project management, construction quality and overall costs.

Investigation of analytical behavior of concrete filled steel tubular (CFST) offshore rock-socketed pile under lateral load

With advantages of high load-bearing and construction efficiency, concrete-filled steel tubular (CFST) pile has been increasingly adopted in the constructions of the sea-crossing bridge, offshore wind farm and port. The mechanism of the outer steel tube effect on the CFST pile has not been comprehensively studied, which may limit the further extensive applications accordingly. This study systematically investigates the structural behavior on one classic type CFST rock-socketed pile under lateral loading through the finite element analysis, from the pile member behavior to the cross-sectional confinement effect between the constitutive components. The influence of the steel tube on the lateral displacement, critical load, and pile-soil interaction is analyzed. The mechanism of the composite action between the outer steel tube and core concrete throughout the full-loading history has been investigated to clarify the confinement effect of the steel tube to the core concrete. The parametric studies have been conducted to study the relationship between this confinement effect and the cross-sectional steel ratio. The findings may promote more efficient design and construction of the CFST pile under lateral load.

Study on Optimization of Cooling System for Mass Pier Column of Shenzhong Passage Non-navigable Bridge

In this paper, the optimization layout of cooling pipes and the measured temperature field of the mass pier column for the Shenzhong Passage non-navigable bridge are carried out, and the finite element modeling software is utilized to simulate the whole construction process, and the temperature time and process model is established for simulation analysis. The results show that the measured hydration heat temperature field in the field construction meets good agreement with the simulation results. The optimized cooling pipe layout scheme saves more raw materials and elbows, and shorts the project construction period; It can realize more effective internal lowering and external protection for the construction of mass concrete structures of piers and columns, which is especially suitable for the maintenance of sea-crossing bridges in windy environmental conditions; The temperature-induced cracks are effectively controlled, which can provide a reference for similar projects.

Closure Scheme Analysis of 3 × 70 m Bearingless Integral Rigid Frame Bridge of Fuzhou Xiamen High-Speed Railway

The hydrodynamic problems associated with the construction of the sea-crossing bridge were proposed. The deep-water approach bridge on both sides of the main bridge of Fuzhou Xiamen high-speed railway adopts the bearingless prestressed concrete integral rigid frame bridge for the first time in the domestic railway bridge design. The rigid frame bridge applies the hanging basket cantilever construction, and there are several options for closure. Because the bridge structure system changes before and after closure, which will cause the redistribution of bridge internal force, the results of internal force redistribution will be different with the sequence and position of closure, and sometimes, there will be great changes. In order to select the optimal closure scheme, this article establishes the finite element model of the whole bridge and analyzes the whole construction process according to the working conditions and the mechanical state of the bridge before closure is obtained. Based on this state, eight closure schemes are analyzed and studied, which provides a sufficient mechanical basis for the determination of the final closure construction scheme.

Analysis of the Effect of Local Foundation Scouring on the Structural Dynamic Effect of a Cable-Stayed Bridge Across The Sea

The foundation scour reduces the restraining effect of the foundation on the bridge foundation, resulting in the reduction of the lateral bearing capacity of the bridge foundation. For the cross-sea bridge, the dynamic effect of foundation scour on the bridge structure is more significant, thus affecting the safety of the structure. In this paper, the maximum possible local scouring depth of the foundation is first calculated to make the simulated foundation scouring condition conform. to the actual project. Then, the m-method is adopted to calculate the stiffness value of the foundation soil spring and establish an elastic restraint model that reflects the restraint of the foundation soil on the bridge foundation, thus setting up the finite element model of the bridge with regard to the foundation scouring. On this basis, taking Qiongzhou Strait cross-sea highway and railway dual-purpose cable-stayed bridge as an example, the effect of foundation scour on the dynamic effect of cross-sea cable-stayed bridges under the action of wind and waves is analyzed, and the influence law of the local scour depth of the foundation on the dynamic effect of the structure is determined. The maximum scour depth of 12m is considered to increase the displacement of the top of the tower by 14. 65%, mainly because the foundation scours reduces the restraint effect of the foundation soil on the bridge foundation, resulting in the reduction of the lateral bearing capacity of the bridge foundation. Therefore, for the cross-sea cable-stayed bridge without foundation soil treatment, the detection and monitoring of foundation scour should be strengthened or the preventive maintenance and reinforcement treatment of foundation soil should be done in advance to ensure the safe operation of the bridge structure.

Numerical Study of the Morphodynamic Response to a Macro-Scaled Sea-Crossing Project in Hangzhou Bay, China

Hangzhou Bay is a world-famous strong tidal estuary with an irregular coastline, unique topography, numerous human activities, and complex hydro-sedimentological environment. The Daishan-Yangshan Sea-Crossing Transport Corridor (DSTC) project is located at the mouth of Hangzhou Bay, which is composed of multiple sea-crossing bridges, an underground tube tunnel, and several man-made islands. The large-scale engineering of DSTC fully connects the cities of Shanghai, Yangshan, Daishan, Zhoushan, and Ningbo. This article discusses the morphodynamic responses due to the construction of the DSTC based on a state-of-art numerical model system from the perspective of its impacts on the hydro-sedimentological environment of Hangzhou Bay, as well as on adjacent projects. This study proved that the variation range of tide level in Hangzhou Bay is mostly within 2 cm after the implementation of the DSTC, while that of the man-made island and piers is only within 6 cm. The tidal prism decrease percentage of Hangzhou Bay is less than 0.5%. It does not significantly change the current field and underwater topography in Hangzhou Bay, except near the man-made islands and the bridge. The effect of the DSTC on surrounding ports and channels is small and limited. That is, the proposed DSTC engineering is feasible from the perspective of morphodynamic responses. The conclusions provide a useful reference for similar large-scale estuary construction projects.

Data-driven modeling of Bay-Ocean wave spectra at bridge-tunnel crossing of Chesapeake Bay, USA

The Chesapeake Bay Bridge-Tunnel (CBBT) was designed in the early 1960s and first opened on April 15, 1964. It is a 28.3-km bridge-tunnel system that crosses the mouth of Chesapeake Bay. Because there is a lack of reliable long-term observations of surface waves near the Chesapeake Bay entrance, accurate forecasts and hindcasts of wave conditions are essential for maintaining and expanding the bridge-tunnel infrastructure. To estimate wave parameters and energy spectra near the CBBT, novel composite data-driven models were developed using the wind, water level, and offshore wave data as input. The developed models provide satisfactory predictions of both integral wave parameters and energy density spectra of sea and swell waves at the Chesapeake Bay entrance. The developed models can rapidly hindcast the wave characteristics and spectra during an extreme event (i.e., the Halloween storm in 1991). This paper provides a novel framework for developing surrogate models to predict wave spectra in the frequency domain and hindcast historical wave climate, which can be applied to other sea-crossing bridges and/or tunnel sites near bay entrances. The data-driven models, based on deep neural networks, allow for estimating waves without a high demand for computational resources, and thus serve as a useful tool for the characterization and simulation of the complex wave environment at the interface of estuary and ocean.

Prediction of buffeting responses of the thin plate under joint action of wave and wind using LSTM and transfer learning

To predicate the buffeting responses of long-span sea-crossing bridges under joint action of wave and wind, a thin plate was taken as the example, and a piston-type wave maker was adopted to simulate the second order Stokes wave in a computational domain. Through the large eddy simulation (LES) and dynamic mesh methods, time-histories of wind field and buffeting response of the thin plate under joint action of wave and wind were obtained. Then, the buffeting responses of the thin plate were predicted using the conventional long short-term memory (LSTM), convolutional LSTM (Conv LSTM) and LSTM with attention mechanism (LSTM-AM) neural network models, respectively. Furthermore, the transfer learning (TL) method was introduced, the method to solve a large amount of source task data was established, and a combined neural network model of TL-Conv LSTM-AM was proposed to predict the buffeting responses of the thin plate. The results show that the prediction accuracies of Conv LSTM and LSTM-AM models are both higher than the conventional LSTM model based on the evaluation indexes of determination coefficient (R2) and root mean square error (RMSE). The prediction accuracies of the buffeting responses can be improved significantly when the above LSTM neural network models are combined with the TL method. Also, there are still some deviations between the predicated time-histories and target ones. For the proposed combined model of TL-Conv LSTM-AM, the values of R2 in three directions of the buffering responses are all larger than 0.996 and 0.983 in the high and low turbulent flow fields, respectively. Therefore, the proposed TL-Conv LSTM-AM combined model has the highest prediction accuracy among them. Similar prediction accuracy can be achieved for longer time duration of the testing data set using the proposed combined model of TL-Conv LSTM-AM. The above phenomenon proves that the effectiveness of this proposed combined model in predicting the buffeting responses of the thin plate under joint action of wave and wind.

On-site wave-wind observation and spectral investigation of dynamic behaviors for sea-crossing bridge during tropical cyclone

The dynamic behaviors of a sea-crossing bridge during a tropical cyclone event which passed through the bridge site in September 2015 are simulated using in-situ observation wave and wind data. The hourly observation data during the cyclone event at the bridge site including averaged wind speed, turbulence intensity, direction, significant wave height, mean period, spectral variations are recorded. The wave and wind spectra are analyzed from raw data and are fed to a frequency-domain framework for response modeling. The stochastic wave actions considering foundation geometry, diffraction effect, wave coherence and second-order quadratic wave force transfer functions are considered using boundary element methods and the wind actions including buffeting loads, aerodynamic stiffness and damping are modeled based on stationary buffeting theory. Results reveal that the maximal structural response occurs near the cyclone eye wall while the storm center is still 80–100 km away but experiences sudden drop when the cyclone eye reaches the bridge site. Deck responses are much more sensitive to wind, but wave dominates the tower and base force responses. Second-order wave load is found to be critical to responses because the sum-frequency wave force could undesirably coincide with the bridge eigenfrequencies.

Coupled Vibration Analysis of Ice–Wind–Vehicle–Bridge Interaction System

Bridges built in ice-covered water regions are mostly in complex marine environments, they not only need to withstand strong wind but also resist the impact of drift ice. However, at present, there is a lack of vehicle–bridge coupling vibration analysis and driving safety assessment under combined ice and wind. Therefore, this study constructs a complete analysis framework of ice–wind–vehicle–bridge interaction to investigate the dynamic responses of the coupled system. Ice load is simulated by a linearized ice–structure interaction model, which is based on the self-excited vibration theory. Wind load on the bridge deck includes steady-state force and buffeting force. Wind load on the vehicle is simulated based on the quasi-steady model. Subsequently, ice load, wind load, soil–structure interaction (SSI), and additional water mass are all integrated into a full bridge model based on a sea-crossing bridge with running vehicles in the Bohai Sea. The results indicate that ice load has a greater impact on the lateral dynamic response of the bridge, the combined action of ice and wind has no superimposed effect on the movement of the bridge but has a restraining effect. Wind load presents a more significant influence on the lateral dynamic response of the vehicle, the coupled dynamic responses of the vehicle cannot be combined by the superposition under separate ice and wind. The combined effect of ice and wind obviously increases the sideslip risk of running vehicles and reduces driving safety.

Shrinkage Compensation Technology of Concrete Filled Steel Tubular Structure of Large Cross-Sea Bridge

In view of the poor accuracy and unsatisfactory effect of shrinkage compensation for concrete-filled steel tubular structures of large cross-sea bridge (CSTS-LCSB), a new shrinkage compensation technology for CSTS-LCSB is proposed. The shrinkage mechanism of CSTS-LCSB is analyzed, including plastic shrinkage, dry shrinkage, autogenous shrinkage, and carbonation shrinkage. The proportion of dry shrinkage and autogenous shrinkage in ordinary concrete and high-strength concrete is determined. The CSTS-LCSB has different shrinkage forms in different environments, and the shrinkage strain state of CSTS-LCSB in different environments is calculated according to the difference. The shrinkage area of the concrete structure is determined, and the expansion agent is used to compensate for the shrinkage area of CSTS-LCSB. The experimental results show that the proposed compensation technology has a good effect on shrinkage compensation and has certain feasibility.

Experimental investigation on the hydrodynamic response and sectional improvement of ballast water Box-type floating breakwater

Floating breakwaters play a crucial role in protecting the safety of marine structures and can provide adequate protection for the temporary cofferdam during the construction of the cross-sea bridge. In order to further improve the wave attenuation performance of the ballast water Box-type FB, in this paper, the physical experiment and numerical simulation of Box-type FB are carried out, and the hydrodynamic characteristics of Box-type FB are studied in detail. The results show that the number of corners and the contact area with waves are essential factors affecting the wave attenuation performance; Given this, a new type of ballast water I-shaped FB is proposed, and the effect of ballast water on the motion response of I-shaped FB and Box-type FB were discussed. Then, the wave attenuation performance and anchor chain force of Box-type FB and I-shaped FB were compared, and the results show that the I-shaped FB improves the wave attenuation capacity and reduces the anchor chain force. Finally, the hydrodynamic response, motion response, wave attenuation performance, and anchoring chain force of the I-shaped FB with different ballast water were explored to improve the technical applicability of the I-shape FB, which provides a benchmark for FB optimization research and engineering application.

Distributed Dynamic Load Identification of Beam Structures Using a Bayesian Method

The distributed dynamic load is difficult to obtain due to the complexity of loads in practical engineering, such as the aerodynamic loads of aircraft and the distributed dynamic loads of sea-crossing bridges. Thus, distributed dynamic load identification is important to deal with these difficulties, which is generally an ill-posed problem considering the inversion of the infinite dynamic loads. The traditional Tikhonov regularization technique is limited on the optimal regularization parameters selection. Consequently, in this paper, we develop a novel distributed dynamic load identification algorithm in combination with the orthogonal polynomials and the Bayesian framework. Thus, the orthogonal polynomial coefficients in the load identification model are regarded as the prior probability distribution of unknown variables in the Bayesian inference. Simultaneously, the posterior probability distribution of the orthogonal polynomial coefficients is derived based on the Bayesian formula and the likelihood function. The regularization parameters and the standard deviation of the response error are also treated as random variables to obtain the corresponding prior distribution in the multi-level Bayesian model. Moreover, the maximum posterior estimate is applied aiming at determining the regularization parameters, as well as the orthogonal polynomial coefficients to reconstruct the distributed dynamic loads. Compared with the Tikhonov regularization, a series of numerical simulations are studied to verify the effectiveness and high accuracy, as well as the noise resistance, and the results illustrate that this approach is effective to reconstruct the distributed dynamic loads.