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This paper introduces new contributions for construction procedures designed to enhance the robustness and precision of stress control in active anchorage and short presetressing units for long-span bridges, particularly addressing potential technical risks. The primary focus is on optimizing stress management for bridge stays, suspension cables, and short prestressing units by emphasizing a unified parameter: stress. The contributions of this research encompass (1) the introduction of advanced load cells for stress control in active anchorages and (2) the implementation of a novel synchronized multi-strain gage load cell network for short prestressing units, crucial in situations where prestressing losses can attain significant magnitudes. To validate these advancements, the authors present (3) a practical experience and results obtained from applying these methodologies in monitoring the structural response during the construction of the Tajo Bridge using the cable-stayed cantilever technique. [ABSTRACT FROM AUTHOR]

Bridge aerodynamic studies are essential in ensuring the safety and acceptable performance of long-span bridges vulnerable to the effects of cross-winds. Aerodynamic studies were traditionally carried out in wind tunnel facilities, but there are now greater opportunities for using computational fluid dynamics (CFD) modelling. Few three-dimensional (3D) aerodynamic simulations of lightweight vehicles on bridges exist, but limited validation and verification work has been carried out. In the study reported in this paper, 3D CFD models were developed for Queensferry Crossing – a cable-stayed bridge in Scotland – containing wind shields and sample vehicles. The models considered the wind effects from a range of yaw wind angles and subsequently determined the aerodynamic coefficients of vehicles. The models were verified by means of a mesh sensitivity study, a domain sensitivity study and comparisons with wind tunnel tests. The models were then validated using the same modelling process but with a different type of wind shield and again comparing the results with wind tunnel test data for the same configuration. The results showed that CFD modelling can determine aerodynamic coefficients to a level of accuracy similar to that of wind tunnel tests. [ABSTRACT FROM AUTHOR]

The profile of the rail expansion joint (REJ) would affect the stable operation of high-speed trains, so it needs to be optimized. An optimization method was presented for the switch rail declining values (SRDV) of REJ at the beam end in a long-span cable-stayed bridge (CSB) through the co-simulation based on SIMPACK and MATLAB. First, based on the theory of rigid-flexible coupling, a high-speed vehicle-REJ-CSB multibody dynamics model was established. The model conducted a detailed simulation of the beam end track system and performed a parameterized design of the REJ profile. Then, 8 dynamic indicators of high-speed vehicles were selected as optimization objectives. The Simulated Annealing Particle Swarm Algorithm (SA-PSA) was employed to solve the objective function and obtain the optimal SRDV of REJ. Finally, the effect of the optimization was verified by the model test. The results indicated that the optimal SRDV had the most significant reduction in the wheel-rail forces, followed by the motion of the bogie frame. The wheel-rail vertical force was reduced by 9.59%, and the wheel-rail lateral force was reduced by 20.56%. The lateral acceleration of the bogie frame was reduced by 8.69%. Under the damping effect of the primary and secondary suspension system, the influence of the REJ profile on the acceleration of the vehicle was relatively small. Therefore, the optimization for SRDV had little effect on the acceleration of the vehicle. Through the model test, the superiority of the optimization results in this paper was verified. [ABSTRACT FROM AUTHOR]

The interface force condition on the cross section of parallel steel wire strands is an important basis for studying the longitudinal friction and slip behavior of wires. In this study, force-chain superposition was proposed to solve the transmission and distribution of transverse forces between parallel wires. The calculation rules for the basic parameters in the solution were determined, and a wire-drawing experiment was designed to verify their applicability. A two-dimensional discrete model corresponding to the cable cross section was established. According to the source and characteristics of the transverse load, the force system is decomposed into two directions to form two force chain analysis paths so that the model assumptions can be applied properly. A recursive algorithm was proposed to solve the two force chains, and symmetry conditions were applied at the coupling position to make the system self-consistent. The normal forces acting on the interface points were obtained by superimposing the results onto the two force chains and were verified against finite element analysis (FEA) results. A long-span cable-stayed bridge was considered as an example to investigate the interface force condition of its cables, based on which the approximate development length of the broken wires and the interface extrusion force of the multilayered beam model were established. The results indicate that the slight twisting of the parallel wire strands under the action of a large cable force provides 85% of the total interface forces, and the normal force is significantly concentrated in the central area of the cross section. The approximate development length of the central wire is only 25.9% of that of the outermost wire, and the minimum slip friction force between the layers accounts for only 21.2% of the maximum value for the multilayered beam model, confirming that the interface force condition has a significant impact on the longitudinal friction and slip behavior of cable wires. [ABSTRACT FROM AUTHOR]

The Gordie Howe International Bridge project is providing a new modern border crossing between Windsor, ON, Canada and Detroit, MI, USA. The centrepiece of the project is a 2.5 km long cable-stayed bridge with 853 m main span over the Detroit River and 220 m tall towers on both sides of the river. In addition to the bridge, the project includes ports of entry on both sides of the border and a new freeway interchange with Interstate-75 in Detroit. The project was procured as a public–private partnership that allowed the proponents to propose either a suspension or cable-stayed bridge, with the ultimate selection creating the longest cable-stayed bridge in North America. The paper outlines the need for the new border crossing and results of the environmental assessment process, as well as describing the project evolution from planning through procurement and into detailed design. The scoping of the bridge design parameters is discussed, including: comprehensive geotechnical investigation; load study to develop project-specific live loading; the approach for durability requirements to achieve a service life of 125 years; special considerations for security; wind engineering; and compliance with both Canadian and US design codes. The paper also discusses the approach to achieving an aesthetically pleasing bridge design. [ABSTRACT FROM AUTHOR]

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

Hybrid cable-stayed suspension bridges combine the advantages of cable-stayed and suspension bridges, mitigating their deficiencies. Due to its super spanning ability, this novel form of bridge enjoys a bright application prospect as a large-span structure. This study introduces an analytical algorithm to estimate the full-bridge response of a hybrid cable-stayed suspension bridge with a vertical uniformly distributed load applied to the main beam. This method is based on the assumption that all parameters, such as the geometric configuration, internal force distribution, and material properties, of the whole bridge under a dead load are known; then, it analyzes the full-bridge response under a live load. First, the minimum and independent basic unknown parameters of the full-bridge response are determined. Next, the governing equations are derived and solved based on the conservation of unstressed length of each section of cable, closure of span lengths and elevation difference in different spans, and conditions for stress balance of the main beam. Thus, the values of basic unknown parameters are obtained. Finally, they are substituted into the governing equations to estimate the full-bridge response, including each bridge component's internal forces and deflections. The proposed analytical method involves no iterative procedures when dealing with nonlinear problems but only focuses on the bridge's state with and without loading. The results are obtained directly by solving the equations, which have the advantages of high efficiency, simplicity, and clear physical meaning. Finally, the feasibility and effectiveness of the proposed method are verified by a finite-element-based calculation of an exemplary asymmetric cable-stayed suspension cooperation system bridge with a main span of 1400 m. [ABSTRACT FROM AUTHOR]

Because of the large number of components and complex evaluation indexes of long-span bridges, it is necessary to adopt the evaluation method suitable for complex structures. Since the hypothetical membership degree of fuzzy theory and the layer weight of traditional analytic hierarchy process (AHP) may have subjective bias, the evaluation precision may be influenced if it is applied independently in bridge evaluation and thus the fuzzy analytic hierarchy process (FAHP) is more applicable to large-span concrete cable-stayed bridge. The traditional analytic hierarchy process using triangular fuzzy number (FAHP) has the shortcomings of computational errors and limited range, so the improved FAHP is adopted. The improved FAHP method introduces the reliability into the judgment matrix, which can not only solve the existing problems, but also reflect the influence of the fuzziness of the man-made subjective judgment on the result. Based on the detection results for a concrete cable-stayed bridge in Jilin Province, the corresponding hierarchy of index system is established, the trapezoidal function is used to calculate membership degree, and the weight of each index relative to target layer is calculated. Improved FAHP is finally applied to assess the security levels of various parts of this bridge and make comprehensive evaluation on the whole bridge. [ABSTRACT FROM AUTHOR]

Running trains on a long-span bridge under earthquake is an inevitable problem for the high-speed railway in seismic regions. This paper aims to investigate the seismically random dynamic behavior of train–cable stayed bridges interaction system using the probability density evolution method (PDEM). The system simultaneously involves the multi-effect of random multi-point earthquake excitations with traveling waves and random track irregularity. The multi-point earthquake excitations, composed of lateral and vertical positions, are generated by stochastic harmful functions (SHFs) and uniformly modulated into nonstationary random processes. The motion equation of such a system is established by coupling the 38-degree vehicles and bridges through the refined random wheel/rail contact relationship and accounting for the phase-lags of seismic travelling waves between pier excitations. PDEM is proven to be applicable to such time-dependent systems and is then used to transform the random excitations into a series of deterministic representative excitations with initial probability. By solving for the corresponding deterministic probability responses, various nonstationary random responses, including the time-dependent probability density evolution functions of random responses, mean values curves and standard deviations, can be obtained easily. A case study based on the cable-stayed bridge is then presented, and the results show the effectiveness and accuracy of the proposed method by comparison with Monte Carlo Simulation. Additionally, the influence of train speed and seismic intensity on the safety and reliability of trains is discussed. [ABSTRACT FROM AUTHOR]

In order to control the collision of long-span cable-stayed bridges with floating systems caused by large longitudinal displacement of beam ends under earthquake action, based on the engineering background of a long-span dual-purpose double-tower cable-stayed bridge, the collision problem of the main approach bridge under earthquake action is proposed. Two kinds of intelligent fuzzy control strategies based on different membership functions are presented, using MR Damper as a control device and modeled by SIMULINK. In this paper, the damping control effect of the proposed fuzzy control strategy on the collision problem of the main approach bridge of the cable-stayed bridge is studied. The results show that changing the range of the membership function will change the size of the control current, and the longitudinal displacement and acceleration of the structure will decrease with the increase in the control current. However, when the control current is too large, the acceleration response will be amplified and oscillated. Both fuzzy controls can reduce collision times, and the peak value of collision force between the main approach bridges and the energy consumption of the MR damper are roughly similar. Based on the control effect of longitudinal displacement response, acceleration response, and collision force response of the main approach bridge and the energy consumption of the damper, fuzzy control A is better than fuzzy control B. [ABSTRACT FROM AUTHOR]

In view of the insufficiency of bidirectional seismic control of long-span cable-stayed bridges as well as the limitations of existing schemes, a multi-direction damping system (MDDS) was proposed and investigated in this manuscript, which can provide seismic resistance bidirectionally. The new damping system owned a unique middle connecting structure, which overcomes the disadvantages that axial instability caused of excessive long rod and the demand of large installing space of traditional dampers. Both the performance stability and constitutive relationship of MDDS were verified by engineering tests, and the equivalent design method was then proposed and proved to be applicable. A detailed finite element numerical model of a super-long (main span over 800 m) column-type pylon cable-stayed bridge which equipped with MDDS in practice was established, the fragility curves of critical components were obtained by non-linear time history analysis, which exhibited the high efficiency of MDDS seismic performance in both transversal and longitudinal directions. Through extracting the median fragility value of 35 sections of the pylon under four damping cases, i.e. setting dampers transversely (TDS), longitudinally (LDS), bidirectionally (BDS), and MDDS, it can be concluded that MDDS performed far better on seismic resistance than LDS and TDS, and made the similar contribution with BDS. On account of half number of damper setting and the reduction in installing space demand, MDDS becomes the optimal choice in practical application for its economic efficiency and superiority. Furthermore, the optimal horizontal installing angle of MDDS was derived through six angle cases which was based on the system-level fragility curves comparison. [ABSTRACT FROM AUTHOR]

The continuous increase in traffic volume requires wider single box girders for long-span cable-supported bridges. Flutter and aerostatic instability are challenging issues for these flexible bridges, especially when they are located in typhoon-prone regions. Aerodynamic countermeasures such as vertical and horizontal stabilizers, which are convenient in operation, saving in cost, and effective in the enhancement of flutter performance, are usually employed to withstand the wind environment requirement. This study investigates the aerodynamic and aerostatic effects of upper central vertical stabilizers (UCVS), lower central vertical stabilizers (BCVS), horizontal stabilizers (HS), and their combinations on two wide single box girders with an aspect ratio larger than 12 at various angles of attack (AOAs). The optimal layouts of stabilizers for the enhancement of flutter performance are studied using a series of wind tunnel tests. Their control mechanisms are examined and discussed using flutter derivatives and step-by-step (SBS) method. A new index of nominal torsional center (NTC) is proposed to intuitively describe the flutter modality. The correlations among different indexes of flutter modality, flutter derivatives, and Ucr are further analyzed. The static coefficients of the bridge girders and the aerostatic performance of the bridge with or without stabilizers are also analyzed. Experiment results show that the values of Ucr for 4- and 5-m-high single box girders increased by 13.9% and 46.3%, respectively, after the hybrid installation of UCVS, BCVS, and HS at their optimal conditions. The analytical solutions indicate that the installation of different stabilizers changes the variation trend of the aerodynamic damping ratio with the wind speed to increase or reduce the flutter boundary. Four flutter modality indexes including amplitude ratio (Ψ), phase difference (ψ), energy participation level (Ph), and NTC are all found that have no obvious correlations with Ucr. The static analysis on a three-dimensional bridge showed that the optimal stabilizer schemes for flutter have insignificant effects on aerostatic performance. [ABSTRACT FROM AUTHOR]

Ideally, the monitoring data collected by the Structural health monitoring (SHM) system should purely reflect the structure status. However, sensors deployed in the field can be very vulnerable to extreme conditions such as heavy rainfall, which results in large quantities of anomalous data and unavoidably leads to the inaccuracy of structural condition assessment and even false alarms. To automatically identify whether the collected data are abnormal or not, a novel deep learning-based data anomaly detection technique combining the time-frequency method and the Convolutional Neural Network (CNN) is proposed in this paper. First, the original time-series data of the SHM system were converted to the red green blue (RGB) images by using the wavelet scalograms. Subsequently, the GoogLeNet deep neural network is applied to construct a classification model by incorporating the generated 2D images. In order to evaluate the performance of the proposed technique, the SHM data (containing seven abnormal patterns) lasting for one month of a long-span cable-stayed bridge were utilized for experimental validation. The results indicate that compared with traditional deep neural network methods, the data anomaly identification accuracy can be improved by using the proposed technique. Different types of data anomaly patterns can be accurately identified, even in the case of small samples. The proposed technique exhibits good accuracy and can be integrated into advanced SHM systems with high fidelity and intelligence. [ABSTRACT FROM AUTHOR]

Long-span cable-stayed bridges often have a design service life of more than a hundred years, during which they may experience multiple earthquake events and accumulate seismic damage if they are located in seismic-prone regions. Earthquake occurrence is discretely and randomly distributed over the life cycle of a long-span cable-stayed bridge and often causes sudden drops in the structural performance instead of yearly fixed seismic performance degradation. This study thus proposes a digital twin-based life-cycle seismic performance assessment method for long-span cable-stayed bridges. The major components of this method include: (1) a seismic hazard analysis-based generation method of earthquake occurrence sequence; (2) a digital twin-based structural response prediction method considering lifetime earthquake occurrence and sequence; and (3) a service life quantification method. The proposed method is applied to a scaled long-span cable-stayed bridge with a series of shake table tests. The results show that the digital twin can closely reproduce the life-cycle seismic response of the bridge under sequential earthquakes. The proposed assessment method provides a more intuitive presentation of the life-cycle seismic damage accumulation process and a more accurate estimation of the service life of a long-span cable-stayed bridge. [ABSTRACT FROM AUTHOR]

Responses of vortex-induced vibration (VIV) of long-span bridges are commonly measured at first via wind tunnel tests of sectional model and then converted to the prototype ones of the corresponding full bridges by some approximate formulae. In this paper, a time-domain full bridge analysis method was presented for predicting nonlinear VIV responses mode-by-mode based on a polynomial type of nonlinear mathematical model of vortex-induced force (VIF) on bridge deck cross section. In this method, the motion-dependant self-excited force (SEF) components of VIF were regarded as fully correlated span-wise in the case of smooth flow, while the motion-independent harmonic pure vortex-shedding force (PVSF) component of VIF was regarded as incompletely correlated along the bridge span. To take into account the incomplete span-wise correlation of PVSF, an equivalent generalized PVSF including the effect of the incomplete span-wise correlation of PVSF was defined by using a span-wise correlation coefficient of PVSF which could be obtained through a sectional model wind tunnel test of simultaneous pressure measurement. As an application example, the VIV responses of 12 vertical modes of a steel box deck cable stayed bridge with a main span of 688 m were analysed, and were compared with those converted with two approximate converting formulae, respectively, based on Scanlan's linear and nonlinear mathematical model of VIF. It is found that the influence of the incomplete span-wise correlation of PVSF on the bridge VIV response is very small and can then be ignored. [ABSTRACT FROM AUTHOR]

In this paper the vortex induced vibration of a cable-stayed bridge with a main span of 252 m was studied at construction stages. Structural FEM and aerodynamic CFD models were made in order to calculate the vibration amplitude of this slender structure. The damping of the pure steel structure and the effect of the tuned mass dampers were measured through on-site vibration tests. Based on the validated structural dynamics model and the simulated aerodynamic parameters, the vortex induced vibration amplitudes were evaluated and compared with the monitoring data gained from accelerometers and wind sensors attached to the stiffening girder during the most critical construction period. [ABSTRACT FROM AUTHOR]

Currently the importance of bridge inspection and maintenance is widely recognized. It seems reasonable to mention that a gantry is essential for the inspection and maintenance of a long span bridge. Therefore, most long span bridges are equipped with a gantry as a permanent access tool. Honshu Shikoku Bridges compose three highways and one railway between Honshu and Shikoku islands in Japan. Three routes consist of 17 long span bridges with a main span of more than 200 m. Since the bridges had been constructed with accumulating knowledge for construction and maintenance from 1975 to 1999, a gantry had also been improved for gaining better access. Despite the improvement, there were still a certain number of inaccessible elements and components, so further improvement is being made to increase access capability due to growing requirements of arms-length inspection and maintenance. There are 152 gantries in total, consisting of four types of gantries: a suspended gantry, an internal gantry, a tower gantry, and a cable gantry. This article presents the gantries installed in the Honshu-Shikoku Bridges, containing improvement histories for each type of gantry in the construction and several efforts to improve access capability in the maintenance. [ABSTRACT FROM AUTHOR]

The present study focuses on the effects of wind yaw angle and pylon interference on the buffeting responses of bridge decks during construction. Two typical cable-stayed bridges with rhombus pylons (RPs) and single-column pylons (SPs) in the maximum double cantilever state were selected as research objectives. The influence of the wind yaw angle and pylon interference on the lateral, vertical and torsional buffeting displacements were systematically analyzed through full bridge model aeroelastic wind tunnel tests. The research results show that the maximum buffeting responses appear when the wind yaw angle is in the range of 5 ° to 30 °. The effects of the wind yaw angle on the buffeting responses become more obvious in cases of high mean wind speeds. The pylon interference effects on the lateral buffeting displacements are more significant than those on the vertical and torsional buffeting displacements. The strong pylon interference effects may lead to non-conservative buffeting response estimation results using traditional buffeting analysis methods. This study demonstrates that it is of paramount importance to take into consideration the combined effects of the wind yaw angle and pylon interference in the design of long-span cable-stayed bridges during their construction stages. [ABSTRACT FROM AUTHOR]

Bridge modal identification using an instrumented test vehicle as a moving sensor is promising but challenging. A key factor is to extract bridge dynamic components from vehicle responses measured when the bridge is operating. A new method based on an advanced adaptive signal decomposition technique, the successive variational mode decomposition (SVMD), has been developed to estimate the bridge modal parameters from the dynamic responses of a passing test vehicle. When bridge-related dynamic components are extracted from the decomposition, the natural excitation technique and/or random-decrement technique based fitting methods are used to estimate the modal frequencies and damping ratios of the bridge. Effects of measurement noise, moving speed and vehicle properties on the decomposition are investigated numerically. The superiority of SVMD in the decomposition is verified by comparing to another adaptive decomposition technique, the singular spectrum decomposition. The results of the proposed method confirm that the bridge modal frequencies can be identified from bridge related components with high accuracy, while damping ratio is more sensitive to the random operational load. Finally, the feasibility of the proposed method for bridge monitoring using a moving test vehicle is further verified by an in-situ experimental test on a cable-stayed bridge. The components related to the bridge dynamic responses are successfully extracted from vehicle responses. [ABSTRACT FROM AUTHOR]

This study proposes a simplified analysis method that couples the bridge and train-track subsystem in a weak form to facilitate the dynamic analysis of the train-track-bridge coupled system (TTBS) under earthquakes. The method includes three main steps: (i) performing dynamic analysis of the bridge under seismic conditions to obtain the response of the bridge deck; (ii) interpolating the bridge displacement beneath each wheelset based on the train's velocity, departure time, and the initial positions of the wheelsets; and (iii) assessing the running safety of the train by incorporating the interpolated bridge response as track irregularity into the train-track coupled system. Steps (i) and (iii) can be analyzed separately using finite element and multibody dynamics software, eliminating the need to create a complex TTBS model that is challenging to achieve within a single software platform. Additionally, based on the method's assumptions, the earthquake excitation on the train can be separated into the seismic inertial effect and seismic-induced bridge deformation, enabling a quantitative analysis of the impact of these two types of excitations on train safety. Taking a 10-span simply supported bridge and a long-span cable-stayed bridge as examples, the proposed method's assumptions are verified by comparing its results with those obtained from a complex TTBS model. Furthermore, the impact characteristics of inertial effects and seismic-induced bridge deformation on train safety for these two types of bridges are analyzed. The proposed method offers robust support for seismic design of bridges and facilitates a comprehensive analysis of the mechanisms through which seismic excitations affect train safety. • Proposal and validation of a simplified method for running safety evaluation of train on bridges under earthquake excitation. • Separation of seismic excitation on the train into seismic inertial effect and seismic-induced bridge deformation. • Analysis of impact characteristics of inertial effects and seismic-induced bridge deformation on train running safety. [ABSTRACT FROM AUTHOR]

Since the excessive seismic support uplift force may cause the support failure of long-span cable-stayed bridges, this study focused on the support uplift force at the auxiliary pier for a double-tower cable-stayed bridge with a main span of 1088 m. A shake table test was designed and performed based on the 1/35-scale test model scaled from the prototype bridge. Details of the test model, including the scale factor, structural member configurations, boundary conditions, and the numerical validation were briefly presented. The test results show that although only the longitudinal ground motion was applied, significant seismic support uplift and compression forces would be generated in the bearings at the auxiliary pier, resulting in the bearing uplift. The vertical vibration of the deck contributed by the first vibration mode of the test model was one of the main causes of the bearing uplift, but no rigid-like pounding effect occurred due to the vertical nonlinear mechanical behaviour of the bearing. Furthermore, the effect of the bearing uplift on the main seismic responses of the test model was negligible. • The support uplift force of a long-span cable-stayed bridge under longitudinal ground motions is experimentally studied. • The seismic responses of the tests model related to the support uplfit force are obtained and analyzed. • Significant seismic support uplift force and compression force will be generated, resulting in the bearing uplift. • The vertical vibration of the deck contributed by the first vibration mode is one of the main causes of the bearing uplift. [ABSTRACT FROM AUTHOR]

Although the wind barrier was set near the bridge tower, more than 10 traffic accidents under crosswinds happen in the bridge tower area within 1 month of the opening operation of a cross-sea bridge. To investigate the wind shielding effect of the bridge tower, a field measurement scheme of wind-vehicle-bridge system, which is a step-by-step test method, was presented and performed on a long span cable-stayed bridge. Firstly, the horizontal profile of wind speed of bridge deck near bridge tower was obtained through the anemometers. Then, the dynamic response of the bridge was measured under the action of normal operating vehicle when the natural wind speed is low. Finally, the response of the moving car was measured when passing through bridge tower, and the wind speed was recorded simultaneously. The results show that the wind-vehicle-bridge system can be tested by step-by-step test method to understand the wind shielding effect of bridge tower. The displacement response of the bridge is still very small when two large trucks meet, and the coupling effect between the vehicle and the bridge is insignificant when a single car passes through the bridge tower. Due to a large porosity of the anti-collision guardrail, the wind speed at the height of 1 m from the bridge deck has changed dramatically when the car leaves the bridge tower on the windward and entering or leaving the bridge tower on the leeward. Among them, the leeward side change is more obvious, and the response of the leeward side vehicle is also greater. The suitable decrease of the anti-collision guardrail porosity in the bridge tower region will improve the running safety of vehicles. [ABSTRACT FROM AUTHOR]

Service performance evaluation is of great significance to the safety, durability, and reliability of bridge engineering. Over the last decade, structural health monitoring (SHM) systems have been widely used for condition monitoring of cable-stayed bridges, massive monitoring data are measured and stored by the sensing subsystems, which provides the basis for service performance evaluation of bridge engineering. Meanwhile, the load test is a common method to assess the construction and service performance of bridges. Combined the SHM systems and a load test of a thousand-meter level cable-stayed bridge after ten years of service, this paper investigates the operating conditions of main structures, including bridge towers, main girders, and steel cables. 52 trucks were used to conduct a quasi-static load on three key sections of bridges. Meanwhile, the GPS displacement of towers and main girders, stress of the main girders and acceleration responses of cables were measured synchronously by the SHM systems. Based on the health monitoring data, the dynamic responses, structural deformation, and cable tension of the bridge were investigated and evaluated by comparing with the finite element (FE) model load test at construction stage. The results show that the service performance of the bridge is basically within the designed conditions. [ABSTRACT FROM AUTHOR]

A cable-stayed bridge is widely adopted to construct long-span bridges. The deformation of cable-stayed bridges is relatively larger than that of conventional bridges, such as beam and truss types. Therefore, studies regarding the monitoring systems for cable-stayed bridges have been conducted to evaluate the performance of bridges based on measurement data. However, most studies required sufficient measurement data for evaluation and just focused on the local response estimation. To overcome these limitations, Structural Responses Analysis using a Limited amount of Multi-Response data (SRALMR) was recently proposed and validated with the beam and truss model that has a simple structural behavior. In this research, the structural responses of a cable-stayed bridge were analyzed using SRALMR. The deformed shape and member internal forces were estimated using a limited amount of displacement, slope, and strain data. Target structural responses were determined by applying four load cases to the numerical model. In addition, pre-analysis for initial shape analysis was conducted to determine the initial equilibrium state, minimizing the deformation under dead loads. Finally, the performance of SRALMR for cable-stayed bridges was analyzed according to the combination and number of response data. [ABSTRACT FROM AUTHOR]

With the advantages of high strength, light weight, high corrosion and fatigue resistance, and low relaxation, carbon-fiber-reinforced polymer (CFRP) is an excellent cable material for cable-stayed bridges. However, the relatively high unit price of CFRP compared to that of steel may hinder the large-scale application of CFRP stay cables. This paper presents the economic comparison between long-span cable-stayed bridges using CFRP cables and the corresponding steel cable-stayed bridges through life-cycle cost analysis (LCCA). Three CFRP cable-stayed bridges with a main span of 600 m, 1200 m, and 1800 m, respectively, along with their steel counterparts, were designed, and their life-cycle costs (LCCs) were calculated. The comparison of LCCs was not only between the CFRP and steel cable-stayed bridges with the same span, but also between the cable-stayed bridges with different spans. Furthermore, the different unit prices of CFRP cables and different replacement frequencies of steel cables were also investigated. The results show that the initial design and construction cost of the long-span CFRP cable-stayed bridge is higher than that of the corresponding steel cable-stayed bridge, although using CFRP cables can reduce the materials used, primarily due to the higher unit price of the CFRP cable. Despite the higher initial cost, the long-span CFRP cable-stayed bridge can still achieve lower LCC than the steel cable-stayed bridge, because it has significantly lower rehabilitation cost and user cost, as well as slightly lower vulnerability cost. Furthermore, with the increase in the main span and the decrease in the unit price of CFRP cables, the LCC advantage of the long-span CFRP cable-stayed bridge becomes more obvious. [ABSTRACT FROM AUTHOR]

The in-service sea-crossing bridge handles a large number of vehicles, while considerable wind exists on the superstructure and wave exists on the substructure simultaneously, on a daily basis. Apart from the service loads, the bridges may also encounter extreme natural hazards such as earthquake, hurricane, etc., which might greatly threaten the structural safety. In particular, this article attempts to illuminate the influence of the simultaneous service and extreme loads on the dynamic performance of an in-service sea-crossing bridge along with traversing vehicles. To this end, a general earthquake-wind-wave-vehicle-bridge (EWWVB) simulation platform is established, which systematically integrates the interactions between earthquake, wind, wave, vehicle and bridge. The safety indicators are also implemented in the proposed platform to enable the driving safety evaluations of the vehicles travelling on the bridge during earthquakes. With the proposed simulation platform, an illustrative example is presented in which a number of road vehicles are travelling on an in-service prototype sea-crossing cable-stayed bridge during a sudden earthquake event. The results indicate that the extreme seismic load could become the dominant load affecting the dynamic response of the prototype sea-crossing bridge as well as the vehicles running on it. [ABSTRACT FROM AUTHOR]

New issues of wind-induced cable vibration, i.e., multi-mode vibrations, increasingly occur in long-span bridges, which are closely associated with underlying damping features. In this study, an analytical method is proposed to identify nonlinear aerodynamic damping in multi-mode wind-induced cable vibrations in fields, involving the assessment of total and mechanical damping. The method is available to extract a series of mono-component resonances/decays from the measured signals based on the analytical mode decomposition (AMD) and random decrement technique (RDT), and then to determine the damping parameters using the Hilbert transform (HT) combined with the smoothing spline or linear least-square fitting. Furthermore, this method is applied to address the vortex-induced vibrations (VIV) of an ultra-long stay cable on the Sutong Bridge. Firstly, the vibrations are reported in terms of a typical event and one-year statistics. Subsequently, the damping parameters are identified to illustrate the in-situ aeroelasticity. The results show that the cable exhibits high-frequency vibrations primarily in the 41st to 43rd modes, and the aerodynamic damping exhibits significant amplitude-dependent nonlinearity. Finally, the damping identifications are employed to reveal the onset mechanism for the vibrations, and a Scruton number (Sc) criterion, i.e., Sc > 5.4, is suggested for mitigating the vibrations. • An analytical method is proposed to identify nonlinear aerodynamic damping during multi-mode wind-induced cable vibrations in the fields. • High-order multi-mode vortex-induced vibrations of an ultra-long stay cable are reported in terms of a typical event and one-year statistics. • The underlying aeroelastic mechanism for the vibrations is revealed through aerodynamic and mechanical damping identification. • A Scruton number criterion, i.e., Sc > 5.4, for mitigating the vibrations is suggested based on the damping identification. [ABSTRACT FROM AUTHOR]

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. • An analytical approach for estimating saddles positions in the completed bridge state of suspension bridges is proposed. • The relationship between the position of the center of the tower saddle and the centerline of the tower is analyzed. • This paper analyzes the eccentric compression of the tower, and clarifies the reason for eccentric compression of the tower. • The impact of two definitions of the intersection point on the form-finding of suspension bridge is analyzed. [ABSTRACT FROM AUTHOR]

The steel-UHPC composite deck is an effective solution to fatigue cracks of orthotropic steel decks (OSD) in steel bridges. However, limited research has been reported on the hot spot stress distribution of the steel-UHPC composite deck. This study investigates the hot spot stress distribution and residual fatigue life evaluation of the steel-UHPC deck in a long-span cable-stayed bridge. The two extrapolation points' strain at fatigue-prone details were continuously measured under in-service traffic flow. The hot spot stress time history at each detail of the conventional OSD deck and steel-UHPC deck were analyzed and compared. The residual fatigue life of each detail was calculated. A three-dimensional finite element (FE) model was established and validated through experimental results. The bridge deck's deflection, the asphalt pavement's tensile stress, and the stress distribution at the floor beam cutout were numerically studied using the validated FE model. The results showed that the UHPC layer significantly reduced the hot spot stress and extended the fatigue life at each fatigue detail. The UHPC layer reduced the bridge deck's deflection and the asphalt pavement's tensile stress. Compared with nominal stress method, the hot spot stress method can better describe the large stress gradient distribution induced by the stress concentration at fatigue detail. • Field strain monitoring was conducted on a long-span cable-stayed bridge under in-service traffic. • The hot spot stress were obtained through two points extrapolation method. • Hot spot stress distribution of the conventional deck and steel-UHPC deck was compared. • Fatigue performance of steel-UHPC deck were evaluated based on monitored data. • Numerical simulation of steel-UHPC deck was conducted by a validated FE model. [ABSTRACT FROM AUTHOR]

The cables of long-span cable-stayed bridges are subjected to substantial tension during long-term service and are more susceptible to corrosion and fatigue failure than concrete structures. Most existing structural health monitoring (SHM) systems do not have monitoring equipment to directly measure cable length, and long-term monitoring of the change in cables is less involved. The displacement response of a bridge is induced by the combination of dynamic effects (wind and highways) and quasi-static effects (temperature). In this paper, the dynamic responses were eliminated by averaging the displacement data for 10 min, and the relationship between temperature and displacement was studied. Based on the monitoring data, the distribution of the thermal field for the bridge was studied and the time variability of the tower displacement was investigated. The correlation was analyzed to study the relationship between the temperature and the tower displacements, the north tower–south tower distance and the tower–girder distances. A strong linear relationship between the temperature and quasi-static responses of the displacements was observed. The thermal expansion coefficient of the effective length of cables was proposed as a quantitative index for long-term cable monitoring. The error in the cable effective length is proposed as the warning index for performance warning research. The results show that the proposed performance warning method can monitor cables and perform warnings when the cable is damaged. [ABSTRACT FROM AUTHOR]

Long-span cable-stayed bridge (LCB) with unequal-height towers is being designed and constructed in metro lines due to its better adaptability to environment and terrain conditions compared to traditional cable-stayed bridge with equal-height towers. However, the asymmetrical arrangement of towers leads to obvious nonuniformity of the structural stiffness along the longitudinal direction, which intensifies the wheel-rail coupled vibration behaviour, and affects the running safety of operating trains and ride comfort. Therefore, train-bridge dynamic behaviour of long-span asymmetrical-stiffness cable-stayed bridge is deeply investigated in this work. Primarily, considering the comprehensive index of frequency difference and modal assurance criterion (MAC), a nonlinear model updating technique (NMUT) based on penalty function theory is proposed, which can be used to optimize the bridge numerical model. Secondly, on the basis of the train-track-bridge dynamic interaction theory (TDIT), a train-track-bridge coupled dynamic model (TCDM) is established. Finally, a LCB with unequal-height towers is applied as a case to illustrate the influence of asymmetrical stiffness on the train-track-bridge dynamic characteristics. Results show that the proposed NMUT is efficacious and practical. For the LCB with unequal-height towers, a significant difference between the bridge vibration at low tower location and that at high tower location appears. The vertical displacement difference of the main beam on both sides of the bridge increases with the distance from the observation point to the bridge tower increasing. The variation of acceleration difference on both sides of the bridge is influenced by the speed of the train and the position of the observation point simultaneously. In general, vibrations of the main beam at low tower location are larger than those at high tower location. [ABSTRACT FROM AUTHOR]

The vehicle-bridge coupling vibration (VBCV) theory is being applied in the safety evaluation of existing bridges, such as cable-stayed bridge. In order to study the dynamic performance and vibration response of urban long-span cable-stayed bridges under traffic flow, and provide reference for the design, construction and safety assessment of existing bridges, the urban cable-stayed bridge with single tower and double cable in service was taken as the research object. The dynamic response of bridges under vehicles with different number, distance, speed and weight was analyzed. And the VBCV of bridge under different vehicle density and speed was discussed. The traffic flow on the bridge was simulated by the cellular automaton (CA) model, a half car model with four degrees of freedom was established, and the bridge models were established by the ANSYS software. According to the displacement coordination and mechanical balance conditions, the two models were connected, and were solved by MATLAB software. The dynamic response of the vehicle-bridge system under the vehicle fleet and random traffic flow was investigated. The research results showed that the vertical displacement (VD) of the main span increased with the number of vehicles, conversely, the vertical vibration acceleration (VVA) decreased. As driving distance increased, the VD and VVA of main span decreased. The VD of main span was not sensitive to the vehicle speed, but the VVA increased with the vehicle speed. The VD and VVA of the main span increased with the vehicle weight, and the VD of main span was proportional to the traffic density. As the traffic density increased, the VVA increased first, then decreased. [ABSTRACT FROM AUTHOR]

With the continuous service time, long-span track cable-stayed bridges are inevitably affected by material time-varying and fatigue load periodic effects, and permanent down-deflection phenomenon is inevitable. The down-deflection of the main girder would lead to the irregularity of bridge deck, which would directly affect the running comfort and safety of the train. The permanent deformation control value should be set reasonably. In this paper, based on the research and analysis of domestic and foreign codes and standards, the evaluation criteria for the service performance of long-span track cable-stayed bridges was determined, aiming at the problem of deformation classification control in the service stage of the long-span track cable-stayed bridge. The limit of permanent deformation of main girder was analyzed, and the decision processing was put forward and applied to an engineering example. According to the vehicle-bridge coupling vibration analysis, the maximum vertical deformation safety control value in the service stage is L/400, and the pre-warning control value is L/500. With the non-permanent deformation value β deducted, the permanent deformation safety control value is L/400- β, and the pre-warning control value is L/500- β. The rationality of the grading control limit of permanent deformation based on service performance analysis has been verified by application analysis. [ABSTRACT FROM AUTHOR]

A partial cable-stayed composite girder bridge with prestressed concrete flanges and corrugated steel webs (CSWs) is a beneficial new type of bridge structure that provides lower structural weight, reduced structural depth, increased span and lower seismic response. The structural responses and cost of four bridge types (a partial stayed-cable composite bridge with CSWs, a partial stayed-cable concrete bridge, a cable-stayed composite bridge with CSWs and a continuous rigid-frame composite bridge with CSWs) were compared and analysed. The results showed that the structural form and response of the main girder of a partial cable-stayed composite bridge are between those of a continuous rigid-frame composite bridge and a composite cable-stayed bridge. Compared with a concrete cable-stayed bridge of the same span, the self-weight of a partial cable-stayed composite bridge with CSWs is lighter, the main beam is lighter and the overall cost is less. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the study is to investigate and reveal this relationship of various engineering demand parameters (EDPs) of this structural type and intensity measures (IMs) under intra-plate earthquakes. Design/methodology/approach: The nonlinear finite element model used was calibrated first to the existing results of the shaking table test to verify the modeling technique. Findings: This paper investigated the relationship between intensity measures and various engineering demand parameters of cable-stayed bridges using intra-plate earthquakes. The correlation analysis and Pearson coefficient are used to study the correlation between EDPs and IMs. The results showed that peak ground velocity (PGV)/peak ground acceleration, peak ground displacement and root-mean-square of displacement showed weak correlation with IMs. PGV, sustained maximum velocity, a peak value of spectral velocity, A95 parameter, Housner intensity and spectral acceleration at the fundamental period, the spectral velocity at the fundamental period and spectral displacement at the fundamental period were determined to be better predictors for various EDPs. Originality/value: This paper investigated the correlation between the intensity measures of intra-plate earthquakes with the seismic responses of a typical long-span cable-stayed bridge in China. The nonlinear finite element model used was calibrated to the existing results of the shaking table test to verify the modeling technique. In total, 104 selected ground motions were applied to the calibrated model, and the responses of various components of the bridge were obtained. This study proposed PGV as the optimal IM. [ABSTRACT FROM AUTHOR]

Long-span cable-stayed bridges are subjected to the risk of collision from passing ships. Conducting experimental study on the collision of bridges and vessels is difficult due to high cost and limited space. In this paper, the behavior of a 1 018-m long-span cable-stayed bridge subjected to ship collisions is numerically studied. Finite element models of the entire bridge and ships are established. Four different dead weight tonnages (DWT), namely, 2 700, 12 000, 30 000, and 75 000 t, with impact velocities of 1 m/s to 6 m/s are investigated. The complete collision process under different loading scenarios is simulated, from which the collision force, bridge responses and local damage are obtained. The calculated collision force is significantly affected by the impact velocity and DWT, and exhibits a linear relationship with the impact velocity. Comparison with design codes shows that different codes vary significantly in estimating the collision force and Eurocode provides most accurate results. The effect of the material model on the collision force is also studied. This numerical study provides a reference for the ship collision design of long-span cable-stayed bridges. [ABSTRACT FROM AUTHOR]

In this study, new-type hybrid faring is suggested to improve the aerodynamic performance of the long-span cable-stayed bridge. The proposed fairing is developed by applying the concept of the multibox section to the normal faring. The proposed faring has void regions inside the faring so that wind passes through the gaps in the faring. As a result, the wind flow is changed and the forces to the bridge section are reduced. The efficiency of the proposed faring was verified by a series of wind tunnel test. From the test result, it can be found that aerodynamic performances, such as drag force and flutter resistance, are enhanced. [ABSTRACT FROM AUTHOR]

Considering the socioeconomic prominence of long-span cable-stayed bridges, it is important to ensure their normal operation after strong earthquake events. To this end, their seismic performance must be based on a proper understanding of the relationship between structural capacity and seismic demand. However, evaluating the seismic demands on cable-stayed bridges is challenging due to relatively long distances between supports and the complex composition of various structural elements. The large dimension in the horizontal direction inevitably leads to incoherent input ground motions at supports, while various structural components such as cables, decks, and pylons make it difficult to define the system's performance limit-state or capacity using a single index or function. This work presents three main contributions to properly assess the seismic performance of a long-span cable-stayed bridge. First, an algorithm was proposed to generate a set of bidirectional spectrum-compatible ground motions for the multiple supports of a bridge. Second, two performance measures were proposed to quantitatively assess the seismic demands and capacity of a cable-stayed bridge: probabilistic comparison index and axial force-bending moment (PM) safety factor. Third, the impacts of the seismic motions on the long-span cable-stayed bridge were thoroughly examined using eight different scenarios in terms of the three aspects: (1) multisupport excitation, (2) assumed soil class, and (3) wave passage effect. For this purpose, the Incheon Grand Bridge was chosen as a reference structure. This bridge has a central span of 800 m and a total length of 1,480 m. The results demonstrate that the seismic demands of the long-span cable-stayed bridge vary along with different conditions of seismic motions, and the proposed performance measures and ground motion-generating algorithm enable quantitative investigation of the impact of different conditions on the long-span cable-stayed bridge. [ABSTRACT FROM AUTHOR]

Long-span bridges face various threats every day due to their sophisticated operational environments. To investigate the operational state of bridges, a real-time dynamic warning method on the abnormity of cable-stayed bridges is proposed based on deflection measurements. The generalized Pareto distribution (GPD) model and finite-element (FE) calculation are used to determine the basic warning threshold. Considering the complicated components of the monitoring deflection signals (e.g., measurement noise, thermal effect, and vehicle load-induced effect), each signal component should be further modeled and investigated to improve the accuracy and effectiveness of the warning system. Because thermal effects are usually not the signal component of interest that may cover the signal fluctuation induced by abnormity, they should be separated from the raw signals. Then, in view of the variations of operational condition over time, the warning threshold is updated termly according to the operational period by using statistical approaches. Finally, the effectiveness of the proposed warning methodology is validated by analyzing the recorded deflection data from the third Nanjing Yangtze River Bridge. As a result, the proposed dynamic warning method is more effective than the conventional static one and will help bridge management departments identify emergencies in time and take inspection or maintenance decisions to ensure structural safety. [ABSTRACT FROM AUTHOR]

• A new vision-based multi-point displacement monitoring system is proposed. • A fast multi-feature matching and location method of light spot is proposed. • The camera-motion-induced error can be well compensated. • The bridge deformation evolution in the time and space dimensions are discussed. The existing vision measurement methods face a significant challenge in the multi-point displacement monitoring of large-span bridges due to the contradiction between the measurement scale and image spatial resolution. Based on a cable-stayed bridge on a kilometer scale, a new vision-based multi-point displacement monitoring system is proposed. The bridge was designed and arranged with a camera network, consisting of a series of double-head camera stations that were connected by cooperative markers. Based on the observed multi-point deflection and lateral displacement, the deformation evolution of the bridge in the two dimensions of time and space is discussed. The results show that the proposed vision-based camera network can accurately monitor the dynamic deflection and lateral displacement across the whole span of the bridge. The measurement errors induced by the camera motion can be well compensated based on the optical constraints of the proposed camera network. The feasibility of the vision method for long-span bridge monitoring has greatly improved. The proposed system can provide a new method for displacement monitoring and fine parameters for the safety evaluation of large-span bridges. [ABSTRACT FROM AUTHOR]

To assess the reliability of wind resistance behavior for long-span cable-stayed bridges, this study establishes a joint probability distribution model for 10-minute mean wind speed and turbulence intensity based on one year of field monitoring data. Firstly, the distribution characteristics of wind parameters at the deck height are investigated. Notably, substantial abnormalities are observed in the anemometer data obtained from the upstream and downstream sides of the mid-span deck. Thus, a novel component-decomposition method is proposed to eliminate these inconsistencies. The decrease in measured mean wind speed and the increase in turbulence intensity resulting from the bridge deck disturbance is considered to restore the actual wind parameters. Finally, the joint probability distribution model is developed using the Gaussian Copula function. The results demonstrate the efficacy of the proposed method in mitigating the bridge deck disturbance on field measurements, thereby establishing accurate and reliable probability distribution models. • Irregular distribution of field measurements of a long-span bridge is discovered. • Effects of the bridge deck disturbance on field-measured wind data are analyzed. • A novel method is proposed to remove disturbed components from field measurements. • A joint distribution model of mean wind speed and turbulence intensity is built. [ABSTRACT FROM AUTHOR]

• The temperature distribution of a cable-stayed bridge is obtained by integrating heat-transfer analysis and monitoring data. • The heat-transfer analysis and structural analysis share a unified FE model, resulting in an efficient and accurate analysis. • The numerical results have a good agreement with the field monitoring data. Varying temperature is a major load of long-span cable-stayed bridges. The temperature effect on the structural behavior may mask the influences of other loads. Conventional studies on the thermal behavior of bridges are limited to regression analyses based on measurement or numerical studies of 2D or local 3D models. This study investigated the global 3D temperature behaviors of a three-tower cable-stayed bridge through the integration of field monitoring and unified numerical simulation. A 3D refined model of the bridge with thermal elements was built, and the thermal boundary conditions were determined from environmental field monitoring data for the global 3D heat-transfer analysis. The calculated temperatures agreed well with the field monitoring counterparts. The temperatures were then input into the same global finite element model with mechanical elements for structural analysis. The temperature-induced structural responses, including the structural displacements and forces, agreed well with the measurement counterparts. The temperature-induced structural response variation pattern and sensitivity were summarized and quantified. This unified numerical simulation enables an efficient and accurate analysis of the global 3D thermal behavior of bridges, as compared with the conventional 2D or local 3D simulation. [ABSTRACT FROM AUTHOR]

Kim, J.; Park, S., and Seo, D.-W., 2023. Application of a smart IoT (Internet of Things) platform providing traffic safety information for marine bridges under strong winds. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 166-170. Charlotte (North Carolina), ISSN 0749-0208. Marine bridges located along the coast, especially long-span bridges such as cable-stayed bridges and suspension bridges, are greatly affected by strong winds and can threaten the safety of citizens who use them. In this study, a real-time disaster information collection and provision platform was developed by utilizing IoT (Internet of Things) and smart control technologies to relieve the anxiety of local residents and bridge users in case of strong winds and large-scale disasters. A service platform that can send warnings to local residents and bridge operators in the event of strong winds or abnormal vibrations was developed by collecting vibration information in real time using IoT-based sensors installed on bridges. By additionally expressing the collected vibration information using the VMS (Variable Message System) installed in the bridge, the bridge traffic and pedestrian safety management function that can support the driver's safe operation was implemented. [ABSTRACT FROM AUTHOR]

Typhoon winds near the external eye wall of a strong typhoon are extremely nonstationary and disastrous due to its vortex and convective origin as well as its high wind speeds. However, typhoon-induced nonstationary responses of long-span bridges are currently analyzed with the assumption of time-invariant wind coherence. By taking the Stonecutters cable-stayed bridge in Hong Kong under Typhoon Hato in 2017 as an example, this paper presents the time-varying wind spectra and coherences for the bridge based on the wind data recorded by the multiple anemometers installed on the bridge. The analytical framework for nonstationary buffeting analysis of long-span bridges under typhoon winds is enhanced by considering time-varying wind coherence and applied to the Stonecutters Bridge under Typhoon Hato. The computed responses are compared with the field measurement responses. The comparative results demonstrate the feasibility and accuracy of the enhanced framework for buffeting analysis of long-span bridges with time-varying wind spectra and coherences. Comparative results with the other two cases of time-invariant coherence functions also highlight the importance and necessity of considering the time-varying wind coherence in the nonstationary buffeting analysis of long-span bridges under typhoon winds. [ABSTRACT FROM AUTHOR]

Since cables are the critical structural components for ensuring the overall structural integrity and safety of cable‐stayed bridges, the portable and rapid cable force measurement has a very important practical significance in the bridge health monitoring. In this paper, a method of simultaneous and continuous estimation of the forces of multiple cables using a self‐developed microwave interferometric radar was proposed. In the proposed approach, first, the time‐varying modal frequencies are identified by the Hilbert transform algorithm from the displacements of multiple cables, which are monitored by the self‐developed radar, and then, the time‐varying cable forces are obtained by the vibration method. In addition, for the problem of multiple cables located in the same range bin when distance test or the test angle is nonideal, a single‐channel blind source separation algorithm based on vibrational mode decomposition (VMD) and time‐frequency analysis was proposed to separate the cable signals. Furthermore, a method based on the spectrum correlation coefficients was proposed to determine the number of decomposition layers in VMD. The "Nanjing Eye" cable‐stayed footbridge was used to conduct field measurement to validate the proposed method. Field measurement results show a good agreement with reference measurements, which demonstrate that the proposed method can perform well in an actual project for portable and rapid cable force estimation. [ABSTRACT FROM AUTHOR]

A pile–soil–cable-stayed 1/70-scale bridge model was designed and constructed to represent an extremely long-span cable-stayed bridge with a 1400-m central span. Shaking table tests were conducted to investigate the wave-passage effects on the seismic responses of the pile–soil–cable-stayed bridge model under uniform and non-uniform longitudinal excitations. Additionally, the acceleration frequency spectra and seismic responses of the bridge model were separately evaluated to compare the effects of uniform and non-uniform excitation. Finally, a 3-D finite element model in OpenSees was built for comparison with the test results. The results showed that the longitudinal wave-passage excitations considerably impacted the acceleration frequency spectra in the vertical direction of the girder and the modal participation factor, which resulted in the symmetric vertical bending mode shapes of the girder to increasingly affect the seismic response as the wave-propagation velocity decreased. The longitudinal wave-passage excitations increased the vertical responses at the 1/2-span of the girder, whereas they generally decreased the longitudinal responses of the girder and tower, as compared with uniform excitation. The longitudinal wave-passage excitations had different impacts on the pile–soil interaction effects for the three studied structural systems of the pile–soil–cable-stayed bridge model. Moreover, the dynamic characteristics and seismic responses obtained from the numerical simulations were consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Orthotropic steel deck (OSD) is widely used in long-span cable-stayed bridges, but vehicle-induced dynamic stresses at its deck-to-rib (DTR) joints often make OSD vulnerable to local failure or fatigue damage. This paper presents a framework for vehicle-induced dynamic stress analysis of DTR joints of OSD in a cable-stayed bridge. The multi-scale finite element model of the bridge is first developed using solid elements to simulate DTR joints of OSD interacted with pavement (local model), shell elements to simulate the most vulnerable girder segment (intermediate model), and beam/truss elements to simulate the rest part of the bridge (global model). Road vehicles are modelled as a combination of several rigid bodies connected by a series of springs, dampers and pivots. The vehicle-induced dynamic stress responses at the DTR joints of a long-span cable-stayed bridge are finally computed to assess the effects of bridge dynamics, vehicle dynamics, asphalt pavement temperature, roughness and vehicle velocity. The results show that the dynamically coupled vehicle-bridge system should be considered and that pavement temperature and roughness are two profound factors affecting the stress responses of DTR joints. [ABSTRACT FROM AUTHOR]

Geometric nonlinearity (GN) and initial internal forces (IIFs) are the basic characteristics of cable-stayed bridges, but now there is no effective method for analyzing the effect of them on bridge-track interaction of continuous welded rail (CWR) on cable-stayed bridge. A method for reconstructing the displacement-force curve of ballast longitudinal resistance was put forward according to the deformation of cable-stayed bridges under the completed bridge state. A feasibility study on the method was conducted via two aspects of the force and deformation of CWR on a 5 × 40 m single-line simple-supported beam bridge with initial deformation. With the multi-element modeling method and the updated Lagrangian formulation method, a rail-beam-cable-tower 3D calculation model considering the GN and IIFs of cable-stayed bridge was established. Taking a (140 + 462 + 1092 + 462 + 140 m) twin-tower cable-stayed bridge as an example, the impacts of GN and IIFs on bridge-track interaction were comparatively analyzed. The results show that the method put forward to reconstruct ballast longitudinal resistance can prevent the impact of initial deformation of bridge and makes it possible to consider the effect of IIFs of cable-stayed bridge on bridge-track interaction. The GN and IIFs play important roles in the calculation of rail longitudinal force due to vertical bending of bridge deck under train load and the variance of cable force due to negative temperature changes in bridge decks and rails with rail breaking, and the two factors can reduce rail longitudinal force and variance of cable force by 11.8% and 14.6%, respectively. The cable-stayed bridge can be simplified as a continuous beam bridge with different constraints at different locations, when rail longitudinal force due to positive temperature changes in bridge deck and train braking is calculated. [ABSTRACT FROM AUTHOR]

To study the nonlinear seismic behavior and seismic resistance of the long-span cable-stayed bridges subjected to earthquakes, the multidimensional and multisupported artificial ground motions are synthesized first based on the in situ site conditions of the bridge considering the coherent and traveling wave effects. Then, considering the material nonlinearity of the cable-stayed bridge, a 3D finite element model is established based on the OpenSees platform, and the nonlinear seismic response analysis of the bridge is carried out under the synthetic artificial ground motions. The nonlinear seismic response of main bridge components such as piers, towers, bearings, and cables is analyzed, and key conclusions and observations are drawn. [ABSTRACT FROM AUTHOR]

Accurate and timely identification of modal parameters of long-span bridges is important for bridge health monitoring and wind tunnel tests. Wavelet analysis is one of the most advantageous methods for identification because of its good localization characteristics in both time and frequency domain. In recent years, the wavelet method has been applied more frequently in parameter identification of linear and nonlinear systems. In this article, based on wavelet ridges and wavelet skeleton, the improved modal parameter identification method was studied. To find the appropriate time-frequency resolution, an optimal wavelet basis design principle based on minimum Shannon entropy was proposed. Aiming at endpoint effect in wavelet transform, a prediction continuation method based on support vector machine (SVM) was proposed, which can effectively suppress the endpoint effect of the extended samples. In view of the fact that the ridges of metric matrices obtained by the traditional crazy climber algorithm cannot fully reflect the distribution of ridges of modulus value matrices of wavelet coefficients, an improved high-precision crazy climber algorithm was put forward to accurately identify the position of the ridge of wavelet coefficients. Finally, taking a long-span cable-stayed bridge and a long-span suspension bridge as the engineering background, improved continuous wavelet transform (CWT) was applied to modal parameter identification of bridge under ambient excitation. The modal parameters such as modal frequency, damping ratio, and mode shape were obtained. Compared with the calculation value of the numerical simulation of long-span cable-stayed bridge and wind tunnel test of long-span suspension bridge, the reliability of CWT for modal parameter identification of long-span bridges under ambient excitation was verified. [ABSTRACT FROM AUTHOR]