Response Of Cable-stayed Bridge Research Articles

Channel-attention-based LSTM network for modeling temperature-induced responses of cable-stayed bridges

Temperature has a significant impact on cable-stayed bridges, yielding structural responses comparable to those from vehicular loads, winds, etc. However, advanced numerical techniques for evaluating long-term temperature-induced responses (TIRs) of cable-stayed bridges are complicated and computationally inefficient. Therefore, this study leverages recent advances in deep learning and develops a channel-attention-based bidirectional long short-term memory network (CABLe) to directly get the complex mapping between structural temperatures and TIRs from the monitoring data. The key concept behind is the proposed channel attention mechanism (CAM), where its attention weights are calculated using a cosine similarity between latent sequential features to find the most informative contents of the signal. A comparison study is conducted with the bidirectional long short-term memory (BiLSTM) to show the benefits of the proposed CAM. The proposed method successfully predicts TIRs of a cable-stayed bridge using the imbalanced data. Results indicate that the CABLe outperforms the BiLSTM network and shows a high prediction accuracy with unseen temperature data.

Structural response of cable-stayed bridges exposed to strong earthquakes during construction

Structural response of cable-stayed bridges exposed to strong earthquakes during construction

Effects of pylon configuration on the response of cable-stayed bridge to sudden cable loss

This paper presents a finite-element (FE) investigation into the effects of pylon configuration on the general response of cable-stayed bridges (CSBs) in the event of sudden cable loss. An example CSB is proposed and analysed using a three-dimensional FE model for H-shaped pylon (HSP) and A-shaped pylon (ASP) configurations; the effects of p–δ (large stress) and geometric non-linearities are accounted for. The FE study was conducted for two scenarios of cable loss – the simultaneous sudden loss of the longest two adjacent cables in the mid span or the side span. The results showed that the general responses of the main-span deck structural elements due to breakage of the longest two main-span cables were comparable for both HSP and ASP configurations, but the responses due to breakage of the longest two side-span cables differed. From a practical viewpoint, the loss of side-span cables may cause notable rotation of the main-span deck for a CSB with HSPs, but not for a CSB with ASPs. The results of this study may be useful for designing a situation of accidental cable loss.

Dynamic response of cable-stayed bridge under wind-wave-current action considering pile-soil interaction

Sea-crossing bridges are generally subjected to the combined wind, wave and current action, making it worthwhile investigating the dynamic response of cable-stayed bridges under wind-wave-current action. In this study, the numerical wave flume is utilised to obtain wave-current action, where a measured spectrum is applied to generate random waves. The stochastic wind field is calculated through the spectral representation model. These actions are validated by comparing experimental and theoretical results. A comparative analysis under different loads provides the theoretical basis for load type determination. The influence of pile–soil interaction is also studied with the consolidation, pile–soil solid contact (PSSC), and soil spring model. The results show that the root mean square (RMS) values of girder displacement are greater under regular wave-wind-current action, while the extreme values of the girder internal force present the opposite pattern due to the statistical characteristics of random waves. It indicates that the statistical characteristics of random waves should be considered to secure the girder safety. For the bridge tower, the random wave-wind-current action has a greater effect on the lateral displacement responses. Furthermore, the model considering the pile–soil interaction gets more flexible, absorbing more energy of low-frequency wave-wind-current action.

Seismic response mitigation of girder displacement of cable-stayed bridge using inerter systems

Cable-stayed bridges have been widely utilized as transportation hubs in mountainous and coastal areas. Once these bridges are damaged during earthquakes, the routine for rescue operations will be interrupted, leading to enormous life and financial loss. Since damage of cable-stayed bridges are mainly caused by excessive displacement of main girders, this paper considers mitigating the displacement demands by implementing inerter systems between tower and main girder. Following brief introduction of inerter systems, a simplified three degree-of-freedom (DOF) dynamic model of a cable-stayed bridge prototype is established and verified by refined finite element (FE) model. Then the design parameters of inerter systems are optimized based on the dynamic amplification factor (DMF) method, while the influence of each parameter on the performance is discussed in detail. To further investigate the efficiency of these systems, the seismic responses of cable-stayed bridge with different inerter devices are computed and compared with the prototype, as well as system with conventional viscous dampers (VD). From the analytical results, the inerter systems are demonstrated effective in alleviating displacement demands of main girder of cable-stayed bridges and outperforming the commonly used VD. This study is believed able to provide basis for engineering application of inerter systems on cable-stayed bridges to improve the seismic performance and reliability against earthquakes.

Tracking time-varying structural responses of in-service cable-stayed bridges with model parameter errors and concrete time-dependent effects

To track time-varying structural responses of in-service cable-stayed bridges, a numerical method considering model parameter errors and concrete time-dependent effects is presented. The finite element model updating of a cable-stayed bridge could be formed as a multi-objective optimization problem, where the updating parameters were selected by sensitivity analysis, the objective functions were constructed based on the first cable forces measurement, and the formed multi-objective optimization problem was solved by the genetic algorithm. On the basis of the updated model, the step-by-step finite element method was employed to track the structural responses of a cable-stayed bridge with concrete time-dependent effects. Also, the numerical method was verified by the actual structural responses collected by periodic on-site inspections on a cable-stayed bridge example. The results indicate that the presented method can effectively track the time-varying structural responses of existing cable-stayed bridges. The relative cable force difference between the numerical results and the periodic measurements remains within ± 10%, while the relative difference of the maximum girder deflection is 4.04% after 12 years in service. From 10 to 12 years in service, the maximum girder deflection of a cable-stayed bridge example increased from 0.264 m to 0.285 m.

Multi-angle and nonuniform ground motions on cable-stayed bridges

The definition of the spatial variability of the ground motion (SVGM) is a complex and multi-parametric problem. Its effect on the seismic response of cable-stayed bridges is important, yet not entirely understood to date. This work examines the effect of the SVGM on the seismic response of cable-stayed bridges by means of the time delay of the ground motion at different supports, the loss of coherency of the seismic waves, and the incidence angle of the seismic waves. The focus herein is the effect of the SVGM on cable-stayed bridges with various configurations in terms of their length and of design parameters such as the pylon shape and the pylon–cable system configuration. The aim of this article is to provide general conclusions that are applicable to a wide range of canonical cable-stayed bridges and to contribute to the ongoing effort to interpret and predict the effect of the SVGM in long structures. This work shows that the effect of the SVGM on the seismic response of cable-stayed bridges varies depending on the pylon shape, height, and section dimensions; on the cable-system configuration; and on the response quantity of interest. Furthermore, the earthquake incidence angle defines whether the SVGM is important to the seismic response of the cable-stayed bridges. It is also confirmed that the SVGM excites vibration modes of the bridges that do not contribute to their seismic response when identical support motion is considered.

Seismic Response of a Cable-Stayed Bridge considering Non-uniform Excitation Effect: Model Design and Shake Table Testing

In the absence of intensive tests on the cable-stayed bridges under non-uniform excitation, this study provides a practical and accurate approach to investigate the seismic response of cable-stayed bridges considering spatially varying earthquake inputs. The cable-stayed bridge model with a scale ratio of 1:120 was designed and tested on a newly-developed dual shake table system. Firstly, the modal test was conducted to evaluate the accuracy of the designed specimen. Secondly, both the same input cases and the different inputs cases were executed to study the wave passage effects on bridge specimen's dynamic response. Lastly, the effects of non-uniform excitation and site classification on the experimental bridge's seismic performance were studied with test results of various soil condition cases. The test results showed that the bending of the girder was magnified, while the swing of the tower was subdued when the effect of wave propagation was considered. Moreover, compared with the same input cases, the different inputs cases reported a larger response to the extent of 80%. Regarding the effects of site conditions, it was concluded that the site of soft soil had more influence on the dynamic responses of such bridge structures than that of the firm soil site.

Dynamic response and parameter analysis on the vehicle–bridge coupling of cable-stayed bridge under over-limit transportation

PurposeOver-limit transportation has the characteristics of large axle load, large number of axles and lateral distribution width. Under the action of over-limit load, the coupling vibration effect of vehicle–bridge is more obvious, and the deformation of bridge components is large. Thus, research and analysis of the vehicle–bridge coupling dynamic response of long-span bridges under over-limit transportation has practical engineering significance.Design/methodology/approachBased on the principle of invariable elastic potential energy, this paper derives dynamic model of over-limit transportation n-axis flat vehicle. The numerical simulation method is used to model and calculate a cable-stayed bridge, and the static effect of the cable-stayed bridge and the dynamic response of vehicle–bridge coupling under different parameters are compared and analyzed.FindingsThe focus is on the influence of vehicle load and vehicle velocity parameters on the stress and amplitude of different cables under over-limit transportation, and the corresponding variation law is obtained.Originality/valueThe research on the coupled dynamic response of cable-stayed bridges has attracted the attention of many scholars, but there are relatively few studies on the coupled vibration of out-limit vehicles and bridges. In this paper, based on finite element software, a vehicle–bridge coupling model under bulk transportation is established.

Development of a Cable Damage Detection Deep Learning Method based on Acceleration Response of Cable-Stayed Bridge

The purpose of this thesis was to select a cable-stayed bridge to which external force may cause damage as the subject, to develop a damage detection deep learning method capable of detecting cable damage, and to test and verify the developed damage detection deep learning method. The damage detection method was developed as a system that utilizes the acceleration response of a structure measured for maintenance purposes. To extract information capable of identifying the damage locations from among the measured acceleration responses, a CNN ID was used to develop the damage detection deep learning method. The developed damage detection deep learning method was developed in a way not independently arranging 1 machine learning model per each measuring point and finally predicting the damage location based on the decision-making results collected from each machine learning model. The developed damage detection deep learning method performed the learning per each machine learning model by utilizing the acceleration response of a structure acquired based on the preliminary damage test. Finally, the damage detection deep learning method that completed the learning verified the cable damage location detection performance by utilizing the data acquired based on the cable-stayed bridge damage test. As a result, it was confirmed that the developed damage detection deep learning method predicted the damage location of a cable-stayed bridge at an average accuracy of 89%. In the current research, only the cable-stayed bridge of the Seohaegyo Bridge was studied, but in the improved study, the research will be conducted on other bridges and damage assessment will be conducted on all cables.

Inelastic response of cable-stayed bridges subjected to non-uniform motions

This paper studies for the first time the effect of the spatial variability of ground motions (SVGM) with large intensities on the inelastic seismic response of the pylons which are responsible for the overall structural integrity of cable-stayed bridges. The svgm is defined by the time delay of the earthquake at different supports, the loss of coherency of the seismic waves and the incidence angle of the ground motion. An extensive study is conducted on cable-stayed bridges with ‘H’- and inverted ‘Y’-shaped pylons and with main spans of 200, 400 and 600 m. The svgm is most detrimental to the pylon of the 200-m span bridge owing to the large stiffness of this bridge compared to its longer counterparts. The stiff configuration of the inverted ‘Y’-shaped pylon makes it more susceptible against the multi-support excitation than the flexible ‘H’-shaped pylon, especially in the transverse direction of the response. Finally, the earthquake incidence angle is strongly linked with the svgm and should be included in the seismic design of cable-stayed bridges.

Influence of wind yaw angle and pylon interference on the buffeting responses of cable-stayed bridges during construction

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 to 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.

PARAMETRIC STUDY OF CABLE STAYED BRIDGE USING DIFFERENT PYLON CONFIGUARTION

Cable stayed bridge are the most flexible bridge and getting popularity because of its economy for longer spans. Cable stayed bridges have good stability, optimum use of structural materials, aesthetic, low design and maintenance costs, and efficient structural characteristics. Therefore, this type of bridges are given preference for long span crossings compared to suspension bridges. A study is carried out to find the dynamic effect on different configuration of pylons of a cable stayed bridge. A pylon is inclined at 5o , 10o , 15o , 20o , 25o and 30o with vertical and horizontal axis both and compared with vertical pylon to study the dynamic response of bridge. The 3D bridge models are prepared on CSI BRIDGE software and bridge is analyzed seismically by Imperial Valley 1947, Earthquake. The bridge response in terms of Pylon, Girder and Cable axial force, moment and torsion is obtained. The study reveals that the different angle of the pylon has great influence in the seismic response of cable stayed bridge. We are getting minimum axial force at 10o in cable at main span, girder at main span and pylon.

Assessing time-dependent damage to a cable-stayed bridge through multi-directional ground motions based on material strain measures

Investigations into previous earthquakes indicated that the seismic damage to bridges was closely related to the length of their service lives. Based on this observation, finite-element time-dependent models of a cable-stayed bridge with a single pylon and wide deck were established by considering the effects of concrete carbonization on various structural components. Ground motion records were selected and matched with the design spectrum of site classification Ⅰ. Different combinations methods of ground motions inputs were compared with respect to the strain distributions of critical elements, and the representative method was then determined according to the maximum responses. The strain limits of reinforcing steel and concrete were defined based on previous studies, and were used to identify the time-dependent damage states of critical elements under earthquakes. The incremental dynamic analysis (IDA) method was applied to comparatively investigate the effect of concrete carbonization on the seismic response of cable-stayed bridge. Using the defined strain limits, the effect of concrete carbonization on the time-dependent seismic damage to the cable-stayed bridge was also discussed. The results show that the strength of steel and concrete can decrease as much as 23.30% and 12.66% respectively due to the concrete carbonization. The coupling damage to the bridge is found under multi-directional ground motions. The pylon is the most critical element during three-way seismic waves, in which the base suffers the most serious damage, the deck-level section follows and the cable anchorage portion remains in slight damage state. Taking the concrete carbonization into consideration, the damage level of the pylon base increases significantly, and brittle failure may occur to the pylon base when subjected to earthquakes with high peak ground accelerations (PGAs). However, the damage levels of other critical portions of the pylon decrease when the concrete carbonization is considered.

Stochastic Response of a Coastal Cable-Stayed Bridge Subjected to Multi-Dimensional and Multi-Supported Earthquake and Waves

In this paper, a stochastic dynamic analysis method for cable-stayed bridges subjected to multi-dimensional and multi-supported earthquake and waves is established based on the pseudo-excitation method. The Monte Carlo method is used to analyze the influence of excitation nonlinearity on the bridge structure response, and the applicability of this method is verified. Stochastic response characteristic of coastal cable-stayed bridges subjected to multi-dimensional and multi-supported earthquake and waves is studied. The influence of water–structure interaction on the stochastic seismic response of main components of the cable-stayed bridge is described, and the influence of key parameters is analyzed. The results show that the influence of excitation nonlinearity on the response of the cable-stayed bridge can be neglected. A greater energy input caused by the rigid additional mass of the hydrodynamic pressure is the reason for the increasing of the seismic response. The influence of stochastic response of the underwater structure of the tower is changed with the site conditions. For the ground motion acceleration input energy being distributed in the high-frequency domain, the water–structure interaction has a greater effect on stochastic seismic response of the underwater structure of the tower. The influence of water–structure interaction on the stochastic seismic response of the underwater structure of the cable-stayed bridge increases with the increasing of the wave height and water depth.

Influence of near-fault ground motion characteristics on the seismic response of cable-stayed bridges

Observations from several earthquakes indicate that near-fault (NF) ground motions have a significant influence on the seismic response of structures. However, existing studies have only discussed the influence of a certain NF characteristic on the seismic response, rather than systematically discussing and comparing the influence of different NF characteristics. Furthermore, current research is only suitable for a specific structure while the influence of NF characteristics on structures with different dynamic characteristics has not been revealed. As an important lifeline project, the safety of a cable-stayed bridge (CSB) during earthquakes is of great concern. Therefore, this paper investigates the influence of NF ground motions on the seismic response of CSB. Firstly, three major characteristics (i.e., the hanging wall effect, rupture directivity effect and high velocity pulse) of NF ground motions are analyzed using NF records of the Chi–Chi earthquake. Secondly, a finite element (FEM) model for modeling a prototype CSB is developed and benchmarked. Then, the seismic responses of the prototype CSB subjected to NF ground motions with different characteristics are analyzed using the benchmarked FEM model. The analyses show that hanging wall effect, rupture directivity effect, and high velocity pulse affect the seismic demand of the CSB to varying degrees. Furthermore, the influences of NF characteristics on the displacement response of CSBs with different fundamental periods are investigated using SDOF systems. The analysis results show that different NF characteristics have various influences on the displacement response of CSBs with different fundamental periods.

Buffeting Response of Cable-Stayed Bridge during Construction under Skew Winds and Pylon Interference

Buffeting is a kind of wind-induced vibration phenomenon of long-span cable-stayed bridges which is easy to occur. Balanced cantilever method is widely employed for the construction of cable-stayed bridge. The maximum double-cantilever state is the most dangerous state of wind resistance. Through the aeroelastic model wind tunnel experiment, the buffeting response of a cable-stayed bridge in construction under skew winds is studied in this paper. The variation law of buffeting response with the wind yaw angle is compared between the two cases with and without pylon. The experimental results show that for the same wind yaw angle the lateral and vertical buffeting responses of the main girder increase with the wind speed approximately in a quadratic curve, while the torsional buffeting response tends to increase linearly. At the same wind speed, the buffeting response of the main girder presents non-monotonic changes with increased wind yaw angle. Under skew winds, due to the disturbing effect of the pylon and the influence of the three-dimensional flow field, the buffeting response of the main girder will be affected by the aerodynamic interference of pylon. When the wind yaw angle is small, the interference effect is not obvious, with the increase of wind yaw angle and wind speed, the interference effect begins to appear. Generally speaking, the aerodynamic interference of the bridge pylon on the buffeting responses can be ignored.

Effects of near-field ground motions and soil-structure interaction on dynamic response of a cable-stayed bridge

Seismic response of cable-stayed bridges is investigated with the main focus pertaining to the effects of near-field ground motions and soil-structure interaction on the dynamic response of the bridges. A 1/60 scale model of a typical cable-stayed bridge was designed and fabricated for the laboratory investigations. Three different types of ground motion records from the 1999 Chi-Chi earthquake, namely far-field, non-pulse near-field, and pulse-type near-field were employed in the experiments and the numerical analysis of the bridge. Laboratory simulation of the soil-structure interaction was accomplished by a box-spring system with interchangeable springs as foundations for the bridge towers. A three-dimensional numerical model of the bridge was developed, and its response was verified by the experimental results. Results from the numerical and experimental investigations indicated that the effects of foundation soil stiffness on the response of the bridge was influenced by the type of input ground motions. The bridge response was amplified when their foundation was in softer soils.

Dynamic response of cable-stayed bridges due to sudden failure of stays: the 3D problem

This paper studies analytically the problem of the sudden failure of a number of stays through a suitable mathematical model, based on the analytical method exposed by authors in previous publications and extended in this study through a 3D analysis. The analysis is carried out by the modal superposition method, and the gathered equations of the problem are solved through the Galerkin procedure and the Duhamel’s Integrals. Characteristic examples are solved and useful diagrams and plots are drawn, while interesting results are obtained.

Vibration response of railway cable-stayed bridges under high-speed train braking loads

With the increase of the running speed of high-speed trains, the longitudinal vibration of the long span railway cable-stayed bridge under train loads has increased significantly. And the probability of high-speed train braking is greater than earthquake. The excessive vibration response will affect the serviceable of the cable-stayed bridge. Fluid viscous dampers (FVDs) and elastic cables (ECs) which are widely used in seismic design of the bridge are adopted to control the longitudinal vibration response of the cable-stayed bridge induced by train braking loads. The influence of the design parameters of FVDs and ECs on the response of the bridge is studied. And the effectiveness of FVDs and ECs on mitigating the longitudinal response of the bridge is also discussed. It is found that installing FVDs and ECs between the deck and the tower is very efficient in reducing the longitudinal vibration of the railway cable-stayed bridge subjected to train braking loads, especially the longitudinal displacement of the deck and the bending moment of the tower.