Span Bridges Research Articles

Development of hybrid rubber damper-restrainer (HRDR) system for structures under sever dynamic excitation

Nowadays, high damping rubber materials are extensively implementing in various types of structure to mitigate harmful effect of imposed vibration and dynamic force to the structure. Although, the rubbers exhibit noticeable damping in the shear action, however, de-bounding, shear rupture and delamination of rubber layers under cyclic loads, undermine the load-bearing capacity of the rubber dampers and increase their maintenance costs. Hence, the action of the rubbers is considerably high under applied compression to generate resistant force to restrain the deformation.For this reason, in this research, a new hybrid rubber damper-restrainer (HRDR) system is proposed. The system comprises a high-damping rubber component designed to dissipate applied vibrations, along with a pair of hyper-elastic rubbers intended to restrain displacement. Therefore, the developed HRDR device is capable of dissipating vibrations while restraining large movements to prevent any damage and debounding of the rubber layers and also, protect the structure from excessive displacements.To examine the performance of the proposed device, the numerical model of a HRDR was developed using the finite element simulation and subsequently, nonlinear dynamic analyses were conducted for the 6 storey prototype steel structure furnished with HRDR device. The findings revealed that the structure equipped with the HRDR device exhibited outstanding response against applied earthquake excitation which is proving high efficiency of HRDR device to diminish vibration effect on structure and prevent any excessive deformations. The HRDR device is applicable to any types of framed structures through installing via chevron brace system in steel structures or short wall in reinforced concrete structures. Furthermore, the developed HRDR device can be implemented in bridge structures, between the deck and pier of bridge to effectively dissipate vibrations and restrain the movement of the bridge span under traffic loads.

Innovative Composite Materials for Improving Structural Integrity and Longevity in Civil Engineering Applications

The following research is on substantial developments of composite materials to improve the structural integrity and durability of construction in civil engineering. Traditional materials—like steel and concrete—have a host of problems associated with them, such as being vulnerable to corrosion, requiring frequent maintenance, and having limited lifespan. This paper reviews such issues in relation to the application of composite materials that are known to have improved properties, such as high strength-to-weight ratios, improved corrosion resistance, and better durability. The challenge posed to civil engineering, however, remains to be the limited durability and high maintenance cost of traditional construction materials. Due to environmental and mechanical stresses, these materials degrade and have resulted in frequent repairs and replacements, eventually increasing lifecycle costs of infrastructure projects. Key objectives of this research include the investigation of the very latest developments in composite materials, the assessment of their impact on the structural integrity and longevity of civil engineering constructions, and the economic benefits of reduced maintenance and longer service life for structures due to these improved materials. These are some of the contributions of the study: it showed that composite materials have much better performance than traditional materials in load-carrying capacity, resistance, and life; comparative analyses establishing dramatic money saving by large order in maintenance cost and lifecycle cost using composites, as compared to traditional materials; and showing the versatility of composite materials for general civil engineering applications like bridges, tunnels, pipelines, and building structures. The results show that composite materials increase the life span of constructions and structures related to civil engineering by a tremendous amount: for example, the load-bearing capacity is improved by 20%, the life span of pavement and bridges increased by 200–400%, the maintenance frequency by 50%, and the maintenance cost by 60%, which justifies their economic benefits very clearly. It has improved thermal insulation, reduced weight for the structural components, and more resistance to degradation by environmental elements, which makes composites a better solution compared with conventional materials. Generally speaking, this paper tries to bring out the prospect of composite materials in application for civil works, providing an alternative that will address issues of durability, cost, and flexibility in infrastructure.

Development of adjustable variable stiffness restrainer for bridge subjected to seismic excitation.

This paper presents a numerical and experimental assessment of a developed adjustable variable stiffness restrainer (AVSR) utilized for short span bridges. This restrainer has the ability to demonstrate multi stiffness capacity in different stages of bridge's superstructure movement to mitigate the severe damage of bridge due to an earthquake. The multi-level stiffness behavior of developed AVSR is achieved by using multiple mechanical springs with different lengths and placed in parallel in proposed design. A small prototype of developed AVSR has been fabricated and tested under incremental and cyclic loading in order to assess the restrainer performance and the behavior has been validated using finite element analysis. Thereafter, the constitutive model of AVSR was derived for the proposed restrainer in order to implement it in numerical simulations. Furthermore, a parametric study has been conducted numerically to evaluate the effectiveness of different parameters on the restrainer capacity. Moreover, the efficiency of AVSR application in a single degree of freedom system has been assessed by performing seismic analysis on a frame equipped with AVSR subjected to different seismic excitations using Newmark's method. The experimental and finite element results proved the efficiency of developed variable stiffness device to exhibit adjustable action against imposed loads in three designed stages. Furthermore, the parametric study results revealed that increasing the section area of the spring wire leads to increase the restrainer capacity. In contrast, the restrainer resistance is declined by an increase in the mean spring diameter and number of coils for each spring of AVSR. The time history analysis results also indicated that the frame response in terms of displacement, velocity and acceleration is improved by implementing the AVSR in the considered system.

End diaphragm and interior cross frame modeling in steel tub girder superstructures

Composite steel tub girders are proven to be an economical choice for long span bridges. However, detailed analysis of such superstructures requires extensive Finite Element (FE) modeling that includes many internal and external diaphragms. This paper is an attempt to study diaphragms and interior cross frames in tub girders and present simplified FE modeling details for the tub girder superstructures under gravity and seismic loadings incorporating accurate end diaphragm and interior cross frame stiffness equations. The simplified model is applicable to design of new tub girder bridges as well as load rating, health monitoring and retrofitting of existing bridges which require more sophisticated models. To this end, first a parametric study using 18 different FE models was carried out to better understand the behavior of tub girder superstructure and its components such as end diaphragms, the composite concrete deck and interior cross frames. Second, the stiffness equations for the end diaphragms and interior cross frames were derived analytically. These were associated with equivalent beam elements, which were used in combination with girder/deck elements to arrive at the simplified model. The resultant FE modeling was validated against detailed 3D FE models under gravity and seismic loads as well as the fundamental modes of vibration. Results indicated that the modeling approach is able to efficiently simulate different component behaviors and estimate the static and dynamic demands on the girders with remarkable accuracy.

A numerical analysis of inclination and rectification of ramp-bridge piers adjacent to surcharge load in soft clay area

The surrounding surcharge has an adverse impact on the service performance of buildings and bridges, and it can endanger their structural safety, especially in soft soil areas. As one case study, the inclination accident of an expressway ramp bridge and its rectification are investigated in this study. Through the three-dimensional (3D) finite element (FE) analysis of the overall structures composed of the bridge span, the pier, and the pile foundation, the whole process of the inclination by the adjacent dumped earth, partial recovery by the unloading, and the lateral pushing rectification of the bridge structure were simulated. The results show that the surcharge load leads to soil displacement near the bridge pile, and the pile-soil interaction leads to the pile deformation, which further causes the inclination of the pier, and the movement of the bridge span. The severity of the accident can be measured by the inclination of the piers and the opening widths of the bridge expansion joints. Due to the plastic deformation and drainage consolidation of the soft clay foundation under the surcharge load, the inclination of the piles and piers cannot be fully recovered after unloading. In order to capture these processes, the FE simulation was divided into three steps. First, the drainage consolidation of the soil foundation were identified by FE simulation and the field measurement of the recovery of the structure after unloading. Second, the effects of soil properties, the surcharge time and surcharge strength on the bridge inclination and the recovery capacity after unloading are discussed. Finally, the rectification of the bridge by lateral pushing was simulated, and the deformation and stress in the pier and pile were calculated to evaluate the safety of the structures. These analyses provided understanding towards the prevention of the bridge inclination under surcharge load, prediction of the recovery by the unloading, and the methods to reduce the residual deformation to meet the specifications.

The Temperature-Induced Deflection Data Missing Recovery of a Cable-Stayed Bridge Based on Bayesian Robust Tensor Learning

Changes in the deflection of cable-stayed bridges due to thermal effects may adversely affect the bridge structure and reflect the degradation of bridge performance. Therefore, complete deflection field data are important for bridge health monitoring. A strong linear correlation has been found between temperature-induced deflections in different positions of the same span of a cable-stayed bridge in many studies, which make the deflection data matrix/tensor have a low-rank structure. Therefore, it is appropriate to use a low-rank matrix/tensor learning to model the temperature–deflection field of a cable-stayed bridge. Moreover, to avoid disturbing the recovery results via abnormal data (e.g., baseline shift and outliers), a Bayesian robust tensor learning method is proposed to extract the spatio-temporal characteristics of the bridge temperature–deflection field. The missing data recovery and abnormal data cleaning are achieved simultaneously in the process of reconstructing the temperature-induced field via tensor learning. The performance of the method is verified with actual continuous monitoring data from a cable-stayed bridge. The experimental results show that low-order tensor (i.e., matrix) learning has a good recovery and cleaning performance. The extension to higher-order tensor learning is proposed to extract the spatial symmetry of the sensor locations, which is experimentally proven to have better missing recovery and abnormal data cleaning performance.

Fatigue life of unified riveted superstructures designed by Transmostproject with the introduction of increased axle loads

The article presents a study of the residual fatigue life of superstructures during the introduction of trains with increased axial loads on bridges with riveted superstructures, designed in the fifties of the last century. Unified metal superstructures have been in relatively heavy duty conditions for more than 60 years. During lcontinuous operation, processes occur in elements and joints that lead to the appearance and development of various damages and varying degree failures of hazard, so it is necessary to decide on the further operation of old bridge spans and their replacement. When determining the fatigue life, the linear addition hypothesis of fatigue damage accumulation was used, taking into account the increase in stresses with the introduction of increased axial loads. As a critical measure of damage, providing a given reliability, the value obtained from the calculation results of several hundred cracks in riveted superstructures of older design standards was adopted. The increase in load from the installation of a ballastless bridge floor is taken into account. To determine the residual fatigue life, fatigue data is used depending on the concentration of stresses magnitude in the attachments of the main truss elements. For a more accurate determination of the rivet joints operation stage, the author carried out a wear-out calculation through operation period. The introduction of heavier train loads will lead to an increase in the accumulation of fatigue damage in the elements. If weak rivets in attachments are found during inspection, they must be replaced with high-strength bolts to increase fatigue life. The author obtained that the residual fatigue life of the span structures designed by Transmostproekt has not yet been fully exhausted even with the introduction of heavy trains with a wagon axle load of 27–30 tons.

Analysis of the Temperature Effect and Influence of Large Span Continuous Rigid Bridge in Mountainous Area

The temperature problem of large span bridges in mountainous areas is particularly prominent due to the large temperature difference. This paper addresses the problem of ambient temperature influence on the construction and operation of large span prestressed reinforced concrete continuous rigid frame bridges. Through finite element modeling and computational analysis of an example of a continuous rigid frame bridge, the simulation results reveal the law of temperature influence on large span continuous rigid frame bridges and provide reference for the subsequent analysis of temperature problems of continuous rigid frame bridges. Based on the force analysis of the model, a series of bridge temperature crack generation mechanisms are proposed in combination with the bridge construction process and concrete characteristics, and reasonable treatment measures are proposed for the control of temperature cracks during bridge construction to ensure the overall quality effect of bridge construction and operation.

Solution to the traffic problems of long and deep water straits–smart submerged floating tunnel and its research

Submerged floating tunnel (SFT) is a new type of structure across long and deep water straits and waterways with good application prospects. The structure is different from the traditional large-span bridges and immersed tunnels, which can effectively avoid difficulty under the construction of bridges foundation in deep water straits and channel, the high cost of large span bridge, influence of typhoons and heavy fog et al. severe weather on the vehicle driving on the bridges, a series of technical problems confronted under the construction of immersed tunnel or tunnel excavation in complex marine geology and the deep sea and risk control and so on. This paper, in the light of the characteristics of submerged floating tunnels and the requirements of marine deep water environment, discusses some of technical challenges faced in the designing and building the SFT, points out that it is necessary to systematically study the design and load condition, the smart composite material and shape optimization, the calculation theory and method for analyzing the structural behavior, the structure safety evaluation, construction methods and key technology, and engineering risk analysis, smart monitoring, evaluation and control, code or guide for design and construction of SFT. It lays foundation for design, construction and engineering risk analysis, etc. of submerged floating tunnel across the long and deep waterways in the future.

Reduction of Train-Induced Vibrations—Calculations of Different Railway Lines and Mitigation Measures in the Transmission Path

The reduction of train-induced ground vibrations by different railway lines and by mitigation measures in the propagation path is analysed in a unified approach by two-dimensional finite element calculations where the reduction is expressed as the amplitude ratio between a specific and the reference situation (the surface track without a mitigation measure). In general, there is no reduction at low frequencies, and the reduction becomes stronger with increasing frequency. A maximum reduction ratio of 0.1 at high frequencies is established with an open trench. Reduction ratios between 0.7 and 0.2 have been found for the other situations, filled trenches, walls, plates, and blocks, as well as for railway lines on embankment, in cuts and in a tunnel. Bridges can produce amplifications due to their resonance frequencies, but also strong reductions due to the massive bridge piers. The influence of some parameters has been analysed, the length of the bridge span, the inclination of the embankment and the cut, and the stiffness of the soil and of the tunnel structure. The dynamic track stiffnesses of a surface, bridge and tunnel track have been calculated by the 3D finite-element boundary-element method for comparison with corresponding measurements.

An autonomous and heuristic approach for extracting bridge frequencies from passing vehicles

The Federal Highway Administration (FHWA) recognizes a need for cost-effective and practical structural health monitoring (SHM) techniques to manage the bridge network. System identification (SI) techniques are the first step in developing SHM frameworks to extract bridge dynamic properties (natural frequencies, damping ratios, and mode shapes). One promising indirect SI technique uses accelerometer-instrumented vehicles to measure the dynamic properties of bridges, such that a few instrumented vehicles could economically monitor a large network of bridges. This study proposes an autonomous framework called autonomous peak picking variational mode decomposition (APPVMD), which leverages an ensemble of signal processing techniques and heuristic models to autonomously extract bridge frequencies from instrumented vehicles. The proposed framework does not require prior information or model-informed training. The framework is tested on four vehicles and 39 unique bridge classes using finite element (FE) models to assess the feasibility of deploying it into practice. The results of this study indicate that the algorithm can make successful bridge frequency extractions in more than 69.2% of the bridge cases using any vehicle and a maximum value of 97.4% using an SUV, while considering the effects of road surface roughness. The influence of bridge stiffness, mass, and span length on the algorithm’s success rate is discussed. It is concluded that flexural rigidity and span length play a significant role in the accuracy of APPVMD. The combined effects of bridge inertia and damping cause heavier bridges to have a higher amplitude signal for a longer duration, increasing the algorithm’s successful detection rate of bridge frequency. Next, the authors examine the effect of reducing the tire stiffness in the truck model on the success of the APPVMD algorithm. The customized truck outperformed the original truck and the SUV by successfully extracting the bridge frequencies of 97.4% of the bridge cases and by having more bridge frequencies predicted in a higher confidence region than the SUV. In addition, the customized truck model is used to verify the APPVMD’s robustness to large levels of sensor noise. Even at significant levels of white noise (1% SNR), as the success rate for bridge frequency extraction using the customized truck only drops to 84.6%. Finally, the influence of vehicle speed on the APPVMD algorithm’s effectiveness is studied. Generally, slower speeds resulted in more successful predictions of bridge frequency, but minor improvements in the accuracy of the frequency predictions were observed at slightly increased velocities, 13.4 m/s (30 mph) and 17.9 m/s (40 mph), but a reduction in accuracy was observed at higher velocities, 22.3 m/s (50 mph).

FEATURES OF CONSTRUCTIVE, ORGANIZATIONAL AND TECHNOLOGICAL SOLUTIONS FOR THE RESTORATION OF REINFORCED CONCRETE BRIDGE STRUCTURES

The article provides information on effective structural and organizational-technological solutions for surveying, designing and restoring the bridge structure, which was partially destroyed as a result of the armed aggression of the Russian Federation. It was established that information from scientific and regulatory sources does not sufficiently reflect the situation with bridges, where a part of the load-bearing structures has been completely lost and it is necessary to carry out work on the construction of new structures with the possible use of a part of the old (undamaged) ones. The current operating condition of the main elements of the structure (bridge web, span structure, supports and support parts, foundations, approaches) is determined. When predicting the term of accident-free operation, it was established that the remaining resource of the bridge, taking into account the actual technical condition of the main elements at the time of the inspection (destruction), which is determined from the equation of element degradation, is completely exhausted. The obtained data made it possible to predict the technical condition of the bridge in accordance with regulatory requirements and to prescribe operational and restoration measures. The use of undamaged underground structures for the construction of new reinforced concrete supports is substantiated, where preparatory work is provided with the use of complex mechanization tools. When concreting the bodies of the supports, the rationality of the new fastening of the braces of the formwork blocks was confirmed, which ensured increased rigidity and stability of the assembled formwork, for which it was proposed to install one plate between the supports on a rigid metal frame structure with a height of corresponds to the lower limit of the concreting massif, with the possibility of attaching braces working in different planes to it. It is proposed not to change the position of the two slabs intended for braces along the axis of the bridge, while they were also placed on similar metal frames. Placing the plates for fastening the braces at the mentioned height made it possible to reduce the length of the braces and ensure their working angles within the most effective limits.

Simulation and analysis of mechanical properties of complex steel cover beam under static load

AbstractIn recent years, the development of high‐speed railways in China has been rapid. High‐speed railway bridges play an essential role whenever the railway intersects with existing facilities in three dimensions. With the increasing speed of high‐speed railways and increasingly complex geographical locations, the span of bridges is constantly increasing. Based on their advantages, steel structures in large‐span bridges are beginning to replace traditional concrete structures. Taking the steel cover beam technology applied in the Fuqiangbao Tremendous Bridge as a starting point, this paper uses Rhino parameterized modeling and Abaqus software to conduct finite element analysis on the stress of steel cover beams. It compares and analyzes stress under different conditions. The results show that the steel cover beam's most unfavorable and unstable position in this paper is at the support on the stress side. This provides a reference for monitoring the steel cover beam after its application in the Fuqiangbao Tremendous Bridge and technical accumulation for the application of steel cover beam technology.

Motion-amplitude-dependent nonlinear VIV model and maximum response over a full-bridge span

Nonlinear motion-amplitude $$(y_{T} )$$ -dependent energy-trapping properties of a bridge model undergoing vortex-induced vibration (VIV) are investigated. Energy-trapping properties of the model undergoing a full-process from still to a limit cycle oscillation (LCO) state are identified. A van der Pol-type model is adapted to describe the amplitude-dependent aerodynamic properties. Nonlinear parameter-amplitude relations, $$\varepsilon {-}y_{T}$$ and $$\xi_{\varepsilon } {-}y_{T}$$ , are established. Nonlinear aerodynamic damping is separated into two parts: the initial damping which varies with the reduced wind speed, and the $$\varepsilon $$ -related part which varies with both the reduced wind speed and the motion amplitude. The initial aerodynamic damping determines the threshold of VIV, while the $$\varepsilon $$ -related part dominates the evolution process and the LCO. The identified nonlinear analytical model is capable of predicting VIV responses at higher mechanical damping ratios. The energy-trapping properties of a section model in time are transformed into nonlinear properties distributed in space along an elongated 3-D elastic bridge span. According to this “time-space” transformation, the convection coefficient, which links the maximum response of a 3-D structure with that of a 2-D (1-DOF) sectional model, can be determined. Compared with a constant-parameter analytical model, an adapted nonlinear one brings to light significantly larger convection coefficients. Finally, parameter overflowing phenomena are revealed and discussed.

Modeling Nonlinear Aeroelastic Forces for Bridge Decks with Various Leading Edges Using LSTM Networks

With the rapid increase in bridge spans, the mitigation of risk to flutter (aeroelastic instability) is of critical importance in the design of long-span bridges, especially considering the more frequent intense hurricanes under climate change. Although the strong nonlinearities of the aeroelastic (self-excited) forces in wind–bridge interactions can be well captured through either numerical simulations or experimental tests, both are expensive and time consuming. Hence, it is important to develop an efficient reduced-order model for the simulations of nonlinear aeroelastic forces on the bridge decks. This study proposes a reduced-order model based on the long short-term memory (LSTM) network to simulate the nonlinear aeroelastic forces on bridge decks with various leading edges, and thus rapidly predict the corresponding post-flutter behaviors of long-span bridges. To generate the training datasets, computational fluid dynamics (CFD) was employed to simulate the nonlinear aeroelasticities of bridge decks with a wide range of leading-edge configurations and wind speeds. Trained on the high-fidelity CFD datasets, the LSTM network takes the motion of a bridge deck, leading-edge angles and wind speeds as inputs and outputs the nonlinear aeroelastic forces on the bridge decks. A hybrid loss function utilizing the prediction errors of both aeroelastic forces simulated by the LSTM network and the bridge deck responses calculated by the Newmark-β algorithm was introduced into the training process to improve the network performance. The prediction results of the trained LSTM model were compared with the CFD simulations, which demonstrated that the nonlinear aeroelastic forces of the bridge deck with various leading edges can be accurately and efficiently acquired by the proposed LSTM model.

Dynamic Behavior of Metro Train–LSB (Long–Span Bridge) System Considering Nonlinearity of Resilient Wheel

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

Buckling behavior of orthotropic steel deck stiffened by slender bulb flats for large span bridges

Slender bulb flat stiffeners with a large height-to-thickness ratio were proposed for the orthotropic steel decks (OSDs) in a large span suspension bridge. The buckling behavior of the panels stiffened with bulb stiffeners under pure compression was experimentally and numerically studied in this paper. Four specimens consisting of four longitudinal stiffeners and a top deck plate were fabricated and subjected to axial compression loading tests. Finite element models were established and validated by the result tests. A parametric analysis was conducted to study the effects of residual stresses and geometric imperfections on buckling behavior. A buckling failure of overall stiffener buckling before the yielding and ductile post-buckling behavior were observed in the tests. A buckling strength of 311∼337 MPa was obtained in the tests. The ratio of buckling stress to yield strength ranging from 0.80 to 0.86 was slightly lower than that of closed ribs, which shows a potential use of the slender bulb flat in large span suspension bridges. The numerical results showed that the residual stresses can decrease the load-bearing capacity by 10%. The residual stresses have a higher influence on the resistance than the regular geometrical imperfections. The standard vehicle load has negligible influence on the buckling resistance, but overload may cause a certain decrease.

The Research on Obtaining the Geometric Dimension of Cable-Stayed Bridges Based on 3D Laser Scanning

The traditional manual measurement methods are time-consuming and error-prone when they are used for cable-stayed bridges’ geometric dimensions acquisition. They are always limited by various adverse conditions such as large bridge spans, the high height of bridge towers, more risk of manual operation, and many other unpredictable factors. In contrast, three-dimensional (3D) laser scanning technology is extremely useful for solving the above problems. After obtaining plenty of point cloud data and point cloud models, precise and accurate geometric dimensions of cable-stayed bridges can be obtained accurately and conveniently. Taking a cable-stayed bridge named XingLinBao as an example, the accuracy and convenience of 3D laser scanning are verified.

Aerodynamic Interference and Dynamic Influence of Wind Barrier on Train-bridge Coupling Vibration System

Wind barrier is an important wind-resistant measure for the running performance of trains on long-span bridges. This study aims to clarify how the aerodynamic interference of wind barrier to the train-bridge system affects the dynamic response of the system. The aerodynamic interference and dynamic influence of wind barriers on the train-bridge system are studied by wind tunnel test and coupling vibration analysis. Wind barriers with different ventilation rates are selected to study their wind-resistant performance on trains travelling in four lanes on the bridge. The results show that installing wind barriers can increase the side and lift coefficients of bridge and decrease the side and lift coefficients of train. The maximum difference is that installing a wind barrier with ventilation of 0 can increase the side coefficient of the bridge by 0.6, while reducing the side coefficient of train in Lane 1 from 1.25 to −0.25. Although the wind barrier has changed the aerodynamic coefficient of the bridge, the maximum dynamic response of train-bridge system depends more on its influence on the aerodynamic coefficient of train. Installing a wind barrier with 0% ventilation rate can reduce the maximum lateral displacement at mid span of bridge by 10 mm, the maximum reduction rate of the wheel from 0.38 to 0.1, and the lateral car body acceleration from 1.1 m/s2 to 0.45 m/s2. The vertical dynamic response of train-bridge system is insensitive to wind barrier. The key effect of optimizing train side coefficient on wind-resistant performance of wind barrier is pointed out.

Evaluasi Struktur Jembatan Gantung Pejalan Kaki Dumpoh, Magelang Jawa Tengah

The bridge analyzed is a suspension type with a function as a pedestrian bridge. The bridge has a total span of 53.75 m and a width of 1.8 m, steel construction with wooden deck. The service life factor, damage to the bridge frame, and overload are certainly a problem for this bridge structure. Evaluation of the structure using survey data from existing measurements at the bridge location, then analyzed using the SAP2000 program. The result is that all tower frames, girders, main cables, hangers, and bridge decks, the nominal capacity is still able to withstand the ultimate load. However, the deflection in the middle of the bridge span is 0.72 m and has exceeded the allowable deflection (L/200). So based on the results of the evaluation of the Dumpoh suspension bridge structure, the cross-sectional strength of the frame is still safe, but the stiffness of the deflection value does not meet.