Response Of Bridge Research Articles

Typhoon- and temperature-induced responses of a cable-stayed bridge

Long-span bridges are subjected to wind and temperature actions. Wind action is generally the governing load of long-span bridges in design, while temperature action is also significant. Accurate separation of typhoon- and temperature-induced responses is thus necessary for in-depth investigation of their effects and comprehensive evaluation of structural performance. This paper separates the temperature- and typhoon-induced responses of the Qingzhou Bridge by using a unified global analysis approach. The field-monitored meteorological data and structural responses collected from the structural health monitoring system installed on the bridge are analyzed in detail, with emphasis on the comparison of those during typhoon Higos (Signal No. 9) and a typical sunny day after the typhoon. Results show that the quasi-static variation of displacement and stress responses are higher on a typical sunny day than those during the typhoon period, which is out of intuition. Through the unified analysis, the temperature-induced responses are calculated, and the typhoon-induced responses can be separated. The temperature- and typhoon-induced longitudinal displacement, mid-span deflection, and stress of the girder are compared. The temperature-induced response accounts for a large part of the total quasi-static recording either on a typical sunny day or during the typhoon period, whereas typhoon caused significant dynamic responses. The typhoon-induced quasi-static and dynamic responses are also in good agreement with the wind tunnel test results. This case study demonstrates the effectiveness of the unified global analysis in separating the temperature effect.

Field observations on the damage to road bridges after the 2023 Turkey Earthquake

A series of large-scale earthquakes occurred on February 6 in southern Turkey. The authors had the opportunity to join the Japan Disaster Relief (JDR) Expert Team and visit several damaged areas in Turkey from March 10 to 12, 2023. This article highlights damage cases of a road tunnel and several road bridges the authors observed around Antakya, Nurdağı, and Malatya. From the features of the observations, this article discusses the following three items for further study in the seismic design of road bridges: (1) seismic details for robustness, (2) seismic responses of bridges with longer natural periods, and (3) post-event inspection.

Non-stationary buffeting responses of a twin-box girder suspension bridge with various evolutionary spectra

The effects of evolutionary wind spectra with different modulation functions on the nonstationary buffeting responses of suspension bridges are uncertain. After considering the nonlinear buffeting force of a twin-box girder, the buffeting responses of a cross-sea suspension bridge under four nonstationary wind speed models with two uniform modulation and two nonuniform modulation functions were investigated in this paper. Through the evolutionary spectral theory, the nonstationary wind speed models at the bridge site with four typical modulation functions were generated and then validated from the autocorrelation and power spectrum density. The results show that the mean and root-mean-square error (RMSE) values of vertical and horizontal wind speeds by using nonuniform modulation functions (NMF1 and NMF2) were much larger than those by using uniform modulation functions (uMF1 and uMF2). Moreover, most of the peak and RMSE values for the torsional and lateral displacement under the NMF1 are the largest, while the RMSE values of the vertical displacement without the modulation function are the largest. With the increase of the circular frequency γ or decrease of the initial phase θ in the cosine function of time-varying mean wind speeds, the RMS values in three displacement responses of the bridge deck become larger.

Seismic response of a ground-bridge structure system in horizontal and inclined liquefiable site to near-fault pulse-like ground motions

Previous earthquake events have indicated that bridge structures are more vulnerable to severe damage when subjected to near-fault pulse-like (NF-P) ground motions. Structural seismic damage will be exacerbated when bridges are located in liquefiable site. Meanwhile, the seismic response of bridges located in inclined liquefiable site is different from that of bridges in horizontal liquefiable site. This study focuses on exploring the seismic response of a ground-bridge structure system located in horizontal and inclined liquefiable site to the NF-P ground motions. The seismic response of the whole system to the near-fault non-pulse-like (NF-NP) and far-field (FF) ground motions is studied for comparison. Two three-dimensional (3D) finite element (FE) models of the ground-structure system considering soil-pile interaction are developed. They are associated with the horizontal and inclined liquefiable site, respectively. The seismic responses of the ground-bridge structure system to the three different types of ground motions (i.e., NF-P, NF-NP and FF) are comprehensively evaluated from two perspectives. On the one hand, the seismic time history responses of the ground-bridge structure system under single representative ground motion are comprehensively assessed. On the other hand, the average responses of the ground-bridge structure system under multiple types of ground motions are explored. The results reveal that in contrast to the NF-NP and FF ground motions, the NF-P ground motions have more significant effect on various responses of the ground-bridge structure system. In addition, compared to the bridge in horizontal liquefiable site, the bridge in inclined liquefiable site exhibits larger seismic responses. Therefore, the velocity pulse effect of the NF-P ground motions and the liquefaction effect of the inclined site need to be emphasized in structural seismic design.

Energy dissipation and seismic response reduction system for high-speed railway bridges based on multiple performance requirements

The emergence of high-speed railway bridges in regions with high seismic intensity has brought attention to the growing seismic challenges associated with these structures. Although the prevalent use of friction pendulum bearings for seismic isolation in China has proven effective in mitigating the seismic response of bridges, it falls short of meeting the safety standards required for high-speed trains. To address the limitations of existing isolation systems, this study employs a combined approach of numerical simulation and experimental research, leading to the invention of performance-controllable isolation bearing and multi-directional energy dissipation dampers. Mechanical models for both components were introduced, and design methods for their key parameters were established based on multi-level seismic defense requirements. By integrating these advancements, a novel cooperative seismic isolation system for high-speed railway bridges was created. Under the influence of moderate earthquakes, the system relies on the shear key to meet the stiffness requirements for normal service. During large earthquakes, the shear key is sheared off, and the damper provides momentary stiffness to control track deformation, enabling the safe stopping of trains. This combination forms a seismic isolation system during large earthquakes, ensuring the safety of railway bridges. The numerical analysis of a high-speed railway bridge employing a cooperative seismic isolation system demonstrates substantial mitigation in the response of both the pier bottom and pier top. This aligns with seismic requirements for the bridge structure. Additionally, the reduction in train track deformation meets safety standards, confirming the seismic performance of bridges and ensuring the reliability of train operations.

Intelligent identification of moving forces based on visual perception

The task of identifying moving forces presents a challenging inverse problem for bridge health monitoring and condition assessment. Existing methods for identifying moving loads rely on complex structural response measurement equipment, resulting in inefficiency and elevated costs. To address these challenges, this study introduces an innovative intelligent identification method for moving forces on bridges using visual perception techniques. The proposed method utilizes cameras to capture displacement changes at specific points on the bridge surface to reconstruct moving forces in the time domain. Initially, numerical simulations were conducted to ascertain the feasibility and robustness of identifying moving forces based solely on the structural displacement response. This phase also investigates the influence of different measurement point combinations on identification accuracy. Subsequently, the accuracy of the proposed method in measuring the dynamic displacement response of the structure was carefully evaluated by an outdoor shaking table test. Furthermore, a meticulously designed simply supported beam model was fabricated, followed by the execution of precise vehicle-bridge coupling dynamic experiments. This phase rigorously validates the effectiveness and accuracy of the proposed moving force identification method at varying vehicle speeds. The obtained results substantiate the proposed approach's capability not only to comprehensively capture bridge response data for full-area monitoring but also to consistently and reliably identify information on moving vehicle forces. This study underscores a pioneering application of intelligent visual perception technology in the field of identifying moving forces. The introduced noncontact intelligent identification method is an effective solution for monitoring moving forces on bridges, which has a wide range of applications in the future.

Effect of Bearing Friction on Seismic Performance of Bridges with Massive Piers Isolated by Friction Pendulum Bearings

Although seismic isolation is a well-accepted design strategy for bridges to provide structural earthquake resistance, for bridges with massive piers, it may unexpectedly pose an abnormal influence on the seismic response of bridges due to the effect of substructure mass. This study investigates the effects of bearing friction and pier mass on the seismic performance of bridges isolated by friction pendulum bearings (FPBs). Nonlinear time history analysis is conducted to demonstrate the variation of the bridge peak responses with different bearing frictional coefficients and pier mass. The inherent influential mechanism of the frictional coefficient of FPBs is also discussed in the current study. The results of the analysis show that for FPB-isolated bridges with massive piers, the peak base shear forces of piers first decrease and then increase with the increase of the bearing frictional coefficient. Such a phenomenon may be attributed to the fact that the inertia force of the massive piers will be altered by the variation of bearing friction. The outcome of this study provides a useful reference for practical engineering that the seismic base force of massive bridge piers calculated under a specified bearing frictional coefficient may be smaller than the actual response and cause reduced safety to bridges.

Floating bridge global responses to slowly varying wave loads

The global responses of a 5530-m-long floating bridge under linear and slowly varying wave loads were studied. The bridge has modes from seconds to around 2 min. A comparative study was carried out applying full Quadratic Transfer Functions (QTFs) or Newman's approximation (Newman, 1974) for slowly varying loads. Four groups of QTFs were computed: one fixed pontoon, one pontoon with specified stiffnesses, three fixed pontoons, and three pontoons with stiffnesses for the mid-pontoon. The importance of damping to the global response was demonstrated by a sensitivity check on the viscous damping. The study showed the importance of hydrodynamic interaction in both first and second order wave loads and responses. Hydrodynamic interaction led to more ‘distributed’ QTF peak values away from the diagonal, which may reduce the correctness of Newman's approximation. Parametric study showed that the floating bridge responses were sensitive to wave direction, wave height and period. This study suggested that full QTFs based on three fixed pontoons provided the most conservative results for the base case. Newman's approximation provided reasonable levels of overall responses but underpredicted specific responses in this study. Though the full QTFs method is preferred in a detailed analysis, the efficient Newman's approximation is considered as a valuable tool for large-scale screening analysis during the early design phase of practical engineering.

Analysis of Bridge Dynamics and Response Characteristics Under The Influence of Axle Coupling Vibration

To ensure the safety and stability of high-speed rail lines and reduce external interference, it is essential to build a large number of elevated bridges. These elevated bridges account for a considerable proportion of the total length of high-speed rail lines. However, when high-speed rail lines pass through earthquake prone areas, the likelihood of earthquakes occurring when trains pass through bridges increases significantly. Therefore, it is necessary to study the dynamic response of bridge structures under earthquake action to ensure the safety of bridges during train operation and operation. The optimization scheme proposed in this article has undergone moderate impact tests, and the results show that the maximum lateral displacement of the bridge can reach 124 mm, while the maximum vertical acceleration is 5.16 m/s2, Exceeded the safety limit of 0.35 g. Through the analysis of train derailment coefficient, wheel load reduction rate, lateral sway force, lateral and vertical acceleration, and Spelling comfort index, we have come to the conclusion that bridges can ensure the safety of train operation in the absence of earthquakes and small earthquakes, and can also maintain certain stability under medium and large earthquakes. These research results have important guiding significance for the design and construction of high-speed rail lines. By optimizing the bridge structure and adopting relevant technical measures, the seismic disaster resistance of high-speed rail lines can be further improved, ensuring the safety and comfort of passengers during travel. At the same time, these research results also provide useful reference and inspiration for the construction and improvement of future high-speed rail lines.

Application of Response Surface-Corrected Finite Element Model and Bayesian Neural Networks to Predict the Dynamic Response of Forth Road Bridges under Strong Winds.

With the rapid development of big data, the Internet of Things (IoT), and other technological advancements, digital twin (DT) technology is increasingly being applied to the field of bridge structural health monitoring. Achieving the precise implementation of DT relies significantly on a dual-drive approach, combining the influence of both physical model-driven and data-driven methodologies. In this paper, two methods are proposed to predict the displacement and dynamic response of structures under strong winds, namely, a Bayesian Neural Network (BNN) model based on Bayesian inference and a finite element model (FEM) method modified based on genetic algorithms (GAs) and multi-objective optimization (MOO) using response surface methodology (RSM). The characteristics of these approaches in predicting the dynamic response of large-span bridges are explored, and a comparative analysis is conducted to evaluate their differences in computational accuracy, efficiency, model complexity, interpretability, and comprehensiveness. The characteristics of the two methods were evaluated using data collected on the Forth Road Bridge (FRB) as an example under unusual weather conditions with strong wind action. This work proposes a dual-driven approach, integrating machine learning and FEM with GNSS and Earth Observation for Structural Health Monitoring (GeoSHM), to bridge the gap in the limited application of dual-driven methods primarily applied for small- and medium-sized bridges to large-span bridge structures. The research results show that the BNN model achieved higher R2 values for predicting the Y and Z displacements (0.9073 and 0.7969, respectively) compared to the FEM model (0.6167 and 0.6283). The BNN model exhibited significantly faster computation, taking only 20 s, while the FEM model required 5 h. However, the physical model provided higher interpretability and the ability to predict the dynamic response of the entire structure. These findings help to promote the further integration of these two approaches to obtain an accurate and comprehensive dual-driven approach for predicting the structural dynamic response of large-span bridge structures affected by strong wind loading.

Vehicle load identification based on bridge response using deep convolutional neural network

ABSTRACT Ensuring bridge safety and longevity through precise vehicle load characterization is crucial for maintaining structural integrity and efficiency. This research highlights the efficacy of deep convolutional neural networks (DCNNs) in analyzing bridge responses. The proposed methodology incorporates abridge model developed in ANSYS APDL, integrated subsequently with Universal Mechanism (UM) software for simulating vehicle-bridge interactions, considering factors such as vehicle load, speed, road surface roughness, and ambient noise. To validate the accuracy and robustness of the DCNN models, the study involved training and testing them on diverse datasets, each comprising 250 randomized samples for various parameters such as load, speed, and surface roughness. Two popular deep learning frameworks, ResNet and Inception models, were employed to assess their capability to identify these critical vehicle-bridge interaction characteristics accurately. The results reveal that the Inception model excelled in vehicle load identification, achieving an impressive validation accuracy of 99.9%. In contrast, ResNet outperformed in vehicle speed identification with a99% validation accuracy, surpassing Inception’s 97.9%. Both models exhibited remarkable resilience to noise, with road surface roughness identification demonstrating exceptional performance, including aperfect 100% training accuracy for ResNet and 99.9% for Inception. Furthermore, to validate the noise robustness of the DCNN model, the load identification is conducted under the effects of measurement noise, and the identification results show that the DCNN model can accurately identify vehicle loads with accuracies of 97.9% at 10 dB and 99.7% at 20 dB, respectively. These findings firmly establish the DCNNs’ capability to accurately identify vehicle load, speed, and road surface roughness, emphasizing their potential to significantly improve bridge safety and longevity.

Dynamic Amplification of Railway Bridges under Varying Wagon Pass Frequencies

Train configurations give rise to a primary wagon pass forcing frequency and their multiples. When any one of these frequencies coincides with the natural frequency of vibration of the bridge, a resonant response can occur. This condition can amplify the dynamic response of the bridge, leading to increased levels of displacement, stresses and acceleration. Increased stress levels on critical bridge structural elements increases the rate at which fatigue damage accumulates. Increased bridge acceleration levels can affect passenger comfort, noise levels, and can also compromise train safety. For older bridges the effects of fatigue, and being able to predict the remaining life, has become a primary concern for bridge engineers. Better understanding of the sensitivity of fatigue damage to the characteristics of the passing train will lead to more accurate remaining life predictions and can also help to identify optimal train speeds for a given train–bridge configuration. In this paper, a mathematical model which enables the dynamic response of railway bridges to be assessed for different train configurations is presented. The model is based on the well established closed from solution of the Euler–Bernoulli Beam (EBB) model, for a series of moving loads, using the inverse Laplace–Carson transform. In this work the methodology is adapted to allow different train configurations to be easily implemented into the formulation in a generalised form. A generalised equation, which captures the primary wagon pass frequency for any train configuration, is developed and verified by presenting the results of the bridge response in the frequency domain. The model, and the accuracy of the equation for predicting the primary wagon pass frequency, is verified using independently obtained measured field train–bridge response data. The main emphasis of this work is to enable the practicing engineer, railway operators and bridge asset owners, to easily and efficiently make an initial assessment of dynamic amplification, and the optimal train speeds, for a given bridge and train configuration. This is visually presented in this work using a Campbell diagram, which shows dynamic amplification and compares this with those calculated based on the design code, across a range of train speeds. The diagram is able to identify train speeds at which a resonance response can occur, and the wagon pass frequency, or its multiples, which are causing the increased dynamic amplification. The model is implemented in Matlab and demonstrated by analysing a range of short- to medium-single span simply supported plate girder railway bridges, typically found on the UK railway network, using the standard BS-5400 train configurations. The model does not consider the effects of the train mass and suspension system as this would require a non-closed form numerical solution of the problem which is not practical for the purposes of an initial assessment of the train–bridge interaction problem.

Modal Parameter Identification of a Structure Under Earthquake via a Wavelet-Based Subspace Approach

This paper introduces a novel wavelet-based methodology for identifying the modal parameters of a structure in the aftermath of an earthquake. Our proposed approach seamlessly combines a subspace method with a stationary wavelet packet transform. By relocating the subspace method into the wavelet domain and introducing a weighting function, complemented by a moving window technique, the efficiency of our approach is significantly augmented. This enhancement ensures the precise identification of the time-varying modal parameters of a structure. The capacity of the stationary wavelet packet transform for rich signal decomposition and exceptional time-frequency localization is harnessed in our approach. Different subspaces within the stationary wavelet packet transform encapsulate signals with distinct frequency sub-bands, leveraging the fine filtering property to not only discern modes with pronounced modal interference, but also identify numerous modes from the responses of a limited number of measured degrees of freedom. To validate our methodology, we processed numerically simulated responses of both time-invariant and time-varying six-floor shear buildings, accounting for noise and incomplete measurements. Additionally, our approach was applied to the seismic responses of a cable-stayed bridge and the nonlinear responses of a five-story steel frame during a shaking table test. The identified modal parameters were meticulously compared with published results, underscoring the applicability and reliability of our approach for processing real measured data.

A nonlinear approach for the simulation of the buffeting response of long span bridges under non-synoptic storm winds

In recent years, extreme atmospheric events are becoming increasingly frequent and unpredictable. These phenomena are often characterized by low-frequency variations of the wind speed and angle of attack, mainly due to large-scale turbulence. These features can be critical for long-span bridges as they can lead the deck in conditions where the nonlinear effects of aerodynamic forces are enhanced. Therefore, it is increasingly important to develop reliable numerical tools to simulate the response of these structures to non-synoptic winds. In this work, a nonlinear rheological model that is able to account for the large variations in wind speed and angle of attack is employed to investigate the dynamic response of two different bridges subjected to two different wind fields. The first scenario is a standard synoptic wind field used as a baseline. On the other hand, the second wind scenario represents an extreme non-synoptic atmospheric event. The results highlight how the nonlinear effects of the aerodynamic forces, in particular those related to the large variation of the angle of attack, could lead to significant changes in the bridges’ response. These effects would not be captured by employing standard linearized methods.

A nonlinear numerical scheme to investigate the influence of geometric nonlinearity on post-flutter responses of bridges

A nonlinear numerical scheme to investigate the influence of geometric nonlinearity on post-flutter responses of bridges

Temperature-based measurement interpretation of the MX3D Bridge

The MX3D Bridge is the world’s first structure produced using metal additive manufacturing (AM, i.e. 3D printing), deposited through wire and arc AM (WAAM). The long-term behaviour of structures built using metal AM is unknown and therefore requires the development of techniques that enable this investigation, to facilitate future widespread adoption of these novel manufacturing processes. The MX3D Bridge is instrumented with a comprehensive sensor network (accelerometers, displacement gauges, inclinometers, load cells, strain gauges and thermistors) to enable condition monitoring through the implementation of data-driven anomaly detection techniques. The structure was exposed to environmental and operational variability (EOV) over an 8-week commissioning period, which demonstrated that its response is predominantly temperature driven. Towards the end of the data collection period the decorative end swirls on the bridge were removed, which is taken as a proxy for damage on a structure built using WAAM. EOV is known to mask the damage-sensitive features used in anomaly detection techniques, such as those produced through the end swirl detachment. This paper explores the use of the temperature-based measurement interpretation (TB-MI) approach to: (i) predict the thermal response of the bridge using the iterative regression-based thermal response prediction (IRBTRP) methodology; (ii) remove the influence of EOV from damage sensitive features; and (iii) detect an anomaly event (e.g. the end swirl removal). Accurate predictions are obtained for the thermal response of the MX3D Bridge across 70 sensor measurement signals through the IRBTRP methodology, with 1.2% and 6.4% average prediction errors for the training/validation and unseen testing subperiods, respectively. Moving principal component analysis and cointegration are used with both the measured and thermal response corrected sensor signals for anomaly detection. The detection of the simulated damage is shown to be significantly improved through the removal of EOV, with damage being detected earlier, with greater certainty and across a wider range of sensor clusters (i.e. groups of sensors). The TB-MI approach and IRBTRP methodology can therefore be used to accurately predict the thermal response and detect damage on components and structures produced using metal AM, enabling the advantages of novel AM techniques to be realised within the built environment.

Effects of soil spatial variability on the seismic response of multi-span simply-supported highway bridges

Effects of soil spatial variability on the seismic response of multi-span simply-supported highway bridges

Probabilistic Comparative Analysis of Vehicle–Bridge Interaction Models for Predicting Bridge Response under Moving Vehicles

Probabilistic Comparative Analysis of Vehicle–Bridge Interaction Models for Predicting Bridge Response under Moving Vehicles

Analysis of Vehicle-Bridge Coupling Vibration Characteristics of Curved Girder Bridges

When vehicles move on a bridge, the coupling effect between vehicles and bridges can affect driving safety and comfort, especially for curved bridges, therefore, choosing reasonable design parameters for curved bridges is crucial. In this article, a three-span curved continuous box-girder bridge was taken as the research object; the entire process of vehicle-bridge coupling vibration of highway curved girder bridges was conducted via numerical simulation and the vehicle-bridge coupling vibration analysis program Cmck 1.0 was developed. Then, the influence factors such as curvature radius, constraint mode, and vehicle characteristics on the vehicle-bridge coupling vibration of curved girder bridges were explored. The results showed that as the curvature radius increased, the dynamic response of the bridge offered a gradually decreasing trend and compared to the vertical dynamic response, the torsional response was more sensitive to the influence of the curvature radius. Different constraint methods significantly impacted the dynamic response of bridges, and the vertical and torsional dynamic responses of bridges under general constraint arrangement of straight bridges were increased compared to those under boundary conditions for curved beam bridges. As the axle load of the car decreases, the bridge mid-span vertical and torsional dynamic responses showed a decreasing trend. In contrast, the lateral dynamic response gradually increased.

Damage of a post-tensioned concrete bridge – Unwanted cracks of the girders

The cracking of a post-tensioned T-beam superstructure, which was built using the incremental launching method, is analyzed in the paper. The problem is studied in detail, as specific damage was observed in the form of longitudinal cracks, especially in the mid-height zone of the girder at the interface of two assembly sections. The paper is a case study. A detailed inspection is done and non-destructive testing results of the girders are briefly discussed. The attention is especially focused on advanced and comprehensive numerical simulations of the bridge mechanical behavior. Linear and nonlinear static calculations are performed employing the Finite Element Method at global and local levels of precision, enabling deep insight into the bridge response during all the stages of bridge construction and after it is opened to traffic. The crack propagation process in local analyses is described by the application of the Concrete Damage Plasticity law, the parameters of which were carefully chosen. The predicted damage patterns closely resemble those observed at the site. The results reveal, that the girder damage process was initiated when centric prestressing was applied, because vertical reinforcement of the assembly section front-end surface was not designed. However, the damage did not compromise the safety of the bridge. Finally, the repair methods employed are described and also a discussion is presented on how to prevent the occurrence of such cracking.