Pylon Cable-stayed Bridge Research Articles

Finite-Element Analysis of Temperature Field and Effect on Steel-Concrete Composite Pylon of Cable-Stayed Bridge without Backstays

The backless cable-stayed bridge has the advantages of beautiful shape and reasonable force, but due to the low overall stiffness of the bridge pylon during cantilever construction, it is susceptible to the effect of solar temperature. To reveal the temperature deformation laws and achieve accurate alignment prediction during the installation process of steel–concrete composite pylons in complex environments, a refined numerical simulation model for the 3D bridge temperature field was established based on the proposed automatic sunshine-shadow recognition method. Subsequently, the optimal time periods for construction control are provided. The results of the study show that, during the cantilever construction of the bridge pylon, one pylon column will shade the other pylon column, resulting in asynchronous deformation that can reach 7.6 mm. The effect of solar temperature on the displacement of the bridge pylon is significant, where the maximum daily change in transverse displacement in the cantilevered state of the pylon can reach 33.6 mm, and the maximum change in cable force value can reach 52 kN. In order to mitigate the effect of solar radiation, the best construction time for the bridge pylon is 19:30~9:30, while the tensioning and measurement of the cable should be avoided from 6:00~18:00. This strategy ensures that the control of the pylon top displacement is maintained within 1/4000 of the pylon height, and the error in cable force is kept within 5%.

Vehicle-bridge dynamic response analysis under copula-coupled wind and wave actions

In the service period, coastal bridges are suffered from wind, wave, and environmental actions, which is a high-risk meteorological environment. To investigate the safety and comfort of vehicle-bridge subjected to the combined wind and wave, Copula-coupled theory is employed to discriminate the statistical correlation from wind speed (Uw) to wave height (Hs). According to the measured data, the combined values in different bivariate return period (BRP) are obtained by the optimal joint distribution (e.g., Clayton Copula). Wind forces on vehicle-bridge system involved buffeting and statical are considered. The wave forces of substructure are derived by Morison and MacCamy-Fuchs equation. A presentative double pylon cable-stayed bridge is employed to explore the effect of wind and wave loads. The vehicle-bridge dynamic response increases as the increase of BRP, especially the lateral displacement of mid-span, which is mainly affected by the first-order transverse bending fundamental frequency of the bridge. All dynamic response indexes meet the standard value.

A general data quality evaluation framework for dynamic response monitoring of long-span bridges

The structural health monitoring system (SHM) of long-span bridges inevitably produces low-quality data. It is important to evaluate the data quality and screen out normal data. Most existing studies on data anomaly detection have focused on abnormal data with abnormal waveforms in time domain. Usually there are pseudo-normal data in the SHM system, which seems normal in time domain. However, the pseudo-normal data of bridge dynamic responses may cause wrong dynamic characteristics identification. In this study, the existing data anomaly detection was further expanded to data quality evaluation, and both obvious abnormal and pseudo-normal data are evaluated. A general data quality evaluation framework for dynamic response monitoring of long-span bridge structures was proposed. The time–frequency characteristics of monitoring data were obtained by continuous wavelet transform, and the data quality was classified and evaluated by constructing and training a convolutional neural network (CNN). The proposed framework was verified by using acceleration monitoring data of a cable-stayed bridge. The results reveal that this framework solves the problem that CNN cannot detect pseudo-normal data through time-domain characteristics, and improves the accuracy of data quality evaluation by using time–frequency information of the monitoring data. The acceleration monitoring data of a suspension bridge and a single pylon cable-stayed bridge were used to demonstrate the feasibility of the cross-object application of the proposed framework. The evaluation accuracy for the acceleration data quality of the suspension bridge exceeded 96%. After the reinforced training of a small number of pseudo-normal data samples, the evaluation accuracy for the acceleration data quality of the cables of the cable-stayed bridge reached 96.8%. The framework shows a good generalization capacity and robustness in cross-object applications.

Mechanical Behavior of Steel–Concrete Joint in a Bidirectional Curved Pylon of a Long-Span Cable-Stayed Bridge

The complex mechanical behavior of a steel–concrete joint (SCJ) in a bidirectional curved pylon of a cable-stayed bridge is investigated using finite-element analysis (FEA) and a 1:4 scaled full-section model test. Formulas for the stress distribution and stress nonuniformity coefficients of the concrete in the SCJ are proposed to evaluate the force transmission characteristic of the SCJ. The FEA results indicate that variations in the section stiffness at both the bearing plate and the end of the steel structure result in abrupt stress changes and distinct spatial force characteristics of the SCJ. The experimental results reveal that the SCJ exhibits better force resistance than the concrete and steel transition segments, and the force transfer is dominant through the bearing plate. The proposed formulas are validated by using the measured results, which reveal significant nonuniformity in the stress distribution. The stiffness variation at the bearing plate, nonuniform concrete stress distribution, and spatial force characteristics should be considered during the design of similar SCJs in spatial pylons.

Probabilistic Seismic Evaluation and Experimental Tests of Multi-Direction Damping System on a Super-Long Column-Pylon Cable-Stayed Bridge

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

Seismic fragility analysis of H shape pylon cable-stayed bridge considering soil-pile interaction

Seismic fragility analysis of H shape pylon cable-stayed bridge considering soil-pile interaction

Seismic fragility analysis of H shape pylon cable-stayed bridge considering soil-pile interaction

Seismic fragility analysis of H shape pylon cable-stayed bridge considering soil-pile interaction

A Practical Longitudinal Buckling Analysis Method of Spatial Diamond-Shaped Pylon Cable-Stayed Bridge

The stability performance is a crucial factor when designing cable-stayed bridges. In addition, spatial diamond-shaped pylon is a novel pylon type applied in bridge engineering. Therefore, the stability analysis of spatial diamond-shaped pylon cable-stayed bridge is of great research value. In this paper, a practical longitudinal buckling analysis method is developed based on energy approach. The possible longitudinal buckling of the top pylon column, the mid pylon columns, and the girder are all considered in the proposed method. The total potential energy of spatial diamond-shaped pylon, girder, and cables is calculated. Then, the buckling coefficients and buckling modes are obtained by the principle of stationary potential energy. The Changtai Yangtze River Bridge is taken as an example, and the accuracy of the proposed method is verified by comparing the results with those of the finite element method. Furthermore, a parametric study is conducted to confirm the applicability of the proposed method. Design parameters, including the stiffness distribution of the structure and the inclination angle of the mid pylon column, are varied. Finally, the appropriate degrees of polynomial functions when hypothesizing buckling modes of different components are discussed.

Study on the multi-criteria seismic mitigation optimization of a single pylon cable-stayed bridge across strike-slip fault rupture zones

Bridge structures across active faults suffer the serious threats from large surface deformation and velocity pulses. This study focuses on developing a multi-criteria optimizing method and investigating the damping effect of the optimized damper system on a cable-stayed bridge across a strike-slip fault. A simplified baseline corrected method is adopted to recover the static offsets in near-fault records and the improved record-decomposition incorporation method is modified to produce artificial across-fault ground motions. A single pylon cable-stayed bridge across a strike-slip fault is taken as the case bridge and the refined nonlinear numerical model is established in OpenSees. The conventional multi-criteria decision making (MCDM) theory is improved by introducing new function forms and a control parameter to assess the best fault-crossing angles of the case bridge. The improved MCDM method is integrated with the beetle antennae search algorithm to optimize the damper system of the case bridge. Finally, the influence of fault-crossing angles and earthquake parameters (permanent displacements and ratios of maximum to permanent displacement) on the damping effect of the optimized damper system are investigated. The results indicate that the cable-stayed bridge reaches optimal seismic performance when the fault-crossing angle is around 90° (75°-105°) as both the biaxial nonlinearity of the pylon and the risk of the girder unseating are reduced. The damper system is efficiently optimized by the proposed method, and the displacement and force demand of the case bridge are balanced. Both the fault-crossing angles and earthquake parameters are observed to have considerable influence on the damping effects. More specifically, the damping effect on most seismic responses is optimized when the fault-crossing angle approaches 90° (60°-120°). As the permanent displacement increases, the damping effect on the pier-girder relative displacement is significantly reduced and the damping effect on the pier moments is moderately decreased. Moreover, the damping effect is improved for all the seismic responses as the ratios of maximum to permanent displacements increase, with the exception of transverse displacement.

Seismic Behavioural study of A-Shaped Pylon Cable-stayed Bridge through Seismic Fragility Assessment

The global acceptance of cable-stayed bridges (CSB) has increased due to their aesthetic appearance and suitability for relatively longer spans. CSBs are the most flexible structure. The behavioural study of CSB under natural disasters i.e. earthquake is a new frontier of research. The current research focused on seismic fragility assessment (SFA) of an A-shaped pylon CSB for Indian seismic zone-V using 25 ground motions. Spectral acceleration 𝑠𝑎(𝑔) is the best IM for a CSB. For the four performance criteria, the fragility curves (FC) have been built using incremental dynamic analysis (IDA). Developed seismic FC illustrates the damage probability of CSB as a function of strong ground motions. It can be used to assess the probability of damage for a specific ground motion index. The pylon drift ratio and bearing displacement have been adopted to produce component FCs. The traditional IDA approach is adopted which involves linear regression. The overall system fragility of CSB has been derived using the Riemannian Manifold Hamiltonian Monte Carlo-based subset simulation (RMHMC-SS). The bound limits exemplify the bridge behaviour under different LSs. Analysis results prove that bearings are the most fragile component; their placements and hinge formulations govern the overall bridge performance.

Analysis of tower foundation of long span single tower cable stayed bridge

The pylon is an important stressed structure in the single pylon cable-stayed bridge. The rationality of bearing platform and pile foundation of pylon foundation is one of the key research contents in the design of single pylon cable-stayed bridge. The main bridge of Tarim bridge in Xinjiang is a single tower double span cable-stayed bridge with span arrangement of (41 + 168 + 168 + 41) m and total height of cable tower of 125m. Arc shaped concrete tower columns are adopted. The stress of cable tower foundation is complex. The stress analysis of foundation scheme is one of the key problems of this project. In this paper, the geological conditions, structural stress, economic rationality, construction convenience and other factors are comprehensively considered, the different foundation types are compared and analyzed, the reasonable foundation type and layout type are determined, and the stress of the pile and cap structure of the main tower foundation is calculated and analyzed. Through the solid finite element model, this paper analyzes the influence of the stiffness deformation of pile cap on the stress of pile group foundation. The calculation results show that the stress of dumbbell shaped pile cap is more reasonable than that of rectangular foundation pile cap, and the number of pile foundation and the calculated pile length are reduced in varying degrees. By adjusting the pile foundation arrangement under dumbbell shaped foundation, the stress of pile foundation can be more uniform, which can be used as the foundation for similar projects. The foundation design provides reference and reference.

Study on the length of cable-free zone of wide cantilever cable stayed bridge with low pylon

Low pylon cable-stayed bridge is a new type of composite bridge between girder bridge and traditional cable-stayed bridge. Because of its good mechanical properties, economic benefits and beautiful shape, low pylon cable-stayed bridge is widely used in highway and urban landscape bridges. In this paper, a wide and low pylon cable-stayed bridge under construction is taken as the research background, and the numerical simulation model is established by using the finite element analysis software MIDAS CIVIL. The influence of the length of the cable-free zone is studied. By changing the length of cable-free zone at the tower root and the length of cable-free zone in the middle of span, the influence of the length of non-cable zone on the deformation, bending moment, internal force and cable force of low pylon cable-stayed bridge at the completion stage is studied. The reasonable value range of non-cable zone length is obtained. The research results will provide theoretical guidance for the design and construction of similar projects.

Axis optimisation of arch-shaped pylons for high-speed railway cable-stayed bridges

In order to obtain reasonable arch-shaped pylon axes for high-speed railway cable-stayed bridges, an iterative optimisation method based on force-balance analysis, a fixed point iterative method for nonlinear equations, and finite element analysis was proposed. The developed method was used to optimise the axes of the arch-shaped pylons of two high-speed railway arch-shaped pylon cable-stayed bridges. The results showed that the arch-shaped pylon axis of a cable-stayed bridge with main spans of 2 × 80 m converged after seven iterations. The absolute maximum bending moments under the service load of the optimised arch-shaped pylons were reduced by 53.15–83.53%, and the maximum and minimum stresses under the service load were reduced by 79.81–106.80% and 52.63–66.74%, respectively. Under a double-line ZK-live load, the maximum upward and minimum downward deflections of the optimised arch-shaped pylons were reduced by 21.30–25.0% and 12.4–21.6%, respectively, which resulted in increased stiffness of the bridge. The optimised axes obtained after inputting different initial axes to the proposed method were identical, and the obtained axis was adopted as the final arch-shaped pylon axis design for the actual bridge. For the second arch-shaped pylon cable-stayed bridge, which had main spans of 2 × 90 m, the absolute maximum bending moments of the optimised arch-shaped pylons were reduced by 77.05–92.08%, and the maximum and minimum stresses under the service load decreased by 117.82–173.91% and 39.00–41.38%, respectively. The results obtained illustrate the suitability of the proposed arch-shaped pylon axis optimisation method and demonstrate its reliability.

Optimization of cables size and prestressing force for a single pylon cable-stayed bridge with Jaya algorithm

In recent years, due to the many advantages cable-stayed bridges have often constructed in medium and long span. These advantages can be listed as an aesthetically pleasing appearance, economic and easy construction, etc. The main structural elements of cable-stayed bridges are listed as deck, pylon, cables and foundation. Perhaps one of the most vital and expensive of these structural elements is stay-cables. Stay-cables ensure the allowable displacement and distribution of bending moments along the bridge deck with prestressing force. Therefore the optimum design of the stay-cables and prestressing force are very important in achieving the performance expected from the cable-stayed bridges. This paper aims to obtain the stay-cables size and prestressing force optimization of the cable-stayed bridge. For this purpose, single pylon and fan type cable configuration Manavgat Cable-Stayed Bridge was selected as an example. The three dimensional (3D) finite element model (FEM) of the bridge was created with SAP2000. Analysis of the 3D FEM of the bridge was conducted under the different combined effects of the self-weight of the structural element, prestressing force of stay-cable and live load. Stay-cable stress and deck displacement were taken into account as constraints for the optimization problem. To optimize this existing bridge a metaheuristic algorithm named Jaya was used in the optimization process. 3D FEM of the selected bridge was repeatedly analyzed by using Open Applicable Programming Interface (OAPI) properties of SAP2000. To carry out the optimization process the developed program which integrates the Jaya algorithm and the required codes for calling SAP2000 is coded in MATLAB. At the end of the study, the total weight of the stay-cables was reduced more than 40% according to existing stay cables under loads taken into account.

Взаимное влияние элементов конструкций на их аэродинамические свойства

Effect of structural interaction on drag coefficient is considered. Numerical study is performed using discrete vortex method. There have been obtained dependences of the mutual influence of rectangular cross sections with different aspect ratios depending on the reduced distance between the cross sections, on their aerodynamics. The effect of structural interaction of cable-stayed bridge pylon legs is investigated on the examples of Golden Bridge and Russian Bridge in Vladivostok.

Girder crack of concrete single pylon cable-stayed bridge

Taking the reinforcement and maintenance project of a concrete cable-stayed bridge as the background, aiming at the stress cracks on the web of the box girder of the main bridge after several years of operation, starting from the actual situation of design and construction, the integral calculation model of the bridge is established by Midas Civil and the local analysis and calculation model of the main girder is established by the general finite element software. Four kinds of analysis and calculation models are analyzed. Finally, it is shown that the web cracks of the bridge are caused by the cable tension when the bridge is cantilevered. On this basis, the concrete and feasible bonded steel plate method is proposed to repair and strengthen the cracks, which is of certain reference significance for the reinforcement and maintenance of the same type of bridge cracks in the future.

Seismic Response of Single Pylon Cable-Stayed Bridge under Scour Effect

Seismic Response of Single Pylon Cable-Stayed Bridge under Scour Effect

Seismic performance analysis of concrete-filled steel tubular single pylon cable-stayed bridge with swivel construction

For the cable-stayed bridge with swivel construction, due to the need of swivel construction, there is no consolidation between the bottom of the pier and the foundation during the construction process. Once an earthquake occurs, it is easy to cause the overturning of the bridge or the destruction of the bottom turntable. It can cause major safety incidents. In order to study the seismic safety of the single-pylon cable-stayed bridge in the swivel construction, it uses ANSYS finite element analysis software to establish a finite element analysis model for the construction stage of the single pylon cable-stayed bridge based on a certain project in this paper. Through the calculation and analysis of the single-pylon cable-stayed bridge with swivel construction under earthquake excitation, it is found that the locating pin at the center of the ball-end hinge has excessive shearing force under the 6-degree and 7-degree seismic excitation. It will cause the concrete around the pin to be crushed or even the ball joint to be destroyed. In view of the above problems, it proposes the seismic measures for arranging anchor rods at the edge of the turntable in this study, and calculates and compares the seismic effects of anchoring arrangements with different diameters and different inclination angles. It shows that the solution can significantly reduce the positioning pin shear force and prevent the upper structure from overturning under earthquake from results.

Nonlinear seismic response of a base isolated single pylon cable-stayed bridge

The vulnerability of single pylon cable-stayed bridges under strong ground motions are of great concern to both researchers and engineers. This paper investigates the seismic performance of reinforced concrete (RC) single pylon cable-stayed bridge equipped with friction sliding bearings under bi-directional earthquake excitations. Three-dimensional numerical models, consisting of the dynamic p-y elements, the fiber elements and the multi-layer shell elements, were developed in this study based on the prototype of a single pylon cable-stayed bridge in Guizhou Province, China, to investigate its seismic response. Three different types of friction sliding bearings were implemented between the base of the RC pier and the pile foundation to mitigate the dynamic response of the bridge superstructure under strong ground motions. The results of the nonlinear time history analyses indicate that friction sliding bearings can effectively reduce the base shear and the bending moment of the RC pier, as well as the seismic responses of substructure, at the cost of increasing the absolute displacement of the deck. To reduce the deck displacement, viscous dampers were implemented in parallel to the friction sliding bearings. Parametric studies and optimization analyses were performed on the critical parameters of the viscous dampers with the target of minimizing the absolute displacement of the deck and reducing the base shear of the RC pier to an acceptable level. The numerical results show that implementation of friction sliding bearings together with the viscous dampers is an effective seismic control approach to mitigate the seismic damage of the single pylon cable-stayed bridge.

Simplified seismic resistant design of base isolated single pylon cable-stayed bridge

The seismic vulnerability of single pylon cable-stayed bridges under strong ground motions in the transverse direction is of great concern to earthquake engineering researchers and bridge engineers. Introduction of base isolation to cable-stayed bridges has been proved very effective in reducing seismic forces in the bridges in previous studies. This paper proposes a direct displacement based seismic design (DDBD) procedure for base isolated cable-stayed bridge under transverse seismic excitation. One of the key aspects of the DDBD is the realization of a uniform transverse target displacement of the deck under seismic excitation, which is achieved by appropriate design of the isolator stiffness at the bottom of the pylon and the ends of the deck. The proposed DDBD procedure is applied in this paper to the seismic design of a single pylon cable-stayed bridge isolated by friction pendulum bearings. The effectiveness and the accuracy of the resulting design are checked by nonlinear time history analyses. The numerical results indicate that the proposed DDBD procedure can predict the deck displacement profile and amplitudes, as well as the base shear within a reasonable degree of accuracy. The case study demonstrates that the proposed DDBD procedure is sufficiently accurate and practical for the seismic design of base isolated single pylon cable-stayed bridges.